alpha cb28 dhw problem

[wardy525]

Hi,

I have the alpha cb28 combi boiler and have had a few problems, i recently renewed the dhw diverter, flow switch and temp sensor.

the problem that i now have is the dhw comes on for 20 seconds and then goes off for 10 seconds, it's the same cycle every time on for 20 off for 10, i could set my watch by it

the ch is fine, no problems at all. all else seems ok, the fan starts, the pump starts !!!

please help, the kids are starting to smell a bit now

thanks wayne.

 

[kevplumb]

sounds like a sludged up dhw heat exchanger

 

[wardy525]

thanks, i'll have a go later. what's the best way to clean it?

thanks wayne.

 

[markymark1234567]

Blocked plate 2 plate heat exchanger. Can be cleaned but it's a pain in the rear. Buy a new one

 

[wardy525]

it's more a pain in the rear having to pay £170 ish for a new one.

once it's off, what's the best way to clean it.

thanks wayne.

 

[dhill]

Cant you pump some deposit remover into it and de scale the boiler and all parts in situ. make sure you flush boiler out afterwards. So much more cost affective then replacing plated heatexchanger

 

[Prof.plumb]

Use a good descaler safe for use in kettles and pour it in with boiling water wait five mins it will all bubble loosen off and clean up a treat.

 

[markymark1234567]

I have used a pressure washer before and blasted the dirt through or get 1 off ebay for about £100