Air bubbles

Anyone help with this little problem, after about 30 mins of running I start to get air bubbles going down the site glass so consequently can’t really tell how much water is in the boiler tried blowing down but still happens

That sounds like priming . How new is the engine?

Hi Mark yes I think your probably right as my pump still puts a small amount of water in even on bypass so over time it’s getting to much will have to try and fix Thanks for reply

Your getting turbulent throthy water and the sight glass collects it. Do you use treatment. Guessing no as all copper boiler.

Crystal sometimes does it when the boiler treatment is getting low. Are you in a hard water area. As this can also contribute to turbulent boiler.

If you “prime” that’s a over filled boiler and your picking water up in to the steam chest. Bubbles or air liberation in the glass can happen at any fill level.