hydronic heating system not transferring enough heat

Unknown

you're getting 10 to 20 BTUs/sq ft... operating as intended. You could up the water temps up to 160, 170 and get more heat out of it... but if you have high heat loss, you picked the wrong radiant installation method. If it's a high enough heat load it's possible that no radiant method could have done the job.. that one least of all.

If you can fix your envelope, maybe that will change. This is why you always do the envelope first, heating second.

bill_82

hydronic heating system not transferring enough heat

i replaced an old radiator system with an under hardwood floor hydronic heating system..i used half inch copper and bubble aluminum insulation to cover tubing with 6 inch insulation under that...not getting the heat transferr that i would expect...this is a do it yourself system in an old house in boston area....don't have flow meters just block values...whole floor system is under 300 feet and have divided into 4 zones...would it be better to convert to one zone...don't know where to start lookin...putting in 150 degree water and getting back 140 degrees...someting should be hotter than it is...thanks bill

ALH_4

tube

Is the tube against the subfloor or is it suspended? If it is suspended, approximately how far is the tube from the floor and the insulation?

bill_82

tube

the tubing is appro. 2 inches from sub floor...with bubble reflective wrap below it the insulation....ck'd flooring surface with ir thermometor and it reads around 75-80 degrees...think it should be more... this is an old house and has lots of heat loss at this time and will address that later but trying to get this new system working right before moving on...

don_185

300 feet

of pex at 35 btus is not alot of btus.What is the heatloss
of the home?

Your floor surface temps looks pretty good to me.

bill_82

tube

don't know the number, windows have been upgraded but walls are not insulated, high ceilings, the furnace is running about 180 deg and the tubing is reading 150 input to system and 140 coming back...didn't know if that was good or was there suppose to be more heat loss to the floor, if that makes any sense... would it make more sense to tie it together and run one zone, thinking ..the water would stay in tubing longer and give up more of the heat or would the end of the line just get colder??? thanks bill

Unknown

that won't help, and if your walls are not insulated, this radiant system will not heat your house to regular room temperature when it's cold out, period.

If you have a mixing device though, you can turn it up a bit to get a bit more heat out of it. but tying the zone together would make this worse, not better.

bill_82

tube

thanks...any suggestions...wood siding...2 story...?//

Unknown

insulate any way you can.

ALH_4

heat loss

I'll second Rob's advice. Crank up the supply temperature. That's all you can do without altering the system drastically. Is the tube 8-inches on center under the floor? At this point, finding a way to cut your heat loss is probably your best investment. Have you looked at Icynene pour foam? The only drawback I can see to this method is with old, already dangerous, wiring in the wall cavity.

joel_19

Bill

We are just west of Boston and I'm sorry to tell you that is just never going to heat your place. I see insulated homes that need supplemental with staple up. we'd never be able to heat a house here without insuation like that. You probably need 30++ BTU per foot of floor area. It's not just about insulation,infiltration is an even bigger factor.



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Weezbo

Wow! this is amazing...this sounds just like another post ...

i just read.

You might be better off installing baseboard at that temp...

convectors can run even lower temps than you might think..

dangling tube heat is relatively expensive to operate when you are finding the need to continually jack the temps UP to get any heating out of them.

what does this copper bubble wrap around the pipe do actually in this formula?

i have never seen it... do you have a picture?

i saw a picture once of something that resembled tin foil dangling off some tubing.. it was freakishly applied and gave it a very "One Off" look.

i use tinn foil also, however i use it to protect tubing from sheetrockers and painters..and sometimes i use it on radiant headders that are out in the sun..that with a contractors grade garbage bag keeps the UV off the tubing...

pipefitter#51

I think What Bill is saying is he used 1/2 copper pipe and a reflective al. foil backed bubble insulation under the pipe to reflect the heat back into the dead air space backed up with pink insulation. I remeber a couple of years ago a radiant system used what looked like baseboard fin tube suspended under the floor to get enough surface area to transfer the heat into the insulated dead air spce.

Phil_20

The plates are used to increase sulface area for increased surface area of the existing tube. It is used when proper water temps do not maintaine the 83 degree optimal floor temp.(before you do the hot foot dance). Bumping water temp until floor is maintained at a max of 85 degrees will do a little. Insulation is the best solution for comfort but equally important efficency.