Potterton Gold HE - Water goes cold after a few seconds

[Mindzai]

Maybe you can post some pictures.

I'll take some pics tomorrow and post them.

One thing is odd, you mentioned 4 pipes, I expect 5 on a combi.

Yes sorry it also has a gas pipe in the middle, and 4 water pipes, two to the left and two to the right The far right pipe (which the filter was in) is, according to the manual, "heating return", and the one to the left is the "cold water inlet". The filling hose connects the two.

The stopcock I mentioned is not part or the boiler, sometimes people put them in so they can isolate the boiler from the water mains.

Then I dont think I have one, just pipes going in from the mains and in/out to the radiators/taps. I dont see anything else connected anywhere along any of the pipe runs.

Do I understand it correctly that your system still uses the old pipes from the previous boiler? If they have not been cleaned properly, you could have debris ending up in the new boiler.
It also sounds like your filling loop is failing; that would be unusually early.

No nothing was re-used from the old system, the new boiler is not even in the same room. It was all put in from scratch.

What makes you suspect the loop is failing? Just to clarify when I said water was leaking out I meant after I had loosened the nut connecting it to the far right pipe. When I tightened it again it wasn't leaking, and as far as I can tell the isolation valves are OK.

Just above and behind the pump is the auto air vent.

Is the air cap on the top just loose?

There is a screw sticking up which seems pretty loose - the cap that it is screwed in to didn't seem to move though.

I would still suspect a blocked plate heat exchanger.

To be honest a blockage of some kind seems to fit - since I had cold water until I drained and refilled it after which its been warm (albeit still fluctuating) it does make me wonder if the sudden flow of refilling it might have dislodged something?

I also noticed in the manual a "hall effect sensor" which apparently has a filter - should I try to get to this to check it too or is not relevant to the hot water system?

 

[Agile]

There is a filter in the Hall effect sensor but thats in the DHW flow line and you have said the DHW flow rate is satisfactory.

The Hall effect has a red LED which illuminates when there is a DHW demand. Does this stay illuminated when the DHWE goes cold?

Tony

 

[kevplumb]

though the flow rate seems a bit low to me, the boiler manual indicates it should be closer to 10.

There is a filter in the Hall effect sensor but thats in the DHW flow line and you have said the DHW flow rate is satisfactory.

come on tony keep up

 

[Agile]

Without an actual measurement of flow rate we dont know.

However, the sensor operates at about 2 li/min which looks a pretty small trickle.

But if he does the test I asked then that will identify if there is any problem there but I dont expect so but everything has to be checked.

Tony

 

[Mindzai]

Like I said in my original post , I measured the flow rate from the hot tap at 5.5 lpm. The flow rate from the cold is much higher.

I know the LED you mean, I will check that in the morning and report back.

Thanks again for the help.

 

[Mindzai]

Right turned the hot tap on the morning and we're back to *lots* of very loud banging coming from the boiler.

I got my girlfriend to run the hot tap and check the temp of the water while I watched the red LED on the hall effect sensor. Even while the temperature fluctuates the LED remains on from the moment you turn the tap on to the moment you turn it off again.

I've attached a couple of pictures, one of the air valve and one of the pipes underneath. Let me know if you need pics of anything else.

I attached the air valve one because I want to check if the brass bit that the screw is in should move? Because all though as you can see the screw is loose, the brass bit doesn't move at all.

Untitled

• Mindzai
• 10 Oct 2009
• 1

Untitled

• Mindzai
• 10 Oct 2009
• 1

 

[bengasman]

Nothing should visibly move.
The filling loop seems ok.
The load banging is not so good.
The noise would also indicate a blockage, but on the circulation side. Or a dodgy pump.

 

[Mindzai]

As far as I could tell, the banging did not seem to be coming from the pump - that was purring away quite smoothly. It seemed to be coming more from the top chamber of the boiler where the flame is or towards the back. It's pretty violent banging, the whole boiler jolts and the pressure gauge jumps around from 1.5 to 2 bar with each bang.

The banging also happens when I turn the heating on too. I bled the radiators but there's no air there, just water coming out of all of the bleed valves.

Is there anything I can do to investigate a possible blockage?

 

[bengasman]

Stick a bottle of hyperflush in the system, and let it circulate.
What happens if you set the temperature selectors on the boiler just above minimum?

 

[Mindzai]

Stick a bottle of hyperflush in the system, and let it circulate.

Right I'll look into that, cheers.

What happens if you set the temperature selectors on the boiler just above minimum?

Turned it to just above min and turned the hot tap on. I ran it for a couple of minutes and it didn't bang. Then while it was still running I turned it up to about 3/4 and as soon as I did it started banging again. I turned it back down and the banging stopped.

 

[bengasman]

Leave it on as low as you can to satisfy your demands whilst the hyperflush is circulating; it can be left in for a long time, at least a month. Turn the selectors up half a notch per week, and see if things improve.
Take a sample from the draincock after a week or so, and tell us what it looks like. If it is dark, you want to give the system a good clean, and install a magnaclean.

 

[Mindzai]

OK I'll do that, thanks for all the help.

 

[Mindzai]

Doesn't look like I can get powerflush from anywhere near me, is Sentinal X400 any good instead? I can get that from screwfix round the corner so saves waiting for a delivery from an online shop.

 

[bengasman]

X400 is ok, but don't know how long you can keep that in.
Kamco will be able to tell you where you can get hyperflush near you.
01727 875020

 

[Agile]

Get Sentinel X800.

Thats stronger but still not acidic.

It only takes 2-6 hours so you can remove it the next day.

Turn off ALL the rads when you first add it to the boiler. Run some hot water at a low flow rate for a while.

Than after 2-3 hours put on heating and open the rads one by one or better open each one just on its own to clean the rads out.

Then drain the whole system and refil and drain a couple of times until its clear.

Tony