PLEASE HELP - Water in the coldwater tank HOT!!!

JohnD · 15 Dec 2006

What can you tell us about the kitchen sink tap?

Has it got service valves on its supply pipes?

Is the "hot" pipe strangely cold? (below room temperature)

Are you unwilling to disconnect the boiler filling loop?

Mark_H · 15 Dec 2006

JohnD said:
What can you tell us about the kitchen sink tap?

Has it got service valves on its supply pipes?

Yes

JohnD said:
Is the "hot" pipe strangely cold? (below room temperature)

NO

JohnD said:
Are you unwilling to disconnect the boiler filling loop?

If it happened with the previous boiler, which was a vented system, why should this be an likely cause of the problem?

JohnD · 15 Dec 2006

Mark_H said:
JohnD said:

What can you tell us about the kitchen sink tap?

Has it got service valves on its supply pipes?

Click to expand...

Yes

Try turning them off overnight, it is a common cause

scaby · 15 Dec 2006

because the water has to be coming from somewhere,i suspect johnd thinks the cylinder coil has a pinhole in it (sorry if i am wrong)but as the system is sealed, the cold water has to be connected and the only place (normally) is the filling loop

JohnD · 15 Dec 2006

Scaby is right, I was thinking that.

and also because

Mark_H said:
...If it happened with the previous boiler, which was a vented system...

You didn't tell me that before.

Mark_H · 15 Dec 2006

JohnD said:
Scaby is right, I was thinking that.

and also because

Mark_H said:

...If it happened with the previous boiler, which was a vented system...

Click to expand...

You didn't tell me that before.

I mentioned that it happened with a previous boiler, but not that it was vented - sorry.

Agile · 15 Dec 2006

They are trying to help you and they know that somehow cold water at mains pressure is entering your hot water pipework and forcing water up into the feed cistern. Or at least that is the expectation based on what you have explained.

I do wonder why the feed tank is not overflowing OR the vent pipe is expelling hot water. Are you quite sure neither of these are happening?

Regardless of what you think please could you disconnect the filling loop. You are in contravention of the Water Regulations if you leave it connected and we want to eliminate it from the problem diagnosis.

Tony

Mark_H · 16 Dec 2006

Agile said:
They are trying to help you and they know that somehow cold water at mains pressure is entering your hot water pipework and forcing water up into the feed cistern. Or at least that is the expectation based on what you have explained.

I understand people are trying to help, and I am very appreciative that people have taken the time to respond - not sure what point you are trying to make? I understand why people are jumping to that conclusion, but I am still curious as to why when the boiler is turned down it doesn’t happen anymore.

Agile said:
I do wonder why the feed tank is not overflowing OR the vent pipe is expelling hot water. Are you quite sure neither of these are happening?

100%

Agile said:
Regardless of what you think please could you disconnect the filling loop. You are in contravention of the Water Regulations if you leave it connected and we want to eliminate it from the problem diagnosis.

Tony

Disconnected.

scaby · 16 Dec 2006

why was the vent to the hot water cylinder renewed? was it done from cylinder to tank in loft with 22mm copper , no joins , fittings or valves of any kind?

JohnD · 16 Dec 2006

Now that the filling loop has been disconnected, either the flow will stop; or I'd turn off the service valves on the sink mixer tap, which is another likely source.

If you turn them off overnight and check in the morning, that should show. If the mixer is letting by, look for a British tap which doesn't mix internally (you will find that British sink mixers tend to have two waterways inside the "spout" so the water shouldn't have the opportunity to mix before it comes out over the sink.

It may be rather bigger than a stylish Italian monoblock, but will work better.

Mark_H · 16 Dec 2006

Ok, so I isolated all 3 of the mixer taps downstairs, checked the washing machine and dish washer, both cold feed only. Filling loop is disconnected and still the pipe is getting hot, and hot water appears to be entering the CWS tank!!!

Aaaaarrggghhh, this is doing my head in, my wife says I am obsessed with it!

I had a new vent from the hot water draw of the cylinder, and that is getting a hot a few inches up, due to expansion. So if there was expansion it should go out the top of the tank and up the vent pipe.

Question: If the hot water cylinder is hot (up to temp 65), should the cold water feed be cold from top right to the bottom, or would you expect it to be hot most of the way then turn cold at the top?

JohnD · 16 Dec 2006

It is odd for hot water to travel up the supply pipe from the cylinder to the cold tank.

This is because the supply to the cylinder enters at the bottom, where the water is not usually hot - it stratifies. So the feed pipe is normally cold.

Can you follow the pipe from the cold-water tank to the cylinder and see where it joins?

I am wondering if there is a loop that is enabling convection currents to circulate.

Also, use a bit of tape or something to mark the water level inside the cold tank to see if the water level rises overnight (when there is no-one using it, but any leak will be continuing)

BTW water should never travel up the vent pipe (unless the water is boiling or the feed pipe is blocked) because it has to travel less high to escape up the feed pipe, and this prevents pressure from building up.

The vent pipe is usually hot for a few inches from conduction and convection within the pipe, but there should be no flow.

Nige F · 16 Dec 2006

Is the shower pump one with a connection between H+C ends as a bypass

.......that`s where the circuit is formed

cold water is going down the cold side to pump -across and hot is returning to Roof cistern

My psychic guide , Randall the plumber told me this

he`s resting with my dear old Grandad, they used to work together

Nige F · 16 Dec 2006

Nige F · 16 Dec 2006

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PLEASE HELP - Water in the coldwater tank HOT!!!

scaby

scaby

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