Temporary radiant heat ??

[1low1]

Newbie here !! I just built a 33x40 post frame building and still need to pour the concrete and here is my dilemma. I don't really have the budget for much more than my concrete. My pex is laid down for in floor heating and the building is un insulated. I can save a lot on labor if I pour before spring. The problem is the ground is frozen. I have enough insulated tarps to either cover walls and ceiling and try to thaw ground with heaters or put heat to my lines and cover them with the tarps. I like the idea of heating the lines but I don't have the $$ for the proper system. I do however have an old boiler I could use temporarily. Is there an economical ( ok cheap) way to set it up temporarily? I don't want to use the boiler long term because it is old and probably not too efficient,and I also don't want to hook up too many hard lines as I haven't fully decided on placement of my system yet. Any Ideas?

 

[sberry]

Wait till spring. Any scheme to save on labor will be eaten back by fooling around. Been there, done it.

 

[RegeSullivan]

If you have properly insulated under the pex it could take a lot of energy to thaw the frozen ground. You might not thaw the perimeter at all.

If it is not properly insulated it will be pretty expensive to heat your building going forward. Properly insulating under the slab and around the slab perimeter is very important for keeping the cost of heating under control and having a comfortable building. Here is a quick read that might get you doing a little research if you have not already done so. http://inspectapedia.com/heat/Radiant-Slab-Heat-Mistakes.htm

This is one of those things you usually only get to do once or is a "wished I woulda" for a life time.

 

[wssix99]

Are you insulted? We had the same problem last year and built a little temporary platform (hanging off the walls) in the corner of the garage and put a gas-fired construction heater on it. If you are insulated, a single heater should make the space warm enough to thaw the ground and keep things from freezing after the pour.

 

[Kaizen]

1low1 I think you need to tell us more. did you put insulation under it? if so then guessing the ground was prepped already? if there are footings and it was prepped already it might be doable but if not then forget it.
just the energy you will use to defrost Canadian frozen ground at this time of the year would be the same you will save.
a cheap thought if you try it is use a water heater and a circulator. depending on the size it might work. pex should have lower temps then boilers normally run at.

 

[1low1]

I haven't got the building insulated yet so that is a problem. The two feet inside the perimeter of the building and two feet outside the perimeter of the building have 3" of insulation. I know some believe that that is not adequate but I am with what a local engineer suggested. Apparently unless I shut my system off for long periods in the winter the I won't recoup the cost of the rigid insulation for a long long time , and if I keep it at a constant temperature for the season I would be fine with just the perimeter.
Back to my problem with the frozen ground, if I can thaw the ground before spring I can save roughly $1500 on the labor because the crew is very slow. If I have to wait until spring everything goes up.

 

[mikewatson]

question is..... can you afford to redo it and tear it all out if it get all fuged up and cracks and shifts from being poured to cold ? its worth the $1500 to not have to worry it

 

[1low1]

If it can't be done with out being sure the ground is thawed and I'm not compromising the pad I won't do it. There is equipment and people who do ground thaw for concrete pours but to hire or rent equipment obviously won't save me anything. I was just throwing the question out there in case anyone had done anything similar. If not I wait until spring.

 

[Bondo]

If it can't be done with out being sure the ground is thawed and I'm not compromising the pad I won't do it. There is equipment and people who do ground thaw for concrete pours but to hire or rent equipment obviously won't save me anything. I was just throwing the question out there in case anyone had done anything similar. If not I wait until spring.

Ayuh,.... Yer right,... No reason ya can't Diy it,....

I think it'd work best if ya tent the floor area, rather than tarpin' the walls, 'n ceilin's,...

Yer only worried 'bout the floor, not tryin' to heat the whole shed,...

Put yer insulated tarps on top of the floor, 'n hook up yer old boiler, 'n let it go,...
It'll be thawed in no time,..

Lower the set-temps on the ole boiler, it's probably runnin' 180° or so,...
Too hot for radiant,....

Once poured, the concrete will build it's own heat, so just cover it, 'n shut the boiler off,...

 

[Kaizen]

just don't think you will be able to thaw it with stuff on the top like attached radiant. if you had radiant in the middle then yes. the thermal mass is just too much imo.
and I completely disagree with the engineer only due to the fact that you'll be wasting heat into the ground. in other words ******* money away.

 

[wssix99]

question is..... can you afford to redo it and tear it all out if it get all fuged up and cracks and shifts from being poured to cold ? its worth the $1500 to not have to worry it

If you aren't insulated yet, it's going to be very difficult to get it done before spring. You have to get the ground warm and for a period of time. Just in the heating costs, you'll spend the better half of that $1500 savings in heating costs.

 

[1low1]

Thanks for all the input, I'm going to ponder my options and talk to my concrete finisher for some more input. Probably wait until spring if I'm looking to save money screwing it up won't accompish that will it.

 

[pstnbly]

I haven't got the building insulated yet so that is a problem. The two feet inside the perimeter of the building and two feet outside the perimeter of the building have 3" of insulation. I know some believe that that is not adequate but I am with what a local engineer suggested. Apparently unless I shut my system off for long periods in the winter the I won't recoup the cost of the rigid insulation for a long long time , and if I keep it at a constant temperature for the season I would be fine with just the perimeter.
Back to my problem with the frozen ground, if I can thaw the ground before spring I can save roughly $1500 on the labor because the crew is very slow. If I have to wait until spring everything goes up.

That engineer needs to go back and re-examine his thermodynamics. Underslab insulation needs to be continuous to provide thermal isolation. Don't pour your slab now, it takes huge amounts of heat to drive the frost out of frozen ground and the risks of placing concrete on frozen sub-base are not worth it. Save your money and properly insulate before pouring the floor, you only get 1 chance to do it right ( 2 if you have a jackhammer )

 

[1low1]

I'm going to be speaking with with my concrete guy this week and delay until spring. I don't want to risk having a lousy pad. Thanks for all the input everybody!!

 

[RegeSullivan]

I encourage you to get really good understanding of the heating system you are installing. Properly insulating under the slab and slab perimeter and placement of the pex can make the difference of at least hundreds, maybe thousands of dollars every year in heating cost of a building that size.

Energy is relatively cheap today. Over the life of your building there will be more up than downs in the price of heating fuel.