Addition over garage - electric or oil?

Hello everyone... We are in the midst of building over our garage (master bedroom, closets, bath) and we are trying to figure out the heating system. The entire house has oil-based hydronic heat with 5 zones. The furnace is about 17 years old. The addition will add about 500 square feet to the heating space.

I also have a Jotul woodstove in the main family room which can heat most of the house (cut my oil consumption by 40% last year).

My contractor is telling me that our best bet is to install electric baseboard with a programmable thermostat for the new room. He says that the thermostat can regualte the electric heat and minimize when the heat runs. The room is extremely well insulated.

I'm inclined to agree with him since we'd really only need the room temp above 50 from 6pm - 11pm.

On top of this is the fact that our oil furnace is probably not big enough for the additional 500 square feet so we'd likely have to upgrade it. Now, given that it is 17 years old I'll probably have to upgrade it in the next 10 years anyway.

So.... what do you think? Does the electric heat make sense in this room? It would be nice to not touch the furnace, and when we do replace it would likely be cheaper to replace with a smaller furnace than a larger (to cover the 500 sq feet). I am just leary about the electric heating costs, but it seems to make sense that we wouldn't be using it all that much (with the programmable thermostat).

Any thoughts? Thanks!

steve

A room over a garage is a cold room. Not many fans here of other than hydronic heat. I would suggest radiant, and the very best insulation you can afford ( not fiberglass) to eliminate drafts.
The heat loss in a room over is very high relative to the rest of your home because of all of the exposure, so be very careful with this.
As to your existing boiler, have a heat loss calculation done, you may be oversized as is, and have plenty of capacity for this additional zone.
To me electric baseboard is a lazy easy , expensive way to heat a space- unless electricity is very cheap in Ct.
Chris

Thanks for the response. The room is very well insulated and should be fairly air-tight.

Any other comments out there?

Electric baseboard and hot water baseboard work about the same as convection heat. So it is a toss up for comfort.

Radiant panels are one of my favorite, but radiant floor are not always a good choice for bedrooms due to floor covering and "heat flux"
Heat flux is the room dimension divided by any furniture that could block radiant output. So a bed (with dust ruffle , closet, drawers, etc should really be calculated out of radiant floor dimension.

Your load on that room may be more than a radiant floor can handle, especially if carpet is your final answer.

I like low mass quick responding heat for bedrooms. An emitter that could be setback for sleeping and accelerate quickly for morning. Baseboard convectors, panel radiators, radiant ceiling or walls are all good options.

I suspect electric rates in your area are up there, and probably going to rise in the near future, from what I hear?

First calculate the actual heat load for the room, Here is a free, manual load calculator www.pprbd.org/plancheck/heat_loss.html

Decide which emitters you prefer, then compare oil to electric as a source as far as operating cost. They do make electric panel radiators and towel warmers for bathroom heaters. I'm not a huge fan of fin tube or electric baseboard in bathrooms. Consider a nice heated towel bar with it's own thermostat and setback timer. Myson and Runtal have some nice ones.

hr

We built a detached "barn" in 2007, that has a full second storey and attic storage trusses to support the roof. We live on a low lot and rather than get into a pissing match with the town for approval we opted to by-pass water to the building etnirely. We've layed all the lines and will be good to go if sewer/water comes to our "neck of the woods". BUT, my workroom is on the second floor of that barn. We installed a furnace and use hot air to warm the space when the stove is not in use. Because there is no water to the building I can let the temperature fall to freezing with little worry, but it's pretty nice to program the thermostat to bring it up to 56-60 degrees before I go out there and start the fire!

I agree that the space will be "cold". Insulate as well as you can below and above the floor and invest in a fully programmable thermostat that will strictly regulate any electric heat required. Insulation and taking control of the thermostat will save you a bundle!

Thanks. The bathroom will have its own hydronic heating element. It is 1/2 in the old space so there is already a water baseboard accessable.

I am not thinking of radiant heating in the floor. This electric heat would be from baseboard heaters, not underfloor heating. The floor is going to be a hickory wood floor.

The main crux is the boiler. If I didn't have to update the boiler due to the extra 500 sq feet I'd probably just do the hydronic, but by putting electric in I might be able to bypass the furnace update for another 6 or 7 years.

Oh, and I don't know how CT measures up with electricity costs, but everythign else here is expensive so I imagine that electricity is as well.

Assume a load of 30 btu/ square foot for example. X 500 sq.ft would require 15, 000 BTU/ hr.

4500 W of baseboard= 15,345 btu/hr. If you know your kw/hr cost you can do the math on operating cost at design condition.

New tight well insulated buildings can show heatloads in the teens, I've seen a few with 10- 12 BTU/ ft loads. Old leaky homes can exceed 30 btu/ sq.ft. This is why a load calc is so important.

Electric would be quick and easy if you have an additional capacity in your fuse or breaker panel, a 240V 30 amp circuit would be needed for 4500W.

Better have an electrician check that before you decide. Many times breaker boxes are close or over capacity on older homes.

hr

Wow... if this reads correctly Connecicut is 2nd in the nation in kw costs only to Hawaii... is that correct!?!? Holy crap.

I'll have to check the bills when I get home.

http://www.eia.doe.gov/electricity/epm/table5_6_b.html


Also, for those in CT, some reading...

http://www.cga.ct.gov/2010/rpt/2010-R-0015.htm

My guess, boiler already big enough, a wall mounted hydronic fan coil, cheap and easy.

If your addition is well insulated I doubt the heat load is going to be over 10kbtu/hr. My the original oil boiler installed for my home was 164k btu, which was about 3x bigger than needed for my construction type. After 3 seperate heat load calcs I came in at 90k on the high side, and this is after 1200 sqft of addition. My new boiler has an output of 90k, which is on the insane side of small for a 4300 sqft house in Southern NH. My plumber-in-law is waiting for this decision to bite my ass, but NUMBERS DON'T LIE! My guess is your boiler could handle it, and the cost of pulling pex to your baseboard is going to be the same as pulling wire to electric baseboard.

I'd go with electric baseboard and a wood stove if the price was the same as for hydronic baseboard only.

Thanks... I've been talking to others offline and there appears to be a 50/50 split. Many would do the electric since it is only one room and I don't have to touch the existing system. Others thik the cathedral ceiling and the fact that it is over the garage warrant the hydronic. Ugg... no easy answers.

My contractor is telling me that the install is about the same in terms of money. I find that hard to believe. Wouldn't the hydronic system cost more? It is a new addition so we have access to all the interior walls, etc...

Hydronic basebord is cheaper than electric, pex is about the same as 12/2 romex per foot, and depending on whether or not your inspector will require arc fault breakers a couple breakers is as much as a circulator. I wouldn't let cost be a consideration if its within $200. Hydronics is better than electric baseboard, and unless oil is close to $5/gal its probably cheaper.