For the past few years my Potterton Suprima 40 boiler has been acting up a bit. When I say acting up I mean that it was not firing up or it was shutting off too soon. Cold showers and cold central heating is not nice. But if you have the mis fortune of owning one of the worst boilers ever to come into being, here are a few tips to get it working that wont break the bank. (I would advise that all work should be carried out by corgi registered personel!)
1) Boiler wont fire up.
The boiler will attempt 13 sparks of the electrode and if no flame is detected it will shutdown. If the firing sequence fails three times, you get lock down. That means reseting the system and letting it try again.
2) Boiler fires up but shutsdown after a few seconds
If the PCB does not get feed back from the electrode that the flame has ignited, it will shutdown and try again. 3 strikes and itgoes to lock down.
3) No spark / weak spark from the electrode.
These are all easy to fix and get your hot water going again.
I would suggest replacing a few things inside the boiler. First to go must be the HT cable. This is the cable that goes into the electrode and back to the PCB. If yours is red, it is a carbon fibre cable and it is crap. Buy a new one. You cant get the carbon fibre ones now, but a nice new copper one will come you way. Look for part ref 8407753. I got mine from keeptheheaton.com for about £5.
To replace it, shutdown the boiler and turn off the power to it. Open the flap at the right and remove panel screw and slide it out. Then remove the three visible screws. The control panel on the right will drop forward if gentrly pulled. The main boiler case will swing to the left and lift up and off. On the PCB near the bottom left is a black cylinder, remove the cables spade connector and pull it though from the bottom of the bolier. Remove the spade connector from the electrode and chuck the cable away. Fitting the new cable is the reverse!
You should think about a replacement electrode if the spark is poor too (see number 3). While the bolier is open, there is a metal panel closing the burning chamber. Remove the short screw at the top and pull off the panel. There is a small screw holding the electrode in place, unscrew this and pull out the old electrode, replace with part 8407754. expect to pay about £8 for one. If you can’t get one of think the electrode is ok,clean it with solvent or a nail file. Mine is bent slightly closer to the burning unit which it sparks to. Use pliers very carefully to bend the exposed metal part, not the white case of the electrode.
The PCB itself is also prone to the soldering cracking. Very tiny cracks appear in the solder on the rear of the board and it fails. Replace it. There is a new version of the PCB that has a plastic case round it and better heat shielding. It will set you back about £200. not cheap. The cheap option is Ebay. They have refurbished boards with a 1 year warranty. If you send your old PCB back you get £10 for it. It should work out at about £25 for a refurbished PCB.
Replace it by removing all spade connectors and block connectors. Take a digital photo of it if you can’t remember where they re-connect to. Remove the 4 screws in each corner. Replace the board and screw it back down. Plug it all back in and close up the casing. Apply power again and enjoy hot water and central heating again.
When you can afford it, replace this pile of junk with something that works!
Stephen