Exel 80 SP. Poor DHW.

[DEEARR]

Appreciate any help with this boiler giving low temp DHW. Limited experience with combies. Have fitted service kit and flow thermistor. Boiler modulates down to to low flame and both main heat exchanger pipes are really hot. Heat not transferring to DHW outlet unless the flow is screwed down to no more than a trickle. Is it reasonable to suspect the secondary heat exchanger. Struggling with this, any ideas.

 

[cross thread]

could be secondry heat ex,but i have had same prob and the heat was passing to rads try shutting off heating isolation valves to see if it improves things.part i replaced was the bobbing that acts as a by pass in the left hand valve

 

[andsam]

Sounds like the plate to plate. If its older model you will require large allan keys to remove it. If the DHW microswitch is screwed onto the housing where the diaphragm is, it is the older model.

Beware some of the fittings that attach the plate to plate are now obsolete.

 

[DEEARR]

Thanks for the quick response lads, Will try isolating heating valves as suggested gordon gas, was the part you replaced in the divert valve.

Andsam, the plate heat exch. is attached to the back of the divert valve and would indicate the older model. Does the fittings your mentioned that are now obsolete make the replacement of the plate heat unit impossible.

 

[DP]

If the heat exchanger is blocked with sediment, replacement will go belly up as well.

Regularly service these boilers. Have not had to change bits mentioned above. But then perhaps I am lucky so far.

I can still get some parts for the Turbo, all parts ( that I have ever needed) for Flowmatic. Excell is newer than Flowmatic.

But then again Glasgow and areas around it is Vokera country (depot is on Maryhill Road)