Insufficient Hot Water Supply to Power Shower

[pearlscafe]

I've just fitted a Mira Vigour Thermostatic power shower but there doesn't appear to be enough hot water being supplied to the unit.

The instructions state "Avoid routing the high level hot feed pipe upward to the same level as the cold tank e.g. into loft space, as air locks may result."

The HW supply from the cylinder is routed into the loft space but under the storage cistern. The pipe is clear but hot water only trickles through.

Would fitting an S Flange help this situation or am I just going to have to reroute the hot supply, which will involve major surgery.

Incidentally, the route of the pipework from the hot water cylinder is unusual in that the supply pipe t's off from the vertical pipe about 3 inches from the top of the tank. The pipe then rises vertically approx 6 inches before the elbow to the vent pipe. Could this affect the insuffient supply to the shower. The shower supply t's off from the main supply pipe not from the vent pipe.

 

[seco services]

has it always been a problem ?
or has it been working ?

sounds like you haven't bled the hot supply fully.
nothing wrong in having the hot supply in the loft under the cws.

remove the filter and let the hot run for a few mins to clear all the air.

 

[pearlscafe]

thanks.

I fitted it yeasterday so it hasn't worked yet.

I have a full bore isolation valve in loft above shower and have tried disconnecting it to check water is getting through but just a trickle even after some time. Have run water back through the pipe so I know it's not blocked.

Will try your suggestion and be a bit more patient.

 

[pearlscafe]

OK, tried that but it hasn't worked.

Removed filters and let the HW run through for several minutes but flow remains significantly less than CW.

Shower runs perfectly on cold setting and when temp increased works ok to a point then the pump starts to struggle and the supply peters off.

I did try reducing the CW supply to the shower to about the same as the HW incase the shower was struggling to cope with unequal pressure but this just had the same effect as above albeit as soon as the unit is switched on.

Have just been informed that a new boiler and HW cylinder were fitted a couple of years ago and HW pressure not been good since.

I'm wondering therefore whether the unusual pipe layout from the cylinder has something to do with this?

Also not sure why pump struggles after initially letting some hot water through. Could this be it's sucking air through? If so would an S flange help this?

 

[seco services]

Removed filters and let the HW run through for several minutes but flow remains significantly less than CW.

then it needs sucking through or blowing through

Have just been informed that a new boiler and HW cylinder were fitted a couple of years ago and HW pressure not been good since.

the pressure from the taps is down to the height of the cws above the taps.
as the cws feeds the cylinder
but has nothing todo with the shower as it has its own pump.
providing the pipework is below the cws and not airlocked the pump does the rest.

I'm wondering therefore whether the unusual pipe layout from the cylinder has something to do with this?

no as i have fitted/worked on many that are fitted this way.

Also not sure why pump struggles after initially letting some hot water through. Could this be it's sucking air through? If so would an S flange help this?

it has air in the pipework but an s flange will make no difference once the pipework is free of air.

so you say you have let it run and its still poor flow, that tells me the airlocks not moving.
as said force it through or suck it through.