Rfh costs ver. convienence/practicality
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We will be building a 1800sq’ two story home on raised foundation On the West coast of Washington. I have mixed feelings on RFH and would like some feedback on options of heating. We do want air conditioner but not necessarily a combo system. I would prefer a system in which I can heat individual rooms separately which I understand this means having individual lines and thermostats for each home run. And of course, this means more money again. What is the time in which it takes to to heat a room with a rise of , say 10-15 degrees?. How does the cost of using a separate heat system from a combo unit (heat/ac)? I do realize that the bigger the system the quicker the heat transfer. But too big/small of a system would be like having too big/small of a ac, right?. I known there is a lot of variables that go into the formula. Location of trades people and how common RFH is in your area does effect overall cost. But it is hard to get “unbiased” opinion when a local sub only wants to do one type of heating system. Another thing, we only have electric or propane for this system. I don’t necessarily want to incorporated the hot water system in the heating system, unless there is a safe, and cost effective way of doing it. I can get going on and on with my questions, but this is probably a good start. Oh yeah, any of you guys in the WA. State area?
thanks for all input in advance….Brian
Replies
As I am exploring the same adventure right now all information has pointed to RFH being the most comfortable and cost efficient to operate. It is also way more expensive to install. For me the benifit come mostly from the fact that I can do most of the work myself saving on labour. Material cost vs a forced air sytem if you want all the zoning etc I would guess at 6 to 8000 for forced and 12 to 18000 for RFH if you go with A/C as well. In some cases you may not get all your duct work to fit quite the way you would like. RFH eliminates floor registers and makes zoning alot easier. Your room temperature rise is dependant on the installation method of the RFH: Warmboard or thermalboard claim faster response, gypsum bases and other cement type bases may take longer but will hold the heat longer and take more work to install depending on the floor coverings. There is a whole lot of information and options to consider with both type of systems. Since you have Electric and propane for a power choice this may also change you options and lead to more or less operating costs, difficult to say. Electricity here is twice the price of heating with natural gas and propane is high as well. The best thing for you to do is start reading as much as you can and make a comparison. If you do not have knowledgable suppliers/installers you may end up with alot of problems.
you have alot of homework to do
Cheers,
Brent
You might investigate geothermal as you appear to be in a possible heat pump area. This would answer your needs in both heat and cool. I am a 13 winter happy user of RFH in slab. Warm feet on the tile is nice. A masonry heater for backup and fall/spring on demand heat. Best of luck in your hunt.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Interesting that you have both RFH and a Masonry Heater. We are building a log house which has both, but in opposite order of importance. Our masonry heater is the primary source, and the RFH for areas of the house inaccessible to the radiant heat of the heater.
Did you build the masonry heater yourself? How has it been for you as far as the work of building the fire, and its efficiency?
You are the only person I have found who has one of those things, so I hope you can help me.
Thanks
Stef
Stef,
My mason buddy (old college roommate) contacted me about the benefits and beauty of masonry heaters as we were planning our house. Being a longtime user of wood stoves as a primary and back up heat source I was intrigued by the idea of burning small amounts of wood and reaping long even heat. The use of the floor heat was already decided on, but as a secondary or primary, if we wished, heat source we decided to add it to the plan. He was in contact w/Tulikivi about being one of their installers/distributors and sent me the info on the soapstone heater. We chose the model, he set it up dry at a home show in NC, took it down and brought it up to Ohio. We assisted, he laid it up. I got a great deal and got to visit with a good friend.
We have been completely satisfied with it's use and functionality. Minimal wood used, long lasting even heat. With the passive solar design of our home it would be possible to heat the 2500 sf with one or two firings a day. The wood used for a firing amounts to maybe 15lbs., part of a log bag (When going with 2 firings a day, full log bag when firing once). Small, big as your forearm, wood is the ideal. Quick, hot combustion lasting maybe an hour to hour/half for the coals to die out. No creosote in the masonry chimney, in use now for 13 winters. Every summer I take of the cap and peer down the chimney. Nada. If I had more firewood available (haven't bought any yet) and wished, the floor heat would probably only be needed in the main area during the coldest non sunny days. We elect to use it as the only heat source in the fall and early spring, and to supplement the floor the rest of the heating season. The wood I pick up as I see it, and glean the lot we live on.
Sorry for taking so much of your time with the bs, but here's how I build and start the fire. I included a shot of the heater so you can get an idea of the firebox. Originally I built the fire like you do in a campfire, sort of teepee style, adding to it as it burnt down. Now, I start with the largest pcs going on the bottom and alternating the stack with smaller as I go up. At the top of the pile, kindling of scrap from my jobs, then a couple of sections of newspaper twisted up. Light the paper at the top, this warms the chimney and starts the kindling. When this burns down and out, she's done. Top down fire was introduced to me by the mason. He has studied his trade abroad and with the local guilds in North America. He is the man as far as those I know building masonry heat.
Any other information, feel free to ask either here or by email.
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Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Calvin,
You probably don't remember but you helped me with a similar masonry heater question over a year ago. Thanks again for your helpful input!!
I thought you might like an update on my project. I decided to build with a Heat-Kit masonry heater as the Tulikivi was out of my price range. I found a local mason who had just started to get into this scene and was willing to work with me on my project. Long story short...it's built but the house is not completely finished. So we have not really "lived" with it yet.
Its still amazing to me to feel the heat this thing puts out 7-8 hours after the fire is out. We also have a bake oven as part of the heater and I can't wait for that first pizza or fresh bread. I've attached a picture for you to see.
Now the funny part...I'm very, very close to heating my house with Radiant floors as well, but have not made the commitment yet. But I will have to real soon. Any more thoughts??
Regards,
Tim
Tim, I've got a memory like the pages of a daily diary. The trouble is I can't remember what page its on. But if I was a help rather than a hindrance, then I am glad.
I'll try to be whatever help I can but I need it narrowed down a bit. Where do you live again? What works here in NW Ohio oft times isn't the set up in other parts of the country. As you probably read above, I'm happy with both.
Now, let me clue you in on an addition to our comfort that I made last summer. The weather had been constantly hot. Up till then our cooling came in the shape of a whole house fan, bringing the temp inside down to what ever it was outside. Most times, comfortable, but still relatively backward in what I hoped was a well thought out house. A drawback of no ductwork nor the bucks for a High Velocity AC. Well, to keep the wife happy, I thought I'd try a window unit in the bedroom hoping with the open house plan that all would not filter down into the lower level while keeping the sleeping comfortable. I don't know if it's because of the r-value of the envelop of the house or it's summer shading or what, but I kick myself in the #### for not trying it sooner. Comfort, low initial outlay and reasonable cost of operation. Nice thing this technology.
I've got one for you. What causes a large sized pic like you posted to appear almost a painting rather than a photograph. Least that's the way I view it.
Lemme know.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Calvin -
I've been interested in constructing a Russian heater when the opportunity presents itself.
Maybe I've been skimming the remarks but nobody seems to mention combustion air source for the stoves shown or discussed.
Are any of these drawing air from the outside ?
Alan
Alan, mine does not have a dedicated air inlet. Think I remember giving it some thought but must have had a dumb attack. And to think I could have used it as a floor drain in the event of a flood from up the hill. Oh well.
Some discussion on outside combustion air here in relation to wood stoves primarily. However, for whatever combustion source I'm thinking it's probably a good idea. With the masonry heater, you want to burn that hot quick fire, so worrying about introducing cold air into the room just in front of the air inlets doesn't seem founded. Course you could probably pipe it somehow right to the fire box. I remember reading something about a concern for fire safety, but in my slab and exiting out the foundation perhaps is unfounded as well. In a wood frame floor system you would certainly want to address the rating of the inlet pipe. Another concern would be on backdrafting other combustion appliances. I have noticed no problem in that area, and even the tightest house in theory has means of fresh air entry in practice. If I were doing this again, I'm pretty sure I would consider outside combustion air for something as powerful as a full burning masonry heater. Best of luck.
Others with way more experience than I are sure to enter the discussion.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Calvin,
I live in central NJ. Winter design temp is 10 deg. F. My construction project was an addition to my existing home. The new construction is roughly 1700 sq.ft , 2 stories using SIPS (structural insulated panels). The heater is on the first floor between 2-3 rooms (family room, dinning room and kitchen) and when fired, should take care of these rooms.
Question: Is it silly to spend money on an expensive RFH system for these areas, when the heater will do the job just fine. I consider the masonry heater as a "backup" more than a primary source of heat. Right now budget is tight, but I could still squeeze it in if I did some of the work myself.
This winter has already been a bear. I'm not sure how much I'll really use the masonry heater when I finally get moved in. I'd like to think that it will be fired a least once a day, but i can't be certain.
I'm starting to realize the amount of wood needed for the winter and I'm not sure if I can get my hands on enough of it during the year without buying it. That's another story... Mfg of the heater says once a day firings can be made with 50lbs of dry wood. In my world that's about 10-11 pieces of split wood roughly 16"-20" long. I've fully loaded the heater a few times and its amazing to feel the heat!
Any thoughts are welcome!
Take care,
Tim
Yow, I need to lay out a disclaimer here Tim. Beats the #### outta me. For one thing I'm a bit confused with your set up, the other thing is I'm no heating design professional. Merely a dumb carpenter who happened to do as I said above. You hopefully can get more info from someone with more expertise. This is an addition? Not really open to the up stairs? How open will the downstairs be in relationship to the addition? and what heats the rest of the house?
In my situation, the Floor heat is in slab, covered throughout with tile. I perceive this to be the best world of getting the heat to the body and surrounding room. The concrete being the mass, the tile not limiting the transfer any. And as a bonus, you don't have to worry about Italians drinking red wine and talking with their hands like you do with lite carpet.
Further, about 1200 s.f. down with an open LR to the upstairs, some ingenius air movement locations back down from up (another 1200s.f. up). The only other heat up is RFH under ply with tile in the two baths (zoned) and a 5' pc. of HW baseboard under the windows in each of the two additional bedrooms(zoned). The master BR has a large opening overlooking the LR which allows the heat up and in. We heat the Domestic HW off the boiler also. The open design of the house seems to have worked well using either the Masonry Heater or the RFH. A couple of ceiling fans and the air path moving the warm air enough for comfort. Admittedly the MBR is cooler than the rest of the house, but we sleep there, don't use it as a sitting room and I like a cooler (65?) room and a quilt. I added the basebds to the two other BR's so guests and a growing daughter could close the door over nite, until then they remained about the same temp.
I think my heater was rated at capable of heating 1800 sf, tho in the early and late winter there's no problem just using it and the bathroom zones. On the coldest days of winter it might be a stretch, but w/2 firings could no doubt do it. I find it odd you would need 50lbs of wood for a firing but if only firing once a day, that uses more wood and maybe your mass needs that. Two firings, you don't need to bring it that far up to temp but wood use probably is the same/perhaps a bit more or less(?). Also, maybe soapstone (you don't mention what it's made out of) is just a bit more responsive or better retainer of heat. In 13 years, I have bought no wood. Initially I burned (more often) what I had cleared for the house. Since, I have gleaned from the woods on the lot, picked up a pile on the side of the road, and brought up from the bottom of the hill (truck) when they ran a sewer line and cleared the road. Man, too easy! Well, the gleanings have dwindled and I'm not getting as lucky picking up roadside wood , so probably going to have to buy for next winter.
When we did this, the RFH was the primary and we struggled about the idea of adding the masonry heater as backup for the same reasons you give.$. We went ahead and are happy we did. I surely would not advise you either way. Describe your situation a little more fully and maybe we can get some other users opinions and maybe a professional one too. If you already have a boiler, that might make a difference. Too bad McGough isn't around here anymore. He'd give you an answer.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Damn, Calvin, You da man!!
What great responses.
When I bgan the design of our house, a few years ago, I thought I was sooo innovative. Passive solar, RFH, Masonry heater. Now I see I was just part of an evolution of thought. Still, nice to be vindicated.
I too admire the Tulikivi units. But, when I began construction, I didn't know about them, and designed the spot for the heater with a giant slab, and as an architectural feature. So, I am building it from scratch. There is a guy on the net who sells plans and instructions for building bake ovens. My neighbor built one, and the design is so elegant I have adapted it to Russinan stoves. The fire box is built with an arched top, fire brick of course, and then the classic series of labarynthine channels. Because of costs, I can't use any of the prefabbed firebrick-like slabs, but this method has stood the test of time, so I think I'll be ok.
I particularly appreciate the description of your method of firing. It makes sence, but is counterintuitive, and I don't think I would have come across it on my own.
Interestng that you are in Ohio. I was born and raised there, now in Colorado.
Well, we are now anxiously awaiting Spring so we can get back to work.
BTW, aren't those european tiles shown above, gorgeous? How are they gotten, anyone?
thanks again, Calvin
Stef
My mason buddy describes the tile thus-"Finally putting those souveniers from the Czech Republic to use". He has traveled extensively studying his craft. If ever a question about it, I would ask him.
Alot of people left Ohio, I can't figure out why, but many ended up in Colorado. Where were you here? Good for you on your project. Hope all goes well and you enjoy living in it.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
My grandparents were from around Tiffen and Piqua, and I was born in Dayton, grew up on a farm outside of Cincinnati, and went to school at Kenyon College in Gambier, near Mt. Vernon.
I haven't figured out where "Glass City" is.
I neglected to mention that our new house is 100% solar, as we have PV panels and passive solar. The electric company wants $10,000.00 per pole, and we are 2 1/2 miles from the nearest one. We are also trying to figure out satellite phones. If anyone knows about those please share.
I used to live near the Czech border (1977). Wish I had bought some of those tiles then.
Stef
Tiffin? another glass city. Toledo is the one I'm outside of. Boy stef, you're roughing it. Pioneering is no easy thing. Gotta hand it to you trying to keep the creature comforts up there. Keep us informed on the house. And gambier? nice town. Was it a dry county when you were there?
__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
As soon as I figure it out, I'm going to post some pics of the log work. I think people might get a kick out of it.
Yes, the county was dry( in the early 60's) but the campus, hardly.
Stef
Here's some shots he sent me of stoves he's working on now. Over the years he's done them with brick, stone, soapstone and tile. Very beautiful and utilitarian when you add bake ovens, cook tops and benches.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
I was this close (fingers held 1/4" apart) to choosing Tulikivi over the free-form masonry one we built. Still wonder "what if". I think what made me choose as I did is that in their catalog I saw the one that was the perfect size and shape, and I got my heart set on it.......and then I learned it was $25K. Couldn't make myself want any of the $7K models after I saw that one, and didn't wanna pay the price of my favorite. Mmmmm, it woulda looked nice...
Cloud, We wanted the one that was sort of "deco", reminded me of an old juke box, nice rounded lines...........this one did the trick according to square footage, was affordable with the dealer disco and wanna get familiar install deal..........glad we did it. But now, Tom has shown me what you can do with the right knowledge and a little imagination. Just think of some of those in the castles of Europe? Mama mia!__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
I liked the deco, but really salivated over the football-shaped one--curves and all that. It woulda been a bad fit for that room though--completely overwhelming the btu needs of the master bedroom. Still, woulda looked damn cool, even if we never fired it.
So how bout a shot of the one you built? and the firing method so stef gets a little more of the story. You have a mas. chimney? You been in there long enough to see the clean burn?__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
No, no, no, I just have a regular fp built of brick and block. No special technology in it. Actually didn't care if it was inefficient, be/c I use it for ambiance rather than heat. The rest of the house is focused on efficiency. Gotta have the fp cleaned this summer.
I am planning to build a house in a few years (remodeling current one), and will use rfh. I will also run ductwork for a/c. I have wondered from someone who's lived in an rfh house for a while about the comfort of the system - if you lose anythign w/o the forced air heat. I understand objects in the room would heat up and your body would feel warm, but the air around you is cold.
Can you elaborate?
thank you,
remodeler
My floor is tile. Your feet are warm. A ceiling fan moves the air gently around. The room is warm. Maybe the couch and chairs are warm, beats me. The idea that you "sort of" get the comfort by just standing there on a warm floor is a bit too surrealistic to me. The only difference I see between RFH and forced air is that the warmth is constant, not just when the furnace comes on. There is no blowing of heated air. No cold spots in the room, no noise. Downside, the window glass bottoms may have beads of moisture because of the lack of blowing air vents that usually wash the glass. Include the ceiling fans and you should be ok. Zoning the heat is perhaps the most important thought to comfort.
No experience with RFH covered with anything else. I was thinking at the time that it would limit the transfer. Others here have put it under carpet, hardwood and vinyl and I would defer to them how that works.
best of luck.
Oh yeah, I live with two women who like it hot. We don't set the thermostat to 62 and expect warm feet to keep us warm. I have the thermostats (cheep round honeywells) away from the passive solar beams and in an open walkway to the back of the room (big open space). They are set at 70 and 72 (diff zones in the same big room) and the girls are happy as a clam. Me, I could be happy at 68. The room temp at 5 ft is what you set it at. And don't forget, if the sun is figured in your plans, and outside sensor (don't have ) is a good idea to tell that heat what's going on before the house cools down or warms up. And the late fall/early spring are an unusual time for RFH. You don't get the quick response, nor does it cool down fast (concrete). It's not your grandfathers heat source. All this only from my experience
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Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
These words of calvin cover it for me, too:
"The only difference I see between RFH and forced air is that the warmth is constant, not just when the furnace comes on. There is no blowing of heated air. No cold spots in the room, no noise."
Now it does feel great to be barefoot all winter, but it's not like that makes your feet warm and your head cold. It's all just more constant, which makes it more comfortable. Contrast that with my last house with radiators or the apt with forced air, when my feet were always cold in winter, because the floor surface was colder than the surrounding air. Our body's surface temp is 91ish, and RFH gets the floor surface temp closer to that, which results in comfort.
You don't get the sense of having a heated couch or heated objects. Everything just seems equal. If you do have an object (my daughter's gym mat, for example) directly on the floor, it will absorb (is that the best word?) heat and you can feel it clearly if you touch it underneath. But other furniture will just feel normal.
How bout this as an add to yours. If you have a tub deck, and it's tiled, and you don't wear pants (or your wife in particular) when you take a bath...........run some hose up under that deck so that baby is toasty. Your wife will love it when she places that bare fanny on the tile.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
When you mean geothermal, are you talking about heat from natural hotwateretc, or from installinf fluid line in the soil about 6"down and using that as a source for heating cooling? please explain. have been in the construction industry for 20 years but alternative heating/cooling resources are pretty much non existant in the southern California area. Everone (most) around here uses heatpumps or the traditional furnace/ac split systems. This makes getting info pretty hard. Most people don't even know what an air tight stove is. -Brian
That would be a ground-source heat pump. Vertical well, or horizontal trench, though deeper than 6"--more like 4' or more. They are good for generating both hot and cold water.
Cloud Hidden, I ment 6 foot, but my fingers always hit the weong keys. Guess thats why I don't play piano... Saw on this old house the system that you are talking about and it seen the were about 6' deep. probably because of the freeze/thaw line and I would assume that they were somewhere in the New England States. Any idea on the cost of systems like this? I know it varies, but, just like the client always asks when you go to their home.. "can you give us a ballpark?" meaning, "we will hold you to that price" Where we are buiding, it is just sand. No clay, no rock, no topsoil, just plain old beach sand. Do you think that 4' might be the max, or can I go shallower? All input is appreciated. Never such a thing as too much info, unless you you have a migraine ;)
The guy who specs this for my designs tells me that horizontal systems are in the neighborhood of $3500/ton. That's the pump, pipe, fittings, trenching, installation. Not ducting, rfh or whatever other distribution method you choose. Vertical is more because the well drilling is more. I won't speculate on depth for different soil conditions and locations. I knew once, but today it's all mushy in my head.
http://www.ghpc.org/about/how.htm
This might give you an idea of what ground source heat pump is. What I call Geothermal.
As to RFH and a moderate climate, I don't know. I find in the fall and spring I use the masonry heater as primary, with the boiler used for only the bath floors (under plywood) and a couple pcs of basebd in the back bedrooms. This because the concrete mass does take a few hours to get up to temp, or if the sun warms the house in the day and the floor was on at nite..........open a window. My system is pretty tech dumb, relies on you watching the weather and knowing the climate change.
With RFH under wood floor application, I guess because the heat up time is shorter you might be able to time it such as you mention-call for heat from thermostat, timed set back of thermostat. I think in a moderate climate I would study up on the geothermal as that's a heat pump's climate area.__________________________________________
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
There's a big diff between hi-mass and lo-mass systems in responsiveness. You have to consider the entire building system. For example, I have a house with a WHOLE LOT of thermal mass, and built on good passive solar concepts. We're in a moderate climate (except for this January, it seems)--NC. Taking all of that together, the RFH in a hi-mass floor works great for me. Sun warms the living areas during the day, so the heat pump (I have GSHP, too) doesn't run at all if it's sunny and 35 or over outside. When sun goes down, eventually GSHP kicks on to supplant the heat from solar gain that is now transferring from the mass to the house. In spring and fall, that solar gain is usually sufficient to keep the GSHP off entirely. Because of the high insulation factor we have and the high mass, the occasional really cold day in spring or fall isn't noticed by us or the system, because the house is really slow to respond to the climate.
If I had a house with say fiberglass in 2x4 walls, I'd likely go with a lo-mass setup. That house will feel the effects of outside temp changes much more immediately, and so you'd want a system that was more immediately responsive. Warmboard or staple-up under floor qualify. Would be easy to have system off during the day, and heat it at night. Of course, such a system would have little memory and would cool just as quickly as it heats. Would also get little benefit from the sun.
There's a host of in-between solutions, too. Gypcrete and light-weight concrete are a compromise between the hi- and lo-mass. They offer some benefits over lo-mass in terms of noise control, and some benefits over hi-mass in terms of lower structural requirements. Some disadvantages, too.
Also, you can mix and match. The main floor could have good solar orientation and be hi-mass, while the bedrooms could be low-mass so that you only heat them the hours you'll be using them.
There are a few more dimensions to the decision than just is RFH good for where I live. Personally, I'd want it ANYWHERE, be/c I'm totally sold on warm floors. But the system design would vary based on a bunch of other factors.
"... all information has pointed to RFH being the most comfortable and cost efficient to operate. "
I'll agree with the comfort part of this, but you will not find any data to support the cost-to-operate part. RFH is a wonderful way to heat, but heat loss is heat loss and the efficiency of the boiler dictates the efficiency of the system. Very few boilers can match the efficiency of a condensing furnace.
Most manufacturers and system designed say that you can expect to see a reduction in fuel usage of 20 to 40% depending on your system. Most of this is based (i would think) due to the fact that you require less heat energy to feel warm in the radiant system and thus the thermostat can be turned down. Boiler efficiency is in the 82 to 89% percent range and other options also reduce costs. Adding an indirect fired water heater for example allows for the boiler to also heat domestic hot water elliminating another combustion process, allowing for a beter insulated storage tank, no second power vent or flue to install etc It is really difficult to compare the different heating systems as there are benifits and pitfalls to all of them. Cost, installation, practicallity, energy savings, availability, budget and the list goes on.Cheers,
Brent
Brent,
I understand that the manufacturer's claim of that kind of savings, but as far as I have been able to determine, not realized in actual installations. I looked into this in great detail years ago as a means to save on my energy costs. The facts is, in my case for instance, having the thermostat set at 60 vs 67, when it is -10 outside, the difference in heat loss from the house about 9%. If my boiler were 85% efficient and my furnace were 94% efficient (which it is), then its a wash. I don't know what people with RFH set their thermostats at to be comfortable.
If a boiler that is sized to heat the whole house is used year-round for domestic hot water, the actual efficiency of the process is nowhere near full load maximum efficiency. I don't know what other option you refer to that "also reduce costs".
I agree that radiant floor heating is the ultimate in comfort, and regardless of the cost, wish I had it. But, reduced energy costs based on manufacturer's claims is not accurate. I have yet to see an actual comparison of heating costs that show any measurable savings. I would like to find something on this, as people ask me about it frequently. Costs for RFH run about $4.50/sf (I'm sure that is disputable) for heat only, where forced-air with AC runs about $3.50/sf.
I "sell" it to design clients on comfort and cleanliness, not on install or operating cost--for the reasons you mention.
Cloud,
Any feedback from happy customers on their heating costs? As mentioned by myself and others, the claims on lower energy use are very prevalent, but I not heard of or seen any "field" data on actual vs estimated energy use.
I am a proponent of RFH, and when I have a client willing to pay for the "ultimate" in comfort, I design hybrid systems for them. But so far as I am aware, cannot tell them it will save them energy. I would like to, but cannot based on manufacturer's claims.
Tim
It's all under construction. One was just turned on, and the HVAC contractor is happy about the performance, but how to compare to a base case when our buildings are a complete system and RFH is just one part? "Estimated use" is a big guessing game when you have fluctuating weather, different heat sources, only rough guesses of heat load be/c of the dome factor, all custom designs so comps are impractical.............all reasons why I make no promise on cost.
The only proper test I could think of was side by side houses with identical families with identical lifestyles. Even then, how do you set the tstats for identical comfort when one is air and the other rfh? fwiw, I don't think we set the tstats lower with our rfh--I just think we're more comfy than with forced air at that same temp.
I was wondering on how efficient a radiant floor system is when you live in an area like Washington State and you are a mile from the ocean? Does this system need to be running all/most of the time, or does the 8-10 hrs a day run time make this type of heating system not practical? Here on the west cost where I live now, (right now is So Cal and we are moving to the Washington Coast in 6 mos) we turn off the heat when we leave, and turn it back on when we come home. We then turn it down when we go to bed and then have the heat(forced air) tio come on about an hour before we get up. Even the electric/gas companies say this is the most cost efficient way to run a system.. Is this the same way in a RFH system? Would it take too long to get the system back up and running in a timely manner? Or, do you just have to wait and freeze until the system heats up? How long does it take the system to get up to desired heat , say 20 drgrees?. I know that every system will be different, but lets just take a average system (affordable) that is designed for correct size home. Does RFH like to stay on all the time? And, is it efficient to run it this way?.
I plan to used a sealed system, so the radiant floor heat will have it's own furnace. does this need to be running all the time to keep the fluids ready to go, or can the "typical" furnace heat up quick enough to avoid having it run all the time, which I would assume would cost more to run.
Enough rambling. Boy, this is just the beginning. I was awake from about 2:00 to 4:00 this morning lying in bed and wondering. I do my best thinking at this time
Setting the temperature back on a RFH system depends on what type of mass system it is. If the RFH system is low mass, the system will be fairly responsive within reason - don't expect to set it back more than 5 degrees and expect the house to warm up within the next hour or two. If the RFH system is a high mass slab system, the mass reacts so slowly that it's best just to set the system to a given temperature and leave it alone. One of the best ways to control a RFH system is to use continuous circulation with outdoor reset. What this means is that the system water is continually flowing and the temperature of the circulating fluid is adjusted depending on the temperature outside - the colder it gets outside, the greater the heat loss from the home, the warmer the circulating fluid needs to be. Tekmar controls out of Canada makes several controls that do this. Check out their website at http://www.Tekmarcontrols.com.
OK, I tried to read this whole thread, but my eyes got fuzzy so this might be a repeat of something someone else already said, but here goes:
one thing about RFH, if you are using hi-mass (heated slab) the whole slab will be insulated from the ground, which will help it to be warmer than one placed directly on the ground like is typical when planning for just and ordinary forced air heat home.
The floor will be warmer because it is de-coupled from the earth.
I have noticed this winter (new shop, built for RFH but its not hooked up yet, just using a space heater at this point) that my relatively small space heater is doing a great job of keeping the room temp well above the exterior temp.
I am sure that this would not be the case if I had not put 2" foam insulation under the whole slab + thermal break all around the perimiter.
So, anyone interested in warmer floors but for some crazy reason can't bring themselves to go with RFH, they can still get about 10 ~ 20% (my estimate) of the benefit by insulating the slab.
Just a thought,
Norm
I didn't read all of the other posts, so if someone has already answered this for you...
"..how efficient a radiant floor system is when you live in an area like Washington State ". The efficieny of the boiler that is the source of heat will be the deciding factor in this, and it will be the same in Maine or Texas or Washingon. The average is 80 to 82% efficient, the best are just over 90% efficient.
Setbacks (ie lowering the temp at night and when you're away) with steam and hotwater systems of all types is not as "cut and dry" as it is in forced air systems. My opinion is that if you have a fairly regular schedule and learn the response time of your system, setbacks are still a good idea with hotwater systems and will save you in energy consumption. The amount of energy it takes to heat your house is directly realted to the difference between inside and outside temperatures. If it is 20 out and your lower the inside temp form 70 to 60, heat loss (and energy consumption) is reduced by 20%.
How long it takes to warm up from a setback depends on the specifics of the system installation. At some of the old, all masonry, steam heated school that I have been involved with, the response time is in days, not hours. In cases like that, setbacks are only recommended for long periods of no occupancy (Christmas and Easter Break).
".. so the radiant floor heat will have it's own furnace. does this need to be running all the time to keep the fluids ready to go, or can the "typical" furnace heat up quick enough to avoid having it run all the time" There are different ways to set-up hot water heating systems, and I am most familiar with circulate water continuously through a "primary loop" and the boiler fires as necessary.
>"..how efficient a radiant floor system is when you live in an area like Washington State ".
I certainly wasn't going to answer this after our prior discussion on the use of the word "efficiency"!!!!!! <G>
Reading between the lines, and taking some liberties, I'm guessing he wants to know if rfh is effective in the moderate Washington State climate. For example, I have clients in TX who were concerned with the effectiveness of using RFH in their climate, because the cold spells come in quick and move out quick, and a lag in the heating of the floor could end up with them missing the cold front entirely and not feeling the heat till the next 70 degree day. Or something like that. I think he just wants to know if he'll be able to have a comfortable house in that type of climate.
The reason for asking how "effecient" a RFH system works in a mild climate like Washington (doesn't really get much colder than 32 degrees in winter is because we are right on the coast), I should have worded it to say "effective or responsive". The weather does not get above 45 during the day at times. This I can understand that the system would have continuous heated fluid running through the lines at al times. But my concern is when the temperatures are warm enough during the days and we only need heat at night. I prefer to use heat in the floors since most of the flooring will be stone or wood. I really don't want to use radiator, floor board, or other types of wall heaters with fans. Because of the relative mild seasons, compared to the East Coast, I'm worried about needing to keep the house heated at all times even though we my not be there. Or, even better yet, having to wait an hour, two or more just to get comfortable if the system is "setback" while no one is at home. Another major concern is how long does it take to get a well designed sytem up and running for a 45 degree home to a 65-70 degree home when it has been basically shut down for the day. In well designede, I mean not over kill/under kill. I realize that the effeciency of the heater, type of lines, square footage, height of ceilings, whether it is a single story or multiple stories, type of heat transfer through flooring, thickness of Gypcrete/concrete/tile backer board, etcetera? If the system needs to be continuously on, then thats is what we will do. We just don't want to be wasting energy(money) for this luxury. Having the luxury of walking barefoot on a warm floors is our main objective, heating the "air space" is the second. This is why I have also considered using two types of heating systems, just to get the heated space up to a comfort level. But this will probably become cost prohibited for our limited budget. I have seen the radiator wall heaters that are tied into the same system and this a possibilty also.
I realize that I am rambling, but I am trying to get as much information/questions answered before we start, not find out later that we have a under rated system and then have to figere out how to fix the problems. It seems that to many "heating specialists" in our area are more concerned on selling either forced air, or they want to sell you every bell and whistle thay only the rich can afford. If I was rich, I wouldn't be here asking questions. -Brian
I understood that to be your question. I think you are asking the right stuff. If you were my client, I'd recommend that you look first and hardest at a continuously running system (the pumps use the energy of a lightbulb or something tiny like that) with an outdoor reset to adjust the temp of the circulating water. It should account all by itself for the mass of the system, the flooring, etc, and maintain the temps you want at the times of day you want them without fluctuations or lags. You should be nothing but comfortable with the least usage of the boiler necessary to accomplish that.
To find a cooperative contractor in your area, consider calling the tubing manuf and getting a referral. Just 5 min ago I was showing the national sales mgr for IPEX (they make Kitec tubing and WarmRite Floor Control Panels) around the dome. If you want, I'll send him an email to see if he can point to qualified installers in your area.
Migraine,
Check the website http://www.heatinghelp.com they have a find a contractor section that should be usefull.
Also check out the "wall" section of the site - most of the hydronic heating guru's in the country hang out or check in there.
I think you are right. Sometimes I read too deep. Given a limited heating season, and the need for a very reponsive system at times, plus, as I understand the area, a very damp climate at times, my recommendations would be more along the lines of air handler with hot water and dx coils, with tubes in the slabs covered with tile, and in the basement, warm air heat elsewhere. AC sized more so to wring the moisture out of the air than to really cool down the space.
Actually Tim, there are a number of condensing sealed combustion boilers that can match the efficiency of a condensing scorched air furnace - Viessmann Vitodense 200, Dunkirk Quantum Leap, Heat transfer product's Munchkin , etc, etc, etc. Additionally, if you take into account the overall efficientcy of the system as a whole, scorcher air isn't that efficient - a circulator for a boiler may only use 80 to 100 watts of electricity; a forced air blower considerably more.
TJ,
I said there were "very few" and those that you mention are in the 90% plus range. I am aware of every one you mentioned, but I can seldom sell boilers that cost 3 to 5 times that of a comparable furnace or an 80% boiler.
A whole system ciurculator that operates on less than 1 amp (80 - 100 watts) at 120 VAC? Never seen a boiler circulator that small. You'll have to educate me about you can circulate the entire volume of a hydronic heating system with less than 1/20 hp.
AFUE ratings for furnaces, by the way, do take into account the efficiency of the entire unit; induced draft fan, blower energy and combustion efficiency included. Boiler ratings on the other hand take no external energy usage into account.
Tim,
Check out some of the circulators by Grundfos - their 15-42 circulator only draws 85 watts. Depending on flows and temperature drop and ft of head it's possible to use a single small circulator on a modestly sized radiant floor system if designed correctly. It should be entirely possible using continuous circulation to supply the heating needs of a 2000 sqr. ft. slab RF with 4 to 8 gallons per minute of flow.
As for the price of the condensing boilers being three to five times as much as a normal cast iron boiler - you get what you pay for. The new Vitodens 200 condensing boiler from Viessmann ( the best of the bunch) may even be on a par with the cost of an 80% cast iron boiler, when you take into account the time and labor saved not having to wire controls and build a semi complicated near boiler manifold. The Vitodens has it own built in controls and if you use Viessmanns low loss header the near boiler piping couldn't be simpler. Besides, you can always pitch the Vitodens as the last boiler the home owner will ever buy - it's that well made!
TJ,
A Grundfos, 15-42 circulator will move 5 gpm at 11 feet of head. I don't believe that you can heat 2000 sf with 5 gpm. At a 20 degree temperature drop, you can get about 5000 btuh from 5 gpm, which is 2.5 btuh/sf. This might count as heating in some parts of the world, but not in most of the continental US. (a 40 x 50 space with r-20 walls, r-33 roof/ceiling and 80 sf of r-5 u=0.2 windows and an outside air temp of 0: 11,115 btuh required to heat to 75 deg inside).
I understand and fully agree with the fact that you get what you pay for. The point was and is, that even with the best and most efficient hydronic equipment available you MIGHT match the efficiency of a gas forced air system, and at nowhere near a comparable first cost. Then you have no means to condition, cool, filter, humidify or dehumidify air, which in any occupied space is very important for a host of reasons.
Tim,
check your numbers. 5 gallons a minute x 8lbs(weight of 1 gallon of water) x 20 degree teperature differential x 60 minute = 48,000 btu per hour at design load. It takes 1 btu to raise 1lb. of water 1 degree f.
That's 24 btu's per square foot per hour at design load, which is very do-able in many parts of the country. Additionally, most homes don't spent but 10 or 12 days total at design temps each year; so the cost of condensing ( read expensive) boilers make's sense.
I'll admit, it's hard to justify the additional up front cost of radiant to the people who have never experienced radiant floor heating for a winter or two; but, for those people who have experienced radiant floor heating - they'll never go back to scorched air heating again, at least not willingly.
TJ,
You're right. I checked my numbers and made a mistake, the standard formula for hot water heat is 500xgpmxdT, which in this case works out to be 50 MBH, 25 btuh/sf which is plenty. But do you get a 20 degree temperature drop for a RFH system? I don't know, off hand. Design temperatures are usually at 99%, which means 36.5 days are at or below the design temperature. Are you willing to have you clients cold when design is 0 and you have -15 for a few days? I'm not. I have RFH in parts of my home, and I agree that it is wonderful. But, it is not as energy efficient in any real installation as a basic, gas forced air system.
which means 36.5 days are at or below the design temperature.
3.65,no?
What temperature percentile do you design for, if 99 is not sufficient? Or how much extra capacity do you build into the system beyond the 99? Or however it's easiest to explain...
>> What temperature percentile do you design for, if 99 is not sufficient?
IMO, you design for 10 or 15 degrees below the lowest temperature ever recorded at your location. When I buy a car, I want one that'll pull the steepest hill, against the strongest headwind, carrying the heaviest load I ever anticipate carrying and still have some oomph left for passing, and I expect to pay for it. Why should a heating system be any different?
But then, I'm a known eccentric.
Uncle Dunc eccentric? I don't believe it! Sounds like you use a semi to run for groceries.
I don't know what all heating systems designers (you're not one those, right?) use but in the city that I work, the ASHRAE 99% design temp is -4, the ASHRAE 99.6% temp is -10. I design to -15. The lowest recorded is around -30. If I designed systems for -45 to 70, most commercially available equipment would not work. Bad advice there Unc.
Tim
>> Sounds like you use a semi to run for groceries.
Yeah, but I only have to go three times a year. ;)
>> ... most commercially available equipment would not work.
Really? How would they fail?
I meant that most readily available units will not provide the quantity of heat required to meet that fictitious load. They would "fail" to meet the load. You can heat an average 4000 sf house with a 125 MBH input furnace assuming an 85 degree temperature differencewhich in most cases is conservative, but the same furnace would not have enough capacity for the 115 degree difference. Most residential furnace manufacturers do not make units with more capacity than 125 MBH (input).
>Sounds like you use a semi to run for groceries.
Question Tim. I know there's a danger in oversizing A/C equip, be/c you'll never get enough dehumidification out of it. Is there any danger in oversizing heating equip, other than capital investment? I was reading in the IPEX manual a caution about not running boilers at too low a temp because operating for prolonged periods at temperatures below the dew point of the exhaust gases can cause trouble. Would this be more of an issue with oversized boilers, or not?
Yes,
I have two units, one for up and one for down.
The dowstairs unit is oversized. I have heard people say that too big of units can cause bad temp swings. I don't have that problem, the temp says constant.
But the blower on the slowest speed is still too way to much. I have to tie down the dog and grab on to a door frame everytime it runs.
"The dowstairs unit is oversized. I have heard people say that too big of units can cause bad temp swings. I don't have that problem, the temp says constant."
The problem with oversized AC units is not temperature swings. It depends on the envivironment and how much oversized. In more moderate and/or humid environments the AC can cool off the house too fast.
As warm, moist air passes over the cold evaporator coil, water condenses, collects and eventually drains out, hopefully through a trapped drain. It takes 15 to 20 minutes or so, for moisture to collect enough to begin to drain. If the AC unit cools down the space within or closely to that 20 minute time period, no dehumidification takes place. What condenses out on the coil evaporates back into the air as soon as the compressor is off. The temperature is kept low and that is the problem. If you lower the temp but do not reduce the total moisture content, you raise the relative humidity. In some circumstances, water will condense on surfaces in the space but in all cases the RH rises. This is a precourser to mold and mildew and general poor comfort.
If you need a 3 ton and have a 4 ton AC, will you mold up your house? Not likely. You just blew $500 on the extra equipment capacity and will continue to pay for over the years in reduced efficiency, excess cycling and eventually premature equipment failure and/or extra maintenance.
Any idea who installed you system?
Tim
Maybe I should have been more specific in my reply, but Cloud said that he knew of the problems with oversizing AC, then but what about oversizing heating.
I was talking about heating. I don't even have AC on the downstairs unit.
It's about 22 years old and hope to hold out for a couple of years when I am ready to do some remodeling including an additon.
The main drawback from oversizing heating equipment is loss of efficiency and a waste of resources (money) to buy capacity you will never need.
Issues of shocking a boiler (not really a problem with flexible water tube type) and condensing combustion products in the furnace area can be overcome with proper system design. In low temperature applications, like RHF, common practice is to have a primary loop, usually at 180, and a secondary loop with a 3-way valve to provide the load loop with whatever temperature is required. In a system where different loads require different temperatures, multiple mixing valves are used. There are boilers designed for low temp applications, but I don't see those often. Residential specialist probably know a great deal more on this that I do. Biggest issue with an oversized boiler (or any type of equipment), is that, without complicated controls and even with themin some cases, efficiency suffers at part load operation. Another concern is that the unit will short-cycle, causing undue wear and tear on the controls relays, gas valves, etc..
In terms of the affect on the quality of the conditions of the space, oversized heating equipment causes no real problems
The design conditions that we use are based on the 70 years of combined expeience that the enigineers in my office have, and not on a precentile. And you are right, 1% of 365 is 3.65 not 36.5. If I were designing in area without that experience to provide some direction, I would use the ASHRAE 99.6% heating temperature to set design conditions to determine the minimum heat required. Usually, because equipment is provided in fixed capacity increments, the "next bigger" size provides you a little margin as well. Also to be accounted for in the equipment selection is how conservative is the load calculation. When I run loads on a school, I am more conservative than if I am running loads on an office building.
Thanks, Tim.
Now can you explain "efficiency" again? (Just kidding!) See ya around.
Sounds like you might work for a wholesaler ... do you have a price range on this boiler?
Also, Is there a case if someone was putting in their ideal system to run rfh and forced air? My design for my next house involves a two-pipe fan coil system which can be switched over to heat easily. (due to working in hvac a long time and having extra materials from that time period in my life). so water chiller in my mechanical room. I'm going to put in the radiant floor heating system but wonder if it is that comfortable such that it wouldn't need supplemental hot air.
btw no one in my area I know has radiant heat. I have never had the opportunity to experience it. Wood stoves, yes.
remodeler
No, I don't work for a wholesaler. The only reason I can see for putting in scorched air in addition to radiant floor heating, is if the rfh system could not meet the heating load requirements or if you have really large daily temperature swings - though this could be addressed with either a fan coil or baseboard heat.
I don't have a wholesale price on the Vitodens boiler though I have heard that it's around $4500 - sounds expesive but, the controls are built in. The Vitodens is a great boiler, it's sealed cumbustion with a titanium stabalized stainless steel heat exchanger and modulating combustion from 5,000 btu's to 199,000 btu's depending on the model. Because the Vitodens is a modulating condensing boiler you don't need to heat the water up to 180 only to have to mix it down to 90. If the house calls for 90 degree water to be circulated through the floor the boiler generates 90 degree water.
Get ahold of a company in your area http://www.bio-radiant.com and look at their Hydro-Air stuff. And all hydronic solution, including A/C. Worth knowing about even if you choose something else.
Brian,
I am also in W. Washington, I am currently building a two story with a full basement, the outfit that I am using is called Olympic Radiant. The guys have been great to work with allowing me to do a lot of the manual labor, and providing lots of options to get the system into my budget. As far as your fuel source you may want to look at using oil, I am using a Buderus boiler with a direct vent system. I will let you know more if you like, we are planning on lighting off this week.
Jason
Brian,
I fired up the boiler on Tuesday night, my basement is wonderful to be in already. I talked to my radiant guys and they told me that they are talking to several other people from your area. Ken and Mark are great to work with and do quality work. Also I have attached a photo of my boiler (it's about 2/3 installed in the photo).
Jason