Oil fired hot water heating?

Howdy all, being from the west coast, I am unfamiliar with oil furnaces. My mom lives in Maine, in a new house she had built in 2003 with the standard oil furnace installation heating the house and also her hot water needs. She also has propane used for her fireplace and stove. All else is electric. Can someone educate me on how the hot water heating works with an oil fired furnace/boiler? Is it like a gas water heater which has a storage tank or is it an instantaneous type where water is only heated when needed by turning the hot water faucet on? I am considering switching her hot water needs to a gas fired instantaneous/on-demand type water heater but want some advice as far as efficiency. Is it more economical to do an on-demand unit vs whatever is in there now using oil? She just had the standard house sized oil tank/furnace/boiler installed new when the house was built. Any efficiency ratings available for oil vs gas? i.e. oil is 60% efficient vs gas which is 80% efficient or?
Any help and/or links would be appreciated..
Thanks,
Mike W
Replies
Greetings Mike,
As a first time poster Welcome to Breaktime.
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
Mike, there are many variations to the system you mentioned. Here is a site that might help.
http://www.heatinghelp.com/
OK, First - she does not have a furnace.
She has a boiler. An oil burner with electric ignition heats fluid that pases through heat exchange coils in that unit. This system delivers heat to the radiators or other exchangers throughout the house as thermostats on different zones call for heat.
The domestic hot water is simply one of those zones. A storage tank for the hot water supply has coiled heat exchanger in it taking hot fluid from the boiler and through the water tank to heat it.
In general, it is a very efficient system.
But for a single older woman living alone, siometimes their lifestyle is such that they only bathe every couple days and run the dishwasher far less often than a full family so an on demand HWH can be more efficient. Whether it is worth installing a redundant system is debateable though.
Another problem we have here in Maine is hard water which regularly stops up these smaller devices causing high maintainance costs.
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tamangel.
heating is sure not my specialty, but I have been advised that conventional oil-fired boilers should be allowed to run year round in order not to shorten their life. That being so, it makes good sense to get some value out of the oil she has to burn and get her hot water out of the thing.
Ron
If her system was installed in '03 the burner efficiency is probably in the 80+% range. They make "em good now. It's also probable that the DWH is an indirect using the boiler heat, tres efficient and also great recovery as compared to gas or electric. In this area, propane and fuel oil costs are about on par on a BTU adjusted basis.