Shower/pump problems.

[GARYF123]

Hi, hope someone can advise!
Just fitted a MX Neptune thermostatic bar shower in an en-suite. Flow pretty poor but so was previous valve. Gravity fed system with dedicated cold from cws in loft to valve in 22mm reducing to 15 near valve. Hot from cylinder in 22mm then down to 15mm near valve but shared with rest of hot services. Base of cws (50 gall) is only approx' 800mm above shower head. Today i fitted a Salamander CT50 twin pump. It is at base of cylinder. The hot is fed from a Essex flange in 22mm to pump then out to valve in a mixture of 15/22mm. The cold is virtually all 22mm. Bends have been formed where possible to eliminate elbows. The problem is when the valve is set to cold, the pump starts then pulses unless i lower the handset down to floor then its ok. If i set it to full hot, it runs fine. If i set it to the standard 38 degree setting, the pump fires on and off with the flow rising and falling! I removed the valve and tried both hot and cold separately and pressure seemed fine with flow easily hitting opposite wall. Checked the inlet filters and they seem fine. Could the valve need regulating or does anybody have any ideas?

Many thanks in advance,

Gary.

 

[picasso]

you need two litres a minute to trigger the flow switches, sounds like you dont have this, you might have to fit a negative head pump .

 

[seco services]

as above.
but does the pipework go up and over the loft space to shower from pump ?

 

[GARYF123]

Hi,
Thanks for replies. The pipework goes from the pump (sat on same base as cylinder), vertical for approx' 150mm, horizontally approx' 150mm then down to floor level and approx' 4m to valve. As i stated earlier, the pump is activated when on full cold or full hot. When set to 38 degrees, it pulses on & off.

Gary.

 

[GARYF123]

Just another thought! The hot feed is fine and is run mainly in 15mm and gets its supply from cws via cylinder. The cold is run in 22mm and comes directly from cws, yet the hot fires the pump but the cold is struggling to fire it! Am i missing something?!!

Gary.

 

[seco services]

personally i would run the cold in 15mm same as hot.

 

[GARYF123]

What would that do? Would it not restrict cold flow even more?

Gary.

 

[seco services]

check the nrv's in the shower are working fully or remove them try.

 

[GARYF123]

Do not think this shower has NRV'S. If it has, cannot see how to get to them.
Would raising the cws by approx' 500mm give enough natural flow to trigger flow switches?

Gary.

 

[dumbrill]

Do not think this shower has NRV'S. If it has, cannot see how to get to them.
Would raising the cws by approx' 500mm give enough natural flow to trigger flow switches?

Gary.

Is the cold feed taken directly from the cold water tank and separately to the cold feed to the hot water tank. None of the pipework to the tank and pump should be shared.

 

[GARYF123]

Hi Dumbdrill,

Yes, the cold food comes from the 50 gallon CWS in 22mm into the pump (reduced to 15mm) then out of the pump in 15mm and increased to 22mm straight to shower valve. It is reduced down to 15mm again to enter valve. All 90 degree bends have been formed where possible rather than using elbows.

Gary.

 

[picasso]

The nrv,s are where the shower nuts connect to the wall threads , take the shower off and turn it so you can see where the water goes into the shower and you will see the nrv,s, getting them out is something else.