DIY Doctor UK DIY Forums

We have an ancient system, an Ideal Concord Boiler that's been running for at least 20 years. Last week the mains fuse blew and after repairing it twice, as it blew again, the controller no longer worked. The boiler is still lit but there is nothing to control it. I tried changing the fuse in the controller but found this confusing as the fuse is rechargeable and comes with a very low charge. I assumed that it trickle charged when connected to the mains. Anyway, no go. I've tried two different controllers to no effect. The wiring diagram on the latest one matches that on the previous one that worked for years. It's probably obvious that I understand very little about this but what am I missing? I would have thought that the controller/timer sits between the mains and the boiler with no other intervening stages so am I just not fitting the right controller or is there something else that is causing this?
Thanks in adveance for any help.

Jim

Hi Jim, you have not said what controler, do you mean the time clock/time programmer? If you do let me know the model and I will advise from there.

Yes I mean the clock/timer. The one playing dead is a Wickes branded RWB200 which has a digital type of timer. I've tried a couple of replacements, one very similar and another which is a dial type, a Siemens RWB2E. The dial type seems to be wired in exactly the same way as the RWB200, the other one possibly wasn't. The thing I describe as a rechargeable fuse is in fact a battery.

Either way nothing works which has led me to think that the problem is in the power supply rather than the timer or the connections. I expected to find a fuse on the timer but nothing can be seen unless I'm looking for the wrong thing or in the wrong place. Actually I don't know where to look as the fixing plate is attached to the wall and the wires just come out of a hole. A fuse might be lurking in there somewhere but I can't imagine how it's fixed.

What puzzles me as well is the fact that the mains fuse blew and if there had been a 3A fuse in between then that should have saved the mains one. But since I've replaced the mains fuse and, although it blew once, the second time it has held up.

Hi Jim
Sorry it's taken so long to get back to you, I've been away. The RWB2 series of time clocks where produced by Landis & Gyr (RWB2 also known as Potterton Miniminder and Glowworm Masterminder) they then became Landis & Steffa and now as Siemans. As you have said the RWB2 range of clocks all had the same wiring the idea being that you unplug the facia from the back plate and plug in a new facia when required. The fact that you have replaced you clock and still have a problem I think means the boiler is at fault. It could be the boilers PCB is needing replaced. However that is expensive(If still available for a 20+ year old boiler)and you should have this verified by a CORGI engineer. A boiler that is 20+ years old is coming to the end of it's useful life and you should be considering a replacement, a replacement will also benefit your fuel bills significantly. A boiler like yours typical 60-70% efficent. A new band A boiler 5 year parts & labour warranty up to 97%efficent.

Thanks, I've also been away. I'm coming round to the fact that I probably need to bite the bullet and get the thing replaced although, obviously I would prefer it if someone said "Oh that's what it is" and just fixed it. The boiler is still happily showing its pilot light, apparently waiting to be given the signal to go. Am I right in assuming that all Corgi fitters can analyse and fix problems with the electrical component parts of a gas system or do I need to find someone who also specialises? Trying to select someone to come and look at this is, of course, already starting to drive me mad what with the mix of gas and electricity.

Jim

Yes I know since the change in part P of the electrical building regs it has become a bit of a nightmare finding heating engineers qualified to carry out electrical work. I would suggest you want a engineer who is a service engineer, they will list themselfs as 'boiler repairs' in there adverts. They should be able to help.

Gas Fitters and Heating Engineers can work on the electrical part of heating installations. From the fused spur supplying power to the boiler. From the main fuse board to the fused spur, is an electricians job.

They do not need part P or any other electrical certificates.