radiant floor heat

[Northern Badger]

I am afraid I may have made a huge mistake, when I had my house built I decided to lay the tubing in the floor for floor heat and in my haste ( my contractor gave me 1 day to do it) I didn't lay insulation below it or vertically around the perimeter. Will this even work now or will the heat simply go down into the ground?

 

[tigmusky]

I don't know for sure! this is what I have heard.. under is not as important as the sides. I hear of alot of people just do the sides with good results.

hope this helps
good luck Daye

 

[Friartuck]

I believe you are right, not insulating was a missed oppurtunity. My only suggestion is to use rigid foam vertically on the outside of the foundation. The time to bring the slab up to temp will be longer (slab plus foundation), but once up the rigid foam will help keep the heat from wicking into the earth. Hope this helps.

 

[HoosierBuddy]

Based on your location, I think you're screwed.

I'd recommend you forget about radiant heat and go with another option. While you could get the radiant to work by throwing enough BTU's in it...it'll cost you a fortune to operate. You'll be heating a huge thermal mass under your floor and also the ground around your garage.

Your best bet is to go with a furnace or unit heater of some sort.

Phil

 

[Northern Badger]

Do you think this is the case even if I were to run insulation vertically around the perimeter of the foundation to somewhat trap the heat under the garage floor, I understand the heat will still travel down to some extent but at least it won't be going out horizantally 3 0r 4 feet around the garage. I was thinking of going down at least 3 feet all the way around.

 

[Northern Badger]

No huh? Ok thanks anyway.

 

[GerryL]

I have no experince without the insulation, but my propane delivery guy asked me how my floor was insulated when it was first fired up. I have 2" under and 1" around the perimeter. I've been impressed with how reasonable it is to heat my 1500sq ft shop.
The delivery guy said he fills tanks for someone in VT (I'm in western MA) without insulation, and he said I would not want his fuel bill. That's the extent of what I know; I've read the ground under the pad acts like a heat sucking sponge, but like I said, I have no direct experience.
-Gerry

 

[Friartuck]

Badger, The important part of insulating the foundation would be to get below the frost line, which for Ontario is likely to be about 4-5 feet below grade, which is a bit more than the 3 feet you mentioned. I'm sure this would work, the issue is at what expense? Once the slab is warmed, how much heat has to be applied to keep it up? You could do a temporary experiment using a hot water heater and circulator pump and see the results. I don't think I would spend any significant money. Perhaps the other suggestion of exploring other heating options might be the wisest overall $$ decision.

Gerry's comment above goes exactly to my point, at what expense??

 

[mobetta]

Did You install a vapor barrier?( plastic sheeting under slab?)

 

[jklingel]

Sorry to hear about this, and you are right; it is huge. The temp differential between the HEATED floor and the soil below will naturally be more (15-20* F?) than with an unheated slab, so your heat losses will be proportional (linearly). Typically, it is recommended to put a minimum of 2" of XPS under a slab, and in Ontario I suspect 4" would be typical. I think rugs and baseboard heat are in your future, or a jack hammer. I'm serious about that. Look into the cost or tearing out the old, unless your house is finished... How about the VB that was asked about earlier? If you don't have a good one, that may be more ammo for a tear-up job. You may want to ask the folks at healthyheating.com, or greenbuildingadvisor.com. Maybe they have some ideas. Any way to insulate and cover w/ the plywood made for retro fitting, then run new PEX in it? Obviously another huge project if the house is near completion. Man, good luck, and let us know what you decide.

 

[jklingel]

Here is one place w/ the plywood; no idea if it is on your plate as a "fix", but that is your call. Good luck. j http://www.warmboard.com/

 

[mustangmccance]

if this is in your house you could use warmly yours, it poured in thinset under tile or you can instal the wyfoil under hardwood floors or carpet. it won't get the money back for the pex but it would warm the floor. just a thought

 

[bazzateer]

Your contractor gave you one day to do it? Who's the boss?!

 

[Northern Badger]

Your contractor gave you one day to do it? Who's the boss?!

In all fairness it was a last minute decision and he had the concrete truck lined up for more than just my garage floor, I'm still the boss but just made a snap decision and have screwed up. No great loss really, just the pex tubing and a few hours of my time.

Looks like I'll be going with another radiant tube heater. Now, for the shop out back I'll be much more prepared to do this right!

As for the comments about jackhammering the floor up and starting over it's not worth it for me, like I said I'll just grab another radiant tube and call it a day.

Thanks for all the positive comments gents, great forum!

 

[bgarrett]

consider pouring a new floor on top of insulation on top of the last floor

 

[Moldy Oldy]

easy fix...try it out as is before getting all hot and bothered..see how much heat is transfered to inside air..you may be surprised..last resort..ceiling hung..gas fired heater....

 

[sneezer41]

Insulate the foundation well, and think about maybe a solar panel with a simple control for a little floor warming. No energy wasted anyway.

I grew up in a Campanelli ranch with heated floors and no insulation, pre fuel crisis. Worked fine, dunno what the bills were like.

 

[dellwas]

Previous owner in our house installed it in the basement. All he did was lay it on top of the concrete, and build a sub-floor above it. It would take three days of constant running before it would heat the room in the basement. Most of the time it was trying to heat the concrete below it. Finally ripped it out last summer, sold the pex, pump, and manifolds on Kijiji.