Potterton Promax HE Plus fires up when timer is off

[mossquire]

Just wondering whether anyone can help with this. I have a 4 year old Potterton Promax HE Plus which fires correctly when the timer comes on and both water and radiators seem to work ok. The problem is that when the timer is off the boiler fires up for a couple of minutes on a regular basis, maybe a couple of times an hour. I was advised it might be one of the zone valves but that has not cured it. This is as far as I go with DIY so I wondered if anyone has any ideas?

 

[diamondgas]

When you say that it has not cured it, what has been done? A bit of history will help reduce the posibilities regards causes. However first port of call would be external demand such as the zone valves! How many are there?

 

[mossquire]

Well when I first moved in about 4 years ago it was a new house and every thing worked well, the hot water was very hot all the time and the central heating worked perfectly. About a year ago I realised that I had an emersion heater and it had been on constantly since Barratts had put it on before I moved in!!! Yes I can hear you all laughing but every emersion I have ever had has had a lit switch in the kitchen. Anyway I turned it off and that is the only thing that has been done to the system as a whole. Since then the system has worked as it should. I cant remember when I first noticed the boiler firing up out of its allotted time so I cant say that it was when I turned the emersion off or not. Anyway when I noticed t about 6 months ago I called a local plumber who took one look at the cylinder cupboard and decided it was too complicated for him. It has two main valves, a large square Range valve and a silver oblong siemens valve.It has an expansion bottle (I think thats what it is) and several black plastic and brasshandled valves as well. The plumber said he thought it might be the square Range valve so I went onto the net and put in my problem to google and it led me to a site which explained that the problem was likely to be that valve which is also known by the name sunvic. The valve isnt made anymore but he would recondition it for £12 which seems reasonable. However he emailed me and told me the valve was ok. All I have done in the meantime is put the emersion heater back on but I have not had the central heating on so cant tell you wgether that is ok but with no valve in place the boiler still fires up as it did before. The only other thing I can think of is that it has not had a second and third year service but, and I will no doubt grt shot for this but the aforementioned plumber (who does my landlords certs) said todays boilers dont have any servicable parts so it was a waste of time. Hey dont shoot me I was willing to pay for it. Thats all I can think of and I will refit the valve as soon as it comes back

 

[diamondgas]

Thanks for the history mossquire

the random firing up can be from either of the valves you've described. I'm assuming you removed the hot water valve actuator (Valve head). If so, and you're confident with wiring, turn of the power to the heating, take out the remaining grey and/or orange 'switch' wires (Note where they came from!) put the power back on and see if the boiler fires up or not! If you're not confident then get someone in who is. It deffo sounds like there's an external wiring fault and the zone valves are the usual suspects!

If you can post up a picture it may also help identify what it is you're describing ... :yesnod:

 

[mossquire]

this is the system apart from the zone valve which is away for repair. I forgot to say (which is no doubt important) that the pump is running 24/7

 

[diamondgas]

Okay mossquire .. thanks for the pics ... With the hot water valve head removed that just leaves the heating valve head. As mentioned B4, are you competent with wiring? If not you'll need to get someone in who is. The black cable from the silver valve goes into a honywell wiring center by looks of it. That is the cable to trace the orange and/or grey on! It's there where i think you'll find the fault! It's these two valves that supply the boiler with a demand for heat!

 

[tm plumbing]

View attachment 3070View attachment 3071this is the system apart from the zone valve which is away for repair. I forgot to say (which is no doubt important) that the pump is running 24/7

Is there no tundish on that install ? or is that it hiding away in the corner behind pipework ? Either way the discharge pipework is not ideal with that 90* bend being so close to PRV & tundish(if that is it) being stuck in the corner a good distance away.
Anyone else see this ??

 

[mossquire]

Thanks diamondgas and tm,
Yes there is a tundish or I presume that is what your on about in the corner at the left back. I have had the other valve back now and will refit it. I am competent at electrics at a DIY level. ie I take pictures and diagrams so its not memory!! Are you suggesting I put the Range valve back and disconnect the Silver Siemens valve which I think is for the central heating, Or disconnect both valves? Any idears why the pump will not stop? I assume it is one and the same problem

 

[diamondgas]

I'd start with disconnecting the one remaining valve mossquire! That way you'll have eliminated them from the equation or, if the pump stops and the boiler stops firing, found the cause! Let us know what happens when you disconnect that valve ... I hope you're noting down where these wires go!!!

 

[mossquire]

Ok, I disconnected the siemens valve and everthing stopped I then refitted the repaired valve and the hot water is working with the motor turning off as it should. I have not refitted the siemens valve as it is for the central heating which I don't need right now. That gives me time to sort it out. Thanks guys you have been fantastic. Next question is do I just get an actuator which I can fit easily (note the newly found optimism) or get a whole valve which I probably would have to get someone in to fit it because the water has to be drained?

 

[diamondgas]

Go for the actuator mossquire if you can still get them ... should be able to. Details should be on it somewhere!

It's a good sense of achievment when you eventually get there! Hopefully you'll see quite a reduction in your gas bills as well as your electric now the immersion heater is off!!! :rockon2:

 

[mossquire]

OMG OMG OMG:rockon2: I was looking on the net to find an actuator and I had the unit there so I just thought I would open it to have a look and so as we are little boys inside I thought I will take it apart and see if I could see anything. Well I was always the one who did it ok but never managed to fix it but when I opened it I saw a wire had come off. It was a dry joint on one side of the microswitch. I fired up my 20 year old £3 soldering iron and OMG its fixed. Tried it and everything works. Thanks to everyone who gave me advice and help. I guess this is the 'power of the net' everyone talks about.

 

[diamondgas]

nice one! I do carry one for pcb's .... glad to hear you're sorted