Overflowing hot water. Help!!

[luckyglen]

Hi,

Just got home to see water pouring out of the overflow pipe at the side of the house. I've been up into the attic and determined its the hot water expansion tank. The ballcock is under water and I'm sure that's not the problem as I've switched the cold water feed to it off and the tank still fills up.

I put my hand into the tank and the water is HOT .

I've got two separate systems. One cellar boiler for CH, one boiler on the top floor for hot water. Both are gas, the HW boiler is a glowworm space saver RF, with a pump, both right next to the HW cyclinder. The hot water doesn't seem to be coming up the vent pipe, but up the feed??? ie filling the tank from below.

I had a similar problem a few weeks ago and thought it was the ball cock - replaced it and it went away. I'm sure that's not the problem now. I've just got a Gas bill that's way in XS of what it should be, so I think the problem's been going on a while.

Reading the pages here, similar problems have been attributed to the coils in HW cylinders, but as mine is gas boiler driven, can this be the problem in this case?

My wife is 36 weeks pregnant and I've had to turn the cold water off, to stop the water pouring out of the house

Any help gratefully received, I'm calling a plumber tomorrow, but I want to know if they know what they're talking about when they come round.

Ta

 

[seco services]

have you any mixer taps ie kitchen sink tap that are mains cold gravity hot supply ?

would say ones passing cold to hot.
isolate the mains stopcock till you locate what one.

 

[luckyglen]

Thanks very much.

Both the shower and the bath mixers are transferring cold to hot. The plumber I've got round has suggested fitting a check-flow valve to the hot water pipe into the bathroom. Does this sound ok?

Alternatively should I look at pressuring/ pumping the hot water system, how expensive are either solutions likely to be?

 

[luckyglen]

Also I have a pressure reducing valve on the cold water into the bathroom fitted, is this of any use?

 

[seco services]

personally i would have the shower at least on balanced supplies.
and a check valve on each appliance.