Urgent Plumbing Advice Needed.....

[Ludwig Venter]

I almost boiled my Convicts right out of their tank...... I have a tap in the front yard to water the front garden an then another in the back garden (very close to the servants'quarters) where there is also a Geyser to their shower......

The front garden hose was open whilst I drained a tank with Convicts in it (standing outside - to about 90%)..... and then refilled it from the garden hose in the back yard...... flushing the water through the (hang on) filter to clean that as well..... I was about 40% filled when I wiped the inside of the filter and burnt my hand in boiling hot water coming from the garden hose....... The water seem to have reverse flowed from the hot water geyser to the garden hose.

When I closed the tap to the front garden..... cold water came out of the back hose again and I could continue to fill the tank.

Do we have any plumbers on TFF who could please explain to me what had happened??? and what should I do do prevent it from happening again??

 

[DrRob]

I'm not a plumber, but I'd go for there being a connection at the shower, possibly at or around a mixer valve of some sort. In normal usage there is no flow because the cold water pressure pushes it backwards but when there is more than one tap on then the nearest pulls water from the hot system as there's no longer enough pressure in the cold water system to keep the connection closed.

Solution to that would be a check valve to stop it mixing if there's any pipe you can see to put it on or a new valve where they meet which is probably at a shower mixer.