Air in oil line oil heater

[paulmars]

See pic. That is my current setup that gets air when i bleed it. Less then 1 second of tiny bubbles shortly after i open bleed port. Heater never cycled off for 45 minutes as i bleed it over and over. If the bleed was closed < 20 seconds, then no bubbles, but if it was open >30 seconds, there was tiny bubbles,but for less then 1 second. Several times I had it open for 30 to 45 seconds after bubbles stopped and never saw any more. Until i closed it for 30 or more seconds.

Ideas?

 

[paulmars]

Why did above post before i finished?

 

[paulmars]

Ignore syphon in fuel bucket. Copper tubing goes into fuel and syphon is not used.

 

[gthomas785]

If you're getting air in the pump it means you have a leak ahead of the pump somewhere or the pump itself could be leaking, or possibly with all that tubing coiled in the bucket there could be an air pocket that's gradually getting into the pump.

Any restrictions in the fuel supply will make it suck in more air from wherever it's coming from. Have you checked the pump filter to see if it's clogged?

Also what kind of fuel are you using

 

[gthomas785]

Also what original issue are you trying to troubleshoot? Does it eventually get air locked or are you just noticing a few tiny bubbles ?

 

[paulmars]

No fuel coil in bucket. Heater fuel oil (diesel).

Was getting air in 38' tubing line from tank. Brought 50' new tubing to replace entire line, but did this test 1st. Replaced flair fitting on pump. Used dope.

Pump strainer is new. Nozzle too.

Original issue was extensive sooting. Now it runs 8 to 10 smoke test after 5 minutes gradually reducing to 0-1 after 20 minutes of constant running.

 

[paulmars]

I replaced the pump flair fitting with new. Im always reluctant in tightening for fear of over tightening. It is quite tight, but i could get another 1\4 or even 1\2 turn, but if i turn it any more, ill need to do one full complete turn and i fear that would be over tightening and may be even be possible. I did cover threads with dope and let it sit after tightening for 48 hours before turning heater on for this test. If it is pulling in air it only does for under 1 second. Maybe by opening bleed port im reducing the pressure differential and that stops air from being pulled in. Another words it might be pulling in air continually when bleed port is closed.

 

[gthomas785]

So first of all you should not be using dope on a flare fitting. Flares rely on the compression of the copper to brass to make the seal. Dope could cause a small leak under vacuum but check all the other fitting and gaskets first

Check the oil pressure after the pump. usually it should be somewhere around 100 psi but the nameplate on the pump will tell you.

If it starts up smoky and clears up after running for a few minutes, I'd be suspicious that oil is leaking into the chamber while the burner is off. That pump may have a bad cutoff, you can also test that with a pressure gauge just shut the pump off and it should hold around 80 psi or higher. That could also be where your air was coming from originally. If it was an overhead line (which it looks like) you'd get some oil dripping out in the chamber and then it would suck air in while draining the oil back to the tank.

 

[paulmars]

I already checked pump cut off pressure and it is fine. Only one end is flair, other end is doped npt.

 

[gthomas785]

Alright sounds legit then. Oil does sometimes have dissolved air that will get pulled out by the pump suction. It's more of an issue with overhead oil lines. If it keeps being a problem you could consider installing a tiger loop or switch to a 2 pipe system with return line.

 

[salecker]

Get a tiger loop and install it
It will eliminate the air.

 

[paulmars]

This setup with 37' line going up 8' then horiz 24, then down 5' has worked since 2012. It worked even longer then that going up 8,horiz 15, down 5 before i moved tank in 2012. Now it's getting air, even when i reduce line to 46". My issue isn't overhead, single line, or lack of tiger

 

[gthomas785]

This setup with 37' line going up 8' then horiz 24, then down 5' has worked since 2012. It worked even longer then that going up 8,horiz 15, down 5 before i moved tank in 2012. Now it's getting air, even when i reduce line to 46". My issue isn't overhead, single line, or lack of tiger

So then it's the pump

 

[paulmars]

I think ur right. Maybe need new pump.

After tightening fittings more. Running for 30 seconds with no bubbles, then his for a few seconds. Then bubbles stopped (2nd pic), then bubbles again.

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ibb.co

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Image IMG-20240221-133614870 hosted in ImgBB

ibb.co

 

[salecker]

See pic. That is my current setup that gets air when i bleed it. Less then 1 second of tiny bubbles shortly after i open bleed port. Heater never cycled off for 45 minutes as i bleed it over and over. If the bleed was closed < 20 seconds, then no bubbles, but if it was open >30 seconds, there was tiny bubbles,but for less then 1 second. Several times I had it open for 30 to 45 seconds after bubbles stopped and never saw any more. Until i closed it for 30 or more seconds.

Ideas?

What got you to the point of worrying about the bubbles, or seeing bubbles?
Are you sure it's something new if the burner dosn't shut off?

 

[gthomas785]

As I said before, a small amount of air dissolved in the oil is normal. If it's not causing a problem, leave it alone. If it is causing your line to get air locked, install a tiger loop. Either way, a tiny bit of air in the oil line is not what's causing your sooting issue.

 

[salecker]

i would look at your air adjustments for a sooting issue.
my boiler was sooting and the air adjustment was way out of adjustment for some reason.