no hot water from my Potty combi (updated-help!)

[KarenDutton]

hello.

Can any of you guys help me

I'm only getting lukewarm water from my boiler. The manual says that it is a "Potterton Performa 24i HE".

If i turn the tap down then i can get the water a little warmer but mostly its staying lukewarm.

I know i'm probably going to have to get a heating guy out but would still like to know what is problably wrong. So i dont seem like a dumb blonde

Karen

 

[Agile]

If the boiler DOES NOT fire up on DHW demand with the heating off then its a diverter valve or switch failed.

If it DOES fire up on DHW with heating off then its likely to be a blocked plate heat exchanger.

May be better to act dumb and flutter your eyelids!

Tony

 

[brian28]

Hi Karen.

I've just had something similar go wrong with mine. My combi is a different model so maybe one of the experts will correct me if i'm wrong.

I was advised to replace the 'hot water pressure assembly'. I did this and also replaced a microswitch that is attached to it. Sorted the problem out.

Hope this helps.

PS: The parts were not that expensive

Brian

 

[brian28]

If the boiler fires up on DHW demand with the heating off then its a diverter valve or switch failed.

If it DOES fire up on DHW with heating off then its likely to be a blocked plate heat exchanger.


Tony

Don't both of these sentences say the same thing Tony????

which is right and which is wrong.

And PLEASE dont patronise the woman. I'm sure she's after some info for fear of being ripped off.

 

[KarenDutton]

Now now - boys. Settle down.

Thanks Tony. My central heating was working fine this morning. I've just put it on again and all my radiators are getting hot.

I have just turned on the hot tap. The flame inside the boiler went higher but only warm water out.

So, does this seem like its the "diverter valve"

Karen

 

[Agile]

Karen, as Brian pointed out, there was a slight error in what I said before.

I have now edited this so please follow the two different situations and let us know the results.

Brian, its obvious to me that she is not going to try to fix it herself and is planning to call someone else in. Whilst you have the skills to do simple repairs she clearly does not so all I can do is identify which of the two possibilities is the most likely.

However, there is no substitute for being in front of the boiler and any arms length diagnostics may not be correct. It would be unfair and might upset any professional being told how to do his job! Even though many dont have adequate diagnostic skills!

Tony

 

[KarenDutton]

Thanks Tony.

Just finished doing what you asked.

The boiler does fire up on hot water (lukewarm) with the heating off. What i have just noticed whilst letting the hot water run is that the heating pipe and kitchen radiator is getting warm as well.

Karen

 

[Agile]

In that case its a fault within the diverter valve.

Its caused by a little find dirt in the system boiler.

The diverter valve can sometimes be cleaned but most often the easiest solution is to replace it. The part is around £100 for a gas engineer to buy.

Tony

 

[KarenDutton]

Hi.

I'm a friend of Karens and also a plumber by trade. However, i dont repair boilers or combis.

She called me this evening about the combi. Today a guy came out to fix the problem with warm water. He has replaced the DHW assembly and also the diaphragm on the assembly below(microswitch with 2 red wires). (i think so because he left the old bits, although the diaphragm looks ok)

Karen then said he ran the hot water and it did get hot, so she paid. However, then the radiators got hot and the combi just kept firing on demand. So, she switched it off and called him but he said its a faulty pcb.

I've had a look and cant work out whats going on. on hot water with the tap running the boiler fires up. The pin on the dhw assembly is hitting the microswitch. The lower pin also hits its microswitch. But hot water is going straight to central heating. Turn off the tap but the boiler stays fired up. (the tap led is lit)

Switch to c/h and the same thing is happening. With all external controls off, the boiler fires up and the hot water led symbol is lit.

I've removed the D/V operating head. There is no movement in the unit at all on either dhw or c/h. The little brass ferrule just rattles in the unit.

Any clues as to whats happened here so i can try and sort it for her and her 2 girls in the morning

Steve

 

[ChrisR]

SOunds like he changed the wrong bit - hunting now for a piccy...
WHich bit is rattling??

Meantime take the head off hte diverter valve (clip slides out) and see if the pin goes in & out when your demand goes between CH and HW. Check for leaks in the top where the DV's pin is - push it (it's hard) is it smooth & springy?


ummm is this the pic...?

Yer, same as that I think for the 24iHE

 

[KarenDutton]

Thanks for the diagram.

Going by it, "390" has been replaced like for like. The old assembly has been left so i could identify it. On "390" is a microswitch with black/white wires. Removing this and turn on the hot tap and the pin comes out. Bottom pin on "102" also comes out. pump spins and boiler fires. Green tap led lights up on the panel but no hot water. Hot water up the flow pipe though. Panel switch selector to hot water only. Turn hot tap off but boiler continues to fire, so have to switch it off at the mains.

Panel selector switch to c/h and hot water. No hot tap turned on but panel tap led lights up and boiler fires up.

I took the d/v operating head off "387" and it rattles - little brass pin inside.

With this off and boiler firing, i pressed the pin inside the assemble where "387" sits - the boiler continued to burn

So, looking at it it all looks ok. I can see the new unit he replaced. Microswitch with black/white attached. Below another microswitch with red wires. Put 387 back. Select panel switch dhw and boiler fires on full even though hot tap not running. hot water going to heating side. panel tap led lit even though no tap on

Then make sure no external call for c/h. stats and timers off. No dhw taps on. select c/h&dhw on panel and boiler fires up. panel tap led lit up showing hot water demand.

Its as if this boiler is continually sensing a demand for hot water (and the tap led flashes) all the time no matter if c/h or dhw is selected. Even thought he taps are off

Karen definately said she had nice hot water before the engineer left

 

[KarenDutton]

corgis must be at the pub

any "sober" potterton experts??


Steve

 

[superdupergasman]

Remove '387' the div motor, run tap and push down the pin manually, trying not to burn or electrocute yourself.

If the water then heats it might be that motor thats goosed, not pushing the divertor into the correct position.

If it still goes down the heating then it might be the inside of the divertor valve thats passing.

 

[KarenDutton]

removed the d/v motor and ran the hot tap. Then i switched the panel selector switch to ch&dhw.

Boiler fired up on full rate and tap led lit up on panel. Pushed the pin down and could hear a slight change of flow. However, hot water pipe stayed cold and heating pipe got hot.

Whatever i do there is no movement from the brass nut within the d/v motor - it just rattles.

But why is this boiler firing up (panel tap led lit) when theres no call for heat or hot water. Would a passing diverter valve do this.

I checked the microswitches and they seemed ok. Neither switches were stuck on.

I'm gonna stay online for a while longer using karens login. Told her i would go back in the morning.

Where is Baxpotti when u need him

steve

 

[heatingman]

You will probaly find the microswitch is fused together, which is why the boiler thinks theres a demand for hot water, but as the dv is in c/h mode it will roast your socks off.