Hrm wallstar problems

[Paul from Peterborough]

Hi I've got a hrm wallstar that has developed a problem, it fires up for approx 2 minutes then cuts out, I've turned the stat on the water tank up to full and the heating stat to full so to me it should be calling for the boiler to be on, but it doesn't, it stays off for approximately 30 minutes then fires up again for 2 minutes, I'm thinking it's the coil ? Has anybody got any other thoughts?
Thanks

 

[Last Plumber]

Hi I've got a hrm wallstar that has developed a problem, it fires up for approx 2 minutes then cuts out, I've turned the stat on the water tank up to full and the heating stat to full so to me it should be calling for the boiler to be on, but it doesn't, it stays off for approximately 30 minutes then fires up again for 2 minutes, I'm thinking it's the coil ? Has anybody got any other thoughts?
Thanks

Which wallstar?

 

[Paul from Peterborough]

Which wallstar?

Hi it's 15/20
Thanks

 

[Chalked]

Circulating pump air locked, or seized.

 

[Paul from Peterborough]

Circulating pump air locked, or seized.

Ok, cheers

 

[ShaunCorbs]

Ok, cheers

no as its too expensive in my locals