Worcester 24i combi-DHW OK - no CH

[bigdavesgusset]

First post, so be gentle with me!
DHW no probs.
CH-Pump starts up, fan runs, boiler will not fire up.
My belief that the CH control (stat/potentiometer?) isn't working/generating a heating required signal.
Any further checks to confirm/disprove my theory above?
It would appear to be a board replacement to solve - has anyone repaired a board by replacing stat/potentiometer?
Thank you in advance.
BDG.

 

[Agile]

There could be several possibilities !

You could measure the resistance of the pot on the temperature control and check that varies as expected as the knob is rotated.

The sensor can be checked for correct resistance.

Although others dont seen to have found this fault, I have encountered several Worcester boilers of the 10 y.o. models which seem to have a failed anticycle and in effect stay off all the time and never cycle back on. Some would run when first powered until the reach the set temp and then stop. Another would be prompted to run by momentarily disconnecting the sensor.

It may well be a PCB fault but I would be checking everything else before changing a customer's PCB.

Tony

 

[bigdavesgusset]

Thank you Tony,
I have already replaced the ch sensor recently so I think that is OK.
I will check the resistance on the pot but turning the CH control to position "11" and tapping it caused the boiler to fire, but the flow pipe didn't seem very hot so i touched the knob again (ooh er missus) and the main burner went out!
I will continue fiddling and let you know how I get on.
bdg

 

[Agile]

I have heard of the pots being replaced but I dont know why.

Your tapping might well indicate a fault.

Tony

 

[bigdavesgusset]

Took PCB out, and 2 of the 3 joints on the pot were dry (tapping the CH control was obviously making the circuit temporarily).
Took pot off, resoldered the pot on, reassembled PCB to boiler and everything now lovely jubbly.
BDG

 

[hammerswinger]

It's always worth checking the PCB for bad solder joints, I would imagine a lot of the time PCB's are replaced when all they need is a couple of dabs with the soldering iron.


Cheers.

 

[Agile]

Thats often the case but for a professional engineer tow things have to be considered:-

a. Its not correct for an engineer to "repair" a PCB.

b. After the repair its still a 10 year old PCB and thus could fail at any time and if it does the customer will reasonably expect it to be repaired/replaced under the engineer's guarantee.

Tony

 

[hammerswinger]

Thats often the case but for a professional engineer tow things have to be considered:-

a. Its not correct for an engineer to "repair" a PCB.

b. After the repair its still a 10 year old PCB and thus could fail at any time and if it does the customer will reasonably expect it to be repaired/replaced under the engineer's guarantee.

Tony

To a certain extent I agree with you....yes you could have an unreasonable customer who would expect a PCB to be repaired/replaced under the engineer's guarantee but if it was made clear at the time of repair that this would not be the case I can't see the problem, I'm sure any reasonable customer would understand this.

I can't see why it is not correct for an engineer to repair a PCB, (Unless there's some rule on this?)....we're not on about changing components here, just remaking a defective solder joint.



Cheers.

 

[Agile]

Under GSUR any components used for gas have to be designed for that purpose.

A boiler PCB is approved for that by the manufacturer. When you have repaired it then it is no longer "approved" and unlikely they will even approve your repair. Firstly they have not tested it and secondly they prefer to sell a nice new expensive one.

Whilst some engineers are honest and say what they are doing there are others who buy Adlink or similar repaired PCBs and then charge the customer the full price for a new one!

Tony

 

[hammerswinger]

GSUR?

The PCB is designed for the purpose and still will be after you have remade a solder joint that was there before, you haven't altered the design of the PCB or its components in anyway.

A boiler PCB is approved for that by the manufacturer. When you have repaired it then it is no longer "approved" and unlikely they will even approve your repair. Firstly they have not tested it and secondly they prefer to sell a nice new expensive one.

I take it this is your own interpretation of some rule, can you tell me where I can view the rules on this?


Cheers.

 

[Agile]

You should ask any boiler manufacturer if they approve of you resoldering their PCBs.

You could also ask Gas Safe and see what they say.

There were also some articles in the CORGI magazine about 3-6 years ago. Dont you remember them?

Tony

 

[hammerswinger]

What does GSUR mean?

Can you point me to the written rules that state what you said?

Have you asked the manufacturers / Gas Safe if they would disapprove of you remakeing a solder joint on a PCB?

No I don't get the Gas Safe / CORGI magazine as I'm not a RGI.



Cheers.

 

[Agile]

If you are not an RGI then its not surprising that you dont know about the rules we have to comply with.

But you should not be repairing boilers if you are not an RGI or familiar with the regulations relating to boiler installations.

Tony

 

[hammerswinger]

If you are not an RGI then its not surprising that you dont know about the rules we have to comply with.

That's right I'm hoping you are going to show me the rules so I can see where it states that a "Professional RGI engineer" isn't allowed to remake a defective solder joint.

But you should not be repairing boilers if you are not an RGI or familiar with the regulations relating to boiler installations.

I wondered how long it would take you to use your party piece!
I'm not repairing boilers, I don't work in that field. I do however have a brain so please don't try to dismiss me just because I'm not an RGI.


Cheers

 

[Agile]

If you have a brain then you should be able to find out where to look up the laws of the counry. Or go on a gas course. Or buy a training book.

D Hailsham has more time to quote the laws as I have to do some practical work.

Tony