Floor Heat Help

[benjamins]

Had no idea where to get honest information so I thought with the wealth of knowledge on here someone might be able to help me out. I built a house this summer, slab on grade around 2200 ft2 with a 250 ft2 bonus room and a 1200 ft2 garage. The house has floor heat with a propane on demand heater as well as a propane furnace. I have been using anywhere from 150 to 200 gallons of propane per month (even before this cold snap). Does this seem reasonable? It seems high to me especially since I have been keeping my garage at 40 (slab temp). We do live in the wide open so wind is an issue, I was just always under the assumption floor heat is really efficient?

I also do not know how to set the floor heat temp vs the furnace. Should I use the floor heat for the main heat and only use the furnace for sudden cold snap to even things out? Or do I use the floor heat to keep the house around say 60 and use the furnace for more of the work? And since I have shown how little I know about anything, Do I use the air temp at the thermostat to control the floor heat or go off the inslab temp (keeping that at 82 keeps the house around 68). I tried going off of air temp and it seemed to frequently over shoot and make it too warm but maybe I didn't have things set right. Thanks for any insight and sorry for the painfully dumb questions!

 

[Zogman]

Where are you located??? What about the mechanical contractor that did your work or was is a DIY??? The floor heat, I assume is a propane boiler. Was the floor insulated underneath and down on the sides???

 

[benjamins]

I live south of Fargo. It was red river mechanical that did everything with laying the tubing and installing the boiler. I know the slab was insulated below the tubes but not sure about the sides, I was not able to be there at that point.

 

[Wall-eyes]

I have a 1,600 sq ft ranch and 1,600 in basement use around 100 gallons month, super insulated when built.

 

[Zogman]

​Sent you a PM.

 

[ShootnBlanks]

There is alot of different variables in your question. Besides how the house was built and insulated, I assume the on demand you are talking is a tankless combi boiler? As in you also run your domestic water off it as well? Is there other appliances that run off LP? Does garage have a secondary heat source for recovery if doors are open alot? You have a dual purpose stat with slab sensor, so u can make some adjustments on floor temp range i assume. And typically floor heat will be set a couple degrees higher than forced air, yes using furnace for real cold snaps and quick recovery. Honestly you may not be too out of line at how much you are using.

 

[BrokenBackJack]

Need to find out if the sides of the slab was insulated as well as under the slab. If not that is a big problem.
How well the house was built and insulated is another big question.
What else uses propane in the house?
Is the garage slab, floor heat as well?

 

[Zogman]

​Times 2 on the sides of the slab.

 

[benjamins]

The only things on propane is the on demand boiler for the floor heat (garage and house) and the furnace. I know the slab was insulated under the tubing but not 100% on the sides of the slab. Im pretty f'ed if that wasn't done huh?

 

[Zogman]

The only things on propane is the on demand boiler for the floor heat (garage and house) and the furnace. I know the slab was insulated under the tubing but not 100% on the sides of the slab. Im pretty f'ed if that wasn't done huh?

No you can dig along the sides and install some insulation board. I have seen it done, its not fun but can be done.

 

[AaronJ]

I just want to find someone that will set me up with floor heat in my shop (elec is fine). I have 3 zone loops. The propane air unit is killing my monthly budget.

 

[BrokenBackJack]

AJ
You now have 3 zones of tubes in the floor if i am understanding correctly?
You currently don't have them hooked up and are running a propane furnace with forced air or the garage style hanging furnace?

 

[AaronJ]

AJ
You now have 3 zones of tubes in the floor if i am understanding correctly?
You currently don't have them hooked up and are running a propane furnace with forced air or the garage style hanging furnace?

Yes. Bare tubes stick out out of floor in my unattached shop. Currently heated with propane forced air unit (propane). My attached garage has floor heat hooked up (electric). My electric bill only goes up 15-20/mo with the garage set at 55 degrees. Went through over 400gal of propane in just over 2 months. The shop propanc usage is insane when I had to heat it to 60 to work on a fiberglass boat project.

 

[remm]

I just want to find someone that will set me up with floor heat in my shop (elec is fine). I have 3 zone loops. The propane air unit is killing my monthly budget.

You got natural gas close by? I'd go NG boiler if possible.

 

[AaronJ]

You got natural gas close by? I'd go NG boiler if possible.

No natural gas. Propane and elec.

 

[espringers]

The lack of ng access in parts of this region is fucking frustrating. None at my house. None at our rental cabin. Excuse for cabin on acorn ridge is the road is a "dike". So, they are not allowed to bore through it despite the miles of drain tile and pumps on the dry side. I could save an average of 200/month at each place with NG v propane at home and electric at the cabin.