Broadway water pump

Are we quite sure that the shower mixer tap is fully open?  If its not, the pump will keep turning off which will affect the temperature control.  If it is fully open then it suggests there is a problem with the mixer cartridge which is easy and cheap to change.  It's a good idea to have a spare cartridge in the van so even if that's not the fault, it won't be wasted.

The shower head cut off valve is a good idea but there still has to be an uninterrupted flow from the mixer tap which there doesn't appear to be in your case.  Removal of the mixer cartridge might reveal it needs descaling or maybe the shower head needs descaling?  Something is interrupting the flow.

inspiredron wrote:

Bilbobaggins wrote:This is what we use  between shower hose and head

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That is exactly the one that I have fitted successfully. In the shower you don't want full flow so, even if your cartridge is a bit scaled up it feels to me that you will need an accumulator. I tinted the control valve because my Shurflo had such high pressure that we were using all the hot tank before we'd got the temperature right.

Ron - we must beg to differ on this.  The mixer tap should be fully opened and then the temperature adjusted.  The benefit of the shower head cut off valve is that once the temperature has been adjusted, the flow can be stopped and started during the shower, without having to touch the mixer tap and therefore readjust the temperature, which you have a problem with.  

Restricted flow can be caused by scale, a faulty cartridge or a tap that is not fully open.  The effect will be uneven flow as the pump pulses on and off, which is not good for it.  An accumulator might help smooth the flow but IMO it's far better to deal with the cause than the effect.  Accumulators are normally only needed when the flow coming out of a pump is unduly jerky whilst it is running, which can afflict some diaphragm pumps but not in my experience the Shurflo.

inspiredron wrote:I fully agree with your first paragraph. As far as the rest is concerned I'd throw another point into the mix.
When I first installed my Shurflo I had a huge amount of pulsing, principally from the cold side and far less on the hot, presumably because the hot tank contents act to absorb the pulsing. The pulsing was accompanied by some water hammer.. I turned down the pressure switch of the Shurflo and that gave some improvement but did not eliminate the hammer. I then realised that the noise was being amplified by the swing wall of the bathroom acting as a sounding board. I removed the panel that gives access to the basin tap connections and slipped some foam pipe insulation over the hot and cold pipes. Not only did that stop the hammer by preventing the cold pipe from jumping as the tap was closed but it also almost eliminated all pulsing. The flow can now be controlled almost to a fine trickle and the Shurflo turns on and off periodically and with a fairly smooth flow.

Thanks Ron.  A difference is that we don't control the water flow to a fine trickle for a shower.  The shower is either fully on or fully off just as it is at home, so the pump is not stopping and starting as reported by the OP.  I don't know if this is what you mean by 'pulsing'. If it is, it shouldn't be happening on either the hot or cold, or for any intermediate mix position on the taps, if the tap is fully open.  When the tap is fully open, the flow rate should be the same whether the water is passing through the hot water tank or not.  If by 'pulsing' you mean the jerky water flow when the pump is running continuously, which is a feature of the diaphragm pump and can lead to a knocking sound from some of the pipes, then that is not the issue reported by the OP and it will have no effect on the shower's temperature.

inspiredron wrote:We seldom use the onboard shower but I'm fairly sure that we don't necessarily have it full on. The .win purpose of the head control valve is to avoid inadvertently altering the hot/cold mix when turning off to soap ourselves. No way is 10l enough to get temperature right and to leave it running for a full shower. 🥺🥺

As I think I have said before, we didn't notice any difference with the shower's control when we swapped the Whale for the Shurflo.  We turn the mixer setting to hot and fully open the tap.  If the shower gets too hot, we turn the mixer setting away from hot towards cold until the temperature is right with the tap fully open.  Like you we stop the shower to lather down and restart to rinse.  When we do this, we fully shut and then fully open the tap taking care not to alter the mixer setting.  This works for us as it should do for the OP.

Paulmold wrote:All this about control valves when you get the same effect by using a trigger shower head.

Not sure I agree Paul.  A trigger shower head doesn't control the temperature.  That can only be done with the mixer setting.

delete double tap

Paulmold wrote:

Caraman wrote:

Paulmold wrote:All this about control valves when you get the same effect by using a trigger shower head.

Not sure I agree Paul.  A trigger shower head doesn't control the temperature.  That can only be done with the mixer setting.

I agree, but once you have adjusted the temp, then no need to turn control valve on and off,  just squeeze the trigger.
The control valves fitted between the mixer tap and shower is literally an on/off switch, temp still needs to be adjusted at the mixer tap.

Totally agree.  So the trigger valve (or shower head cut off valve) initially has to be open to allow the user to adjust the right proportion of hot and cold water using the mixer valve with the mixer tap fully open.  Once adjusted the user can use the trigger valve to stop and restart the shower with a reasonable chance that the temperature will not change.  It is replicating the on off function of the mixer tap which some find it difficult to use without altering the position of the mixer valve which will alter the temperature.

I am reminded of the shower I had in some digs a few years ago.  It didn't have a mixer valve.  All it had was a hot tap and a cold tap which each had a different pressure and flow rate.  It took so long to get the temperature right, there was no way I was going to turn both taps off so I could lather down and then turn them back on again for rinsing.  A shower head cut off valve would have made a huge difference.  Things aren't as bad as this with our motorhome showers as the hot and cold water pressures and flow rates are the same and the mixer valve adjusts them to achieve the right temperature.  A thermostatic mixer valve such as the ones we have on our showers at home would be better still were it not for their weight, bulk and cost.

Paulmold wrote:

rgermain wrote:I have fitted a shut off valve, only because if I accidently hit the mixer tap I don't get a cold shower and wet clothing
Otherwise as Caraman says.
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Richard

Again,  that can also be avoided by fitting the trigger shower head. Unless you press that trigger, water doesn't come out.

Out of interest, do you leave the mixer tap open when the shower is not in use i.e. rely solely on the trigger valve to stop any flow?