Combi boiler & Mira Mixer Shower.

message from TOGGY on 13 May 2004

Have just installed a Combi boiler to replace our old hot water tank
and system. Our shower is fed from the cold tank (this is now the
only appliance supplied from the cold tank). On trying the shower
this evening it appears that due to the increase of hot water pressure
this has pushed back up into the cold tank causing it to overflow.

My question obviously pertains in how to remedy this. Is is possible
to fit a non return valve to the cold supply to the shower or would
supplying the shower direct from the mains cold remedy this, or again
would this require a non return valve.

Any help requiring this would be much appreciated

Cheers

tiggy

EricP replied to TOGGY on 13 May 2004

Simply connect the mains supply to the tank, up to the cold supply
from the tank and remove the tank. Mains pressure on H & C, no
problems.

BillV replied to EricP on 18 May 2004

That is the simplest solution.
When the shower was new there would have been varous flow restrictors in the
install kit to balance the flow for various setups e.g. mains cold in +
gravity hot, or combi hot + gravity cold.
No doubt these restrictors are long gone now though.
Maybe the shower is not even suitable for a combi at all..

BillV replied to BillV on 19 May 2004

Just happened to see a Mira 88EV on display today and it said "designed for
gravity fed only ... can be used on pump to 1.5bar max". So if its one like
that its no good for a use on a combi where you may be getting 3-4 bar
pressure.

Archived message: Combi boiler & Mira Mixer Shower. (UK D-I-Y Home Repairs)