Oil expert needed

[Mike2007]

Tigerloop problem.
Top outlet oil tank feeds Tigerloop after underground section.
Tigerloop bubbles endlessly inside from return pipe. It then eventually locks out and needs bleeding.
Everything triple checked for loose joints but still nothing.
New hoses fitted today and still it bubbles away!

 

[muggles]

Well that Tigerloop doesn't comply with regs for starters. Needs to be all-metal construction as of about a year ago.

Sounds like it's drawing air in somewhere, or the bypass screw hasn't been correctly installed/removed (boiler dependant). What's the boiler make & model, and what's the approx height difference between the bottom of the tank and the burner?