Header Tank Overflow All aspects of plumbing questions and answers, help, tips and information

[Steve Roberts]

Can anyone please tell if it's possible for the header tank water level to rise when no water is entering through the Ball Valve flow or the expansion pipe?

When the Washing Machine is used the water level rises to a point above the overflow level, I can only assume that back pressure is causing water to enter the tank through one of the two cold water supply pipe at the base of the tank.

Firstly, is this possible? And secondly, how can I fix it?

Any help would be gratefully received

[plumbbob]

I assume you mean the larger hot water header tank not the small central heating header tank?

Yes, this can happen. It is a recognised fault.

If this only happens if the washing machine is on and it utilises both hot and cold fill, then I would suggest there could be an internal fault with the machine.

Test the machine by turning off the hot connection and try running a medium or cool cycle. Does the fault occur?

Another way, disconnect the hot fill pipe and start a wash cycle. Does water back flow out of the disconnected hot pipe?? It should not.

[bd3cc]

Someone will correct me if i am wrong, but pipes at the base of the tank are outlets, not supply pipes.

[Dave From Leeds]

bd3cc,
Outlets to supply something (hot water system or cold taps / toilet / shower!

plumbbob,
Surely, if the hot water connection to the washing is turned off, the fault can't show itself because there would be no route to the header tank from the washing machine.

Steve,
Try plumbbob's second suggestion. But allow the machine to fill first, then turn off the machine and turn off hot water feed to it before disconnecting the hot fill pipe from the machine. After that switch the machine back on.

[plumbbob]

"plumbbob,
Surely, if the hot water connection to the washing is turned off, the fault can't show itself because there would be no route to the header tank from the washing machine."

Well, that actually was the point, it might STOP the fault occurring and prove what is causing it.

On your second point, if the washer is allowed to fill before disconnecting the hot hose, then I doubt if anything would happen as I believe the fault is water back flowing whilst the washer is filling. If it happened at any other time, the header tank would be over flowing continuously.

[Dave From Leeds]

Sorry plumbbob, yesterday I was thinking that it might be that the washing machine was pumping water up to the header tank when emptying, hence my comment about filling the machine first.

Steve, please ignore what I said to you and follow plumbbob's original suggestions.

[Steve Roberts]

Thanks guys!

Sorry for the delayed reply, I have now turned off the hot supply to the washing machine and I'll let you know how it goes!

Cheers