Water being back fed from immersion tank to cold water storage

[jonilea]

HELP!Can anyone please advise? I've exhausted my knowledge and am going mad!! I have a cold water tank that overflows once a day, really quickly. It seems that the warm water is being pushed back into the cold storage tank from the indirect cylinder. the heating system is a sealed pressurised system, and there has been no loss of pressure(or Water) from the system , eliminating the possibility of a ruptured coil in the immersion tank.Any ideas?

 

[Ray Stafford]

Does it always happen at the same time of day or at the same time as some other event?

Have there been any new mixers installed recently?

 

[jonilea]

There has been no changes to the system in 8 years, and the time is not constant although it is mainly during the early to mid morning.

 

[Best]

^^ My first thought also. Seen this happening a few times. Told this to an elderly man on the phone who had a plumber out 4 times to the ballvalve on his cold tank ripping him off.
I mentioned new mixers & he said he had that plumber fitting a monobloc kitchen sink mixer & the wider 2 hole type in garage sink.
I went down & found the monobloc to be passing mains water through to the hot & up to the cold tank. Either a new mixer needs fitted or check valve on hot below mixer. Personally I would replace the mixer if new as it is faulty if passing through body

 

[mikeyc]

Had this a few times with it happening mostly in the morning when people shower. If the shower is on mains cold but tank hot and you can get to the pipework easily - try fitting a pair of non return valves.

 

[jonilea]

I appreciate the help, but unfortunately the shower is fed from cold water tank, and mostly this occurs before anyone is up and using any appliance. If i put a non return valve on the cold feed to immersion tank whats the downside? it would probably just push the water through the expansion pipe wouldn't it?

 

[Ray Stafford]

Ok, odd one.

Just an outside possibility. You mention you have a sealed (pressurised) heating system. Do you leave the filling loop permanently connected? You aren't supposed to, but lots of people do. Try disconnecting it. I'm just thinking that maybe it is letting by, and that there is a hole in the coil, but its only when there is a peak mains pressure spike that its enough to push back through the stored supply.

 

[Best]

I assume you have made certain that the water is coming back from the hot tank up the cold feed? As Ray says, disconnect the filling loop hose to rule that out. If problem still occurring then it is a mixer of some sort fault

 

[smtplumbing]

Is it the big water tank of the small one

 

[stevetheplumber]

have you tried lowering the water level in the tankthe level may have crept up over time and now there isnt room for the exspansion from the ho****er i would chuck a new ballvalve in and reset it 3 inches below overflow

 

[Gray0689]

Is there a Willis heater connected (small cylinder at side of cylinder)

 

[gasmanrob]

Walk around the house any where you have a water source listen to it use s screwdriver as a listening stick if needed and touch the pipe work one of the hot pipes will be noticeably colder then everywhere else. Problem El solvio!

 

[bashmaystor]

As mentioned above, I would also check the following:
1. All the mixer taps for letting by cold main pressure.
2. Make sure the cold water storage ballvavle is not leaking from any joints inside the tank.
3. Make sure the water in the cylinder is not overheating and discharging from the vent pipe.
4. Remove the filling loop and check for pressure drop.

Let us know what it was.

Cheers

 

[jonilea]

Thanks to all of you for the advice and help in this matter , it turned out to be a pressure spray for cleaning that had both feeds but the outlet was controlled via a hand trigger, when the inlets were left on the mains back fed to the tank when it was not in use, as gasmanrob says ---------
PROBLEM EL SOLVIO!!!!!! Thanks again