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Cold oil effect on vacuum gauge?

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wmechanic01
wmechanic01 Member Posts: 26
Hi was just curious if below 18 deg outside with outdoortank and garber under crawl space would cause a vac guage on filter to read high 15 -16 during end of 10 minute furnace cycle , new filter only a day old , clean oil new lines new tank 2 pipe system about 55 ft run from tank to burner with about a 3 ft lift up to the burner thanks for all the input !

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  • HVACNUT
    HVACNUT Member Posts: 5,863
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    That's pretty high. Is the 2 pipe off the top or suction line gravity? All exposed oil lines insulated?
    Doesn't take much for the fuel to gel in that temp.
  • wmechanic01
    wmechanic01 Member Posts: 26
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    That's what I'm thinking it's slightly gelling, it's still running though , it's a top feed tank
  • Jamie Hall
    Jamie Hall Member Posts: 23,439
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    If it's #2 fuel oil, and not diesel, it probably does not have an anti-gelling additive in it -- and it's gelling. Gets much colder, and it will gell and completely stop up the filter. Outside tanks for fuel oil -- not underground -- should use an anti-gell additive or diesel (might note that diesel purchased in the summer may not have the additive either!) in cold weather, in my opinion.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,622
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    That is pretty high vacuum. 15-16" is getting close to maximum before you have problems. How much oil is in the tank? If your getting low on oil adding oil will reduce the vacuum. Additive may help. If the filter is in a cold location you may want to consider moving it near the burner in the summer
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    If you are getting -18° temperatures, you better either have additives, or 25% kero, because that fuel should be gelled. The 2 pipe is also working against you as that oil is not warming the tank as some people think. That return line is ice cold, as cold as the supply. If the return line gels/clogs, you will blow out your pump seal.

    There was an error rendering this rich post.

    HVACNUT
  • wmechanic01
    wmechanic01 Member Posts: 26
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    Yes there is a anti gel in the fuel I am over half a tank of fuel I thought at this point were were done with these super cold days and didn't get kero like usual , I'm just curious if it's causing the vac guage on the filter to be so high because the oil viscosity is thicker than when it's above freezing . I never payed attention to that gauge before that's why I'm just a little curious thanks!!