Borderline negative head shower / RSP 75 pump-is this fix OK

[seco services]

yes as they are both from the same cws.

the flow to the bath is ok but that is well below the cws.
your showerhead isn't, and you need 1 l/min per side to kick that pump in.
so the higher you raise your showerhead the less l/min your going to get.

so you need the max flow your gonna get the least restriction the better.
you'll be amazed what a restricted iso valve can do.
you may be ok, but its alot easyer that moving a tank.
so check one of them then go from there.

 

[Norton750]

Understood and I will check them out.

So in conclusion, if they are unrestricted and the problem does seem to be solely related to the resistance of the NRV's alone, do you forsee any problems if I leave them out?

 

[seco services]

not really if its all functioning ok.

 

[Norton750]

Thansk for the advice and I'll update once I've checked the gate vales.

 

[seco services]

 

[Richard C]

Just to add a little to Seco’s gate valve comment; you should always use full bore valves throughought the pumped system, the bore on cheap gate valves is very restricted & even the decent ones are not full bore, & will restrict flow to prevent you getting that all important 1 litre/min to kick the pump in. The only ones that are really full bore as far as I know are gas compliant lever valves but fitting them may or may not help in your case. You say the pipe work from tanks to pump is 22mm but what size have you used from pump to mixer valves?

Removing filters may help but you are effectively removing safeguards which could ultimately do more harm than good & with no check valves, in addition to the overrun you’re currently experiencing, you may start to get ghost pump starts if the system starts to loose pressure after a period of use. You are way below Salamander’s recommended head on the shower head but, remember, it’s not just the distance to the shower head that’s important, if you have up & over pipe work to the mixer, it will have exactly the same effect. I fear you’ve probably bought the wrong pump & raising the cws tank may be the only permanent solution.

 

[Norton750]

Thanks Richard,

I have left the filters in - I've only taken the NRV's out. The pipework from pump to valve is also in 22 right upto the two inlets in the valve and it is not up and over pipework - it runs straight from the two pump outlets to the valve which is a distance of @ 3 feet.

It's been 4 days now since removing the NRV's from the valve and I've not experienced any problems - the pump is always kicking in on all outlets and the overrun is half a second at most - no ghost operation of the pump either todate.

I've re-read the Salamander paperwork and on their diagrams they are only showing the need for a single NRV to be positioned on the hotside of the outlet pipe from the pump on an up and over pipework instalation. On a set up similar to mine - pump and HW Cylinder fed from the same CWS and non up and over feed from the pump to the outlet - there is no mention of a NRV being required.

I will speak to Salamander tomorrow but am assuming that this means that NRV's is this installation are not required and that I will OK by leaving the set up as it is.

Will update once I've spoken to them