Unvented issue with pump

[jitenbulsara]

I have an issue with a unvented system on a separate plan with mega flow cylinder.
I replaced three trv's and also a two port valve on the heating.The boiler and cylinder r in the loft.I fittedo and all was OK for three days and know it fails to fire up every two days unless you loosen spindle on the pump as it is very very hot.Once you unscrew the spindle ithe fires up now so OK for a few days.
My question is do unvented systems get air locks n how long should it take to get out now how or should I bexpect chEckington pump resistant whic is my hunch

Any help or ideas appriciated

 

[ShaunCorbs]

yes any system can have air locks, and you will have to clear it, also if pump / spindle keeps stopping pump is fecked

 

[Tonycane]

Sounds like a weak pump

 

[jitenbulsara]

Did wonder that's why I asked as I have not come across air locks in an unvented system before and it happens every two days .There is a resistance check for pumps right ?. Should be between so and so ohm's

 

[Masood]

Did wonder that's why I asked as I have not come across air locks in an unvented system before and it happens every two days .There is a resistance check for pumps right ?. Should be between so and so ohm's

If it's happening every two days it sounds like you have a small leak somewhere which is dragging air in. As already said, if pump is sticking regularly it's knackered - probably overheated so much one of the bearing surfaces have warped a bit.

Pump resistance is only a check of the motor windings - they may be OK but if it's sticking due to warpage it won't necessarily show an unusual resistance..

 

[Gasmk1]

is pump fitted in correct plane ie horizontal or just below horizontal if its vertical with bleed at top then air can get caught in the pump and it will overheat

 

[jitenbulsara]

is pump fitted in correct plane ie horizontal or just below horizontal if its vertical with bleed at top then air can get caught in the pump and it will overheat

OK but the system has been there for x years and this is the first issue.thumb vents not letting any air out so it must buy the pump