Summer water heating solution
user-6623302
| Posted in Mechanicals on
Looking for a summer water heating solution. I am considering an indirect heating solution with a electric back-up. An indirect is a great heating season solution but keeping the boiler on all summer is a waste. My fuel choices are electric or oil, no gas available. Anyone have experience with these? I know that the best solution is probably a HPWH and PV panels but I am not well situated for solar.
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Replies
Jonathan,
Oil-fired water heaters are expensive to purchase and require a lot of maintenance. I don't recommend an oil-fired water heater for a single-family home.
So your two choices are to either (a) run your boiler and your indirect water heater all summer, or (b) buy an electric water heater (either an electric-resistance water heater or a heat-pump water heater).
A heat-pump water heater uses between 1/3 and 1/2 as much electricity as an electric-resistance water heater. The energy savings have nothing to do with whether or not you have a PV system.
For more information, see this article: Domestic Hot Water: No Perfect Solution.
I agree with Martin. The choice of a HPWH over electric is largely based on economics. If the HPWH is located in a naturally warm area, the efficiency can be very good. HPWH's also dehumidify the surroundings, and this can be a big bonus with basement locations that most people don't figure in their calculations. If you can avoid a basement dehumidifier, that's $500 or more that you can spend on the WH, not to mention the energy wasted on running a dehumidifier.
Your OP didn't make it clear, but you should be using whatever WH you get as both your indirect fired WH and your summer WH, using an external plate heat exchanger rather than an internal coil unless you find an indirect fired WH with electric backup. This avoids the cost of 2 tanks.
And don't automatically fall for the indirect-fired WH being "free" heat in winter because the boiler is already running. Heat is heat, and if you're heating with oil, it's getting to be expensive heat. Even in the shoulder seasons, a HPWH will probably be cheaper to run than the boiler. In the dead of winter, the HPWH is stealing heat from its surroundings and that heat is probably provided by the boiler, so you're essentially paying for the oil anyhow. The point is, you can save a lot of plumbing if you skip the indirect fired WH, and that can make the choice of a full-time HPWH an easier one.
All of this changes with low-cost natural gas if you've got it locally, but oil burning is inefficient and getting to be expensive.