warm water coming from cold tap in bathroom

JohnD said:
While Bab has his tea...

There should be no mixing of the water in the central heating and in the taps.

there is a fairly uncommon sort of hot cylinder called a primatic that can let mixing occur if it goes wrong, otherwise, if the hot coil in the cylinder has split - but your symptoms do not appear to match this.

If there was some piping wrongly connected it might allow mixing.

My money is on the vent pipe (expansion pipe) from the circulating boiler water venting hot and dirty water from the radiators. If the vent has been positioned over the cold water tank it can cause the conditions you describe. You need to go and sit in the loft with a torch while the boiler is turned on and off, hot taps run etc.

the vent pipe will (should) be a 22mm pipe, which comes up (usually from the airing cupboard) into the loft, rises several feet up, then is bent down in a curve over a tank so that any water that comes out of it runs down into the tank.

Let us know if this is happening.

Was the radiator water flushed, either with chemicals or a machine? I think this is going to be one of the things you need to do, as well as adding inhibitor when you have got all the loose muck out.

Were your old radiators rusty? Or why did they need to be replaced?
Click to expand...

Hello John,

The old radiators were rusty and full of brown sludge. The radiators were not flushed. If the radiators were plumbed in wrong would this be a problem?I know the pipe you are talking about. I will get up there first thing in the morning and see what is going on. If the problem is as you expect how do i overcome this?

Thanks in advance.
 
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JohnD said:
Benny2006 said:
The vent is dipped in the water level.
Click to expand...

In the big tank or the little tank?

How high is the water level in the little tank?

Have you got a pipe cutter?
Click to expand...

In the little tank. The water level is high in the little tank. I have a pipe cutter.
 
For a start, stop the vent pipe from dipping into the water, either by cutting it short, supporting it from the roof timbers, or lowering the level of water.

Establish whether it is venting from the radiators or the hot cylinder, and whether it is venting into the CH feed and expansion, or the Cold Water tank.

Brown water and rust means that air (and probably new water) is getting into the radiators. This should not happen. It might be a design fault. The new rads will go rusty if not fixed.

When you're in the loft, identify as many pipes as you can, and sketch thenm or take some digital photos.

Also, turn the CH pump to its lowest speed after you have had a look in the loft - a fast pump can cause pumping-over which causes air to get mixed into the water and cause rust.
 
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Benny2006 said:
...In the little tank. The water level is high in the little tank. I have a pipe cutter.
Click to expand...

See if you can adjust the ball valve so that the little tank will only be refilled if the water drops below 4 inches deep. Look at the ball valve to make sure it is not dripping when it should be shut.

Bale out the water to 4 inches.

If there is a lot of rust and mud in the bottom bale this out too, and mop it out with a sponge.

Support the vent pipe, e.g. by roping it to the roof timbers. If this does not hold it above the top of the tank, shorten the pipe with your cutter.
 
JohnD said:
Benny2006 said:
...In the little tank. The water level is high in the little tank. I have a pipe cutter.
Click to expand...

See if you can adjust the ball valve so that the little tank will only be refilled if the water drops below 4 inches deep. Look at the ball valve to make sure it is not dripping when it should be shut.

Bale out the water to 4 inches.

If there is a lot of rust and mud in the bottom bale this out too, and mop it out with a sponge.

Support the vent pipe, e.g. by roping it to the roof timbers. If this does not hold it above the top of the tank, shorten the pipe with your cutter.
Click to expand...
Adjusting ball valve now. The valve is not dripping. There is alot of crap in the tank. I will clean out properly. I will tie vent pipe to roof timber. Where can i find the ch pump to turn to lowest speed?
 
Usually next to the cylinder or next to the boiler. In some cases it is inside the boiler casing. You are looking for a cast-iron item about 5 inches diameter and deep, with 1-inch or bigger pipes going into each side, and an electric flex going into a connector block.

Probably like this
p3467462_l.jpg
 
Not a galvanised cylinder by any chance, with old steel pipework. And maybe even a galvanised storage tank.
 
Thankyou everyone for all you're help. I will let you know how it is after being cleaned through tommorow.
 
System all clean now the pump beside the boiler was not working either.
Thanks all for you're help.
 
That's great news (apart from the pump). Next, buy a litre of Cleaning and a litre of Anti-Corrosion chemicals (Sentinel is quite good) and follow the instructions.
 
D

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