In my next house i am considering installing radiant heat. I have a few questions though, is it really as good as the websites claim?? it seems the air is still cool and you would feel cold. I live in Georgia and it gets into the low 20s in the winter, the furnace runs all the time, will it be more efficient? also the diff between electric and hydronic, which is better? I will still need duct work for the ac system… thanks for your help….
Frank
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Partial answers from WNC....yes, it's worth it. No the air is not cold. For a whole house, as opposed to a single small room, hydronic is almost always the only smart answer. If I were building another house, radiant floor heat and a central vac would be my two starting points, and I'd figure out the rest of the house around them.
Ever go outside on a nice Spring day, when it's 50 degrees out, and the sun just warms you up? Radiant heat. Now step under a tree. in the shadows, where the sun can;t reach you. Take the sun away and just be surrounded by 50 degree air. It'd be a little chilly.
Poor analogy, but...
I do think radiant is the most confortable form of heat out there. Actually, I've lived with most forms of heat, and I'll revise that to say RFH is indeed THE most confortable form of heat to live with.
Economical? It does run more efficiently than other types of heating. There are many, many variables, but nost of the houses in my neighborhood (CT) are within a few years of being the same age. Similar contruction materials, though I'd like to think my house is tighter than theirs. The square footage of my house is larger than both of my immediate neighbors, by about 35% and 50%. Yet I use less oil than both of them. By about 20% and 30%?
Scientific? No.
However, it seems effficiencies of 15-30% are not uncommon.
The one area where radiant heat lacks is in the somewhat moderate, between seasons...take early fall, where you may have a 40 degree day followed by a 65 degree day. Simplistically, your house will warm itself on the 40 degree day, and by warming the mass of the house, think of your house as a huge heat sink. The next day it's 65 degrees, and you house has all those BTUs stored up...which may result in the interior being overly warm.
That's the major drawback of RFH. In hihg-mass situation, RFH works best in steady-state conditions. A series of cold days, vs cold-warm-cold-hot, etc.
Again, an overly simplistic explanation.
You can minimize these thermal overshoots by using a low-mass system (staple-up or sleeper) vs a high-mass system (slab). Quick response vs long-term heat loading.
Lots of variables, and a designer can design a system and use controls that will work for you.
When I visit neighbors, the comfort level between a warm floor (RFH) and a cool floor (forced air) is dramatic.
Electric radiant cen be used to take the edge off and supplement forced air. For example, use electric radiant under the floor tile sin your bathroom. the forced air wamrs the space, the radiant takes the edge off and by warming the tiles, make the space much more confortable.
Typically, electric can't be effectively or economically be used to heat an entire house.
Typically.
The most edfficient is typically gas or oil heating water, and circulating that heated water.
Lots fo variables, regionally etc.
>That's the major drawback of RFH. In hihg-mass situation, RFH works best in steady-state conditions. A series of cold days, vs cold-warm-cold-hot, etc.
This is the one area I'd have to disagree with you, but it's likely more a function of the building construction than the heating method. A high-mass, well-insulated, exterior-insulated, properly-solarly-oriented building will perform superbly under these conditions, and will likely not even need the RFH to maintain comfortable temps. I revel in the hot-cold-hot-cold days of early spring and late fall when neighbors have smoke pouring out of their chimneys and we don't have anything running.
Now if we change that building structure to be high-mass floors with poorly insulated (in light of the spelling thread, the first time into this sentence I accidentally skipped the 'a' in "insulated"!), low mass walls, then I'll agree with you. The mass couldn't respond fast enough. But put the right walls there and it's a perfect match.
ok guys thanks for all your info , greatly apprciated. Now what about a do it yourself installation, i have seen some ads for this as well... is it doable?
Yes radiant heat is the best and yes it's doable. The on-line company I used spec'd out the whole system and gave me great phone support during the installation. I did a staple up system, so a lot of time was needed for hole drilling, pipe pulling and plate stapling. Quoted price for local install was $20,000. My DIY price for materials and some new tools $4,500.
Steve, who did you use for the RFH? Also, are you both forced air and RF?
Did you use pex?What is your heat source? Thanks, PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home
Steve,
On top on Paul's questions, What type of finish flooring do you have? Did you insulate between the joists? Was this a whole house or partial? Is it over the basement of crawlspace? Did you do the second story? How about the heat pump/boiler set up and cost?
I will be having a kitchen remodel (complete gut) and thought that since I have access to the whole room and floor above that I could install this system for the back portion of the house.
TIA
FreddyS
I was adding a 2 story addition 1000 sq ft to my home and wanted RFH. After learning everything there is to know about it and a few local price quotes (yikes) I went with http://www.radiantcompany.com. They spec'd everything out and gave great phone support.
Because of the low cost in DIY I decided to install it in my existing 1st floor and part of my existing 2nd floor and then I ripped out my baseboards ( after I knew the RFH worked). When I redo my existing firstfloor Living/dining rooms I will tear out the ceiling and convert the rest of my 2nd floor to RFH.
Some will say my install materials were overkill but since it was DIY the extra $400-500 didn't seem to be a big deal to me. I did a staple up install using 7/8 pex pipe, with plates. I ran plates the whole length not every few feet. Then stapled in a reflective foil 1" below the pipe and then 6 1/4 batt insulation. I have a full unfinished basement plus the new construction so access was not a problem.
I already had a boiler for baseboard heat so there was no cost there, but the boiler is set at 180 for the baseboard system so it goes into my radiant manifold through a mixing valve to bring it down to 130. It returns at about 120-125.
Quick install tips. Use a Milwaukee right angle drill with self feeding bit to drill holes. 7/8 pipe does not have as tight a bending radius as 1/2. Don't try to thread 400' of pipe from one end to the other start in the middle or use splices (yes they are leak proof). Electric staple gun not manual. Lay out your holes on paper first before you start drilling and make sure the holes are to code and don't affect the structural integrity of your joist.
Believe it or not I have the following flooring materials in my house: solid oak, linoleum, laminate, ceramic and carpet. Every room is comfortable and if installed correctly none will be damaged by RFH or block the RFH.
I don't set my house temps back at night, I leave it locked at 68 and that keeps my wife happy. In the 2 years that I have had it we have had many people comment how comfortable they felt and they didn't even know we had RFH.
RFH can be very DIY-friendly. It can also bite you in the arse.
You need a little of a lot of things...a little guidance, a little skill, a little smarts, a little patience.
Know your strengths and weaknesses, and be smart enough to get help where you need it, if you need it.
HI,
I gotta echo those thoughts. I had radiant put in my new house 4 years ago. Very nice feel, operating costs are the same as my other house at half the floor space (both good energy packages). If I did it again, I would DIY, I learned alot because my heating contractor didn't know what he was doing and I had to carry the responsibilty of doing a good job. Next time, I would pay closer attention to tube placement, and be sure to have separate loops under each type of floor. I have laminate in my kitchen, carpet in a family room, he ran tubing under the lam into the family room. When the fam room calls for heat, that part of the kitchen can get warm quick. Overall, I'm extemely satisfied, the outcome of my contractor's shortcomings was that I paid for a Chevy system and his supplier made him put in a Cadilac system. I have a thermostat in every room, variable opening wax motors control loops so most have some water running thru them all the time. No lags or overruns, even on sunny cold winter days. Real happy in SW Michigan.
Gary
I have laminate in my kitchen, carpet in a family room, he ran tubing under the lam into the family room. When the fam room calls for heat, that part of the kitchen can get warm quick
Just a thought, do you have the proper padding under that carpet. The wrong type can impede RFH performance dramatically.
Yeah, we went around in circles about that. Heating Ktr. said it didn't matter, but then they had screwed up on the mixing valve during the install and our water temp to that part of the floor was up to 150 one night (I heard 2 tremendous BOOMS!!! in our house that night, I thought the place was coming down!!!!). Glad we had the right padding at that point. We have 1/4" rubber padding under normal cut-pile carpet. R value is maybe around 4 total. I did have to put foil-bubble-foil insulation under the family room floor to get the heat going up instead of down. It fixed a cool family room, and I lost 8 degrees downstairs in the basement with the heat off down there. I have 1 1/2" gypcrete floors on the OSB thruout. Radiant everywhere but the stairs.
Gary
Just a thought, do you have the proper padding under that carpet. The wrong type can impede RFH performance dramatically.
I tried to do the right thing and use rubber padding over my RFH as recommended by the Carpet Association. Every store I went into on Long Island looked at me like I had 3 heads. I was told, They don't make it any more, it's not needed, can't get it, to expensive or it doesn't last. Some pulled out foam padding and said it was rubber.
I had to go with a thin padding and a low cut pile. Lag time has not been to bad.
Thanks to the internet I knew more about carpet than most of the carpet salesman I talked to.
Yeah. Been there, done that. But I just insisted they get me the padding I wanted. "But it's going to cost $3 sf more for that padding, sir" Oh, ok was my response. That response to show them I was serious got them working on getting it for me, I think.
Like almost every other industry, evryone only works on having the "best price". Sometimes, we as consumers have to educate salespeople that we are in need of services, not just cheap prices.
"ok guys thanks for all your info , greatly apprciated. Now what about a do it yourself installation, i have seen some ads for this as well... is it doable?"
IMHO, heating systems are far more complicated than most folks imagine. A lot of folks get themselves into deep trouble with those online package providers, and wind up paying a second time to be bailed out. I'm not saying it can't be done, just that their technical materials skip over a lot of important application-specific details that should be considered. Some of them really push those 'open' combo DHW/Heating systems as a way to save money, and I feel this is false economy (and a code violation in most places). Anyways, it would be worth investing in some independent training before deciding if you want to take it on.
If you are really serious about getting into it, I would suggest reading this textbook as a start:
http://www.hydronicpros.com/Publications/MHH2/MHH2.htm
It even comes with a sweet software package for designing heating systems. Best of luck.
I'll concede a couple of points to you on that one, but, in average or even above-average typical stick-frame construction, RFH does tend to suffer from thermal over-and under-shooting in the 'tween seasons when sequential days are warm-cold-warm, etc.
I'm in full agreement with you that a well-insulated shell, such as your dome, is far superior in these situations. And that includes stick-framing with non-standard insulation.
A well-designed system can minimize the effects as well. Still, the gist of my post was geared more to "typical."
I'm loving life right now. Fall is my favorite time fo the year, and outdoors it looks like October this morning. Was outside playing catch with my son before he went to shcool this morning.
Both of us in shorts. Frostbitten kneecaps? Who cares!
Never give in!<g>
Yeah, my comments sprang from what I've learned here from you and David T about response times of hi-mass in frame construction. I don't design those types of houses, so I take my own comments there with a grain of salt, or at most two, but if I did, I'd likely favor the lower mass installations. I see in neighbors' houses how quickly the inside conditions change with the weather, and would want an hvac system that could accommodate.
Just read the other day that 1/2" SR has only a 10 min heat memory. I don't know what delta T they were talking about, but from the context I gathered it was something like how long it takes to lose any heat absorbed from the sun when the sun goes down.
My own place is spoiling me with regard to the weather. It's barefoot and shorts much longer than is warranted by the weather, and it gets me a bit of a reputation at Meili's school and gym. Helps that I grew up in cold PA, at least cold compared to NC. I know I've pushed the seasons too far when a 6 yo begs, "Dad, pleeeeeease don't wear your sandles again today." Maybe tomorrow I'll wear real shoes. I think I can hold off on sock another month or so, though.
I've only installed radiant in 4" slabs. It works great. Nothing quite as nice on the bare feet as a warm floor in the morning.
If the house is built properly and well insulated, it's an efficient and effective system.
I agree with everything Mongo said, and would add one thing. Under a slab, the addition of 4' of 2" rigid insulation anywhere around the perimeter (stemwalls, turndown) will add to the efficiency, and R-foil under the slab will dramatically reduce the response time.
We've discussed R-foil to death here. The general consensus as I understood it was that there is no way this stuff can work as advertised. The arguments all make sense on the terms that they are presented, all I can say is we must all be missing something because I've used it and it works. The floor seems to heat up in about a third less time than you'd expect, which is a lot. At 60 cents a square foot, I think it's money well spent.
I've tried R-foil directly under the slab, and also under about and inch or two of sand, with the slab over the sand. The sand was expensive, time consuming, and generally irritating for everyone on the job (mostly me), but the difference in the quality of the slab and the performance of the heating system was so remarkable that I would do it again.
DRC
"also the diff between electric and hydronic"
You have to be carefull making comparison because you are talking about two different things here.
Electric is both an energy source and a method of delivering that energy to a radiant system.
Hydronic is only a method of delivering heat energy to (in this case) a radiant system. You still need a source of energy.
That source of eneregy can be gas (natural or bottled), oil, wood, electric boiler, or electric ground source heat pump.
You need to check your cost of the different energy sources and equipment costs.