Constantly bleeding...

[Tomo72]

Hi all, newbie here.

I've been in my house ~2 years, it was built in 1998 and has a boiler that heats the hot water and stores it in a tank (not a combi)
Since I moved in I had to constantly, maybe every 2 to 3 days, bleed 2 or 3 of the upstairs radiators. When the heating comes on early in the morning the noise the radiator in our bedroom makes a terrible gurgling/bubbling noise that wakes me up, I'm assuming it's air in it. The pump failed a few months ago so a plumber friend of ours replaced it. A few days later I saw one of valves either side of it leaking, top one IIRC. The plumber friends business partner came round and replaced those. Since then the gurgling noise is worse and I now have to bleed the same radiators every or every other day to keep the noise down. Since the plumber(s) visit, the bleed valve on a vertical pipe next to the hot water tank no longer works so I can't bleed that anymore, it's a type that you have to undo slightly to let the air out, I can see pliers marks on it so I'm thinking he's tightened it down too far and now it's stuck. I'm trying to find out where all this air is coming from, I can't see water dripping from any of the valves/pipes on any of the radiators so I'm a little stuck. 
Any help/advice would be most appreciated. 

Many thanks
Paul

 

[Armo74]

Constant bleeding can either be a sign of a build up of magnetite in the rads or a blocked cold feed.
You could try the magnet test on the cold feed where it tee's into the flow pipe from the boiler to see if there is a blockage.
If there is the magnet should attract to the copper pipe

 

[Tomo72]

Thanks Armo74,

But I don't quite understand

the cold feed where it tee's into the flow pipe from the boiler

The boiler is fed from a small tank in the loft - do you mean the pipe from that to the boiler?

Although the system fills ok, it's just a couple of radiators need frequent bleeding

 

[swbjackson]

It could be pumping over or drawing air down the open vent. If it's got worse since the new pump went in it's possible because the new pump has been set at a higher speed.

 

[Tomo72]

Thanks Mike,

The new pump is set to the lowest, setting 1. Is it possible to test for drawing air down the vent? How? and how do I stop it if it is?
Is the vent the "overflow pipe" that comes out above the feed tank or is it a different pipe?

Sorry for all the questions, I'm no plumber, just trying to find out what the problem is with my system, the noise is driving me mad.

 

[Whitespirit66]

Thanks Mike,

The new pump is set to the lowest, setting 1. Is it possible to test for drawing air down the vent? How? and how do I stop it if it is?
Is the vent the "overflow pipe" that comes out above the feed tank or is it a different pipe?

Sorry for all the questions, I'm no plumber, just trying to find out what the problem is with my system, the noise is driving me mad.

The vent pipe for the ch is the one that curves over small loft tank like a shepherd's crook.

Watch it when the heating is on to see if water comes out - pumping over.

To test for it drawing air, fill a large glass of water and hold the glass with end of vent pipe sumberged under the water. If the water starts disappearing with the heating on, it's drawing.

Have you done the magnet test yet? Trace the route of the pipe that exits from bottom of tank downwards, until you reach a point where it tees into the main system pipes. Put magnet on and around tee.

 

[Tomo72]

Thanks for the clarification on the parts Whitespirit66

I'll carry out these tests in the next few days or over the w/e when I get a chance

 

[Tomo72]

Hi all,

It's been a while but I have finally carried out the "glass of water" test. It didn't appear to suck any water in or spit any water out, it did, however, have bubbles coming out of the pipe, quite large ones about one every 1 to 2 seconds when the heating fires up but then slows and probably eventually stops, I only had the pipe in the glass for a minute or so.

As for the magnet test, I couldn't find the "T", is this likely to be in the loft, in the airing cupboard or right at the boiler?

I have taken a photo of something in the airing cupboard that appears to be on the pipe from the tank in the loft but it's difficult to trace, could this be what you mean by the T

 

[Tomo72]

Anybody?

 

[45yearsagasman]

Thats the part in question. The 15mm pipe is the cold feed connection and the 22mm pipe goes up and loops over the small tank. Get a magnet and check all around there. If the magnet is attracted to the copper it indicates a build up of magnetite inside. You can also try igniting the gas that you are venting from the system. Invert a can over where you are venting and collect the gas and then try igniting whats in the can. If it goes pop then you have hydrogen.
That require some treatment.

 

[Tomo72]

Thanks Pete,

I'll look at that just as soon as I can

 

[Tomo72]

I've finally got round to doing the magnet test, I haven't had the time to do the gas test yet though, it's a very busy time doing the house up.

The magnet did stick to the "device" pictured above and to the pipes above and below it, it also stuck to the pipe above and below the pump too.

So, does this mean megnetite is present in the pipes? Advice please

 

[Tomo72]

Ummmmm... bumpety

 

[Tomo72]

I guess I should add something like X400 http://www.sentinel-solutions.net/product/detail/central-heating/liquids/x400-system-restorer/
run it for a few weeks then drain down and add something like x100 http://www.sentinel-solutions.net/product/detail/central-heating/liquids/x100-inhibitor/

 

[Terry7556]

Tomo the chemicals will not hurt but usually it's quicker and better to cut out and replace the blocked pipework
After you or someone else has done this. , put the cleaner in, drain down fill up and add inhibitor