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Air in oil line oil heater

paulmars1

Plastic
Joined
Dec 26, 2011
Location
florida usa
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?
 

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There is an air leak somewhere in the line. Check all fittings. Could also be a kink that made a very very tiny hole in the copper line or just a place where the line is corroded through.
 
For this test I replaced the pump flare 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. 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.
 
Did you use flare or compression fittings?

Only flare fittings should be used and you need to make a good clean flare. Redo the flare with a good quality tool.
 
Pipe dope on flare fitting is a bad idea. It makes them, harder to seal. Oil or grease is better. I have no idea what you are doing. How can air get into a pressurized oil line. is this maybe a suction line?
Bill D
 
Dope on the fitting npt end into pump, flair on other end to copper tubing. The tubing pulling fuel from bucket is at a vacuum. It is new line with only one fitting into pump.

With 37' line from tank had after drip. Pump cut off pressure fine. Air during bleed. Removed filter & its fittings, but still air during bleed. Bought 50' tubing to replace entire line. Decided to try test shown in pic 1st. That still shows air during bleed.
 
Dope on the fitting npt end into pump, flair on other end to copper tubing. The tubing pulling fuel from bucket is at a vacuum. It is new line with only one fitting into pump.

With 37' line from tank had after drip. Pump cut off pressure fine. Air during bleed. Removed filter & its fittings, but still air during bleed. Bought 50' tubing to replace entire line. Decided to try test shown in pic 1st. That still shows air during bleed.
I have a propane boiler and it had air in the radiators. I had a repairman come out and he blead the air supositly. It ran 1/2 hour after he left and air was again in the lines. I went to YouTube and figured out the problem. The bladder tanks bladder was old and broken, allowing air into the lines. Ihad the repairman come and install a new one. It worked, no air in the lines. I also had them put in ew antifreeze in the lines incase the electricity went out and the pipes wouldn't freeze. I paid for the part, but not the labor.
 
Einstein said the definition insanity is doing the same thing over and over expecting a different result.

Clearly what you are doing is not fixing the problem. As I said before, try redoing the flare with a quality flare tool. Also replace the fittings with different ones. Until you try doing different things you will never fix this.
 
Im trying to find the air breach. By using the short tube ive proved that it wasn't the line to the tank. So it must be the pump, unless i didnt tighten that single fitting. So, i tried that. Only thing left is the pump.
 








 
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