Kingfisher 2-based CH/HW system not pumping

[dnrichard]

Hi

Apologies for starting a new thread about my CH/HW issue. I've done this because it's a different problem to the one resolved in the other thread.

I've put a schematic of my system in my photo album taken from the boiler's manual. From what I can see, this lower schematic is how my system has been plumbed.

The problem is that the boiler fires up for about a minute and then turns itself off. During this time it sounds like a kettle heating water to boiling point. The upper outlet pipe that goes to the pump and then to the motorised valve does not get hot. The middle return pipe that the cold water feed connects to does not get hot. But lower return pipe does get hot (but this could just be the boiling water settling to the lowest point).

I don't think that the boiler itself is faulty. I think it is turning itself off because the water is not circulating through it.

I've had it power flushed and I also cleaned the F&E tank in the loft.

My instinct is that the pump itself is not working. It's about six years old and the system has been fine up until now. But it could be that there's a valve somewhere that lets water through one way and not the other?

Because after the power flush the pump was replaced the wrong way (pumping into the boiler - the boiler's manual does say it can circulate water either way) and the HW and CH systems worked great (though I got circulation through the F&E tank - which I know is bad so I got the pump turned the right way round again).

This confuses me. Why the pump would power the system fine one way but not the other. Hence my question as to whether there's a secret valve somewhere that could be blocking the correct flow of water in the system.

I'm unfortunately not working at the moment so I would like to have some insight into what needs doing before I get someone in. If it's a new pump then that's fine but I don't understand why it would work fine one way but not the other. Is there something about gravity in this system that would aid a failing pump circulating water round the system one way but not the other?

Thank you for any insight anyone can give me. When I'm working again I actually want to get the whole CH/HW system replaced because it's clearly old but I just cannot afford to do this at the moment.

Thank you.

Richard.

 

[Jordon]

Did you have the system installed or was it fitted when you moved in?? It may of had a non return fitted to the flow by a third party if it was causing crossing over when just the hot was on, so when plumbing the new unit in the installer may of had a the fault you described but instead of sorting it they turned the pump around. My advice is to get a engineer in to test the the system over.

 

[dnrichard]

The system was installed, and old, when I bought the house six years ago so I don't know its entire history. I've had numerous new parts (pump, bits on the boiler) but don't have its installation history.

The non-return that you talk about. There is a junction on the outlet pipe between the boiler to the pump (this is the "flow" pipe that you talk about, right?). It looks like a junction that joins two pipes together with a bolt on top. It is a bit corroded. I've added a photo to my album of it taken above the boiler. The correct water flow should go from right to left.

EDIT
Yes, it looks like Part 1039 on this page
http://www.johnsonvalves.co.uk/non return.htm
END EDIT

If it is a non-return, could it have stuck/failed so that it actually allows flow in the wrong direction but prevents flow in the right direction?

The system has been working with the pump in the right direction for the last six years so if this is a non-return valve and it is the culprit then it is not letting water through in the right direction and it is letting water through in the wrong direction. Is this possible?

Thanks.

Richard.,

 

[Nige F]

Your picture is of a safety valve - not a non return one You can do 2 things to the pump 1 vent it and 2 see if it`s running :By unscrewing the big slotted screw on the round face of the pump - Do this with the boiler thermostat turned down/off and the boiler cold - so you don`t get hot water spitting out of the hole where you remove the vent screw . With power to the pump you should see the end of the spindle spinning in the hole you took the cap out - you can give it a spin with a screwdriver if it`s stuck .Vent until water dribbles steadily out - then screw back in place and power up pump+ boiler

 

[dnrichard]

Nige

That's it .

Thank you. I had to buy a new screwdriver with a large head but it must have taken about 20 seconds to fix it. A few splutters and then a steady stream.

The boiler has now been on for 15 minutes, the right pipes are getting hot in the right order and the radiators are getting warm.

Now, I'll just go ground and bleed them and check the F&E tank but I think we're done.

Thank you again.

Richard.