Low Pressure When Both Taps Turned On

[dave030801]

I have an unvented megflow system. The pressure to both the hot and cold taps in the bath is good when using them one at a time. But when both taps are turned on the pressure on both taps dips considerably. I guess the cold water pressure dips because it is feeding both the tap and also refilling the megaflow cystern as the hot water is used. But why should the hot water pressure dip?
Thanks for any answers on this.

 

[Bernie2]

The same cold water enter's the Megaflow to come out as hot. So they are both at the same pressure anyway. You may notice the hot appears to dip more than the cold, that is usually due to the resistance to flow through the Megaflow and its fittings.

 

[migoplumber]

you should have a mains feed to megaflow, next in line is stop tap, then pressure reduction and a t (incorporated in a 1 piece body) the split t should then feed the cold supply to cylinder (to become hot water) and the cold supply to rest of house.

if your have reduced flow when opening both taps, either

1) the mains pipe into the house and indeed the cylinder is too small
2) the installation hasnt included the equalisation t and there is a pressure/flow difference between hot and cold.

hope that makes sense.

good luck
shaun