potterton performa 28i

[wards]

i must be having brain drain on this one,customer getting intermittent hot water,attended and checked thermistors,limit stat,burner pressure,all correct values,they had a new secondary plate heat exchanger and divertor assembly fitted three months ago(not by me).i have checked all connections and have found no issues,anyone have any thoughts on this one.the only issue i found was the collar on the flue connection in the boiler had split and i have replaced that.any replies appreciated.

 

[jtsplumbing]

Whats the water flow like ??

 

[wards]

flow is fine mate,

 

[lame plumber]

flue in let blocked with ivy, had it on a 105e last week

 

[wards]

flue inlet is fine and operates as normal in c/h mode.

 

[dave1]

When you say intermittent do you mean it runs hit and cold or it doesn't work at all sometimes?

 

[wards]

hot then cold then hot then cold,it fires up reaches temp then cuts out then fires up again reaches temp and again cuts out,no fault lights are on?

 

[lame plumber]

so did my 105e but as soon as dhw demand went on and extra heat asked for, locked out for 2 mins and then off she went, only found problem when i lifted the burner cover off and all worked ok, give that a go first. could be failing fan not clearing flue gases properly but aps still ok, happens

 

[ambrosia]

is the boiler turning off and on in the same way as if its the plate heat exchanger, if it looks like a duck and quacks and you did say you didnt change it yourself

otherwise does it do it when heating is on and is it switching to heating halfway through customers shower,
i'm wondering if its the diverter valve or microswitch

if not could be pcb of sticky gas valve

still reckon its the plate heat exchanger, how dirty is the water

 

[wards]

fan runs fine and makes no difference if cover is removed/fitted.still get the same issue with water temp.

 

[dave1]

And who's to say the played heat ex hasn't blocked up again? It's worth pulling it out and checking.

 

[wards]

i would have said it was the plate heat exchanger but that has already been changed,had a look at pcb and no visible signs of damage/scorching or burnt tracks.

 

[jtsplumbing]

Remove and recheck Plate EX , do you know for certain that it was a new one that was fitted ??

 

[wards]

the divertor assembly is still nice and shiny the heat ex was changed has no age related signs.

 

[wards]

correction the heat exchanger that was changed shows no age related signs and has a clean looking label on it.

 

[Billy Bob Bob]

flow pipe getting hot in dhw mode?

 

[wards]

feels like heat transfer gman,but not bypassing.