Ferroli 901 short cycle

[Gasmk1]

Thanks for reply. It was a brand new pump

For 50 that’s very cheap

 

[oz-plumber]

FWIW, I never been able to claim a warranty on a pump replacement in a system and I've been in the game 25 years.

The only pumps I've ever managed warranty on are new boilers on new systems.

Pump warranties on existing systems - no chance

 

[NEILC25]

new pump went in no problem, solved issue, just a case of getting refund on damaged one now.

 

[NEILC25]

new pump went in no problem, solved issue, just a case of getting refund on damaged one now.

OK, this is a new development, it's still short cycling, however the period of time between it switching off and on again ids shorter so water is actually hotter because by the time it starts getting cold it starts warming up again. However ive just replaced a sink in the bathroom and when I turned off the water and drained taps the last of the water in the cold tap was warm, I read this may be something to do with thermostat in boiler being constantly in on position, could this have been the problem all along?

 

[Winnywood]

This sounds like a faulty venturi causing the pressure to the pressure switch to fluctuate. On some models this is a hard high temperature plastic and goes very brittle with age. Worth a check as they're quite cheap.