Pre-heat function not working

[mvarrier]

I have a potterton 24i boiler. Recently the hot water pre-heat function has stopped working. I have it set maximally clockwise but unless the central heating is active the water gets very cold and takes a long time to heat up. This is obviously quite inconvenient when you want a quick shower in the morning.
There are no fault lights, adequate pressure in the system and everything is otherwise functioning fine. Any suggestions (for a complete novice) appreciated.

Matt.

 

[Agile]

Are you sure you know what boiler model you have?

Do you have a cylinder?

Tony

 

[mvarrier]

from the manual...
"1. The Potterton Performa 24i HE is a fully automatic gas fired wall mounted condensing combination boiler. It is room sealed and fan assisted, and will serve central heating and mains fed domestic hot water.
2.The unit incorporates a small storage cylinder built into the boiler providing hot water the moment the tap is turned on."

It certainly used to do this function but now it doesnt

 

[petit_pablo]

I imagine there is an issue with preheat differential valve and/or the Hw differential too.

 

[Agile]

Right, this is a Performa 24i HE then.

I was not aware that they had continued the instant version when they produced the HE version.

Their instant models have not been very reliable, mostly because the expansion vessel they use has a very limited life. Although not a terribly expensive part thye ioften need the boiler taking off the wall to replace it.

But the internal controls needed are relatively complicated and some of the faults can be difficult to diagnose.

I expect you will need a competent local engineer. The fixed price repairs from Baxi/Potterton would resolve the fault but a local independent should be considerably cheaper as only relatively cheap parts are involved.

Tony

 

[mvarrier]

Thanks tony that's very helpful

 

[Agile]

If choosing the local engineer option be aware that not all those advertising to repair boiler will be able to work effectively on this model.

You should ensure that you are not paying them by the hour regardless of them being able to diagnose the fault. You need a no-fix no-fee!

Nor should you have to pay for new parts because the engineer was unable to correctly diagnose the problem.

The makers fixed price repair is probably about £300 so you should not have to pay more that that at the maximum.

I find that most of these just need one or sometimes two smaller cheaper parts or just something cleaning.

Tony

 

[mvarrier]

Thanks again