Potterton Suprima 80 CH trips electrics, HW ok

[oldbutnotdead]

That boiler (Suprima 80) is still a decent bit of kit- decent efficiency, very few moving parts to fail. The weak link is the PCB- prone to failure (your symptoms do NOT indicate PCB fail) and replacements are expensive and still prone to failure. Rather like your old Volvo (and my old Citroen), if the black box packs up it tends to go beyond economic repair.
For now, this fault should be a straightforward fix for a competent electrician with the right test gear. Treat it as a wake-up call- nothing lasts forever, time to start contemplating (and budgeting for) a replacement. Advantage of planned replacement- you can take your time, consider any other changes you might want to make, schedule it for the summer when you will get much more competitive prices for boiler swaps. And don't be pressured into a combi unless you really want one- they don't suit all circumstances.

EDIT Since the dhw is pumped that rules out the pump as being the failure point. Or drops the probability massively anyway. You should have 2 2 port valves (unless the original installer decided no-one would want heating without hot water being on)- one probably near the cylinder controlling dhw, another one somewhere controlling the heating. If the heating one has a manual override lever, use it- the rads should get to full temperature (not just warm) while the cylinder is being heated

 

[DP]

Hi blueloo, I know in my heart, it's inevitable, but I've just had to replace my 19 year old Volvo, which finally stopped being worth repairing and I just can't do another investment at the moment, although I know it's coming and soon! I've got to find a way of limping on with this system for a year or so if it's possible.

Forget boiler is the issue for the time being. I as a heating engineer would say Suprima is not that bad, have several clients with this boiler. If a boiler needed parts ( positive diagnoses) and these were eye watering lay expensive, then consider a new boiler. Can you imagine, if funds allowed, you replaced the boiler and electrics still tripped.

 

[DP]

chucking reclaimed parts into unsuspecting customers heating systems

Take it you have proof of that.

 

[BlueLoo]

Take it you have proof of that.

Daft question

 

[DP]

Daft question

Not really. I would never stick a recycled part in an appliance unless it was warranted and customer gets advised that has taken place. You do have a low opinion of others yet constantly pushing your ideas that do not work in real world.

 

[BlueLoo]

That boiler (Suprima 80) is still a decent bit of kit- decent efficiency, very few moving parts to fail.

I know the guts of the Suprima like the back of my hand, i've been at it so much during its life.
The Boards are dreadful. The Mk1's last 12 months. the Mk2's perhaps 5 years. There is a cottage industry selling the MK1 refubs for £50.
The Mk2 Boards need a new chassis and is 4 times as much, but my last replacement board for it was salvaged off a scrab boiler for £30.
The fans are equally crap. The front bearing sits above the heat box and dries out in a few years, you can replace the fan, or, replace the bearing on it if you can find one. I was lucky and took mine to a bearing specialist and got a new bag of them for £10. I need the bag...

What else is in it? A cast iron lump He/EX, a burner and a gas valve. Thankfully, neither of those have committed suicide yet, although i'd throw the boiler in the bin once it gets to the gas side of things. (Usual gas caveats apply obv).

Efficiency is 78% seasonal. Average at best, even for non condensing.
Still, its designed and built with tractor engineering so it can be maintained with farmers know how lol.

(The above is only a story only and in no way suggests that anyone involved maintains, modifies or repairs boilers in anyway whatsoever )

 

[Gasguru]

I've held back so far but your posts are getting tiresome.
You joined at the beginning of the month and you're averaging 25 posts a day....bored by any chance?
It would be helpful if you laid of slagging the trades.
Take your winging somewhere else...this thread has descended from helping a diyer to a slagging match.

 

[Lucy Bags]

So, should I call an electrician or a gas safe plumber? What, would you say, is a reasonable call-out charge?
Thanks for your help, everyone!
Oh and what equipment should I check they have before I book them?

 

[BlueLoo]

A solicitor to get your money back?

Electrician, one who is used to working on heating systems. Try a heating/boiler engineer for suitable contacts (or use them!)

 

[ericmark]

An electrician has three tools to help him sort the problem.
1) RCD tester.
2) Insulation tester
3) clamp-on ammeter with a 0.001 scale.
Unlikely the RCD but not unknown, and the clamp-on will only show a fault while it happening, so the insulation tester is his best option, and he would normally start at the consumer unit, this is because switches and relays are normally in the line, so if he tests neutral to earth he can still find the fault even if switched off.

Once he has found a leakage he will slowly test to get closer and closer to the fault, until found.

Although often he will look first for some obvious fault, it may not even be the central heating, it could be some thing on same RCD, seems unlikely however from what you have said, but the big problem is earth - neutral faults, which are more likely to cause the RCD to trip the higher the load, you say whole house RCD which makes me think maybe an old 100 mA unit and a TT supply, today we have at least two RCD's and 30 mA which makes me think maybe old one.

100 mA = 23 watt, so could be a wiring error, but even if the electrician can't find the fault, it is likely he can use a RCBO which is an MCB and RCD combined so when it trips it does not take out whole house. It depends on the distribution unit modern consumer units can take RCBO's but some older units there is no option to use them.

 

[ianmcd]

As it is intermittent when the RCD trips turn the CH and HW both down one at a time on their thermostats, see if turning one of these down causes the RCD to operate, it is not the boiler pcb

 

[oldbutnotdead]

Electrician. As mentioned, if you can get someone who is familiar with control systems then great. If you can be at the house when they are there you can save a lot of time being a 2nd pair of hands.
Callout charges depend where in the country you are and how you make the booking. This time of year you're going to struggle, if you can use any of the workrounds mentioned to stay warm over Christmas you can book it in as a job for sometime in the new year and not pay callout. Up here (t'frozen North) £100 would get me 2 hrs plus of someone's time, expertise and test gear.
Where to find electrician- as usual, ask neighbours/friends if they've had any work done. Avoid national 'chains', avoid most of the websites, have a look see if your local trading standards run any sort of trusted trader scheme (some councils do, some don't)

 

[Lucy Bags]

That boiler (Suprima 80) is still a decent bit of kit- decent efficiency, very few moving parts to fail. The weak link is the PCB- prone to failure (your symptoms do NOT indicate PCB fail) and replacements are expensive and still prone to failure. Rather like your old Volvo (and my old Citroen), if the black box packs up it tends to go beyond economic repair.
For now, this fault should be a straightforward fix for a competent electrician with the right test gear. Treat it as a wake-up call- nothing lasts forever, time to start contemplating (and budgeting for) a replacement. Advantage of planned replacement- you can take your time, consider any other changes you might want to make, schedule it for the summer when you will get much more competitive prices for boiler swaps. And don't be pressured into a combi unless you really want one- they don't suit all circumstances.

EDIT Since the dhw is pumped that rules out the pump as being the failure point. Or drops the probability massively anyway. You should have 2 2 port valves (unless the original installer decided no-one would want heating without hot water being on)- one probably near the cylinder controlling dhw, another one somewhere controlling the heating. If the heating one has a manual override lever, use it- the rads should get to full temperature (not just warm) while the cylinder is being heated

 

[Lucy Bags]

My hubbie has managed to do the manual override thing and at least some of my radiators are getting hot! Hurray! We will be warm this Christmas! We will try to find someone to run the tests and sort it out properly in the New Year.
Thanks to you all for help and advice, I will post in the New Year once the problem has been resolved (here's hoping) so that the next person to encounter it doesn't waste quite so much money.
Great forum and once again, thanks to all! Happy Christmas!

 

[Harry Bloomfield]

RCDs detect the total fault current and there's always a chance the boiler trips it but the fault lies elsewhere....hence an electrician with the test gear is often better at locating the problem.

My turn to laugh - they don't measure fault current at all, they measure the difference in current flow between that of the L and that of the N. If the difference, becomes greater than a set amount, then they trip.