Infloor heating can’t keep up

northernsoul

Moved into a old house that has a small foyer between outer door and inner door. The space is about 6x6 with a tile floor.  No wall insulation and the outer door is very old thin wood  and drafty.   The foyer has a true comfort in floor electric heating - not sure the wattage or size.

If I set the thermostat to 77F it struggles all day to try to get there and the room air temp is always about 15-20 degrees cooler than the thermostat temp.  Right now it’s below freezing outside.  I’ve tried to seal the door gaps with weatherproof strips but the door really does need to be replaced with a solid insulated one.  

 I’m not sure if the prior owner just intended for the heating in there to keep that foyer above freezing as it seems it would never be able to get the room up to 70 or higher and the room is really just a mud room for shoes and coats etc.   I just feel I’m throwing money away to keep them room somewhat warm.

is there anything I can do to improve the efficiency?    How can I see If the heating coils are even working properly? 

Zman

Do you have an amp meter? IR camera?

EBEBRATT-Ed

First thing if you really want to heat this without heating the outdoors is fix the doors, install insulation and a vapor barrier. Then you will probably find the electric heat adequate. An amprobe will tell if the elements are good. You might want to open it up and clean all the dirt and dust out. If it's floor mounted i am sure it needs it.

northernsoul

EBEBRATT-Ed said:

First thing if you really want to heat this without heating the outdoors is fix the doors, install insulation and a vapor barrier. Then you will probably find the electric heat adequate. An amprobe will tell if the elements are good. You might want to open it up and clean all the dirt and dust out. If it's floor mounted i am sure it needs it.

thanks - we are replacing the door in the spring so that should help.  The foyer walls are original stucco (1870) so would like to avoid  opening them up.   

I can feel some heat through the tiles but I don’t know exactly when it was installed- based on the wall thermostat model I’m guessing 10-15 years ago. 

Will see if I can get an infrared camera to see heat distribution before I tear up the tiles and trim etc.

kcopp

Makes me wonder if the intent was not to actually heat that space but just warm the floors and keeps boots dry.
Where there is so little insulation and a garbage door you will never get there...

HVACNUT

What's under the floor? Slab, crawlspace, basement?

northernsoul

HVACNUT said:

What's under the floor? Slab, crawlspace, basement?

Good question - not a basement as there is only a partial basement - it’s either a concrete slab on the ground or flooring above joists on sill.- I can’t see between the joists as someone filled the area with spray foam. Praying that when they installed it they put down some insulation and didn’t lay coils right on a slab.

Jamie Hall

A heated mudroom? How luxurious. But unless the door is tightened up, the slab is actually insulated, and the walls are insulated... the best you can hope for is that the floor is warm. Sort of.

Chris_L

kcopp said:

Makes me wonder if the intent was not to actually heat that space but just warm the floors and keeps boots dry.
Where there is so little insulation and a garbage door you will never get there...

Yes, it is unusual for electric floor heat to be the only source of heating. The output is only 12 or 15 watts/square foot.

In this case, that means at most about 400 watts total, which isn't going to be nearly sufficient for a poorly insulated entryway.

I had electric floor heat installed in a reconstructed sunroom a few years ago with R38 insulation in the ceiling, R30 in the floor, and R20 in the walls. It is the only source of heat. It works ok, but only because there is an open doorway to the home (and a steam radiator next to the doorway).

PC7060

What @Chris_L said. 

This topic comes up often on johnbridge.com; a great site with a bunch of friendly knowledgeable tile folks. 

Under tile floor electric warming systems such as Schluter Heat or WarmFloors are design for bare foot comfort and are not intended to heat the space.   

I expect the temp you are setting on the control is the floor temperature as these systems have embedded sensors under the tile. 

jumper

Jamie Hall said:

A heated mudroom? How luxurious. But unless the door is tightened up, the slab is actually insulated, and the walls are insulated... the best you can hope for is that the floor is warm. Sort of.

Even powerful floor heating cannot keep up with continuous frigid air to make room toasty. But is 50° so bad?

In milder climates I've heard of contrary approach. Floor is heated with solar thermal and slab is NOT insulated. Eventually ground stores enough heat to provide comfort all the time. So if OP is rich he can leave heat on 24/7 all year and report back in 1924.