Oil Furnace Question


Old 05-24-14, 03:01 AM
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Oil Furnace Question

Hi all, I have a Dunkirk oil furnace that all I use it for is to heat my domestic hot water (DHW) in the summer with the tankless coil. I do not use it to heat my house. It's about 20 - 21 years old. Yesterday I shut down my outdoor wood fired boiler for the summer and fired up the oil furnace. It fired right up. I noticed that after it heated the water and it turned off, the temperature gauge continued to climb for an additional 25 to 30 degrees. I'll be honest, I've never paid attention to what the gauges did before this season, I just happen to look at it when passing it. Is this a normal thing with an oil furnace or is this something I should be concerned about? Thank you in advance for the help. Roger
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Old 05-24-14, 05:26 AM
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Sounds normal... As long as the burner turns off what the aquastat tell it too.. Its usually called heat soak...

Curious at what temp is the high limit?

Wondering why no use of an electric HWH???
Old 05-24-14, 01:39 PM
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Thank you for the reply. That's a relief.

Because I don't use it to heat my house, the high limit is set at 170 with the low at 150.

My dad had the system installed about 20 - 21 years ago and he was sold on the "on demand hot water" for the oil furnace. About 3 years ago I installed an outdoor wood fired boiler and it heats an indirect, Superstore hot water tank. I simply disable the tankless coil on the oil furnace when I'm heating with the outdoor boiler. The oil furnace is on "stand-by" throughout the winter. Essentially it's my backup heating system now that I use the outdoor unit as my primary heating system. Before I installed the wood burner, I was spending about $5,100.00/year for fuel oil. I now spend about $100.00/cord for firewood. Due to the long and brutal winter I spent about $800.00 worth of firewood this winter. Not too bad considering I'm heating about 3000sqft 1840's farmer-house.

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