Potterton Suprima HE overheat indicator?

Dunkwho

Any plumber\boiler installer people out there with some experience of the potterton suprima HE unit? Just had one installed, all lovely and quiet compared to the bang bang banging of the old limescaled up one ! Over the weekend I found the unit locked out with the red overheat protection light flashing, duely reset and all was OK for a day, then locked out again. Since reseting and turning the thermostat on the boiler down its not done it again (yet?) so was digging around for some background info on what this lockout protects against and what might bring it on? boiler thermostat too high, return path too high pressure causing heated water not to be cycled appropriately, pump running too slowly (its on 2 of 3, avoid 3 to keep noise to a minimum), etc etc? If its a problem then I'm happy to get them out but always like to know what\why before hand and try to resolve myself rather than dragging someone out and (more importantly) buggering up my day\work to be at home for their visit ! :rotfl:

Cheers
Duncan

moneysavingplumber

The Suprimas have been the one of the biggest problem boilers for overheats, they recently updated their PCBs to overcome it.

It may be to do with the automatic bypass that should be installed somewhere on the system. The flow and return temperatures should generally be twenty degrees apart on a condensing boiler, 60-40 is the given ideal. The return may not be achieving a high enough temperature. Really these temperatures should be checked on commissioning of the boiler. If it's been sized, fitted and commissioned right, there should be no chance of an overheat occuring. Occasionally it is a faulty PCB or faulty overheat stat/thermistor that causes these problems.

What rating is the boiler? It's usually given as a multiple of ten, ie 30, 40, 50 etc. If it's rated at 60,000 BTU or more (output) then the 22mm tails supplied on top of the boiler should be uprated to 28mm immediately according to the manufacturer's instruction. Alot of installers don't bother, and connect straight on to it in 22mm, and that can cause overheat as well as scale build-up.

Call them back if in any doubt.