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Adding an inline check valve or foot valve to an overhead supply line

mrcoder
mrcoder Member Posts: 83
edited March 10 in Oil Heating

Carlin tech support recommended to add an inline check valve to my overhead oil supply line.
I know some of the purists here will say: "Dont do that, the line should just be made perfectly air tight". I agree, in a perfect world… but for the moment, lets go with: maybe the support guy at Carlin is not being a complete idiot. I am curious to hear from those of you who actually do/done this.

1) Inline check-valve at the top of the tank, or an in-tank foot valve? (The Carlin guy recommended in-tank) .
2) If it is a foot valve, would you attach a filter screen at its inlet?
3) Valve brand recommendations? E.g. I have seen SMC, which checks all the boxes,
yet not insanely expensive.

I know the valve should have Viton rubber parts, for optimal oil resistance, and I would select the valve body based on the type [pickup] tube the valve attaches to. (Brass for brass, and stainless for stainless) . Viton is best, but BUNA (a.k.a. Nitrile) is also OK.

Low cracking pressure is preferable 0.5 or 1/3 inch to minimize the extra lift required.
"Lead free" is not required.

Inexpensive check valves typically feature silicon rubber. Not ideal for oil exposure, never mind biofuel. Purpose made foot valves usually come with a screen, but I see some plastic ring where the screen attaches, which is questionable.

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,478

    In the tank would be better

  • mrcoder
    mrcoder Member Posts: 83

    Thanks Ed!

    Currently have a straight 1/2" copper pickup into the tank. I imagine I should shorten the pickup by the length of the check valve.


    Flare the end, and attach the check valve (with a flare adapter)? It is a 400G Roth tank. How far should the end of my pickup+valve end up from the bottom?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,478

    Maybe 3-4"

  • HVACNUT
    HVACNUT Member Posts: 6,674
    Screenshot_20250310_181913_Samsung Notes.jpg

    I have a feeling the Carlin guy wasn't an idiot at all, but was late for a lunch date. Have you tested the fuel pump?

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,334

    Outside above ground oil tanks, and below freezing weather leaves the idea of a foot valve in the tank a bad idea in my opinion. On the rare occasion of an oil line freeze up, I like to pump air pressure and som liquid tank treatment (Hot 4in1 or Super Heat for example). a foot valve will prevent that from happening. if you have a check valve outside of the tank, then you can easily find it and remove it , insert a flare union for the needed service, then put in back after the fuel line is clear.

    Just the thoughts of someone that has found his share of frozen fuel lines at 11:00PM.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • techforlife
    techforlife Member Posts: 120

    I disagree with check valve in general. It only complicates everything. It would have to be removed and line reassembled to blow out a clogged or frozen oil line, then reassembly. If installed in the tank, you would have to haul it out of there and deal with the unclogging and the mess every time it clogs up. A check valve is only masking a problem anyway. IMO fix the problem without complicating future servicing. Single oil supply lines under lift (vacuum) or overhead conditions should have a Tiger Loop to be practical. It will eliminate the accumulation of microbubbles and perhaps make up for any minor imperfections in fuel supply integrity.

  • techforlife
    techforlife Member Posts: 120

    Carlin tech assist desk jockeys have no clue. How many clogged foot valves have they dug out of oil tanks in a snowstorm in the middle of the night.

  • mrcoder
    mrcoder Member Posts: 83
    edited March 13

    @techforlife: Given the latest data on my problem, I tend to accept what you are saying. I have added a couple of check valves at the top of my roth tanks, and they did not make any difference. The lockouts still occured. So I will not bother to move the check valves into the tank.


    What made a difference is tightening the nuts at the tigerloop flex hose. This eliminated the issue for a week or two, which were otherwise happening 2x a day. The nuts would still get lose over time, and the problem then would come back. I figured out why: the flex hoses were twisted CW upon install, so there was residual tension in them which caused the nuts to come loose. On the tigerloop side to the flex line, the nut is not turnable, so the line trying to un-twiset itself can undo the nut over time.

    All other connections in the over head oil feed are flare, checked them all and they look solid.

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