Biasi 24SE CH/DHW probs

[LordThornber]

Hello all, apologies if this has been covered, but try as I might I can't seem to see a definitive answer, perhaps there isn't one...

Switch CH on and temp rises rapidly to 80 +, rads scorching, DHW boiling hot. Water pressure is OK. Cleaned thermostat probe. Could this be anything connected with the diaphragm which we replaced last year?

Any help most welcome and thanks.

Martyn

 

[transam]

biasi combi , when in the H.W mode the temp of the primary circuit should not excede 75 degs C , max temp of H.W exiting boiler 55 degs C , in heating mode max temp 85 degs C . I assume we are talking about a biasi prisma or the early riva .

 

[LordThornber]

Transam, cheers yes it the Prisma.

 

[Agile]

The CH and DHW temps can be reduced by turning the control knobs anticlockwise!

Thats if its working properly.

Tony

 

[LordThornber]

Cheers for that Tony, nothing much happening with the controls, hopefully a plumber contact will finally turn up today with a much needed repair...

It's b****y freezing here....

 

[Agile]

That would be a very odd fault if the boiler does not control the CH or DHW temperatures.

A wrongly set up gas valve could give that effect to a degree but would still turn off the gas when it gets too hot.

Both temperature sensors going open circuit together at the same time is also unlikely.

A possibility is that the DHW sensor has been o/c for some time and now the CH sensor has also failed.

Ask the engineer to make sure he has two sensors with him. Or you could measure the resistance with theb boiler cold should be around 10k.

Tony

 

[LordThornber]

What a quality reply, cheers again Tony, I will pass your comments to engineer when he arrives.