heatline s24 compact combi intermittent hot water.

[byronelvis]

hello.i went out to this combi a few weeks ago.upon diagnosing the fault (hot water for a few seconds then cold)as a blocked secondary.the customer then whips out 2 old secondary exchangers...."you mean like these ones mate".after the second was fitted,it ran well for a few weeks then same problem.
so i ran the heating for a while then using the downstairs drain off,hot flushed all the rads individually ,to reveal,comparatively cleanish system water, although this lad seems to be a messer,and i think he,s tried to have a go at flushing.
as you can imagine,i am dubious to charge for a power flush,and new secondary HE under these circumstances.any other ideas, or should i go with my training,properly flush,install a new exchanger,add the sentinel.also,what is the best thing to soak 1 of his old exchangers in/how long for,so i can try this before putting him to to much expense.time seems to no obstacle as it has apparently been in this state for 9 months now.

 

[Blackadder43]

After 2 HE already and relatively clean water are you sure its not the DHW diaphragm split ?

 

[twgas]

Were the 2 old HEs dirty?

 

[Happyplumber]

Where is the hot water diaphram lolz .............................................................................................

 

[byronelvis]

yes the 1st one was full of rust scale(the second one i was unable to examine,it was apparently in his shed somewhere).the hot would run warm,then scalding and the burner then would shut down,for a period untill re-ingnition all within a period of around 10 seconds.
i have yet to go back to it because the guy needs to book a day of soon because of his massive dog that lives in this house too.so because of this tight schedule i just need to be armed with a few ideas if plan A fails.ha ha,cheers guys.Does Heatline have technical helpline number?
Brent.

 

[ChrisR]

A thought - it could have a lot of flux residues in it , making compounds which preferentially block the plate with the water not looking too bad. I think I've had this before, pH was low. Ran it with X300 and flushed, cos it's designed to clear residues. Hasn't recurred. It's always a mystery really though!

 

[Agile]

Its quite common to have cleanish looking water but still enough solid bits to block the plate HE.

If there were space, a line strainer would be a good idea.

But I have seen blocked plates caused when there is a filter fitted on the return but someone has used the TRV to remove pressure and the dirt has come cack through the flow. Well thats my best guess of what that should have happened.

Tony

 

[Happyplumber]

Its very unlikely to be the heat exchanger but worth taking out and cleaning ,I have repaired three of these this week and the fault is relatively simple once you get into it.

The first one i worked on did consume a bit of brain power but once you find out how it all works then the other two were a whizz .good luck.

 

[twgas]

.the customer then whips out 2 old secondary exchangers...."

yes the 1st one was full of rust scale(the second one i was unable to examine,it was apparently in his shed somewhere).

Mmmm