Hot water in expansion tank when CH cuts in

[stewartp]

Please help!

I have a Flamingo 50s boiler with a copper tank,pump and expansion tank.

My expansion tank fills up with hot water when the CH cuts in within a minute or 2.the boiler also makes a terrible noise like air or lack of water in it then the boiler cuts out.The expansion tank is full of brown water.The hot water is coming from the vent.

So at the mo my boiler is throwing gallons of hot water into the garden and my heating is non exhistant...is it in need of complete flushing or is it new copper tank or what...

Any help greatly appreciated.....!!!

Thanks in advance

 

[Softus]

My expansion tank fills up with hot water when the CH cuts in within a minute or 2.the boiler also makes a terrible noise like air or lack of water in it then the boiler cuts out.The expansion tank is full of brown water.The hot water is coming from the vent.

Sounds like a severe case of pumping over, to the extent that the system isn't circulating at all.

See if you can locate the blockage with a magnet on the pipework - start near the pump and the cold feed.

In any case you're going to have to drain down and do a lot of flushing.

 

[stewartp]

Thankyou very much for that response !!!

It sounds like I may be able to do this myself !

I know where the lowest point in the CH is and it's lower than the lowest rad,Do i just run the heating and just let it all drain out till running clean?or do I add a cleaner for a couple of days then drain off/flush...

The boiler itself cuts out prematurely even though the wall stat is open and the rads are barely tepid now as it's not on for long enough..If i turn the boiler up to 3/4/5 it cuts back in again but only for a minute or two.But it's worked fine for 10 years on 1.5 of 5 and the pump 1 of 3.....I have microbore which may of interest...

So the fact that the water in the expansion is brown means ?????

many thanks for your help !!!

Stewart

 

[Softus]

Do i just run the heating and just let it all drain out till running clean?

NO! The boiler and pump must be off if you're draining.

or do I add a cleaner for a couple of days then drain off/flush.

Certainly consider adding a cleaner, but there's not point in adding anything until you can get the water to circulate. In extreme case such as yours you may have to cut out sections of pipework to achieve this. Don't make the mistake of thinking that this might be quick and simple.

Drain first, then remove the pump to check that its inlet port isn't blocked.

But it's worked fine for 10 years on 1.5 of 5 and the pump 1 of 3.....

It hasn't worked fine at all - it's been limping along while building up to the current situation.

I have microbore which may of interest.

It certainly creates more opportunities for blockages.

So the fact that the water in the expansion is brown means?

It contains rust. It's commonplace, and not a problem, it it's only a little, but if you have great gobs of sludgy rust then it generally indicates that the radiators are in an advanced state of corrosion.

 

[stewartp]

The noise is all around the pump area next to the copper tank.there is a small cylinder about 6/7 inches high x 3 inches which is above the pump which is also making a noise,,,sounds like air.Is this an indication that somewhere near the pump is a blockage?

 

[gas4you]

This sounds like an air seperation unit. You could cut this out and replace with a Myson Aerjec, or configure the pipe yourself so you don't need an aerjec

 

[stewartp]

I've just been told by a passing plumber that it sounds like the cold feed is blocked!

???

 

[gas4you]

Check first that you have water in F&E tank and that ball valve has not stuck shut.

It could be the cold feed blocked or the blockage in the air seperation unit as said before.

If you bleed your rads upstairs do you get air/water out or nothing?

If eventually nothing then sounds like cold feed blockage. This will be at point that cold feed joins system.

Before you do any pipe work you could turn off cold fill gate valve, disconnect bottom nut, then open valve into bucket to prove that blockage is after valve and not in F&E tank.

 

[stewartp]

This is a fantastic forum and it's a breath of fresh air to find knowledgeable heating engineers that won't rip me off.I think some plumbers have given the trade a bad name with the rip off technique..

Thank you ! I will try all the things you've all said and report back !!!


Once again thank you for your support!!!!

 

[stewartp]

I have checked the cold feed and it's fine runs and refills straight out of the lowest and furthest rad,have just drained the sysytem and now gonna check the pump in /out to see if blocked,after which I've got a fernox cleaner to put in for a couple of days and then go from there.........

There is quite a bit of silt in the Top up tank!

buy for now

 

[stewartp]

It's all becoming clear !

My boiler (Potterton Flamingo 50s) fires up OK but cuts out before the rads are warm.I've checked the Cold feed from Expansion and it's fine,running right through to the bottom rad, so no blocks there.

Can I guess that the pump must be knackered because it sounds awful (rushing,bubbles and rattling eratic speeds ect ect....

I've filled it with Furnox cleaner,scorching hot water is still venting into the Topup tank,,,gotta be the pump right ???? even the 3 speed switch is eratic and stiff...

Thanks

 

[stewartp]

I've taken the large screw out of the end and the pump appears to be spinning freely although it is making a noise that wasn't there before .It also isn't speeding up when I increase the setting???

Thanks