Potterton promax 15 he - Strange noise and then leak

[Sohail92]

Hi got a potterton promax 15 he. Pumps with the cylinder in the airing cupboard but boiler is in utility room. So recently I've found in that can hear a loud clunking noise (around the pump I think, not sure) and then the boiler locks out. When I go to the boiler I hear a hissing sound as if steam is escaping and then notice wetness on the worktop.

Done a bit of investigation and it looks like theres a leak at the flow switch. As I'm not qualified for a repair like this I've called out an engineer but was wondering if anyone knows what this would be and what the approx costs normally are?

Here's a video of the leak in action:

 

[ianmcd]

sounds like you have more than one problem , but you dont really give enough information, you mention pumps, it is possible that you have more than one pump , but unless you have underfloor heating that would be unusual, the water drip needs sorted but cant see how that is the cause of your problem

 

[Sohail92]

sounds like you have more than one problem , but you dont really give enough information, you mention pumps, it is possible that you have more than one pump , but unless you have underfloor heating that would be unusual, the water drip needs sorted but cant see how that is the cause of your problem

Hi sorry for the lack of information. From what I can see there is just one heat pump in the airing cupboard with the unvented cylinder and the expansion vessel. There are also 2 zone valves there. We don't have underfloor heating.

That's kinda what I was thinking. However it feels as if they are related.. There's no drips when it's working fine but intermittently, say once a day I hear the loud clunking and find at that point the flow switch is leaking and the boiler has locked out. During normal operation of the boiler there's no leak.

 

[ianmcd]

yes that is normal , you have an S plan system, post some pics of your valves and pump, if motorised valves are fitted the wrong way round , they will work but sometimes clunk when trying to close, the boiler leak will still need to be addressed, but unlikely to be the cause of the clunk

 

[Sohail92]

Here's a pic of the valves, pump etc.

Both of the levers of the zone valves are at the top, so I assume they are correctly installed?

In the past I have had the heating zone valve not close so the heating came on with the hot water. I took off the valve and manually rotated the spindle after a squirt of WD40 and its been fine since. Thinking about this further... it does seem like the problem with the loud clunking happens when the heating has reached temp and needs to switch off.

Thanks for your help

 

[Sohail92]

Update

Spoke to the engineer and mentioned the banging/grinding type noise.. Showed him the video of the flow switch leaking. He told me he reckons its the heat pump so changed it with a new one. When draining the water it was black. He mentioned it should have a powerflush done.

Few hours later and we hear the hissing noise coming from around the flow switch where the boiler is and water all over the worktop.

Was really hoping this would be fixed as we have a 3 month old baby and want the boiler working to keep the house warm. Does anyone have any ideas, should I push for him to replace the flow switch?

 

[kidgreen61]

I've replaced 2 of those flow switches recently, it's a bit of a pain to do because you may have to drain the system to change it.
The other factor is how much wriggle room there is in the flow pipe.
One of the ones I did was really awkward because there was a very short length of pipe & there was no movement in it, I had to cut it.

The other factor is that some of those switches don't easily come out.

One I replaced 3 yrs ago started leaking again this week, customer replaced boiler.

 

[Sohail92]

I've replaced 2 of those flow switches recently, it's a bit of a pain to do because you may have to drain the system to change it.
The other factor is how much wriggle room there is in the flow pipe.
One of the ones I did was really awkward because there was a very short length of pipe & there was no movement in it, I had to cut it.

The other factor is that some of those switches don't easily come out.

One I replaced 3 yrs ago started leaking again this week, customer replaced boiler.

Hi mate, interesting tbh my boiler must be a good 15 year old so I guess I should expect these sort of problems now.

Did your customers have any symptoms like mine where there was a loud hissing and drips coming out of the area where the flow switch joins? Thanks

 

[kidgreen61]

Hi mate, interesting tbh my boiler must be a good 15 year old so I guess I should expect these sort of problems now.

Did your customers have any symptoms like mine where there was a loud hissing and drips coming out of the area where the flow switch joins? Thanks

No hissing, just leaked when cold.

Your banging will probably be pump related, or a zone valve switch sticking in the on position, causing boiler (and maybe pump) to come on but nowhere for water to go.

 

[Sohail92]

No hissing, just leaked when cold.

Your banging will probably be pump related, or a zone valve switch sticking in the on position, causing boiler (and maybe pump) to come on but nowhere for water to go.

Just had a new pump and still get the noise. I'll ask the engineer to check the zone valve instead. Although there are two zone valves (one for hw and one for ch) the problem seems to occur on either hw or ch demand so that made me think they might be ok.

My flow switch doesn't leak when cold it only ever leaks after the boiler has locked out and made the noise.. Feel like this could get very expensive

 

[dilalio]

Your system is full of funk and needs cleaning. Maybe too late for the boiler hex to make it through this... Could try a chemical flush and see what you get out.
But issues like this is a 15yr old boiler and a system to match!

 

[kidgreen61]

I just remembered that one of these boilers had random firing issues caused by the leak from the flow switch, the water had got into the PCB causing a short which would make the boiler fire even though there was no demand.

 

[Sohail92]

Update

Engineer came today, replaced flow switch and said hopefully this fixes the leak. Apparently he said we can't get the flow elbow any more as it's no longer made so if that's the issue I would need a whole new boiler... Is it just me or does that sound a bit extreme?