Potterton Boilers – anyone know their onions?

We have a very old Prima 100f, which seems to end up costing us a couple of hundred a year in repairs. I still see this as better value than 5k or so to replace. We have an issue where the pilot fails to ignite for ages then switches on for 30 seconds or so before going off again. I’m sure there was a very obvious reset button years ago but now we just have the cross headed thing in the photos (maybe this has been chaged during a previous repair).

Anybody know if we have to turn this thing – it won’t depress in the way a switch would? Obvioulsy I’ll be calling someone out but I’d like the house not to be freezing for the kids!

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That looks similar to the reset button on my boiler. Doesn’t do anything until there’s a fault then it pops out. I push mine back in and it seems to work again.

That is an overheat thermostat reset, if you can’t push it in then it hasn’t overheated (or it is faulty), but it wouldn’t get to pilot lighting sequence if it had operated.

There is usually a reset on the front from memory.

Not sure if it would cost £5K to replace it though, should be a fairly simple boiler change.

Also it is a fairly simple boiler with not a huge amount of components.

Instructions here which gives a flow diagram for operation https://www.dhsspares.co.uk/userfiles/Boiler_Manuals/POT263.pdf

Does the pilot actually light, does the fan run?

In terms of economics think about the energy saving, not just maintenance, new boilers are way more efficient by design and old boilers are way less efficient than when new. Plus how priceless is getting up with the house warm.

Not sure if it would cost £5K to replace it though

I’m guessing it’s a system with an open-vented HW cylinder. You could replace the boiler with a new open vent-specific one – Veissman do one for around £1000 iirc – but I think most heating engineers would recommend switching to a pressurised system w/unvented cylinder and that could easily reach £5k to install.

Cp – how old is the boiler & where are you? We have a Potterto profile about 20yrs old was exhibiting similar fault, boiler engineer swapped the pcb to get it sorted.

First off, I’m not a heating engineer and don’t recommend anyone who isn’t gets stuck in on impromptu boiler repairs. That said, IME if the fan is spooling up then down again repeatedly then it’ll probably be the electronic control unit that’s failed, part no 407677. The part’s around £200 retail but it usually fails because of some electrolytic caps which basically just age out in the pretty harsh environment inside your boiler. You can replace the guilty caps at trivial cost if you can use a soldering iron but no heating engineer is going to want to faff around doing that. Of course it could be something else but I believe replacing the control unit is pretty much the first step on the troubleshooting flowchart in the manual Bear linked to.

I take the point about efficiency but on purely financial grounds a boiler would have to be very inefficient for quite a while to come anywhere near justifying early replacement. Though I think the OP’s boiler must be knocking on for 25 years old by now and if he’s paying out £200 on an annual basis…

edit: Just had a look on ebay and you can pick up a new PCB for £75. It’s a plug-in part, and with the likely cost of any engineer callout being north of that figure I’d personally be inclined to give it a try.

In terms of economics think about the energy saving, not just maintenance, new boilers are way more efficient by design and old boilers are way less efficient than when new.

Only if set up correctly – unless the new boiler is able to run in its condensing mode the energy use will be identical to the old one.

Having said that it won’t be five grand to replace, that’s a British Gas price.

This guy might be able to help

https://www.netaheat-repairs.co.uk/

Thanks all, turned out to be something else! Boiler fine – return valve I think he said, upstairs in the airing cupboard where the tank is.