testing combi external heating controls

[drew100]

another question from myself regarding fault finding.
on combi boilers what is the best and quickest way to speed test that the combi external controls programmer and stat are working. ive been told that the best way is to measure at the pcb but how do you recognise stat and prog connections on pcbs in the absence oF M.I. 's. thanks chaps

 

[Softus]

What are the symptoms of the DIY plumbing or central heating problem that you wish to solve?

 

[fazedup71]

drew100 as i have seen your other post are you CORGI? do you have a problem with your own boiler? your questions seem vague to say the least

 

[petit_pablo]

how do you recognise stat and prog connections on pcbs in the absence oF M.I. 's. thanks chaps

They are pretty obvious usually. What are you trying to test?

 

[drew100]

yes i am corgi registered .have been for 2 years. have been installing for two years and fed up with it. getting into repairs./fault finding now. would simply like easy trick of the trades for quick fault finding regarding my questions. ive met guys with years of experience who clain they can falut find but are shockingly bad at doing the basics first. dont wnat to end up liike them!!!thanks

 

[Softus]

Fault-finding isn't about tricks and knowledge; it requires a basic understanding of the function of each discrete component, and the ability to work systematically.

Experience isn't essential, but will yield the answer more quickly because you'll come to trust your intuition.

 

[namsag]

External controls are usually wired to terminal strip within the boiler which then goes to pcb , (ignoring neutrals/earths) live out live back basically just a big live loop through switchd side of clock to roomstat and back to boiler. But testing there will not tell you what is faulty. Put clock on demand and test for power getting to and leaving room stat and going back to boiler

 

[drew100]

thanks a mill . nice to see someone helpful. not all of us have 20 years experience and im not afraid to ask questions which may seem basic. like i said previously there are alot of engineers out there who struggle with a multi meter and testing components and these guys are in the trade yonks!!! again thanks for the help. all i wanted to know was quick methods of testing components in-situ without any drama!!!

 

[gas4you]

The simplest way to test external controls does not need any test equipment.

Locate the switched live in the boiler terminal block, remove it and link it to the permanent live, thereby eliminating all controls outside of the boiler in one quick test.

Note do not link perm live to a switched live where the boiler needs volt free(24V) switching, otherwise say goodbye to the pcb

 

[drew100]

thanks esp gas4u bloke. will try out tomorrow. can you explain what you meant by the volt free 24v switching. i thought all combi roomstat had perm live switched live plusn neutal and earth??

 

[gas4you]

I was just pointing out that some combis, such as the Ideal Mini, so I presume also the Biasi, utilise 24V external controls, so if you just blindly connected 240vac to this switched live return it would blow the pcb.

As always read the MI's first if you are unsure

 

[drew100]

thanjks guys .