Boiler kettling? Banging pipes etc

[Gav74]

Hello everyone.

I've been through the Wiki and other posts and they've been some help, but I'm just a DIYer and I'm a bit stuck and we have no heating or HW.

I have a Potterton Suprima 40L boiler and we've had trouble with it in the past but it's been fine recently.

Now, when the heating or HW comes on, it fires up (fan runs, gas lights everything seems OK) then the boiler makes a kettle boiling noise, pipes start banging, boiler shuts down. (sometimes the pipes start banging after the boiler shuts down).

I've found the circulation pump in the airing cupboard and the big silver screw in the end, but that just unscrews until there's a dribble of water but it won't come out so I can't try manually turning it?
Should I be able to hear or feel the pump operating if it's working? Because I can't hear or feel anything?
Is there something else I should know about the screw?
Is flushing the system worth the effort if I'm not sure about the pump?

 

[twgas]

Sounds like a circulation problem, most likely causes are;

• pump not working
• no water in system
• blockage in pipework

 

[Gav74]

Sounds like a circulation problem, most likely causes are;

• pump not working
• no water in system
• blockage in pipework

Thanks, that was what I thought/was hoping.

The tank is full so there should be water in the system.

So, if I don't have a screw that I can easily remove from the end of the pump and manually check it, how else can I check if the pump's working?
Should I be able to feel or hear it operating?

 

[Agile]

It certainly sounds as if the pump is failed.

If you listen to the pump with a screwdriver then you can hear it turning but you have to know what they sound like.

The obvious question is why is the pump screw not coming out?

It may be necessary to change the pump but if the screw were removed it might be possible free up the pump.

Tony

 

[JohnD]

The tank is full so there should be water in the system.

wrong

the most common blockage is in the F&E pipe where it joins the larger circulating pipes. So the water from the tank can't get down into the system.

If you bleed the highest radiator in the house, does water squirt out forcefully?

Is the pump hotter than the pipes joining it?

 

[Gav74]

The obvious question is why is the pump screw not coming out?

Tony

Thanks Tony, it doesn't actually feel like it's meant to. It unscrews then remains in place like it's held with a spring.

I'll post a picture when I get home after work.

 

[Gav74]

the most common blockage is in the F&E pipe where it joins the larger circulating pipes. So the water from the tank can't get down into the system.

If you bleed the highest radiator in the house, does water squirt out forcefully?

Is the pump hotter than the pipes joining it?

Thanks John.

I'll check those things when I get home.

 

[mickyg]

is it a hexagonal plastic nut? sounds like you might have a CP/myson pump. In that case the nut should be attached to the spindle of the pump, pull the nut loose and turn it. with power to the pump the nut should spin on its own.

 

[Agile]

If its a CP53 then the nut is a spinning know.

You unscrew anticlockwise and when its loose you bull it towards yuo and it engages in the end of the rotor and you can twist it and if its free then the rotor will turn with the knob.

If it is free but not turning then you need to check for 230 on the pump input terminals.

Tony

 

[Gav74]

OK, this is the pump:

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I've taken the black plastic cap off, unscrewed the silver one underneath, pull it and turn it and it turns OK.

I've turned it all on and I can hear the mid-position actuator moving, but there is no power at the input terminals.

What's next please?

 

[Gav74]

OK, ignore my last. I was being an 4rse.
Once I remembered that the boiler was turned off, there was 240v at the pump input;

However, the boiler did it's usual, but this time I noticed that the pump body got quite warm even though the pipes either side were stone cold?

 

[JohnD]

the pump body got quite warm even though the pipes either side were stone cold?

signifies pump jammed (or dry or not circulating for some other reason)

especially if it gets too hot to keep your hand on.

 

[twgas]

if you gently pull on the end nut, and the pump is working, the nut will spin out of your grasp - they spin quite fast so be careful. If it doesn't spin the pump is dead.

 

[Gav74]

Thanks for your help everyone.
I decided the pump was definitely dead, so I replaced it and now have central heating and hot water.
All for £50 (and that included the girt big wrench I needed for it) as opposed to the £75 call out fee just to start with, which seems to be the lowest around here!

This forum's saving me a lot of money when things go wrong

 

[JohnD]

It is worth giving system a chemical clean. For £15 you can buy a litre of Sentinel X400 and let it circulate for 4 weeks before you drain it out, rinse, and add inhibitor. It is nopt time critical so you can do it at your leisure, but after 4 weeks it starts to lose its power.

If your system is an old open vented one, it will usually have a lot of black sediment in it, and this is one of the things that clogs pumps and wears them out.