Biasi MVP Boiler Issue - Help Please!!!

[James2711]

Hi. I have a 19 year old Boiler, it's a Biasi MVP Combi.
In the last 7 days, the water has started to get warm then gone back to stone cold - even when I regulate it as carefully as possible, it still turns cold after about 10 seconds max. The Central heating is toastie with no issues - I have spoken to a couple of gas guys who say "change your boiler mate", sadly, this is not an option..
Any advice would be appreciated!!! Thanks...

 

[davisplumbingandheating]

Just replaced on of these they are very much similar to early vokera's.

First thing to check, switch heating off and run hw,does burner stay on through hot water demand, if not i would look at micro switches on front of diverter valve and check hw diaphragm isnt holed etc

They are basic boilers but having been around for 19 years not many combi's can say that,i know a few early Vaillant sine 18's that are just about still going.

 

[bengasman]

Does it go hot cold hot, on once back to cold it stays cold?

 

[Agile]

There are not very many of these still working. I wonder if I have been to yours!

I thought they had a DHW flow switch and a motorised diverter valve?

The system flow switch is a common failure point and I even have a couple in stock.

Its not sensible to guess what your problem is and you need a proper boiler engineer to diagnose the problem.

If the secondary heat exchanger has become blocked then that would be an interesting challenge to clear!

Why do you say replacing the boiler is not an option?

Tony