Hot water runs hot then cold then hot

[KingSam]

Hi I have a

Baxi duo-tec 28he boiler, the hot water heats up the the boiler turn the gas/heat off and the water runs almost cold, then it switches on and the water heats up again? any ideas? I think the CH maybe doing the same.

Many Thanks
Sam Hubbard

 

[gas4you]

I would think the plate HE is blocked on the system side.

If the ch is really doing this as well I would check the primary ntc first.

 

[KingSam]

The plate HE is the one connceted, near the pump and 3 way valves? not the larger one in the Burner area?

if so can this be cleaned? or does it need replacing, I'm able to replace anything water side but can't touch the gas side.

Many Thanks
Sam

 

[mickyg]

the small one as you described. Whip it out and have a look. If its full of crud you can try flushing it out with a garden tap. flush through from the cleaner side first and keep tapping it and shaking it. Hand if you got some silicone grease to put on the washers before you replace it. help prevent leaks

 

[KingSam]

thnaks
will try this and see what happerns.