Domestic Hot Water

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Old 04-22-09, 04:54 PM
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Domestic Hot Water

Hello

I have a Well McClain Oil fired Boiler(~80% efficient according to last service tag) heating a 3 zone system (2 small baseboard room/zones and 1 large zone 2000SF w/8 old radiators) in a 1910 home.

Currently I am spending $1000/year to heat hot water using propane with an 11 year water heater that has been exposed to ultra hard water. I think this very high cost but no idea.

My question is using a new tank heated by boiler going to be better in terms of cost? From what I understand these tanks can last 30 years.
 
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Old 04-22-09, 05:45 PM
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While indirect water heaters are an efficient way to produce domestic hot water there are more reasons for high fuel bills. Boiler sizing, boiler piping, construction of home, control strategies etc. If the combustion efficiency is 80% the AFUE is lower than that.
 
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Old 04-27-09, 08:22 PM
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Consider a solar collector to supply an indirect tank, with the oil boiler as a backup. Payback from the energy savings should be about 5-7 yrs, maybe less with the gov't. energy credits.
But using what sounds like a huge boiler to heat DHW in the non-heating months is not efficient. I would go with a replacement LP fired tank-more efficient. Maybe you could soften the water...
Tom Beer 4U2
 
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Old 04-29-09, 06:52 AM
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The chimney vented water tanks as as inefficienct as they come. A lot better to use an indirect with a boiler. The question is is it efficient with the boiler you have?????? With an 80% combustion efficiency that means the AFUE efficiency may be in the mid seventies or less. An indirect would be the right step if you are planning on replacing the boiler in the near future (next couple of years). Have the indirect properly installed and make the boiler cold start.
The direct vent gas fired tanks are more efficient and also the tank-less water heaters but that would be my last choice.
 
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