Electric Radiant with uninsulated floor

Kjmass1

I have a 150 sqft room that we want to be a mudroom. It's raised/2nd floor with exposed floor joists to the elements (Boston climate).

I'm thinking for minimal heating like 65 degrees, I could get away with a 2000w wiremat to heat the room under the tile. (150sqft x 15w per sf). Could this work? Obviously not the most efficient but curious if it could keep up with 0 degree weather in the winter.

I could easily throw up some fiberglass batts in the joists but I don't want any critters. Spray foam is another option given how small it is. Wall insulation is average at best.

Thanks!

Snowmelt

This is a hydronic forum not an electrical.

hot_rod

If the room is somewhat insulated you should be fine.

2000W is about 6820 but/hr, that should add some heat to 150sq feet. How much depends on the tightness and insulation in the room.

Electric cable or mats are ideal for small spaces., insulation below is a must. Fiberglass batts, at least 6". Possible sheet foam if the wire mat manufacturer approves it. I think either could attract critters, especially if it provides a warm nest.

Zman

hot rod said:

If the room is somewhat insulated you should be fine.

2000W is about 6820 but/hr, that should add some heat to 150sq feet. How much depends on the tightness and insulation in the room.

Electric cable or mats are ideal for small spaces., insulation below is a must. Fiberglass batts, at least 6". Possible sheet foam if the wire mat manufacturer approves it. I think either could attract critters, especially if it provides a warm nest.

Absolutely.....

SWEI

Rock wool?

Kjmass1

hot rod said:

If the room is somewhat insulated you should be fine.

2000W is about 6820 but/hr, that should add some heat to 150sq feet. How much depends on the tightness and insulation in the room.

Electric cable or mats are ideal for small spaces., insulation below is a must. Fiberglass batts, at least 6". Possible sheet foam if the wire mat manufacturer approves it. I think either could attract critters, especially if it provides a warm nest.

Thanks- that's great to know. My heated floors in my bathroom crank and could easily heat that space by themselves. I'll look in to suggestions for underlayment before I tile the floor.

RobG

Snowmelt said:

This is a hydronic forum not an electrical.

Why would you say that? The web site is named "Heating Help", not "Hydronics Help". Please be courteous.

Kjmass1

Just an update- I installed new windows and door so that should help tighten things up. I'm planning on going down to the studs to properly insulate as well as do fiberglass in the joists covered with plywood.

I was mistaken on size, it is actually 80 sq ft not 150. The heated floor mat I'm looking at is 12w /sq which should be plenty.

Another option would be this wall heater which I use in one of our closets...it definitely cranks out plenty of heat and might be an easier solution vs heated floor tiles.

http://www.amazon.com/DeLonghi-HMP1500-Mica-Panel-Heater/dp/B005MMN75G/ref=sr_1_19?s=home-garden&ie=UTF8&qid=1436365967&sr=1-19&keywords=space+heater

Mark Eatherton

Critter control in insulation can be achieved by putting a dryer softener sheet in each bay, every 10 feet or so of the stud/joist bay. It's a standard in my mountain community, and we even leave sheets around the perimeter of the floor, and have never had a mouse or chipmunk issue.
Whooda thunk.

And if you have an existing critter issue, spraying a mint extract in the area will chase the critters away. Used that in our storage shed, worked like a champ. Also works on bats, if need be.

ME

Bob Bona_4

I've heard of that before, Mark but have not tested it. What's the life span of the sheets? They lose thier aroma after a time I would think.

Kjmass1

So I've insulated the floor joists below with R-21 batts and I'll add plywood on top to keep any animals out. I mentioned adding floor mats to my tiler who has done a lot of work with me before and he had some hesitations using it in a non-heated room like this. Would large swings in temperature cause cracking? It could go from 0 degrees to 100 degrees in theory. If I need to run the floor in the winter just to keep it from cracking, I'm probably better served with another heat source.

What about underlayments? Hardie board...ditra or redguard necessary?

I'm also trying to keep thickness to a minimum...one door is @ 1.5".

Thanks.