potterton performs 24 problem with heating

[Steve46]

I have a potterton performa 24, the hot water works fine but the heating will come on for a minute or so then will go out. The radiators only get warm as the boiler goes out.22 mm pipe comes of the boiler on the flow and return for about a metre or so then reducer s down to 15mm to all the rads . I removed the thermistor from the boiler but still connected to the wiring and tried the heating and all the rads got hot, which leads me to thinking the boiler is fine but the pipes are under seized due to being 15 mm to all the rads.
If anyone has any ideas would much appreciate some advice .

 

[Agile]

How have you come to be looking at this boiler when you dont seem aware of the history.

It probably could still give a reasonable performanance on a small system even with the undersized 15 mm pipework but to do that is likely to need two engineer's setting checked and adjusted.

I assume you have already checked the return filter ( if fitted ).

Tony

 

[Spikey101]

It seems odd that it works if you disconnect the thermistor, which should rule out a blockage as if the boiler was truly backing up and overheating it'd kettle like mad which im guessing it didn't? I doubt it'd be a pipework problem, ive seen systems with 10-12 rads all on 15mm (Rough cowboys who put it in, but don't fix what's not broken eh) and plus onto that it wouldn't have worked from day one?

My thought would be the diverter playing up and not opening fully (Well, after making sure like Agile says there's not a blocked filter or valve turned off), but again it would have kettled when you took the thermistor off and ran the boiler. Is the boiler actually really hot itself on the flow as close to the boiler as you can touch when it turns off?

 

[Steve46]

It seems odd that it works if you disconnect the thermistor, which should rule out a blockage as if the boiler was truly backing up and overheating it'd kettle like mad which im guessing it didn't? I doubt it'd be a pipework problem, ive seen systems with 10-12 rads all on 15mm (Rough cowboys who put it in, but don't fix what's not broken eh) and plus onto that it wouldn't have worked from day one?

My thought would be the diverter playing up and not opening fully (Well, after making sure like Agile says there's not a blocked filter or valve turned off), but again it would have kettled when you took the thermistor off and ran the boiler. Is the boiler actually really hot itself on the flow as close to the boiler as you can touch when it turns off?

The flow temp is hot with and without the thermistor connected, I thought about the diverter valve but seen as the flow is hot and the boiler not looking locking out on overheat that I wAsnt sure, also the divertervalve is expensive to fit, I might have to change the diverter valve and see, what would u recommend

 

[Spikey101]

Like you say diverters can be expensive and a pain to change (Although I don't remember what the performas are like) so i'd probably keep on trucking till I was sure.

If the hot water works fine, and the heating works fine without the stat in, but with the stat in just takes forever and goes off at temperature then something weird is happening. The flow must be backing up for some reason but not badly enough to actually overheat the boiler when you take the stat out so i'd triple check for any obvious blockages and failing that i'd probably have a good check over the diverter or any other mechanical interventions inside the boiler. If still nothing shows it's head then after crying for a bit i'd let the customer know the problems thoroughly and let them know im gonna plumb for the diverter. If it was my own boiler i'd just change the damn thing but Mrs Jones won't be happy if it doesn't solve it!

 

[gigz]

Try another thermistor ? Or test that one properly.