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canuck the pro
canuck the pro, Plumber
Category: Appliance
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Experience:  Plumber
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Help !! I have a potterton Combi 80 that was in the flat

Resolved Question:

Help !!
I have a potterton Combi 80 that was in the flat when i purchased it back in 2002. I have had two problems with it in the past, but cant understand this new problem.
Problem 1 it was totally not working ( no power ) a new pcb board was fitted ( engineer could not get the EXACT same one, but fitted one that worked ok) that was in 2007
Problem 2 the pump went, back in 2013, and again was replaced with a CP61 circulation pump. seems to work but now makes a noise. old pump that came out looked like an industral type pump just smaller in size and was a fantastic pump.. very powerful..you could hear it working..i am kikking myself for not asking to keep it as i dont know the make or model :(
NEW CURRENT PROBLEM..
it keeps going on lockout and seems to stay on after the tap is switched off.. so i thought if i turn off the heating this may solve the issue as i do have an air problem in the rads (having to keep bleeding and refilling).. the heating is now off at the switch and now the problem is .. after the tap is turned off, the boiler keeps running until it goes to lockout and the rads are also getting hot even though the heating is turned off at the switch on the front of the boiler !!!
i am fitting aliddin CO2 self bleeding to the rads on sat ( in the hope this will cure my air problem) but am puzzled as to why the boiler is over running until lockout and also the rads get warm even though they are switched off. also i have noticed the boiler making a clicking noise as if the boiler is going on off on off on off .. its going click click click click like 4 clicks in a row.. whats the problem with my boiler ?? HELP !!
Submitted: 2 years ago.
Category: Appliance
Expert:  canuck the pro replied 2 years ago.
canuck the pro :

Hi, my name is ***** ***** I have been in the home improvement and repair field for 20 years. I will be very glad to help you today. I would first check that there is not any debris stuck in the flow sensor and if the flow sensor tests out alright then the thermistor should be tested for continuity. If the thermistor tests fine then inspect the expansion tank diaphragm. If diaphragm tests well then failed PCB again.

Customer:

ok thank you ... my email address is *****@******.*** i once used this site before so it keeps saying my email address is already registered but dont know why it wont accept it again today when i asked you a question... i am not a rich man very poor in fact is the thermistor the over run therministat ???

canuck the pro :

The thermistor is the temperature sensor. Not so sure about the email part. I only answer the questions but I can forward to our moderators after I have answered any further questions that you have if you like?

Customer:

hello again ... sorry to sound thick .. is it like a rod that that goes into the boiler with a some sort of cable/lead that goes to a electric box that sits inside the boiler ??

Customer:

am just trying to understand how my boiler works :)

canuck the pro :

It looks something like this

Image result for potterton thermistor
Full Size Image

canuck the pro :

The thermistor senses the temperature

Customer:

oh because my neighbour says my problem is the over run thermostat has failed and i looked that up for pics.. but my neighbour is no engineer at all..

canuck the pro :

The over run thermostat is working fine since it is firing when it should not and then the over run thermostat is activated and then going into lockout. That is the one thing we know for sure is working great.

Customer:

sorry about this i dont understand the last answer .. "working fine since it is firing when it should not"

Customer:

ok sorry i understand the answer now.. i had to read again

canuck the pro :

very good

Customer:

i personally think its the pcb board again, if i replace and still have the problem then i will have a spare.. i am no engineer but am sure i can change myself as it looks easy enough.. is it ok to change myself ?? would you say ?? if that does not cure it.. then i will call out you an engineer.. wopuld this be an ok plan?

canuck the pro :

I think it is an excellent plan. I actually agree with you that the board is the most likely. If you remove it and inspect the back of it you may even find scorch marks on it.

Customer:

i think its the pcb board as its heating up the rads (even though heating is switched off) when the hot tap is running.. and it makes clicking noises

canuck the pro :

Yes. a failing relay on the board is the most likely.

Customer:

ok .. yes i agree .. in my heart i thought it would be.. i still have the old pcb board ( the original) so will take this to an outlet and say i want one of these !! its got all the codes on it.. but as its at home and i am at work.. i dont have them to hand.. not that it makes any difference !!

canuck the pro :

Excellent. Let me know if there is any more information I can offer. You can still comment or ask questions if something comes up even after positively rating my service. I am running out on a call right now and will certainly respond to anything when I get back. Should be no more than an hour or two.

Customer:

ok.. not being a pc geek i dont know how to get back to you after i have rated you but you have my email address :) drop me a line next week and i will tell you how i got on .. thank you so much for this advice.

Customer:

*****@******.***

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