cyclinder stat blowing fuse

[polo1]

Given that the system has operated for various periods......should/could any combination of parts draw significantly more than 3 amps. Is the pump sticking?

 

[Guitarist]

Considering that the stat is purely a switch (most are even class 2), it's unlikely that this can be the problem. I would definitely be disconnecting the electronics and IR testing the circuits.
Also worth checking that the 3A SFCU isn't also supplying something else

 

[Marvo]

If the plumber wired it up then the plumber should be localising his own faults. If not give him a reasonable hourly rate and reinstall the thing to a standard where it can be easily worked on then go about finding the fault assuming you don't discover it during the reinstall.

 

[ayjay]

trying to sort out a c/heating problem on a website is pure stupidity
the o/p shouldn,t tackle the job if he knows f/all about c/h wiring and shouldn,t charge any money as he,s out of his depth
he should tell the customer that he know sweet f/a, and recommend someone who does

 

[chrish_1977]

It's been quite warm recently so I bet everything has been ok when either the hot water or ch has been on independently, but when both on there is a problem, time to delve into the wiring centres and trace everything through, I had a similar problem, my plumber friend did a load if work to a system and when he finished it isn't work, although it all worked before he started, I traced it to the pump not working correctly, but he would t have it that that was the problem, moral of story always check everything yourself and don't listen to plumbers who play with electrics

 

[Wiresandthings]

Plumbers + electrics = disaster!! Similarly electricians + plumbing = usually disaster!!

It needs tracing through from experience

 

[ayjay]

i give up

 

[JonnySegway]

Before I continue I will admit I did not carry out as thorough testing as I should have. I had just finished another job for him, just as I had packed up the van and was about to drive away "could you go and look at a problem for me..." I then had a very short window to get the job sorted out. Enough excuses....

When I started testing, nothing made sense at all, I couldn't identify any cables leaving the programmer and arriving at the junction box. I didn't want to start taking everything apart so I simply went through each step.

Disconnected the hot water side of the programmer: power stayed on. With HW ON channel disconnected everything stayed on.

Then disconnected each item on the HW side. The usual culprit I find is the pump but the fuse still blew with that attached. When I disconnected the cylinder stat the fault was removed. It was at this point I tested the cable I had disconnected at the programmer (blue) with the cable I had just disconnected (red) and realised there was a join somewhere. Indeed; on digging around I find another (hidden) junction box, which explains my initial problem with identifying cables when testing and making sense of how it had previously been wired.

We changed the stat, ran the hot water and central heating, everthing was okay.

In an ideal world I would probably return and rewire the whole thing so that there is only one 10-way junction box but we are not in an ideal world.

I was just enquiring as to whether people here have encountered a common problem with regard to cyclinder stats in order to at least give me a starting point when I return. I am quite prepared to put several hours aside on Monday to just start testing everything one by one but thought it doesn't hurt to have some advice in advance as my experience with these systems is limited

 

[Petej999]

Why did you think the cylinder stat was the problem? What tests did you do?

 

[Petej999]

Agree no good just changing bits without testing first

 

[DPG]

It was 8 years ago so I wouldn't worry about it.