***Pls help alpha 240 eco dhw problem...***

[entech]

Hi all ,first post and great site.
I have a 240 eco combi approx 10 yrs old.
Last serviced approx 6 yr ago.

The fault it has developed is that if you run a bath or shower the hot water will run cold after approx 10 mins (this varies thou sometimes 5 or 15 mins)then fluctuate between hot and cold .
I have left the shower running and watched the boiler to see what is happening.

I saw that the boiler was working normally then the main burner would shut off and the amber neon light would come on for approx 10 secs then go out and the main burner would light up.this cycle would then go on every 2 - 3 mins.

I have checked the diverter assy and both plungers and microswitches are working fine.

I have aslo had the dhw temp sensor replaced ( next to the sec heat exchanger).

The central heating system of the boiler works fine.

Any help or comments will really be appreciated.

Thanks

 

[namsag]

Plate heatexchanger partially blocked

 

[entech]

is that the heat exchanger at the bottom of boiler.can i clean / remove debris or does is req new part.

cheers for reply

 

[entech]

can you explain how heat exchanger would create fault as it is initially delivering hot water for approx ten minutes so water is flowing thru exchanger ok. i cannot see any temp sensors on heat exchanger itself or anything that will command the burner to go out from the heat exchanger.

cheers

 

[gasmick2]

Hi it does sound like the plate heat exhanger and it will close the burner down with the temp stat because the flow rate is not as it should be
another thing to look for is to make sure the diaphram on the domestic side has not got a small pinhole or has gone floppy inside if it does then it will relaese the microswitch and then turn the boiler off,, but i would go for the heat exchanger change it rather than trying to clean it out there not that exp

 

[entech]

replaced air press switch and cleaned dhw plate heat exch in acid.

all works fine now.

cheers all for help.

 

[Agile]

Why did you replace the APS ???

Tony