Solution To Potterton Suprima Fault

cleanwipe

My boiler was tripping out evry hour or so until I fixed the PCB by resoldering the joints on the back as they are notoriously poorly soldered:

Remove all power to the boiler and remove the plug in terminals and four screws holding the pcb in place.
You may need to use a magnifying glass to examine the soldering especially where the plug in terminals are soldered.
Options are.
(a) re solder the poor joints
(b) replace with a reconditioned pcb from compumerv on eBay £35
(c) replace with a new pcb £135
If you do a Google search for 'suprima' you will find considerable information on this very same problem

Good luck!!!

:beer:

dkmulvey

Just to add my 'lock-out' experiences, I had the same problem with my Suprima 40. After reading the various threads on here, I came to the conclusion it was the PCB and so ordered a reconditioned one from compumerv (price has gone up to £55, but you now get a 12 month warranty).

Fitting it wasn't much of a problem, and the replacement PCB arrives with full instructions. One screw takes the side panel off, another lets the PCB casing hinge forward, and then the PCB itself is held in with 4 screws. All cables plug in and out via clips - I had mine replaced in 15 minutes.

Everything was fine for a day or so after - until I started getting the lock-out problem again! Going back to the forums, I discovered that there's two temperature sensors (one for water flow temperature and one for overheat detection), which if either fail can also cause the lock-out problem. So back onto the web again, and I ordered replacement sensors from MJT Controls (part numbers 404516 and 404517) for a total price of £24.89. The temperature thermistor was a straightforward push-in job, but the overheat thermostat needs to be unscrewed with a 17mm spanner. If access to the sensor was anything like mine (both are located on the pipes), a spanner that's open at one end and with a socket type ratchet at the other would be a good investment. I got one for around a fiver at the local B&Q, without which I don't know how I'd have got the thing off!

Anyway, sensors replaced, switched the boiler on, and the damned thing still had lock-out! So, got in touch with compumerv to tell them to prepare for my PCB to be sent back to them, who replied back (that same evening) with the suggestion it could either be the breather pipes, or the electrode lead from the PCB that triggers the gas igniter. The breather pipes can get blocked with crud (which they weren't), although as well as powering the sparker, the electrode lead also tells the PCB that the gas has been lit. If that's faulty, the PCB thinks the gas hasn't lit (even though it has), and so goes into lock-out.

So took the main body of the boiler off, and upon checking the electrode lead's connection it fell apart in my hand! So I went to the local Plumb Center to get a replacement lead (a good idea to phone to check they've got it in stock beforehand) for around £5, replaced it, and the boiler roared into life! One week on, and the boiler's shown no sign of the dreaded flashing red light.

So to summarise, if you're getting lock-problems, try the following:

• Get a replacement PCB first, as these seem to be the most common cause. I can't recommend compumerv highly enough for this - do a search on eBay for them (cost: £55).
• If this doesn't fix it, try blowing through the breather pipes to make sure they're clear (there's two of them that run between the PCB bit and the main boiler). Doesn't seem to be a common cause of lock-outs, but it's free to check, so you might as well give it a go next!
• Failing that, check that the electrode lead that goes from a big black thing on the PCB to the igniter under the gas outlet is in good condition - any doubt then replace (cost: ~£5).
• If it's still not working then replace the two temperature sensors on the pipes (cost: £24.89).
• Still not working - then give up and get a friendly plumber out.

Worst case scenario, you've just shelled out the best part of £85 and still had to call a plumber out - but at least you've already ruled out a heck of a lot of things.