Low pressure at shower

[scottpetrie]

Hi
My shower has really low pressure, especially the hot. Its a gravity fed system and a thermostatic shower, fairly new. The pipes feeding the shower come from the loft. Cold comes from the tank, along and down the wall. The hot comes from the hot water cylinder, up into the loft, along and down the wall to the shower. Im in a bungalow so theres not much height between shower and loft tank anyway. I will be fitting a pump at some point, but just wondering why the hot in particular is so low. If I turn the shower fully cold, the pressure is higher, but if I turn it to fully hot, it barely trickles out. Any suggestions? Could it be the fitting coming out the top of hot water cylinder is partially clogged up? The rest of the hot water in the house is fine, its just the shower. I wonder if its because the hot pipe goes up through the loft?

 

[CBW]

All copper? What size piping? If the top of the cylinder was clogged up, I’d be expecting poor pressure at every outlet.

 

[echoes]

If the hot goes 'up and over' via the loft, it's asking for an air lock - which would result in a trickle.

 

[scottpetrie]

Yeh copper, 22mm. Its been that way as long as I know off. Its my grandads old house and his old shower was similarly poor. Was just wondering if there were maybe any valves or something in the airing cupboard that could maybe be not fully open.

 

[CBW]

if there were maybe any valves or something in the airing cupboard that could maybe be not fully open.

There could be,but it would have to be for shower only. As suggested, could be an airlock.

 

[scottpetrie]

Yeh could be. How could I cure it?

 

[echoes]

Is there any air vent at the highest point of the hot shower pipe (where it passes through the loft)?

 

[scottpetrie]

Not been up in a while, but not that I can remember

 

[CBW]

It’s not the easiest to do if not done before.

 

[scottpetrie]

Im not sure it is an airlock as its not quite trickling, or spluttering or nothing, its just really low pressure compared to the rest of the hot water in the house

 

[Harry Bloomfield]

It's the difference in pressure, between your hot and cold supplies. Your cold is at mains pressure, your hot has very little head of water to give it pressure - that combined possibly with tap/mixer intended for hot supplied by a combi boiler at mains pressure. An electric pump in the hot supply will make a dramatic difference.

 

[echoes]

OP says cold to shower is direct from CW cistern. (Not mains)

 

[scottpetrie]

Yeh its not mains cold

 

[echoes]

Air locks in low pressure pipework can cause a trickle rather than a splutter when the trickle is not enough to shift the air 'bubble'.
Once the air starts moving through the pipe and arrives at the outlet, then the spluttering happens.
The trick is to get the water moving through the pipe at a speed sufficient to shift the air (in either direction) so it either vents or is pushed through the tap (or shower).
Sadly, hot water from a cylinder often has air bubbles in it. Usually these are vented up and away from the pipes feeding the outlets but will be caught by any 'inverted U' shaped pipework (like you seem to have), especially if the velocity of the water is slow.

 

[scottpetrie]

I know I will have to fit a pump, just thought there may be something I could do at the water cylinder end to maybe help. Plus, not sure where the pump would go. Probably in the airing cupboard, but just means pipes would be coming down from the loft to go back up again