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?

[BliarOut]

Some must be tank fed, surely?

[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?

[BliarOut]

Nope, it'll stop the tank refilling but gravity will keep the water flowing. There might be a stopcock on the outflow from the cold water tank.

[XanderH]

No water at the main stopcock? Odd. Gatevalves on hot water cylinders do shear off internally if turned off too tightly, mine did and I had to have a plumber change it.

[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

[B17NNS]

The electric shower and kitchen tap will be supplied directly from the rising main.

Are these working with the stop cock in an open position?

[dave144]

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

[B17NNS]

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

[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.

[B17NNS]

Well it will help eliminate a faulty stop tap.

Surprised the kitchen cold tap isn't working though.

[Gingerbread Man]

dave144 said:

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?

right, I'm trying to make sense of your couple of posts, so bare with me.

So you've got a low pressure hot and cold system. Mains should feed the kitchen tap and then rise up to fill the tanks in the loft (heating header tank and low pressure cold water storage tank).

While you were working on the system, you tried the isolation for the incoming mains (stopcock) and the cold feed (gate valve?) to the hot water cylinder (not 100% on this bit?).

You now have no hot water through out the house, but the mains to the cold water tank in the loft still works/ fills?

You mention that your electric shower still has water going to it. This will be mains fed, so your mains seems fine. Your kitchen tap should also have cold (where you turned off the incomming main?) and the outside tap should be on the main too.

Your washing machine should be mains fed as well, but it wouldn't be the first one I've seen plumbed into the low pressure and as you mentioned that it isn't working, I'm assuming that it must be plumbed on the low pressure side of things.

Bathrooms quite often have a mixture of low pressure and high pressure feeds. You may for example have a mains cold tap on the bath to aid quicker filling. A low pressure feed for the toilet to reduce the condensation that a mains fed supply can create.

To check if a tap is mains or low pressure, cover the spout with your palm and turn it on. If you can hold back the water, then it's low pressure, if not, mains pressure.

If your cold water tank in the loft is full, then you should have cold to all of the low pressure cold taps in the house. If not, I'd think it was an airlock stopping the flow. If you push the ball cock down, does it continue to fill, or is the mains not working there?

dave144 said:

"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."

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

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

[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.

[Gingerbread Man]

dave144 said:

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)

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.

[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.

[Gingerbread Man]

dave144 said:

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.

The ball valve letting by could be a few things.

The ball valve could be buggered, diagram split, could be some crud stuck in the valve stopping it from shutting off. Turn off the mains water and undo it and have a look.

The float could be full of water holding the valve open.

It can't be the mains valve being jammed shut, due to the cold water tank filling up. This proves that you have mains water coming in.



Gate valve wise, it's not uncommon for these to fail. On the cold feed to the hot water cylinder, is the gate valve above the hot water cylinder? If so, open the hot taps and drain off any water that comes out, then undo the bottom nut of the gate valve. This will tell you if water is getting past the gate valve, or if the valve has jammed shut.

[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"

[Gingerbread Man]

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 gate 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.

Edited by Gingerbread Man on Sunday 13th March 22:03

[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.