Central heating boiler pump running continuously

[goodtyneguy]

Hello folks I just discovered your excellent forum and thought it would be an ideal place for help.

It's a grundfos pump working with a potterton suprima 30L-100L wall mounted fan assisted balanced flue gas boiler. The boiler was installed in feb 2002 and has been working without a problem until now.

The boiler tripped out last night when I had it on the 24 hour setting to heat some water up. The red LED light is flashing and pressing the reset button has no effect.

I turned off the temperature control and programmer but the pump continued to run. It was n't until I turned off the electrical mains supply to the boiler that the pump stopped running. The pumps electrical feed cable comes from the boiler and has an overun on it to continue to pump the residue of hot water when the boiler switches off. This is the only pump in my system.

I left it until this morning then switched the electrical mains supply to the boiler on, the pump started up again and continues to run all the time. Again, turning on the programmer and the temperature control to activate the boiler has no effect. The boiler will not even attempt to fire/spark up. The installation and service instructions says that the status of the boiler is "lockout" as evidenced by the red light flashing two times per second. There are no motorised vlaves in my system if that's any help.

If someone could help me diagnose the problem it would be greatly appreciated.

Thanks

 

[goodtyneguy]

Oops

 

[goodtyneguy]

Anyone.... please?

 

[kevplumb]

err suprima

has it had a board and loom change ?

 

[goodtyneguy]

Hi Kevplumb, no it has operated without any problems since it was installed in Feb 2002 other than it was tripping/locking out ocassionally before the problem I have now.

I was looking at the installation and service instructions and was wondering if the overheat sensor or the temperature sensor might be the culprit? I presume they have some say in the pumps operation and if either of them have failed in the pump on position I presume the pump would run continuously whilst the boiler would be in lockout mode?

They both sit in the outflow (I think it's the outflow) pipe and look easy to get to once the cover is off. Can they be tested and if so how?

Thanks

 

[45yearsagasman]

The sensors are reliable on this boiler but the PCB's were not.If as you say the PCB is original then a modified one will fix your problem.The kit has a new wiring loom etc and should be fitted by someone competent to remove and replace the combustion cover correctly and perform all the relevant safety checks afterwards.

 

[45yearsagasman]

Duplicated

 

[ismellgas]

Pump over-run possible faults - water temperature thermostat/sensor or faulty micro switch. I hope this is of some use pal

 

[goodtyneguy]

Thanks for your replies 45yearsgasman and ismellgas, can a run this past you please.

My boiler is overdue a service and in order to possibly pin point the problem and save a little on the cost of this repair I was thinking of doing the following myself:

Scenario:

1) Carefully removing the combustion cover and the two sensors mentioned above i.e. the temperature and overheat sensors and have them tested. Is this possible. If so and they prove to be faulty, replace them myself then call out my competant person to service the boiler and obviously replace the combustion cover. I presume all the necessary safety checks will be performed as a part of the service.

2)If it's not the sensors - which is more likely baring in mind 45yearsagasman's comments - and does turn out to be the PCB would a reconditioned one from these people be worthwhile. I can call into this place they are just down the road from my home, pick one up for my competant person to install and have him/her do the service at the same time? If not such a good idea where is the best place to get a new PCB, either to pick up or to be delivered to my home?

Your comments and advice are appreciated, thanks.

 

[goodtyneguy]

The sensors are reliable on this boiler but the PCB's were not.If as you say the PCB is original then a modified one will fix your problem.The kit has a new wiring loom etc and should be fitted by someone competent to remove and replace the combustion cover correctly and perform all the relevant safety checks afterwards.

Spot on other than only the side cover housing the PCB needed to be opened. The boiler is up and running again. As I replaced the PCB myself -£50 for a recon/part ex board - tomorrow I am going to arrange for a gas safe engineer to service it. In the mean time the boiler and gas will remain off. The weather is not cold enough where I live for central heating at the moment. I cook with electric and have a hot water tank equiped with an immersion heater so I should be able to manage until the service/safety checks are done.

Thanks again for your help.

 

[XKESTONMAN]

i hope u will tell the engineer u have worked on it, and changed the pcb
before he takes on the service.

 

[goodtyneguy]

i hope u will tell the engineer u have worked on it, and changed the pcb
before he takes on the service.

Thank you for your comment and I would be grateful if you elaborate upon that point.

Thanks

 

[XKESTONMAN]

ok i understand u want to save cash in these hard times, and that u left the boiler turned off ,untill checked. but i think he needs to know u fitted parts to it. a pcb is still a critical part of the safe running of a boiler
flame rectification, ignition timing,lock out over heat,ect which it reads of the sensers
so has this reconditioned board been approved ,so i would ,if i was
the service engineer , advice a new approved one from manufacturers.
another reason is i have seen pcbs that have been on fire.
so not good for house insurance , if they discover its a recon board.



also seen what costomers do when they feel its ok to meddle whith boilers.
one costomer removed the combustion chamber door, so it could work.

cheers

 

[goodtyneguy]

ok i understand u want to save cash in these hard times, and that u left the boiler turned off ,untill checked. but i think he needs to know u fitted parts to it. a pcb is still a critical part of the safe running of a boiler
flame rectification, ignition timing,lock out over heat,ect which it reads of the sensers
so has this reconditioned board been approved ,so i would ,if i was
the service engineer , advice a new approved one from manufacturers.
another reason is i have seen pcbs that have been on fire.
so not good for house insurance , if they discover its a recon board.



also seen what costomers do when they feel its ok to meddle whith boilers.
one costomer removed the combustion chamber door, so it could work.

cheers

Thank you for taking the time to express your concerns. It was a number of gas engineers and a heating company on another forum that suggested I should either get a new or recon PCB. I do take health and safety issues very seriously, for example I have a carbon monoxide detector in the cupboard where the boiler is installed despite the boiler being room sealed. I was wearing a seat belt when driving long before it became law. Never the less I will have a word with the engineer before he arrives to do the service and if he insists that I do have to replace the PCB then so be it. Invalidating building insurance and the risk of fire and possible fatalities for the sake of money is just not worth the risk.