thinking of electric boiler

jacobsond

With propane going sky high Im thinking of going dual fuel and adding an electric boiler to by current hot water heat.What is the best way to decide on the size of the electric boiler?My current furnace is over sized at 150,000. Aprox 2000sq ft house. 1/2 the house is 100yrs old little insulation except the back plaster between the studs 2x4 walls. The other half  is 2x6 walls well insulated. I think I have at least 20in insulation in the attic. Right now I have a few 120V base board heaters installed on their own thermostats to try to supplement and some good quality oil filled space heaters. I can easily keep the downstairs 65F. I would like to add the boiler and use my current baseboards.I dont like to shut the hot water heat down because there is a supply and return in the outside walls and I am afraid of freezing. I have never had an Issue with freezing even at the -25 it can easily get here it still concerns me. There has never been a heat load calculation on the house.

SWEI

Heat loss calculation

is always your first step.  How many feet and what kind(s) of baseboard do you have?



I'm assuming your "furnace" is actually a boiler.  Assuming it's an 80% unit, you would need 146 Amps at 240V to equal its output.



http://www.eia.gov/neic/experts/heatcalc.xls is worth a few minutes of your time.  Around here, electric resistance heating works out to $2.78 per gallon LPG equivalent (again, for an 80% boiler.)

jumper

individual heaters are preferable

I especially like low wattage oil filled.

Gordy

Agree

With SWEI, and jumpers comments. Around my neck of the woods electric is 12 cents a kilowatt after all the fees. A sizable electric boiler would equal what your paying on LP almost.

MikeG

Propane vs Electric

In my neck of the woods NW Ohio, like other places there is a propane shortage they say.  Fills are limited to 100-200 gallons.  Temps have been -10 at night and single digits during the day.  I'm burning $2.67 a gallon propane right now but when they come and give me 200 gallon any day now it will be $4.32 a gallon with all taxes and fees.  I have a Munchkin boiler at say 90%, electric at 100% at $0.12 KWH.  I can plug im my 240v 4000 watt electic heaters and save $14 per million BTUs.  With temps we are having I was going through 2% a day, 10 gallons, soooo $26 - $43 a day.  Generally design day is 0* here, but truthfully we don't hit that for very long. Below zero not unheard of but not opften. This winter is the exception.  My propane supplier blamed it on the farmer and the good fall harvest and all the corn that had to be dried. I figured my heat loss at around 36,000 using design of 10* and 68* indoors.  Looking at the numbers and usage it was pretty close.  The boiler ran pretty much steady for those real cold days.  Had -17 with 30 mph winds which did make a difference.  I have finned copper BB so I think it was more an issue of under radiated in one area.  The boiler was fine.  Also some of the propane suppliers around here have encouraged their customers to any form of alternate heat.  Some have even offered electric heaters at cost.  The issue with an eltric boiler is the possible cost of the service upgrade  Just my thoughts

SWEI

36,000 BTUs per hour

is only 44A at 240V.  Unless you have a 100A service, that should be do-able.  If you have enough degree-days an air source heatpump might be worth considering.

hot_rod

cost of electricity

does vary widly, ND typically has low cost energy and often times offers really low off peak rates. This is where a lot of the thermal storage concepts and products are developed. if in fact you are in the $.07 range, an electric boiler may be a good hedge.



i'd invest in tightening up the home as much as possible first, do the load calc, then look into the breaker panel and see what you have loaded, contact an electrician for sizing help.



Solar potential in that sunny part of ND?

jacobsond

electric

I have a 200A pannel and 30A off peak water heating panel.If I would go the off peak way I believe I can increase the off peak amps. I have considered looking into thermal storage off peak with rates as low as .04 but I am not sure how that would tie into my current hot water boiler setup. For now I have plenty of 20A circuits in the house so overloading the electric with the oil filled space heaters is not really and issue.My design flaw of the pipe run upstairs in outside walls is my concern when I use a lot of electric and the boiler doesn't run. .It might be better to move those pipes this summer.

                                     I would have to combine some circuits to hook up an electric boiler

to anything other than off peak and honestly I don't know if I would want a boiler that pulled over 30-40 amps which would mean an electric boiler to small.

SWEI

Thermal storage

is relatively simple with hydronic heat.  Basically a tank full of water that you heat duing the off-peak times, then draw just what is needed out of the tank all day long.



I'd suggest you start by finding out what the off-peak service is capable of as a first step.  I've not seen a utility drop capable of less than 125A installed in the past decade or two.

mjcromp

duel fuel boiler

Electro Industries makes a top notch electric boiler that is set up with a duel fuel control.

If your electric company has a program for being able to shut off the electric and switch to gas this boiler is setup for that.