Help! Potterton Combi80 CH fault, DHW OK

[IgorS]

Hi, first time poster

From yesterday, my Potterton Combi80 started to behave strangely. This is the fault explanation from me and I'm no expert in this field:

- When DHW is triggered by turning the hot water tap ON, red light on the PCB board goes ON, gas chamber looks & sounds OK, pressure is OK (black and red gauge arrows) and hot water is flowing OK (from the tap). Heating time is the same as before.

- When DHW is triggered off by turning the hot water tap OFF, red light on the PCB board goes OFF and boiler returns to idle mode. No obvious problems.

- It seems that microswitch (attached to DHW Diapragm Flow Switch) is OK as when I turn the hot water tap on and off, microswitch is "physically" switching positions (that rather smallish white thing is moving inside the microswitch itself).

Now, problem is when I turn the central heating ON (manual or timed) boiler is starting to behave. After .... let's say 60sec or so, black arrow (from the pressure gauge) is starting to rise rapidly and boiler is locking up. When I reset the boiler and turn the hot water tap ON, black pressure gauge is slowly returning to original position (1.3 - 1.5 or so), there is some erratic pressure from the tap itself ... but all in all system is "somewhat" returning to "normal".

On the broad level, I noticed that boiler is more "noisy" ... there is more pronounceable "shhhhhhhh" then before. It's somewhat hard to explain by using words

If the fault is serious, can you recommend any decent London based boiler service company (or man). I had terrible experience in the past, so I'm pretty much paranoid about calling somebody from yellow pages.

PS I hope that my fault explanation is clear to you. If not, I will try to be more precise.

 

[ChrisR]

Quite likely the pump failing. If the pump's dead, the HW would basically work, but come out a bit hot, with the boiler overheating at lower flow rates. The heating wold boil the boiler in seconds.
A merely moribund pump would be going down that track.

One thing to check is the automatic air release valve on top left of the boiler. The cap should be loose. Often they're left done up because they get scaled and leak.

Several of us cover parts of London, nobody's daft enough to try to cover it all!

 

[IgorS]

Hey Chris, thx !

Huh, pump was replaced with the brand new one (I hope) approx year ago. Is it possible that it's such low quality pump ?!

Now, that "shhhhh" sound I mentioned last a bit (5sec or so) after I switch off the HW tap and boiler returns back to idle state. I'm not quite sure from where "shhhhh" is coming from (around pump area I guess) as sound is mixed with everything else. Is that maybe a faulty pump spindown ? Also, pump is very hot to the touch.

Also, I think that air release valve is closed but loose ... as far as I could tell as it's rather hard to reach (because of the boiler surroundings and position).

I appreciate that nobody is crazy enough to cover London ... lol ... fair enough. I'm in W5 (Ealing) area.

Also, one more thing. When boiler is in idle state and doing nothing (and dead silent) black pressure gauge is slowly going up! Strange.

 

[Agile]

If the fault is serious, can you recommend any decent London based boiler service company (or man). I had terrible experience in the past, so I'm pretty much paranoid about calling somebody from yellow pages.

We have adverts in some of the Yellow Pages but we are paranoid about going to do repairs for people who think that they can repair their own boilers because they usually have a problem coming to terms with paying over £100 to have a professional do it for them!

Tony

 

[IgorS]

If the fault is serious, can you recommend any decent London based boiler service company (or man). I had terrible experience in the past, so I'm pretty much paranoid about calling somebody from yellow pages.

We have adverts in some of the Yellow Pages but we are paranoid about going to do repairs for people who think that they can repair their own boilers because they usually have a problem coming to terms with paying over £100 to have a professional do it for them!

Tony

Hey Agile,

I really don't have a time or nerves to argue with you. My point was that I had some terrible experience in the past and I need just some guidance if a) If problem is minor and fixable by me (and I'm technically and hardware minded) b) who to call ... even if that includes yellow pages.

I really don't understand your attitude. I never mentioned that I object calling professionals ?! and I never mentioned that I object paying money for their work ?! and I never mentioned that I will fix the boiler by myself if it's serious technical fault (let alone the safety matters). Most importantly, I know my technical limits.

But I DO object:

- When I pay £380 for freaking PCB replacement (later I discovered here that it was just solder joint, usual problem for this PCB, and was I able to fix that).

- When I pay almost £300 just for the pump replacement. The same pump which is maybe dying on me now.

Now you see, I'm paranoid because of my past. Nothing wrong with that I would say.

PS

NO, I DON'T object paying the professionals for their honest and professional work.

 

[Agile]

But I DO object:

- When I pay £380 for freaking PCB replacement (later I discovered here that it was just solder joint, usual problem for this PCB, and was I able to fix that).

- When I pay almost £300 just for the pump replacement. The same pump which is maybe dying on me now.

We would charge £178 plus parking in our local area to diagnose the fault and supply and fit a new PCB.

We are not allowed by our registration agents to "repair" boiler parts! Nor would I want to resolder your old board and have you complaining when it failed the next week for a completely unrelated cause. Far better for me to fit a new one for a customer who appreciates a professional approach with a guarantee.

You imply that you DO want to repair the boiler yourself and object to paying a professional if you can resolder it yourself. I would ask you why you did not do that if you were able to diagnose the fault and repair it yourself and confirm that the boiler was working safely afterwards.

We would charge £149 plus parking in our local area to diagnose the fault and supply and fit a new pump.

We also explain our charges in advance, whether asked to or not, and only charge a fixed price diagnostic charge.

But then we have to pay to be CORGI registered AND we have some adverts in Yellow pages as well !!! That must really make us cowboys!!!

Tony

 

[IgorS]

Tony,

We would charge £178 plus parking in our local area to diagnose the fault and supply and fit a new PCB.

Thanks for that!

We are not allowed by our registration agents to "repair" boiler parts! Nor would I want to resolder your old board and have you complaining when it failed the next week for a completely unrelated cause. Far better for me to fit a new one for a customer who appreciates a professional approach with a guarantee.

Fair enough!

You imply that you DO want to repair the boiler yourself and object to paying a professional if you can resolder it yourself. I would ask you why you did not do that if you were able to diagnose the fault and repair it yourself and confirm that the boiler was working safely afterwards.

Eh ?! Because I didn't want to mess up with the electrical affairs! Let alone the electricity + boiler combo itself. Matter of the fact is:

After the work was done (10min PCB replacement) and I paid for the service, I was started to get suspicious about what I actually paid and I started to dig around. That's the reason why I stumbled across this forum. Also, I found out the price for PCB too and found out here, on this very forum, that this was common problem with this PCB. As I had my old PCB with me, I identified the same problem and approx costs for PCB replacement. I guess that my comment you put on bold (above) was probably product of my anger, because I'm VERY friendly with soldering. Besides, PCB replacement itself is not a big deal too.

So, you see, I trusted you, professionals ... maybe blindly. Actually, that was the first time I started to get suspicious about the costs. Honestly, right now, I really don't appreciate throwing the money away easily and my pockets are not that deep. Hopefully, you will understand.

We would charge £149 plus parking in our local area to diagnose the fault and supply and fit a new pump.

We also explain our charges in advance, whether asked to or not, and only charge a fixed price diagnostic charge.

Thanks for that!

But then we have to pay to be CORGI registered AND we have some adverts in Yellow pages as well !!! That must really make us cowboys!!!

Eh ?! Did I mentioned that you are cowboys ?!

PS

and YES, rip off professionals I called were from yellow pages! I didn't say that they are not professionals! Their service is just expensive!

PPS

Do we really need to continue in this direction ?

I'm calling someone tomorrow. So, I would kindly ask for any further advice you may have ... or should we stick with the cowboys thing ?!

 

[ChrisR]

It might be blocked with boiler rust. Undo the allen screws, take the motor off and have a look. Drain first, and don't use the boiler isolating valves because they'll pee all over the floor.

What make is the pump? Some of the cheap ones really don't like dirty water, they wear rapidly.


Oh and by the way, Tony/Agile isn't a cowboy but he comes on a very High Horse!

 

[IgorS]

It might be blocked with boiler rust. Undo the allen crews, take the motor off and have a look. Drain first, and don't use the boiler isolating valves because they'll pee all over the floor.

Cool. Thanks for that. That hissing sound I mentioned above (and it's present also 5-10sec when the system enters idle mode) may suggest that pump is somewhat struggling. It's very hot too.

What make is the pump? Some of the cheap ones really don't like dirty water, they wear rapidly.

It's "Circulating Pumps" "CP61" CODE: 8104E0106. It's the same pump as previous one (which died year ago). Also, I noticed that warranty date on the pump is "310708". I guess that this means it's still under the warranty. Question is ... what to do ? I don't have any pump warranty paper with me. Just the invoice from the guy who replaced the pump year ago ... and believe it or not he didn't install the pump properly (washer) so I had to call other people again (as he was on holiday) and pay the money for the installation fix. Boiler was leaking all over the place. Shocking.

Oh and by the way, Tony/Agile isn't a cowboy but he comes on a very High Horse!

Oh, that would be a scene I suppose that, apart from our little chat, Tony wouldn't object riding his pretty horse all the way up to the W5 and visit my boiler, personally Don't get me wrong, I really appreciate his efforts to put the things into the right perspective.

 

[Agile]

I'm calling someone tomorrow. So, I would kindly ask for any further advice you may have ...

My advice would be to check their charging rates BEFORE they come. If it was me then I would be wary of anyone who charged by the hour for diagnostic work because you pay more if they are slow and incompetent.

We have to charge a fixed diagnostic fee because I can hardly spend an hour driving there and just charge for five minutes to identify the fault on a time basis. I think thats better for the customers because they know exactly how much its going to cost before we come. Even our £84 is too much for some people though they expect us to come free to diagnose teh fault so that they can change the PCB or pump themselves.

The pump guarantee does NOT apply when the pump has been damaged by dirt in the system and thats almost always the case!

Tony

 

[IgorS]

My advice would be to check their charging rates BEFORE they come. If it was me then I would be wary of anyone who charged by the hour for diagnostic work because you pay more if they are slow and incompetent.

We have to charge a fixed diagnostic fee because I can hardly spend an hour driving there and just charge for five minutes to identify the fault on a time basis. I think thats better for the customers because they know exactly how much its going to cost before we come. Even our £84 is too much for some people though they expect us to come free to diagnose teh fault so that they can change the PCB or pump themselves.

Thanks for the tips, Tony. Well, that fixed diagnostic fee is reasonable enough to me. At the end of the day, you have to keep your thirsty van running and London is everything but not small city. I suppose that on top of that there is servicing fee per hour plus any spare parts (costs). Is that, let's say, acceptable term ?

Speaking of pump replacement. Well, guy who changed my pump struggled a LOT. Firstly, he couldn't loose the pipe joints for an half hour or so. All in all, he spent an (at least) hour changing the pump. Amazingly enough, boiler was starting to leek after few weeks as washer was eaten out. I wasn't sure from where the leak was comming from, so I called other people in panic (as original guy was on holiday). So, I'm really vary on replacing the pump by myself, after seeing him struggle that much.

The pump guarantee does NOT apply when the pump has been damaged by dirt in the system and thats almost always the case!

Huh ... didn't know that


Just verified the pump again, by just running the hot water via tap. I can feel the vibrations when I touch the pump. It's hot too. As Chris suggested, unless top of the pump is dismantled via those hex screws, there is now other way of telling in which state it is ... or if the source of the problem is pump alone.

PS I mentioned above that pressure is rising when system is idle. Forget that. My water inlet (water from fill loop) was not cut off properly (while I was feeding the boiler with water, in order to move the pressure up to the 1.5 or so). So, boiler had rather smallish and constant water intake from the fill loop.

Also, is it normal that sometimes when I start the central heating manually via control switch on the front (CH on constant) it won't start ?!


PPS If the system is dirty, I guess that I may have circulating problems like this. I guess that system cleaning is rather time consuming and expensive task ?!