water heat - oil versus electric

Off the top of my head, I think we're at .16 per kwh. I just checked my oil distributors website, and they're listing at:

DAILY OIL PRICE =3D $4.199/gal

Reply to
Pauli G
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Generally speaking, most homes in New England have full basements and this is where the water heater is normally located; this area may be finished or unfinished and, by extension, conditioned or semi-conditioned. For roughly six months of the year, a HPWH would be pulling heat from the home when there is presumably at least some heating demand, while during the remaining six months it would provide free dehumidification and cooling.

That could be key. Living on the coast, I run my basement dehumidifier seemingly non-stop from May through September; otherwise, I run into serious issues with mould and mildew and musty odours. If a HPWH eliminated that demand by providing both hot water and "free" dehumidification, it would save me about 1,800 kWh/year (i.e., 150 days at an average of 12 kWh/day). So, in this case, not only would a HPWH cut my water heating costs in half, it would eliminated the second largest electrical load in my home after my heat pump.

With respect to winter operation, we should still come out ahead. Assuming the HPWH is located in a fully conditioned space that is heated by oil (arguably our worst case scenario), it would likely consume 10 to 12 kWh of space heating demand per day depending upon how much hot water is used. It then becomes a matter of comparing how much oil would be used by the OP's boiler or furnace to supply the heat subsequently taken away by the HPWH versus the amount of oil that would be needed to provide the same amount of hot water using a conventional, stand-alone tank. Most oil-fired boilers and furnaces have an AFUE of 75 to 85 per cent -- a conventional, stand-alone oil-fired water heater would have an EF of 0.50 to 0.55. Thus, to generate the same amount of hot water, an oil-fired boiler or furnace "feeding" a HPWH would consume about one-third less oil than what would be required to operate a stand-alone tank. Moreover, an oil-fired water heater would suck conditioned room air up the stack 24 hours a day whereas an electric or HPWH would not.

When you add it all up, a heat pump water heater makes a lot more sense, even when your electricity costs are almost double the national average.

Cheers, Paul

Reply to
Paul M. Eldridge

Hi Paul, I have talked with my plumber/HVAC guy and canceled my order for the replacement Bock oil water heater - I'm going to convert over to electric water heat now. Question: what brands/models do you recommend? I know I should get a 9 or 12 year warranty one, but anything specific that you like brand wise? (50 gallon)

Reply to
Pauli G

Get what has the best insulation and install thermal breaks on the water lines at the heater.

Reply to
ransley

Hi Pauli,

I'm not sure there's a lot of difference between one brand and the next -- I get the impression most are made by the same handful of manufacturers who just slap on the appropriate name as they come off the assembly line. For example, the Sears Kenmore model I brought home yesterday is made by State (I also heat my DHW with oil and this electric tank is a temporary stand-in until such time as I can get my hands on a GE HPWH).

If you think a HPWH makes sense, see if you can lease an electric water heater from your local utility during the interim -- some still offer this service but most have abandoned this practice which dates back to a time when electrical utilities were competing with gas to build load. If this option is available and you don't plan to keep the tank very long, it could save you some money provided you can terminate the lease without penalty.

That said, if you plan to buy your own tank, look for one with a high EF rating, preferably 0.93 or better. Also, check to see if your state and/or utility offers rebates or low-interest financing on high efficiency models (again, some do/some don't). With respect to warranty, find out who else in your neighbourhood has an electric tank and see how long they generally last; if you live in an area where tank life is cut short due to aggressive water, a longer warranty might make sense, but keep in mind that if it's pro-rated by years of service, it may not be worth a whole lot should your tank require replacement towards the latter part of the coverage.

Definately take a look at TOU rates if you think you can shift a reasonable amount of your electricity use to off-peak hours. Your electricity is particularly costly, so you could presumably save a good chunk of change without hopefully too much inconvenience. If you do decide to go this route, get a larger model (e.g., 80 gallon) so that you have sufficient capacity to ride through the peak periods.

Cheers, Paul

Reply to
Paul M. Eldridge

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