Potterton SUPRIMA 40L won’t turn on, trips RCD immediately :(

[eonone1]

Hi

My Potterton Myson SUPRIMA 40L appears to have a problem.

At first it was running for a while then it tripped the RCD. I wasn’t able to see if it was a call to heat or not.

Now the next day when I’ve tried to turn it on (using a fuse switch nearby to the hive controller) it immediately trips the main RCD, which in turn drops all power to sockets downstairs and upstairs.

Any starting points to check out please? It’s pretty difficult to test as now it seems to be consistently tripping if I try to switch it on. Which then of course turns off the internet, fridges etc and anything plugged in any other room. :/

Never mind not having any heating or hot water right now.

 

[jj4091]

If it is tripping the rcd it would suggest the possibility of a water leak. Might be best to get a gas safe heating engineer to have a look.

 

[eonone1]

Thanks jj!

 

[eonone1]

Could it have anything to do with this?
I haven’t noticed any leaks but the line scale there would say otherwise. Also that black box on the side with the cable going to (controller box?) looks to have a little water around the point of the red arrow.

That cream box isn’t used anymore really. I don’t touch it. As the Hive was fitted years back so it stays always on.

 

[Elkato531]

The first thing the engineer should do is determine whether the fault lies with the boiler or with an external component. Pumps are a regular cause of tripping electrics. The fact that yours looks like it does points to it being the cause.
The wiring looks like a poor diy job and certainly needs checking, tidying up and securing.

 

[eonone1]

Thanks. It was indeed the circulator pump that had a slight leak. The cable coming out of the black part of the pump was disconnected from the control box on the wall and the boiler came on with tripping the rcd.

I was told that pump only really helped woth the hot water coming out the tap quicker when turned on and that it wasn’t necessary if I didn’t want to pay the £300 for a new one then the fitting and labour on top of that.

So for now it’s disconnected and I haven’t noticed any difference.

Is that all that pump does then?

 

[Elkato531]

I didn't look too closely at the pipework in the pictures and didn't notice it was secondary circulation. Its job is to push hot water round a loop bringing it closer to hot outlets so that it doesn't have to come all the way from the cylinder each time a tap is opened. They are expensive as they are made of brass to cope with fresh water. There will be another similar looking pump nearby to push water around the heating system.

 

[Harry Bloomfield]

I was told that pump only really helped woth the hot water coming out the tap quicker when turned on and that it wasn’t necessary if I didn’t want to pay the £300 for a new one then the fitting and labour on top of that.

So for now it’s disconnected and I haven’t noticed any difference.

Is that all that pump does then?

Yes, it's a circulation pump, and perhaps it wasn't functioning before - which is why you have not noticed any difference. Idea is/was, to have the hot water arrive at the tap when you turn it on, much quicker, because it circulates through a loop, passing close to the taps. Downside, is that because the pipes are kept hot, a lot of heat is lost from the pipes, while ever the pump is on.

A slight problem you have now, is that there will be two ways, via the pipe loops, for the water to get from the hot water cylinder, to each tap - so that will lengthen the time a little, for the hot water to appear, and still waste heat. Closing those pump isolation valves, either side of that failed pump, will help with that..

 

[Elkato531]

Closing those pump isolation valves, either side of that failed pump, will help

Better to keep both sides open so that it doesn't create a deadleg with stationary water and the possibility of stagnation and bacterial growth.

 

[eonone1]

Thanks very much for advice Harry and Elkato. I’ll leave it as it is for now. I don’t think it was working anyway like you say, as the time to get the hot water is the same to me. Makes sense. It prob failed a while ago and I didn’t even notice until water got into the cabling of the pump and shorted things out. Well at least we are up and running. Hope the 22yr old boiler gives me a few more years yet!

 

[Harry Bloomfield]

Better to keep both sides open so that it doesn't create a deadleg with stationary water and the possibility of stagnation and bacterial growth.

Good point! Better to remover the loop part, if practical.