Shower pump problem?

Question

I've installed a varispeed shower pump inthe airing cupboard below the hot tank. I've run the cold from the storage tank in 22mm pipe, the hot from the hot tank in 22mm also. When I open the shower mixer the pump comes on but I only get hot water, then the thermostatic valve closes to regulate the temp, and I get nothing. I've run the discharges in 15mm.

The hot flow energises the flow switch on the hot side, but does it also need a flow on the cold site to energise the cold side switch? Are the hot and cold pumps separate within the casing? I think the problem is that I've run the cold supply from the storage tank in the attic, down to the airing cupboard, but then back up to the attic again to tie-in to the old shower pipe to the bathroom, effectively reducing the head. Previously it was ok because the pipe came straight from the cold tank to the shower, travelling in the attic. Now I think I've reduced head by going back up to the attic to tie in to this line. Any ideas?

Answer 1

There will be an impeller on each end of the motor, so if the pump runs it will pump both hot and cold supplies. There must be something else restricting the cold from flowing?! Have you piped to the valve correctly? Is there a valve on the cold that you haven't opened? Have you assembled and set the valve correctly? The head will be the same, as you haven't altered the heights, so that will have no effect.

What shower valve have you fitted?

Answer 2

Hi,
The idea of fitting a pump, is to power the water to your shower mixer rather than depend on gravity feed; the pipe work configuration sounds OK, head of water would not be a problem and the pump will draw water from any storage you connect to; Unless you have a restriction in the line, a closed valve or internal blockage, the pump should deliver water to the shower. I think the problem is with the thermostatic shower mixer, it is possible something's wrong with the thermostat within the mixer. One way to fined out if it is the mixer; Is to disconnect the hot & cold from the mixer and switch the pump on manually and see if it pumps water.
Be Safe, Skew. (plumbing for over 40 years )

Answer 3

Sounds if you have carried out installation correctly. Try turning thermostat on shower to hottest setting and turn on, does hot water come out, ok, now turn shower to coldest setting does cold water come out, can you hear pump running. Pumps do have flow switches on them and I have known them to stick, isolate supply disconnect top hose and you can see the needle valve wiggle it to check its not stuck, reassemble and try again. If still problems check the shower over most can be taken apart in situ.

Hope this helps

Plumber