noisy cold pipes after fitting pump to hot

[arthuc01]

Hi

I have an old Fortic hot water tank. Basically the water pressure from that was awful so i fitted a small water pump to the hot.

Now the Hot water comes out at a decent pressure but when I turn the hot tap off the cold pipes start making a very loud high pitched noise. (I think its when the hot water tank fills again)

I would have said there was air in the system but the only thing that has changed has been the installation of this pump. Which is after the Fortic's cold tank (obviously)

Pressure on Cold - about 4bar
Pressure on Hot (without/with pump) = 0.1/1.5bar

With these pressures i don't think i'm drawing too much water for the system to catch up and The noise starts irrespective of the volume I draw from the hot - so even if i take a little i get this high pitch squeal and shaking pipes

Any ideas as to what may be causing it and how I can get it to stop - I'm a failry competent DIY-er

Ta

Chris

 

[joe brown]

turn your stopcock down a notch !

 

[arthuc01]

I got all excited by your suggestion as it was quick and easy to try but sadly it still happens when the cold flow is knocked back a bit.

One thing though with the flow reduced it was easier to hear that there is a bit of a pulsating noise to the cold flow

 

[oldplumber]

try replacing your inlet valve to the fortic and if it is a potsmouth type ball valve damp it with a yogurt pot hanging off the ball lever to slow any vibration.

 

[Plumbstar Tom]

either fit a PRV (pressure reducing valve) to the cold mains inlet or try a new fill valve for the cold tank