Under subfloor radiant heating costs?
Morning All,
I’ve had some coffee and this presents my mind to start asking questions. I have a 16.5’x18.5′ family room that is vaulted. The elevations are 12′ on one long wall and 18′ on the other. This is a room with a drop-in fireplace (never used) and difficult to keep comfortable without $300/month NG bills for $65ºF ‘comfort’.
I currently have access to the area of the basement where this room is located. Unfortunately for me, the builder used BC I-joists instead of trusses, and they span the width of the room, on 24″OC except for 2-3 additional joists for canterleaved requirements for that drop-in fireplace.
Curious as to the relative cost for DIY install of a radiant floor heating system of the kind that installs itself from underneath the floor, which is currently carpet. Also, the consequences and addressment of the future-flooring acommodations if I transition from carpet to HW or tile.
Ideas? Links? Anything would be helpful.
Replies
What makes you think that putting radiant floor in will decrease the $300/month gas bills? Heat loss is heat loss, and if the room loses enough heat so you have to burn that much gas, it doesn't matter HOW you deliver the heat.
Maybe you should look into "envelope" improvements like better windows, insulating the rim joists, etc.
I agree that my five-year old Anderson double-pane windows are crap. Actually, I wasn't looking to decrease the NG bill, but rather use the heat where I am at and not 12' above (vaulted ceiling) where I am at. Do you not like radiant heating?
Also, I thought about how often the other first-floor rooms need heating (per desired warmth), but aside from heating food in the kitchen, about 90% of our first-floor time is easily spent in this room. I thought a one-room radiant system would afford per-room would afford better focus of heating endeavors. I know this is asinine and completely illogical, but then again I am a nutty homeowner. lol
Actually, I like radiant heating alot...enough to become well enough versed so I designed (with some remote consulting), built, and installed a radiant floor system for my 1600 sq foot house.
The benefit for you will be one of the classic benefits of radiant floor...it heats the objects instead of the air so you will feel more comfortable with less BTU input. But maybe only save 15% - 20% of your heating bill.
I'm assuming that you presently heat with forced air and alot of the heat ends up in the peak of the ceiling. If so, keep in mind that the installation of heat emitters under/over/ the subfloor is only part of the deal. You also need to look into boiler and control strategy.
A couple of good resources, if you like wading through forums, are:
http://www.rpa-info.com/FrontPage/FrontPage.html
http://forums.invision.net/index.cfm?CFApp=2
Yes, the home is presently forced air. Starting around this time of the year, heated force-air also generates a lot of static electricity and dries the air to a painful nose condition.
"..heated force-air also generates a lot of static electricity and dries the air "
This is a common myth. A forced air furnace cannot create or destroy matter and that includes moisture (water). There are three common ways to dehumidify air. One is by exhange with drier air. One is by cooling the aire below its dew point and condensing the moisture out of the air. And the third is by passing the air through a dessicant. Heating air by forcing it across a hot metal surface (i.e. a heat exhanger) does not remove moisture from the air stream.
The static electricity IS a byproduct of dryer air, though not caused by your furnace.
Well, the air isn't drying out if I have just the blower running, nor if I run the AC. While I agree that the current Summer-to-Winter pattern brings lower humidity, I've had dryer air inside my house while its being heated even when its raining outdoors.
And I know the static electricity is a byproduct of dryer air, which is the problem I stated. And I am not necessarily picking on 'heated forced air' as much as forced air in general.
it doesn't matter HOW you deliver the heat.
Not true. This is the beauty of radiant heat. With forced air, the floor is 65deg, eye level is 68deg and the ceiling is 80deg. Very bad on wallet. If you have radiant heat, the floor is 70deg (toasty feet), eye level is 68deg and ceiling is 65deg. You get out of life what you put into it......minus taxes.
Marv
As you see, I totally agree....just didn't want the original poster to think that he would save bundles of money with a real leaky envelope.
http://www.radiantec.com
http://www.radiantdirect.com
I'm certain there are others...
Both advocate a water heater instead of a boiler, which would be a simple DIY install, and perhaps appropriate for a small area such as yours. Radiant works under carpet, just not as well. Use the staple up aluminum plates (radiantec) they will help get the heat through. Pricing estimates are on both pages. I've found that 1/2" Pex is cheaper from your local plumbing house, and I prefer radiant direct's manifold setup - it looks simpler than the radiantec I used in my last house.
There is a claim that w/radiant you can set your thermostat lower, thereby reducing the temperature differential from the ouside and pressure gradient accordingly, lessening cold air infiltration. So if this is really significant, you may see some savings, although it might take a while to offset installation costs.
Good luck!
Quote: " There is a claim that w/radiant you can set your thermostat lower, thereby reducing the temperature differential from the ouside and pressure gradient accordingly, lessening cold air infiltration. So if this is really significant, you may see some savings, although it might take a while to offset installation costs."
There was a not very scientific survey done in Canada a few years ago in which a university student simply visited persons with radiant heat installed (from customer lists from installers and with the clients permission).
Surprising find: many (majority) people had their T'stats set higher than with other forms of heat. The surveyer only had an accurate t'stat to determine if any of the t'stats she read were really off in calibration. Seems like we need more study!!!!!!! There's a manufacturer of electric radiant ceiling panels in Canada that claims "radiant ceiling panels will consume about 1/3 - 1/2 less energy than conventional "hot air" systems. We should all be moving to these systems!!!!
Well, this unscientific Canadian has her thermostat set higher. In this kind of weather, it's a pain to adjust the heat. you almost need to raise the heat at night, to get it warm for morning, and lower it in the morning, to get it cool for the evening.
If you like fast response heat, forget radiant. No more kicking the thermostat on for an hour the morning while everyone showers and gets breakfast. Kids come in cold from an afternoon in the snow (memory from last year, no snow yet) and you can't do a quick heat up.
So, I can believe that people leave the thermostat set higher. It's easier to open the window an inch than to try to figure out what you're gong to be doing, and what the weather will be doing, 24 hours from now.
Thank goodness for our south windows. That helps take the edge off during the day. (
If your system were properly controlled, you would have no issues unless you are looking for dramatically different temperatures during different periods of the day.Radiant should be set to a comfortable temperature and left alone. If you have different areas w/different requirements, they should be zoned seperately and controlled properly.Your problems are not problems w/radiant. They are problems with your system.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
The same company that claimed that also claimed a cooling effect by running water through the tubes (open system) in the summer.
I like radiant heat very much, but I'm not too certain of some of the wilder claims.
And I like my house warm at night too, so the temperature lag isn't a bother to me.
I do agree it is not "powerful" heat like the huge fossil fuel fired forced air furnaces. (sorry got carried away with the aliteration) Insulation might be the first solution for the original poster.
Treat every person you meet like you will know them the rest of your life - you just might!
That cooling effect is completely bogus, as it sounds like you surmised.Radiant is quite powerful. It's quite comfortable. It just has different requirements and issues than FHA or baseboard heat. Properly controlled, there is virtually no "heat lag" in a very wide array of circumstances. The system can be made to anticipate its own mass effect.Water temperatures should be appropriate, preferably modulated depending on load (outdoor reset) and at good thermostats made for radiant used. Even just using good thermostats can be a huge difference over the basic round honeywells on most systems; we generally recommend Tekmar's 500 series thermostats unless there is a large need for true indoor temperature feedback (i.e. large, fast solar gains and high mass radiant).-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Keep in mind radiant alone may not be adequate (bad windows, vaulted ceiling, carpet). A basic heat load calc would let you know.
Also, it is pretty unlikely.. unless you live in a very mild climate... that a water heater and lightweight plates will do this. Perhaps with heavy gauge plates (50% cost increase, roughly) a water heater would work, or perhaps with higher temp water lightweight plates would work. with 24" o.c. joists, you also have a choice to make; 8" o.c., hard install, or 6" o.c., easier install. 6" o.c. is obviously more material but the install is a lot easier than threading every foot of pipe through every joist penetration you make.
If you do not have an existing hydronic system though, this could be a pricey add on. If you do have an existing hydronic system, excellent!!
Just to prepare you for some stuff you will see as you research;
1. don't waste money on reflective insulation, go for R-value instead under the tubing
2. Bigger pipe does not emit substantially more heat than smaller pipe.
3. Never install wider than 8" o.c. in joists
4. You will see some efficiency benefit due to reduced stratification, but I agree with johnny if energy savings is a primary goal, attack your envelope before you do anything with your heating system.
5. Heating water MUST be seperated from drinking water!!!
Best of luck!
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
If I were to address the envelope, which is appropriately mentioned here, I would literally have to tear down this spec house that is five years old. The The General Craptractor of this development did a poor job, and only after three years did developer get rid of him.
I've often commented about my swiss cheese home in that there are more holes than doors and windows. I asked several times in the first couple of years about what good is it to have double-pane windows is nothing around the doors, windows, and exterior-walled outlets are blocking the Winter wind from removing heat from the home, and Summer heat being allowed to blow hot air into the home.
When I mentioned about housewraps, I was pointed out the absurdity of the builder spending $1500 additional cost on a $250K home as "it wouldn't benefit" (his words, not mine). So, unless there is a way to remove the siding, doors, and windows, seal the openings and cavities around, then I'm lost (like any inexperieced homeowner) as to how to approach this.
BTW, I wired and insulated my basement (1100 SqFt) and about to drywall it. Its cooler down there in the Summer, and warmer down there in the Winter. And I'm an idiot homeowner and not a General Craptractor. Not picking on GC's, except for the one that never his job in the first place. Thankfully, he isn't GCing anymore (runs/owns a golf shop).
Perhaps blowing in some insulation would be useful? Just a thought, I understand that retro'ing insulation is tough.-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
When I'm using RFH in a basement slab are there issues I should be concerned about if I want to later construct interior walls in the basement and fasten them to the floor with tapcons or hilti? I'm wondering about puncturing the tubes- are they set deep enough or do I keep an diagram of their location?
Thanks
Skippy
Take scupulous pictures of the actual tube layout before pouring, make up a dimensioned drawing of the layout, and don't lose them. Then before drilling or nailing, turn on the system and get down on your hands and knees and feel for the warm stripes. Or damp mop the floor and watch where it dries quicker where the tubes are. Or get one of those laser temperature sensors like Frenchy has and shoot around with the system on.
ah, the wetmop trick is a decent one too if your floor is fairly level, good call johnny!-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Or you can use cork flooring. Its swells up unaturally when it gets wet from below. Ask me how I know.
And that crown staple leg held 70 #s of air too.
Edited 11/1/2005 3:14 pm ET by johnnyd
What we do is try to anticipate the future partition layout and lay the pipe so it won't be a problem, and also to allow for future flow balancing/zoning by room if necessary. A diagram, to scale, would be a must there.Later, you have three possibilities;1. trust your diagram and lay walls as you anticipated.2. Hire someone with a thermal camera to come in and spot pipes for you, and nail the walls.3. Use construction adhesive in *all* questionable areas instead of nailing the wall plates down. With a decent diagram, you should be able to nail some of the wall plates and glue others and get a decent final result.I would not trust the tubing to be low enough unless you have a very thick slab and you can be absolutely sure the nails can't reach the tubing.-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Consider a blower door test. Radiant is nice, but it sounds like in your case there is plenty of low-hanging fruit for the taking. Your best cost/benefit ratio may be found elsewhere.
There are many steps that can be taken without major deconstruction.
Nuke,
Have you considered a couple quality ceiling fans to stir up the stagnant air that is high in the room? Also if you don't have a couple high returns on the system, it isn't much of a problem to extend the cold air return in the inner walls to up high, this will also help to get that stagnant air back into circulation. One other thing, depending upon your furnace and the efficiency of it, putting it on continuous circulation will also keep the air moving for less stratification. The above issues, in addition to plugging drafts and insulation issues, will be less costly and could bring your room back into an acceptably comfortable environment.
Regards,
Virginbuild
Nuke,
I overlooked one other factor; is your fireplace draft and damper fully closed with a really good seal? That alone can really be your culprit, destroying your comfort zone.
Virginbuild
Dang Virgin beat me to it I would suggest the same, ceiling fan, though not the most attractive may help push some air down. Also a room that size may have a cold air return if possible move it up.