I have a 1957 house with an unfinished basement, so there is easy access to underneath the main floor. I am considering a “staple up” radiant floor heating system. How well does this work? I live in a fairly mild climate, Portland, OR, but I’ll need to be able to heat through the subfloor and hardwood floors.
Any recommended suppliers?
Does anyone live near Portland so I can see a system like this in action?
Max
Replies
radiantic is the main source for do-it- yourselfers. My brother-in-law did his house with it and found it a not very difficult job to do. I will say that walking on his floors is really nice and not having to deal with the drafts that come from forced air is also nice..
I bought my tubing from a heating suppier and got Wirsbo The rest of the sytem will come from radiantic since they are so unreasonable about do-it-yourselfers.
While my brother used a boiler I think I'll go the hot water heater route, lower cost and more efficent system. I've done the energy calculations and a 50 gallon water heater should do most of what I'll need and then I'll supliment it with the nearly new high efficensy forced air furnace I already have.
Niether he nor I have ever done this sort of thing before and there is a learning curve. Don't tackle a project like this over a weekend and expect everything to be perfect. This is best done in the summer so you have plenty of time to order and get those parts you failed to order or need more of..
Were you guys putting in a staple up system underneath existing subfloors? I don't want to have additional heat sources. Is the radiant sufficient to heat the house on its own? I live in Portland, OR so it is fairly mild here in the winter, rarely snows, but it can get below freezing occasionally.Max
Half of my brother-in-laws house is old floors and half is new..
My flooring is a real challenge in that the sub flooring is actually 2 inches thick! the hardwood floor on top is actuallu one inch thick! total is three inches!
Heat is simple to understand, if you get a chunk of wood to 70 degrees it will transfer that 70 degrees to the air above it.
what you need to figure out is the heat loss thru things like insulation/ roof/ windows etc. then you can calculate how many BTU's and where to put them for your most comfortable effect.
As for addional heat sources you need to understand Minnesota, 40 below isn't uncommon and I've been thru even colder! Thus my suplimental heat sources.. Freezing! Ha! We've had snow fall in every month of the year ! Yes, August! Do your energy calculations add a small amount for worst case and you'll be fine!
Just so you can understand the size of the problem in my case I have close to 6000 sq.ft. I'll have 52 windows and intend to heat most of the house with a single water heater!
OK, I'll have a back up water heater and the forced air furnace as suplimental, plus three fire places.
Edited 1/4/2005 7:17 pm ET by frenchy
Works very well, though it requires proper design for tubing layout and controls. Design considerations are somewhat more complicated than most folks expect.
What sort of heat source do you have now?
This outfit is good for both design assistance and supplies:
http://www.aimradiantheating.com/
I have baseboard electric right now, and I want to get rid of those completely. They are inefficient, ugly, and always right where you would want to put some furniture. Have you done this type of staple up yourself? Do you need additional heating or is the radiant sufficient? How many runs of tubing per joist do you have?Max
"Do you need additional heating or is the radiant sufficient? How many runs of tubing per joist do you have?"
Designed properly, you should not need any other heat source. Heat transfer through wood floors is quite good. I prefer the aluminum plates to spread conduction out, though some folks have reported good results with plateless or suspended tube. How tubing is affixed is a big design factor. Number of tubes per joist depends upon heatloss characteristics, length of run, water temperature, and flow. Typically, you try to start runs and add extra tubing area near outside walls to compensate for heatloss. In the field, 2 tubes per joist bay is common. Design is very important for good results. Takes some research or hired expertise to get it right.
Thanks for the information. I read on AIM's website that I should avoid heat transfer plates due to possible visible striping on the surface of the hardwood floors, and that only reflective insulation is necessary underneath the tubing. Other things I have read conflict with this. Some people on other message boards say that the plates are necessary. I am trying to get the right answer on this one as it seems pretty important. Won't reflective insulation placed underneath the tubes work just as well with or without plates?
"Thanks for the information. I read on AIM's website that I should avoid heat transfer plates due to possible visible striping on the surface of the hardwood floors, and that only reflective insulation is necessary underneath the tubing. Other things I have read conflict with this. Some people on other message boards say that the plates are necessary. I am trying to get the right answer on this one as it seems pretty important. Won't reflective insulation placed underneath the tubes work just as well with or without plates?"
This is a matter of great debate. Personally, I favor the plate argument. Plates enhance conductive transfer, allowing for lower water temperatures, and faster response time. I like AIM as a supplier, and they tend to have good pricing, but I disagree on this point.
I have read a number of studies on this. Thermal imaging shows that plates improve conduction, and disperse heat over a wider area. The 'suspended tube' camp argues their method saves money and install time (while providing even heating), but then the suspended tube specs require higher water temps. In the case of condensing appliances, higher operating temps means less efficiency. Also, many suggest PEX-AL-PEX tubing for suspended, which costs a lot more. This has to do with the difficulty of getting regular PEX to stay put and remain supported in a suspended application (it does also add some thermal mass). You also become more reliant upon the insulation below, and would want to be more fussy about sealing the cavities tight to keep the hot air captive. In my assessment, any labor or cost savings with suspended are wiped out by these additional considerations.
Anyways, the more questions you ask, the more conflicting opinions you will get...
If you are serious about becoming educated in hydronics, consider this text by the oracle of wet heads:
http://www.hydronicpros.com/Publications/MHH2/MHH2.htm