Potterton kingfisher mf

[Richmac]

So just a few days before Christmas and my boiler decided it didn't want to play anymore. After ringing 5 plumbers with nobody willing to come around till the new year I'm wondering if there is something I could do myself to get it working again for a few weeks. Its a potterton kingfisher mf fitted in 1999 and there is no sign of life. As I understand the fan needs to turn before the gas valve will open and try and light. My fan won't start but according to the voltage tester the supply is live. The fan turns freely by hand and the bearings feel fine. Any retired heating engineers got any tips a complete novice could try before he gives up please

Regards Richard 

[RobH]

I'm not a heating engineer but if there is definitely a supply voltage there the winding may have gone open-circuit , so  you probably just need a new fan - but you are unlikely to get one delivered this side of Christmas.  There seem to be two different ones depending on the boiler:

https://www.boilerparts.co.uk/Ranges/POTTERTON/KINGFISHER/KINGFISHER MF CF90/242084?

https://www.boilerparts.co.uk/Ranges/POTTERTON/KINGFISHER/KINGFISHER MF CF90/242083POT?mode=triplemode=triple

You can do a basic resistance check of the motor winding if you have a multimeter.  

 

Edited December 20, 2022 by RobH

[RogerH]

Hi Rich,

if you go on EBay and input you boiler you should get a hit on a boiler repairer/supplier in Watford. 

They can still supply parts and repair PCB's for my Gloworm KFB50  30+ years old.

https://www.ebay.co.uk/itm/281104014151?hash=item41731adb47:g:TjsAAOSwvBpbRHJx&amdata=enc%3AAQAHAAAA4CKAm3DZVZD%2BDdvIe%2Ba4nPmw%2F5i5TYnM9SreOIYIHJgUauslFPlMutQ1e127UDoMmPhReG%2FNMNqRLvlVgDhufxABBH6VoajtvfmJZt3WHdTuKD0hG72sy7sW%2FsMnU9%2Fb%2F5OWrv3H627TgM7GXQ%2BNZLG3Z1UFtW3Yp2z6UlfPmLnWDdMwLweWTe288G8SSOJanlbmlYuCmsYi4mbkxReDh5poUuVgXQPFziq6fRDw36PeVFpa8cwxqIZBfCEu3E3ooUqme0hn6E8IskSDCv3%2BjuyHSzcZPSJ07dKk%2BLu%2BrsPb|tkp%3ABFBMjv_JkKZh

Roger

Edited December 20, 2022 by RogerH

[mikeh]

Hi Richard,

If you've got a multimeter and feel confident to have a go, there's a fault-finding guide on page 32 onwards of the manual which this link takes you too (it'll download a PDF file). If not, is there someone local to you who might give you a hand? If you can identify the faulty part that would be a good start.

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjd_aaMkYn8AhVaQkEAHWM2BwUQFnoECDUQAQ&url=https%3A%2F%2Fwww.acwilgar.co.uk%2Fboiler-manual-pdf%2Fpotterton%2Fpotterton_kingfisher_mf%20cfl%2040-100_install%207.pdf&usg=AOvVaw1Kg1sZx8sqe-qr6dbJg2ug

If it is the fan or something relatively simple to change, you may be able to get hold of one, either from a supplier or from eBay, if you go & collect it.

Good luck

Regards

Mike

[mkmick]

Simple test, disconnect the plastic hose that connects near the fan housing gently suck or blow this will fool the pressure switch if the boiler goes through its firing sequence you need a new fan.

[Richmac]

Thanks for your replies guys. Unfortunately I don't know how to use a multimeter although I have one and I also don't feel comfortable using one with the circuit live. I will try mkmicks trick after work and see how I get on, thanks Mick. Thanks to all who posted links much appreciated. Does anybody know if the fan is easily replaced? I can't find a video for my boiler? 

[RobH]

The fan is very easy to replace- just one fixing screw. See paragraph 4.8 on page 29 of the pdf that Mikeh linked to. 

[Richmac]

Unfortunately the suck test from mkmick didn't work. Still not firing up. I guess I'm into the PCB board now? 

[Charlie D]

I changed the fan on my Worcester a couple of times until I eventually gave in a few months ago and had a new boiler fitted.

As well as the wires to the fan there could well be a rubber (silicone?) tube or two as mentioned previously. This (These) go to a pressure switch that tells the control board that the fan is working. If you have 2 tubes, make sure you know which goes where.
Looking at your picture it seems like there is only one.

I discovered on mine that over time the heat had cause the tube to get brittle and it eventually broke, so check the tube for hardness and be careful if it looks a bit fragile.
A broken tube will result in the pressure switch not working and the control board shutting the system down.

However, for the pressure switch to be of any use the fan must first rotate. As it seems that your fan does not rotate at all, I would guess it is either the fan motor or the control board that is at fault. My fan replacements were both because the bearings were shot. Everything worked, but the noise was impossible to live with.

I replaced the control board on my Worcester but it is a bit of a hassle as there are many connectors with wires going into it. (Also quite expensive.)
Lets hope that is not your problem.

Charlie.

Just read your last post. As I have just mentioned, the tube is only relevant after the fan has started. In your case the fan has not started, so I don't think the suck test has any relevance.

Edited December 21, 2022 by Charlie D

[RobH]

21 minutes ago, Richmac said:

Unfortunately the suck test from mkmick didn't work. Still not firing up. I guess I'm into the PCB board now? 

There are two fuses on the PCB - it would be worth checking those first. 

If there really is 230V across the fan motor terminals ( the two violet wires) then the motor must be faulty if it isn't turning. 

[Charlie D]

Richard,

Just realized something that may have caused a bit of confusion.

You said :
“My fan won't start but according to the voltage tester the supply is live.”

Later on you have said.:
“I don't know how to use a multimeter although I have one and I also don't feel comfortable using one with the circuit live.”

This gives the impression that you did not try putting the meter across the wires going to the fan, but you simply checked that there was power going to the boiler it’s self.

Please can you clarify, as you really do need to check if there is power actually going to the fan it’s self.
But I also totally understand your reluctance to go inside the boiler with a meter if that is the case.

Charlie

[RobH]

Sudden thought - Have you tried pushing the RESET button on the control panel? 

[Richmac]

Hi Charlie yes I used a voltage tester to test for power not a multimeter. And Rob Yes I have tried the reset button, if only. Thanks again for trying to help me 

[Charlie D]

Richard,

Thanks for the clarification.

I await Rob's comments, but to the best of my knowlege I think all that proves is that there is a voltage to one side of the motor, it does not prove that there is a retun path.

If you are not happy poking about in a live box, (And I don't blame you at all if that is the case) then I'm not sure what else you can do.

My money would be on the control board. As I mentioned before I have had one go faulty, but it is a bit of a costly gamble if you replaced it and then found it made no difference.

Charlie

Edit... I just looked on eBay and the control boards seem to start at about £50, which is not too bad. Also the connectors are a lot easier to sort out than the ancient Worcester boiler that I had. So not so traumatic as I first thought.

Edited December 21, 2022 by Charlie D

[mkmick]

Just to clarify the hose in your picture isn't the one that is used for the test from memory the red hose that connects to the air pressure switch is the one.

There is a sequence to a boiler firing  If you are sure that you have power to the fan then that would suggest that  the PCB is ok.

[TorontoTim]

I may be a bit late to this, but I have found that there are videos for almost ANY household repair you can think of on YouTube.

Google the boiler name, "repair" or "fault" (or the specifics if you know what it is) and click on the videos option at the top of the screen, just below the search bar.

Tim

[RobH]

1 hour ago, Richmac said:

Hi Charlie yes I used a voltage tester to test for power not a multimeter.

Unfortunately as Charlie says, that sort of tester doesn't really help with the fault. It doesn't draw any current and will show 'live' even with the most tenuous of connections which might be unable to power the motor.  

 

 

 

[Richmac]

51 minutes ago, mkmick said:

Just to clarify the hose in your picture isn't the one that is used for the test from memory the red hose that connects to the air pressure switch is the one.

There is a sequence to a boiler firing  If you are sure that you have power to the fan then that would suggest that  the PCB is ok.

The red hose just goes nowhere Mick. Are you suggesting I connect a pipe to it for the test? I'll never get my head in there!!!

[RobH]

The clear pipe is the right one - the pressure sensing outlet on the fan is the stub pipe it is connected to at the bottom. 

There is another thing that can fail and prevent the fan running.  That is the overheat thermostat. If that is open-circuit the boiler won't run. 

 

 

 

 

 

[Richmac]

25 minutes ago, RobH said:

The clear pipe is the right one - the pressure sensing outlet on the fan is the stub pipe it is connected to at the bottom. 

There is another thing that can fail and prevent the fan running.  That is the overheat thermostat. If that is open-circuit the boiler won't run. 

 

 

 

 

 

Hi Rob Yes I saw this and connected my multimeter to the the thermostat and it shows a circuit so assuming this is closed? Also the fault finding guide suggests then if voltage is supplied then replace PCB 

[Richmac]

I've checked the two fuses in the PCB and they are fine thanks Rob for suggesting 

[RobH]

There is one last test you could do if you feel confident enough. 

Isolate the boiler and pull the two violet wires from the motor.  Find a spare mains lead, fit it with spade connectors and connect it to the motor instead.  Plug it in and see if the fan runs.  If it doesn't the motor is duff, if it does the PCB is probably faulty. 

Unplug it from the mains right away as soon as you have finished and DO NOT leave the modified mains lead lying around  as it is highly dangerous with un-insulated ends. 

Edited December 21, 2022 by RobH

[Charlie D]

OK so you CAN use a multimeter .

 

What I am about to say is done entirely at your own risk.

Make sure the power to the entire boiler is OFF.

Remove the two push on connectors from the fan motor.

Set your multimeter to measure AC 250 volts (Or more).

Push the multimeter probes into the purple connectors from the fan.

(If you are at all concerned, wrap these joints in insulation tape.)

Let go of everything from your hands, but make sure you can read the meter.

Switch the power back on.

 

See what the reading on the meter says, and let us know what the reading is.

 

Charlie.

[ntc]

Do you have zone valves?

[RobH]

5 minutes ago, ntc said:

Do you have zone valves?

That is a very good point.  We are all assuming the fault is in the boiler but that may not be the case. 

Boilers are part of a system that usually includes a timer (programmer) and thermostats.  If the boiler heats a hot water cylinder as well as radiators, there are usually one or more motorised zone valves which 'steer' where the water goes. The room and tank thermostats operate the appropriate valves and the valves in turn have switches which send  power to the boiler only when the valve has reached full travel. 

The boiler and water circulation pump cannot operate until they receive power from the motorised valve. 

Do you know whether the water circulation pump is operating?  If it is the zone valves (if present) are probably working OK but if the pump doesn't run either then maybe the fault is with a valve and not the boiler.