Bubbling in cold water tank.

[kels]

Hi, my cold water tank in loft flooded last week (in cold weather) sending water into the airing cupboard and spare room . I called a plumber who looked at the tank and said nothing was wrong and to keep an eye on it! Now at night I can hear a bubbling noise (like air bubbles) coming from the tank for a few seconds in the evening/night. Everything else seems fine though, perhaps I am being paranoyed! Any ideas anyone?

 

[WHPES]

Why did the tank flood?

Sounds like something is wrong if you keep hearing bubbles every few seconds.

What is your boiler?

 

[kels]

Hi, the plumber didn't know why it flooded, 'something may have frozen in the cold'!
The bubbling noises are only 1-3 times an evening and last for a few seconds.
My boiler is a VokeraMynute 20e. As far as I know it's working fine, heating and water same as usual, no hot water in cold tap etc! Thanks.

 

[piperdave]

sorry just to clarify are sure it was the cold water tank ? u should have two tanks in the loft a big one which is the cold water tank and a smaller one which is your f+e tank for your heating unless ur heating is pressurised ,

a possible problem could be the ball valve letting by and the overflow being frozen giving the water nowhere to go therefore coming over the top of the tank.

or it could be ur heating system pumping over which could be the bubbling your hearing and the overflow being frozen on that also giving the water no other choice but to come over the top of the tank

 

[kels]

As far as I know there is only one tank in the loft, which feeds the hot water tank on landing and boiler.
If it is that the heating boiling over should I get someone in to look at it? The pressure on the boiler is never the same and drops to .5 when turned off.

 

[Plumbstar Tom]

Whats the thermostat on your Hotwater tank set at?

 

[kels]

Hi Tom, it's set at 60 degrees. Hot water gets very hot tho!

 

[Plumbstar Tom]

Seems strange you say you only have one tank?

If thats the case it would be ideal to ascertain where the bubbles are coming from, which vent pipe

It is possible that you HW tank has a faulty theremostat, it should be set at abot 55 degrees, any chance you can measure the temp of water from a hot tap?

 

[kels]

I've been told that i have a 'sealed system' which doesn't have a feed and expansion tank. Have turned the thermostat down and will look into buying a thermometer! Don't fancy waiting in the loft one night to see where noise is coming from! Thanks.

 

[WHPES]

If your boiler pressure gauge is 0.5 it is too low. Add more water via the filling loop to top it up to 1.0. When you top up the boiler, bleed all the radiators and any other bleed points (there will probably be one by the cylinder), then check the pressure again.

NB Pressure will rise and fall as water expands when it gets hot.

Are you sure the bubbles are in the tank and not just noise being transmitted down the pipework?

 

[kels]

I guess it's possibly the pipes, but it really sounds like air/water bubbling up out of water if you know what I mean! I'll top up the water and bleed the radiators like you said, perhaps it's best to ignore any noises untill something else happens! Thanks for all your help.

 

[Plumbstar Tom]

For bubbles to be created it is usually a sign of something being to hot too hot

If its coming out of the vent from your HW cylinder then its possible your tank stat has gone

It is difficult to diagnose with out knowing if it is bubbles and where they come from

Would be ideal if you witnessed it but as you said you can stay in your loft for hours lol

 

[kels]

I've turned down the thermostat in the airing cupboard and I didn't hear it last night so perhaps that's what it was? Who knows? Anyway fingers crossed, maybe I can set up a video in the loft to catch the culprit!! Thanks again for your help!

 

[WHPES]

Your cylnder stat should be set at around 65 degrees C.

 

[piperdave]

im sure its between 55 and 60 it should be set at whpes

sorry i stand corrected its between 60 and 65

 

[Winston]

Should be at 60, Wonder if the coild in the cylinder has a leak and then going up into the cold water tank, does the cold water feel warm? Hence the low pressure on the boiler.

 

[kels]

O.K. After days of looking etc, we've come to the conclusion that the hot water was on for too long (old potterton timer - water and heating on at same times) Have been manually turning off in evening and noises have stopped! If we have any more poroblems we'll get the hot water cylinder checked out. Thanks for all your help.