# electric heat question.

I am converting a detached one car garage at one of my rental houses to a studio (living space) and I am going to be adding electric baseboard heat. I just need some help on sizing the baseboards so I have adequate heat. I have attached a very rough sketch of the dimensions. TIA

I would advise that a qualified licensed professional familiar with local codes be hired to design/size, estimate and install the required equipment.

Make certain your electrical system can handle the extra load.

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One watt for one hour = 3.413 Btu.

David is correct. To do it properly you should determine your heat loss this can be done by a simple heat loss calculation. You need to know what insulation levels are (walls, ceiling and floor if any), window & exterior door sizes, external wall area (can’t tell from your drawing what if any part is attached to the house. And climate data for your location.

Or call an HVAC who will guesimate what you need and then over size it a bit to be sure. With elec baseboard it won’t matter as much if your over sized if they are controlled separtely.

The rule of thumb to size electric baseboard for spaces insulated to current standards is one watt per cubic foot of heated space. A proper heat loss calculation is more accurate, but with electric baseboard, the rule of thumb might slightly oversize the units, but that’s no big deal for electric baseboard heat.

The watt density of most electric baseboard is 250 watts per lineal foot.

Assuming 8 foot ceilings, the 16x12 space would need 1500 watts of heat, or a 6 foot heater.

The 16x24 space would need 3000 watts of heat. You can do this one several ways. Two six footers, an 8 footer and a 4 footer, four 3 footers, or whatever combination gets you 3000 watts of heat distributed nicely.

I just noticed that there’s a bath tucked in there. I would drop back to a 5 footer in the kitchen there, and put a two footer in the bath. A bit of extra heat, for fast pre-shower warm ups, is a good idea in a bathroom. In that living room, I would be inclined to do an 8 footer under the large window, and a 4 footer under the smaller window. This will keep most of the usable wall space open for furniture placement, and still provide good heat.

The apartment is going to have its own service.

Thank you guys. That is the advice I was looking for.

On a side note, and I mean no disrespect, I was expecting to get a response like Barry’s. I feel that too often we fall back on our “Home Inspector Responses” to defer when helping each other out. I would not expect anything else because you do not know me or my experience but I got a chuckle out of it. I will be performing the work myself which I am more than capable of I was just unsure of how to size it. The installing is not a problem.

I just find it funny because I know what I am doing and to have someone tell you to have an expert do it for you is sort of a kick in the *** but like I said before, I take no offense because you do not know me or my capabilities.

Thank you again for the responses.

Carmine

I’m not familiar with your part of the country, other than it is north of the M/D line and I assume is quite cold in the winter and possibly warm and humid in the non-winter months.
That being said, I noticed you didn’t ask/comment about A/C, dehumidification loads, nor about the utility cost to operate BB over say a Heat Pump or fossil fuel piggyback (either split or packaged) designed system. The space is small, but even at 500+/- s/f and 3 diff. areas to service, it may be worth looking at. Much more comfortable, reliable, flexible environmental control. Certainly more up front cost, but comfort and utility savings may out way the basic design you’ve chosen. I’d check out the local Utility Co. for a probable cost-free energy analysis. Depending on planned use., the investment maybe superior to your first choice.

Just a thought, one you’ve probably already considered. Good Luck

Thanks for the input Greg. I actually was exploring other options quite similar to your suggestions with my HVAC Tech that I used before home inspections. It would be a nice route to go however I am doing this project with a very limited budget. I am trying to maximize the amount of return for this propery as possible with a limited budget. Also, the utilities are my tenants responsibility so I am not too concerned with my utility savings.

Interesting, Mark. Up here in Nova Scotia (7500 DD or so), we use 7 watts per sq ft for a house with 2x6 inch walls with R20 insulation in walls and R40 in attics. For an older house with 2x4 inch walls (walls-R12 and attics -R32), we use 10 watts per sq ft. Both of those assume average air tightness and window sizes.

## Quote: Originally Posted by Marc D. Shunk The rule of thumb to size electric baseboard for spaces insulated to current standards is one watt per cubic foot of heated space. A proper heat loss calculation is more accurate, but with electric baseboard, the rule of thumb might slightly oversize the units, but that’s no big deal for electric baseboard heat.

WOW! sounds close to the same to me 0ne watt per cubic , and 7 watts per sq foot and seven feet high are close , and slightly over size = 15% comes out about 10 watts per sq. foot…
Sounds like you are both playing with similar figures .