Poor combi boiler flow rate for hot water

[otherparty]

Hi guys
I have a Potterton Performa 24, probably about 7/8 yrs old. Central heating has always been fine, but hot water has always been a problem. Even 5 yrs ago, when i moved in, if i opened the upstairs HW taps fully i would not get properly hot water. As such, I have always had to minimise the flow rate.

I've lived with it till now, but now it's really bad! The other thing to note is that the large burner flame will usually switch off before the water gets really hot. It seems to cycle on-off a bit too frequently now.

I've checked out some other posts and it looks like it could be the Plate Heat Exchanger, where hard water can cause scaling. Does this sound right? I've checked that the heating flow pipe stays cold (to rule out the Diverter Valve). Are there any other possibilities? I've even been considering getting a new boiler as i'm that annoyed with it!

Thanks for all advice.

 

[Agile]

I am, surprised that you have apparently put up with poor performance for five years!

As you seem uninclined to engage professional help, the boiler settings may well have drifted seriously since installation if never properly serviced.

Its most unlikely the plate HE is lime scaled. Its almost certainly blocked on the primary side by dirt from the radiators. Thats even more likely if the filter is not fitted on the return.

There is also the possibility that you have a cold water crossover in your house!

Tony Glazier

 

[otherparty]

Yeh, crazy isn't it! Thing is, i always figured it was just because the boiler was crap and that i would just make do until i could afford to get a new boiler. I was also not expecting to live here for so long.

When i had it serviced, i did ask about the poor HW flow rate, but the technician seemed to confirm my thoughts that the boiler is just not up to the task.

I'm happy to engage prof help, if that's what's needed. As i mentioned, i was even considering a new boiler. If this one can be fixed, i'll still save myself a fair bit. Do you think that's the best way to go in this case? Alternatively, if i simply replace HE, would that solve the problem if, as you say, it is blocked on the primary side by dirt from the radiators?

 

[Agile]

I have not seen your boiler so I cannot say exactly what is the problem in your case!

All I can say is that its a perfectly acceptable budget range boiler and when working correctly will deliver the rated output.

It is totally repairable!

Tony

 

[otherparty]

OK, thanks. Is it worth a try to change the HE first? Or should i just get someone in to look at it?

 

[Agile]

I always recommend properly diagnosing a fault rather that just throwing parts at it.

There could well be more than one problem!

But its your decision!

Tony

 

[otherparty]

Ok, i'll try to get someone to check it out. Apart from the obvious (yellow pages etc), any tips as to where i should look to get someone? I'm in London SE13.