So I am thinking about putting in a 50 gal high-efficiency electric hot water heater to augment it, so that I can turn the boiler off when the domestic heat is not needed, e.g. over the summer. I understand others have done this, and have done quite alright saving money with a manual switch-over, so that their DHW is electric during the warm months and the oil boiler is "off" during the summer months.
However, being a bit of an engineer, I want to complicate this setup -- can anyone give me advice or gotchas on my plans?
- Electric HW heater is on full-time. - DHW comes from either electric, or boiler, and is switched by a zone valve, e.g. like a Taco 3-way. - A second Aquastat / temp switch installed on the boiler flips the zone valve to draw hot water from the boiler whenever the boiler temp is over a certain setpoint, say 120F. - A timer is rigged into the boiler Aquastat, so that the boiler is normally off (full cold), but goes on to the lower setpoint (~130F) when the timer is on -- this would be for anticipated high hot-water demand days / times, I am thinking 2x / week when a lot of laundry is done. The boiler is also on to the higher setpoint (~180F) whenever there is a call for domestic heating, (of course).
My aim is to utilize the lower fuel costs of the oil boiler when the thing is hot anyways due to a domestic heat call, or at certain limited times of the week when it switches on in order to supply a heavy hot-water demand (and economize the fuel cost). The aim is to keep the boiler cool, and supply hot water from the electric tank, at all other times.
Kind of different, does anyone see any gotchas?
And two more questions along this thread, if anyone has any advice. - Where can I get an idea of anticpated future electric costs -- I am in CT, and pay $0.16 / KWH which is kind of high -- but the price has not escalated to the rate that oil, gasoline, etc. have in the last 4-6 months. - Where can I get some info on the standby heat loss from an electic hot water heater -- I don't see much on the manuf websites.
Thanks much for any advice!!! T