Cold water Chaos, help needed!

[dave144]

Ive had a on going problem with my open flue boiler drawing air into the system so decided to turn off the water feeds and drain the system down to check for debris etc. Turned the mains under the sink and the cold feed near the hot water tank off and on to make sure they moved freely and now the system has descended into chaos!!

I now have no hot water running but cold water supplied to the the tank. I have cold water to the electric shower and to the bath tap, but none to the toilet, basin, washing machine etc.

I've taken the isolation valve under the sink apart and there is no feed there? How is some parts of the house recieving a cold feed and others not? Surely with the cold water you either have a feed or you don't?

I'm at my wits end with this, can anyone shed any light to this?

[dave144]

but wouldn't closing the main isolation valve under the sink stop any supply to the rest of the house? If not how would I stop a leak in the house?

The cold water from the bath should come from the same as the toilet, shower etc? not from the hot water feed?

[dave144]

Would this have anything to do with having no cold water downstairs? I was thinking that maybe the isolation valve under the sink has closed and stuck closed even though i have now opened it again.

To be honest the valve is in a bad way and could with replacing but (a) it means cutting out the back of the unit to gain access and (b) I need to isolate upstream from this before attemping, which is the valve out on the street.

How can turning a valve off and on make such a problem? I've even tried the outside tap and that has nothing either.

To get rid of the air in the system I have had to boil off the air from hot water by removing the stat from the boiler for 15-20 mins, but now when I try it the water simply spills out of the side of the house via the overflow pipe.

The system is an old one and will be replaced this week with a baxi/valliant combi I think

[dave144]

electric shower yes but other than the bath tap no? makes no sense to me

[dave144]

B17NNS said:

And when you turn off the stoptap the shower stops working?

Didn't try that. Was dumbfounded that the shower was working at all.

[dave144]

Gingerbread Man said:

Air out of the hot water taps or the heating system?

Edited by Gingerbread Man on Sunday 13th March 15:38

Well it was to get air out of the hot water but you can hear the air being forced around the CH system (CH switched off whilst doing this)

[dave144]

Everything is correct that you have written above. Would it be possible that the shower, bath, cold water tank are all high pressure feeds and the rest of the consumers ie washing machine, toilet etc are low pressure feeds.

If I press the float valve down in the tank then it fills up, but oddly now it seems to not want to stop and is causing the tank to vent outside.

I can only assume that either the mains valve or the gate valve is jammed shut? I thought about there being a airlock in the cold feed last night and tried to clear it by back feeding the hot water from the washing machine onto the cold feed and still nothing.

[dave144]

Gingerbread Man said:

Air in the hot water will gravitate out via the taps/ vent pipe.

Air in the central heating system should be bled out through the radiators/ bleed vents at the boiler/ highest points. If there is an air lock, you can always put a hose on a drain off and pull water and air through and out of the system.

That is what I do when bleeding the radiators, ensuring that that the system is down before opening the rads.

[dave144]

All valves are below the cylinder. Where the tank is housing the float valve, there is also another what looks like a feed that comes into the bottom of the header tank with a red isolation valve attached, what is this? Is it the feed to to the cylinder, and isolating this prevents water leaving the header?

I still cannot get my head around why theres no water to the downstairs though?

Hope to get it sorted soon as the toilet is getting a little "fragrant"

[dave144]

Gingerbread Man said:

If your central heating isn't a sealed pressurised system then you should have a smaller header tank in the loft to take up the expansion. The water will be mucky.

As you have low pressure cold water in your house, there should also be a much bigger tank in the loft. Should have a lid over it but this might not be the case. This water should be nice and clean. Should be drinkable.


The cold water tank may have a few feeds coming out of them. Typically there are two. A dedicated feed to the hot water cylinder and a feed supplying all the taps that aren't mains with low pressure cold.

The valve (red head to it is a great valve - a low pressure only valve) you are talking about, is this coming out of the heating header tank or the cold water storage tank? Lets call heating header and cold water the cold water storage. I'm assuming the cold water storage tank.

So yes, this could isolate either the supplies to the cold taps, or the cold to the cylinder.

Everything you say is correct. The red valve head is situated under the header tank. If there was a fault in the header tank would it prevent flow to the taps etc if they have been plumbed into the low pressure side after the tank.

[dave144]

Thanks for all the advice. I'm going to have to put the trouble shooting on hold now as im back at work and the little one is asleep at six...not ideal by any means.

[dave144]

finally got round to getting some pictures

the valve under the sink


no water!


This valve feeds the expansion and header tank


the tank which houses the leaking float valve


the other tank which i have not dare open yet

Still cannot get my head around it. Tried the hot water again, the boiler fired up for two minutes and then knocked off. When I went upstairs the hot water had heated the upstairs rads and I could feel a hot pipe to the tank, but no hot water at the taps.

[dave144]

bump?