Vokera Maxin 28e hot water hot then cold then hot

[phil55]

I have a Vokera maxin 28e, When hot water tap runs boiler fires up and you get hot water then after a minute it runs cold for 10 seconds then heats up again.
If I watch the flame it goes to high then low then high then goes out. It then reignites is it meant to do this? or just cycle between high and low flame?

Thanks for any advice

Phil

 

[corgiman]

sounds like a blocked DHW heat exchanger to me.

 

[phil55]

What is the best way to check this? Can I clean it?

 

[Terrywookfit]

Remove it and flush it out !!
It will be the primary side that is blocked!
Kettle descaler works well and then reverse flush until black flaky deposits
are cleared!!
Alternatively buy a new one and fit while descaling old one as it will be an annual job unless system is flushed and inhibited!!

 

[phil55]

thanks

 

[phil55]

Are you talking about main heat exchanger or domestic heat exchanger?

 

[Terrywookfit]

Domestic !!
At the bottom of the boiler!!

 

[corgiman]

In my experiance this never works and i would suggest its replacement

 

[Terrywookfit]

In my experiance this never works and i would suggest its replacement

In my experience it always works if you are prepared to spend a little time and effort!!

Probably cheaper to replace than labour involved but when you need to it can be done!!

I keep a few spares that I have power flushed for convenience!!

 

[ChrisR]

Agree with Terry on this one. Never had aproblem cleaning one yet.

ALso the boiler may very well need checking, if it's going out when it should be going LOW, Corgi job.

 

[phil55]

Thanks for the advice. I removed heat exchanger and used descaler last night and refitted, all in all 1 hours work and seems to be working fine now. A lot cheaper than buying a new heat exchanger.