Garage sub floor heating problem

[sask-doo]

New gf has subfloor heating in her garage. Got the water heater fired up this week got a few leaks fixed. Topped up and pump primed.. Heat is flowing and it is warming up.

However...

She said she was never able to get it warm ambiently. Above freezing but not warm enough to work out there in a tshirt. Ill get specs on the circ pump and water heater later. But i dont quite understand what could be wrong.

Dad had a shop with subfloor heating as a kid and i remember being in there in a tshirt lots. I dont know the r value of whats in the walls and roof. Was done when she moved in.

Id ask dad but hes passed on. So is this normal for subfloor... It drying well an keeping it above freezing.. Or is this off?? I think im missing something here as it should be hotter then this.

 

[storm1972]

if its a cemented garage floor you should feel warmth to the touch at the very least, sometimes there can be an air blockage , or a leak in the system, plumbers should have a gauge installed on the system during the concrete pour that will hold a constant pressure, if that pressure bleeds then there is a leak in the system, typically in the apex lines if they concrete installers werent careful during the pour.It can any number of things really, however a plumber would give you some better insight, i am only speaking from past experiences installing the lines ect.

 

[Summiteer]

Is there insulation under and around the outside of the slab? If not you can burn a hell of a lot of gas and do nothing but melt the snow outside the garage. Are the lines coming back to the water heater warm? If they are almost as hot as going out there may not be enough pipe in the concrete to allow heat to transfer to the slab. If the water is cold coming back to the HWH there may not be enough flow to heat the slab. What temperature is the water going into the slab?

 

[SledMamma]

New gf has subfloor heating in her garage. Got the water heater fired up this week got a few leaks fixed. Topped up and pump primed.. Heat is flowing and it is warming up.

However...

She said she was never able to get it warm ambiently. Above freezing but not warm enough to work out there in a tshirt. Ill get specs on the circ pump and water heater later. But i dont quite understand what could be wrong.

Dad had a shop with subfloor heating as a kid and i remember being in there in a tshirt lots. I dont know the r value of whats in the walls and roof. Was done when she moved in.

Id ask dad but hes passed on. So is this normal for subfloor... It drying well an keeping it above freezing.. Or is this off?? I think im missing something here as it should be hotter then this.

Definitely not normal. We have a wood boiler/radiant floor system for our whole house: more than 5000 square feet when you include the garage. The floors are always warm. The garage floor is warm enough to wear bare feet and work in a t-shirt. At this point, it isn't taking much fuel to accomplish this either, since it hasn't been very cold. I fill the boiler once a day with wood and it is ambiently warm everywhere in my house, including the basement. The old owner told me when we first moved in that if we didn't feel the heat, it probably had air in the system that needed to be bled out. After that, suspect the thermostats or pumps... That's all I know.

 

[sask-doo]

Im question the insulation. She didnt have it done.. So i dont know the history on it. There are two other lines coming out of the floor that im wondering if there not other cycles.. But ive seen lots of garages where there is 2 extra pipes not connected to anything.

 

[Crazy8]

Right now the slab temp. in my garage is about 17c, ambient temp is about 13c. I all comes down to insulation. Under slab, walls, ceiling and doors. I have R12 foam below slab, R20 walls, R60 ceiling and R16 doors. If it's not an insulated door you will have a hard time keeping heat without forced air.

 

[mach123]

I also think it sounds like under or no insulation below, losing all the heat down and nothing pushing it up. How many lines going into slab and how many coming out. Or what do you see as of lines in total.

 

[sask-doo]

2 lines in 2 lines out. Only one set is being used currently. Im gonna try to set it up so that both r running..

Ps
Whats the best place to have ur pump. On the outlet so its forcing to the lines or on the return so its forcing to the tank. Or does it matter?

 

[Open Season]

There's more restriction in the lines and it's easier for a pump to push than pull so put it downstream of the tank.

 

[rsaint]

Hooking up the 2nd set of lines will help but the hot water heater is not the best choice for efficency. What size are the lines and square footage of garage.

 

[250mark1]

You can't not legally use a hot water tank for under slab heat unless you also pull domestic hot water off of the same tankDue to plumbing code changes a few years ago as hot water heaters are not designed for space heating

 

[mach123]

x2 and can be very dangerous,

 

[Summiteer]

2 lines in 2 lines out. Only one set is being used currently. Im gonna try to set it up so that both r running..

Ps
Whats the best place to have ur pump. On the outlet so its forcing to the lines or on the return so its forcing to the tank. Or does it matter?

If you put the pump on the inlet to the heater it pumps the water after the slab has cooled it off some.