"Limp Arbor" wrote in message

An oil-fired furnace that provides domestic hot water is in effect an
instant water heater. They only keep a few gallons of water hot when
idle and can easily keep up with showering and washing clothes.
Another benefit is the furnace stays running year round and doesn't
collect moisture and rust out.

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Next to electric though, it is the most expensive way to heat water in the
off heating season. Many times at night I'd lay in bed and hear the boiler
turn on to keep the water hot as it is a poorly insulated setup. The
utility are is also considerably warmer than it has to be from the heat lost
to atmosphere. With my new system, that part of the house has dropped about
10 degrees. There are many better ways of heating water. Yes, it does keep
up as you say, but at a cost.


A
storage tank will just cool and waste energy if you pay to heat it to
180-190.

That is exactly what an electric/propane/gas water heater does/is so
it would be just as efficient and ignoring the sillyness of last year
oil is cheaper than gas and way cheaper than electric.

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Keeping 40 or 50 gallons hot in a well insualted tank is economical though.
My tanks loses about 6 degrees in 24 hours. It can go a day, maybe two,
without the boiler running at all. New tanks generally have two inches of
foam insulation on all sides. It should not be heated to 180 degrees
anyway. 130 is sufficient.

As for oil cheaper than gas, perhaps where you live. Where I live it is
about 50% higher.