boiler size/efficiency

Joe Brix

Then the only "waste" would be allowing the water to go to high limit and then the thermostat is satisfied, there would be BTU lost from piping and boiler as the heat radiated out to spaces you probably didn't want to heat. An outdoor reset would help, but your biggest issue is probably the cost of electric.

Why is a safety oil tank in a basement such an issue? You must have propane and natural gas in use and this could be more of an insurace issue. Electric houses burn down also.

Slingshot

Boiler sizing/efficiency

Here in St. John's, Newfoundland, Canada (the most eastern point in North America and the oldest city in North america) we are seeing a big increase in the sales of electric boilers and a decrease in oil fired units. This is due to several factors, mainly the strict enforcement of oil tank regulations, perpetuated by insurance companies after a record one day snowfall of six feet that ruptured many tanks and had the enviroment people freaking out. Also the debate on chimney/direct vent etc..
Our local electricity supplier will take a set of new home plans and tell the homeowner what heat loss is and what size boiler and main breaker panel they require. A new home is assumed to have R-20 walls, R-30 ceiling, 8" concrete walls for the basement with 4" cicrete floor. Low E windows. The rule of thumb they use is 7 to 10 watts per square foot or 24 - 35 Btu/ft. Taking this calculation a 3000ft house would require a boiler output of 21kw to 30kw. The catch is that when you install a boiler above 24kw you have to also install a 400Amp main panel which gets expensive so what most contractors do is use the smalest one possible. Sometimes this is TOO small. These boilers do not have outdoor reset. They have several elements that come on in stages. On a call for heat one BANK of elements is energized, thirty seconds later another and so on until all elemants are on. If the load is not heavy the boiler just cycles on its high limit.
I sold lots of these with widely varying results. I have one in a brand new house that has a light bil of $800.00+ a month bill. I have another in a bigger house that is running $500.00 month.
Can someione tell me what would be the effect of undersizing/oversizing the units?
Also, a few of the higher bills were from homes that were not occupied and the lower ones were. The h/o speculates that when they finaly move in the bills will be through the roof.
Any feedback would be greatly appreciated.
John O.

Slingshot

Oil Tanks

The insurance companies have a very bad taste in their mouthes since all the big oil spills a few years ago and as a result have been very specific about what they will accept in regards to oil tanks. The local chapter of Canadian Oil Heat Association has lobbied government to impliment new rules and enforce the old ones. Because our trades people did not always follow the CSA B139 code when installing or changing these tanks the situation just got worse and worse as time went on. The insurance companies can and do request modifications or upgrades that are not part of our code, nationally or locally. Apparently, they can do this. If they want an oil tank painted purple before they insure it they have that right. Because there has been such a big issue made of this around here oil heat is seeing a big slip in new homes and some older ones are going to electric when their oil fired boiler gives up.
I agree with you on electricity being 100% but there is something fishy going on when two houses of the same size have heat bills of so much difference. I am hearing that the hydro company has a charge for "demand" service. If there is a spike in demand you pay more. I am not sure how they do it but it would sort of explain the cost diff.
John O

Mike T., Swampeast MO

You might have given your own answer.

"I am hearing that the hydro company has a charge for 'demand' service. If there is a spike in demand you pay more. I am not sure how they do it but it would sort of explain the cost diff."

Particularly if they compute that high-demand rate based on a percentage of the size of the service. By using a [perhaps] undersized boiler on a 200A service, you might be paying more per kw/hr because of the high load percent. Surely the utility company can give you the specifics.

Nick_16

electric bills

Yes, the reason for your high bills is probally the demand charge. I live in Northeast Ohio, USA and our electric here is VERY cheap! Gas is about $1.50/therm and electric is about $1.05/therm. We have the option of have our demand count or not. You may want to look into that. I currently have electric forced air but am in the process of installing radiant with electric boiler. I don't know what brand you have but the one I was looking into you can control how many elements come on. So for example:

20 KW boiler = 4 - 5kw elements. You could set it only to kick on 3 instead of 4 and let it run longer to heat the water. This would help if they are oversized and would reduce your demand load.