Baxi 105e –Gunged up DHW Primary or Secondary heat exchanger

[Adam75]

Before I start taking the boiler apart can someone please advise if the symptoms below indicate that the DHW Primary or Secondary (plate) heat exchanger needs cleaning?

I’ve read quite a few posts and they seem to contradict!

Symptoms: water stays hot for a while, then goes cold, then back to hot & so on. The burner turns off, the temperature lights drops from 80 to 50, burner comes back on.

I think it's the DHW plate (secondary) heat exchanger I need to descale?

Thanks
Adam

 

[gaspro1981]

Adam your problems do sound related to a blocked secondary plate
However without checking the temperature differential across the plate you are only making assumptions mate
Easy enough to take out the plate to plate h/e and check takes about half an hour if you go careful

 

[dcawkwell]

Secondary plate.

If the boiler is getting to full temperature and cutting off
it isn't able to supply the heat to get the dhw hot and is cutting off.
Secondary plate remove. Brick acid shake and flush .

Sorted.

 

[Adam75]

Hi

I successfully cleaned the secondary heat exchanger and the hot water has been working like a dream until today!

The shower has started to go hot, cold, hot etc so signs that the hex is getting blocked again.

Is the next step to do a mains flush? Assuming its getting clogged up again with all the sludge in the rads.

Or is a power flush easy enough to do?

Cheers
Adam

 

[dcawkwell]

Hi

I successfully cleaned the secondary heat exchanger and the hot water has been working like a dream until today!

The shower has started to go hot, cold, hot etc so signs that the hex is getting blocked again.

Is the next step to do a mains flush? Assuming its getting clogged up again with all the sludge in the rads.

Or is a power flush easy enough to do?

Cheers
Adam

Blocked up system. Remove a radiator attach hosepipe from mains
to one radiator valve. Attach another hose pipe to other radiator valve for draining.
Close the flow and return valves to the boiler.
Open a radiator at a time then flush through with mains.

Sorted.

 

[Terry7556]

do you tickle the rads with a rubber mallet as you run the water through?

 

[Terry7556]

do you tickle the rads with a rubber mallet as you run the water through?