water overflows when i use the hosepipe/pressure washer All aspects of plumbing questions and answers, help, tips and information

[stormin]

Hi

when I connect the hosepipe to the cold water tap in the kitchen, after a short time water pours out of the overflow pipe from the loft/roof.
The same happens if I have the karcher pressure washer connected.
Obviously if i turn the tap off, all returns to normal.

I have heard of the hozelock non-return valve or something, could this be the issue or fix the issue (i dont have one), but now I am guessing.

I do not have another other problems with the water supply in the house.
Any advice would be gratefuly recieved
thank you

[htg engineer]

if you have a monobloc / mixer tap then the cold water must be going up the hot water pipe and filling the tank in the loft, causing it to overflow.

Fitting a non return valve to the hose would not stop this. But a non return valve should be used when using a hose to prevent contamination of cold water supply.

The only way round this is to
a) fit a outside cold water tap
b) stop using the mixer tap as the supply of water
c) fit a non return valve to the hot water pipe, under the sink.

[stormin]

thank you htg engineer

yes the kitchen sink tap is a mixer tap, so I will do as you suggest.