Advise please on shower mixer

[Deleted member 93861]

Hi Last year I replaced a Thermostatic bar shower mixer valve in a rented property and all seemed ok ,but recently the owner said it wasn't working properly .When you turn on the valve nothing happens but if you turn on the bath tap briefly, it works fine ., they also made it work by twisting temperature valve which was not in the default position & seems to be their go to method ,but it didn't work when I tried it.The shower is fed by a pump and feeds another shower on-suite which has no problems, but the pump does not come on if the bath is used. On inspection the filters were clear and when installed again it worked as it should, but the next day people had used and it was not working properly again .Could it be the original installer did not put non return valves on the feeds
Thanks for any advise

 

[Dkdc71]

Recheck the pipework runs if you can sounds like when the bath is turned on with the shower valve the fluctuation is activating the float switch in the pump ,should be independent supplies but if it was retrofitted it might have always been wrong from day one hope that helps Tom

 

[Best]

What head of water (cold tank) is on the shower head?
Are the pipe runs done up and over?
Is the pump positive or negative head?
Did you also check the filters that are inside the pump inlets (or some have inlet washer filters) ?
Also are the float switches clean and freely moving?

 

[Deleted member 93861]

Recheck the pipework runs if you can sounds like when the bath is turned on with the shower valve the fluctuation is activating the float switch in the pump ,should be independent supplies but if it was retrofitted it might have always been wrong from day one hope that helps Tom

Thanks, I think your right about that -I'll check it tomorrow cheers

 

[Deleted member 93861]

What head of water (cold tank) is on the shower head?
Are the pipe runs done up and over?
Is the pump positive or negative head?
Did you also check the filters that are inside the pump inlets (or some have inlet washer filters) ?
Also are the float switches clean and freely moving?

Thanks I'll check it tomorrow

 

[Deleted member 93861]

What head of water (cold tank) is on the shower head?
Are the pipe runs done up and over?
Is the pump positive or negative head?
Did you also check the filters that are inside the pump inlets (or some have inlet washer filters) ?
Also are the float switches clean and freely moving?

Ok sorry for delay
so its positive head system
Cold gravity fed 2.5 metres from bottom of tank to hot tank
pipe runs underfloor same level
Pump filters had very little limescale but mesh was clear
looks like all other taps on this floor are on same pump
as to the float switches, I didn't take them out incase it broke -looked clear -
Salamander pump Right RSP 75
static head Max 10 metres
Max liquid temp 65c
Duty Lpm 2.15 bar max 2.2bar
2010 installed

flanged on top tank

Just before I turned on the electric to pump I run the shower and it worked although weak -but went back to delayed action with power on and requiring tap or other shower to work again

 

[Best]

It should work with that pipework, but the head of water for shower is actually the distance from the base of cold tank to the shower head (outlet).
Nice diagrams!

 

[Old Account]

I like the filling loop

 

[64degrees]

Cold feed is activating the pump, not enough head from hot supply, needs a negative head pump

 

[Deleted member 93861]

Cold feed is activating the pump, not enough head from hot supply, needs a negative head pump

Thanks any ideas where to get one ?

It should work with that pipework, but the head of water for shower is actually the distance from the base of cold tank to the shower head (outlet).
Nice diagrams!

Ah right, dohhh
cheers

 

[Best]

Negative head pumps can be quite expensive. I prefer the Stuart and Turner pumps - Monsoon range.
Screwfix sell them.

 

[Deleted member 93861]

Negative head pumps can be quite expensive. I prefer the Stuart and Turner pumps - Monsoon range.
Screwfix sell them.

Is this the answer or a complete pump?

 

[Best]

View attachment 33915 Is this the answer or a complete pump?

No, if you had to replace your existing pump you would need a twin pump similar looking to what you have at present. You can get them in negative head which have a small expansion vessel on them. I actually think your pump should work as the head of water to both cold and hot is what starts your existing. If you have a shower handset attached to a shower hose (not fixed) and lower the handset every time you want the shower pump to start, you might find it works.
Otherwise a negative head pump is the answer and will always start as there is a pressure charge in the outlet pipes with it.
The Monsoon negative head is about £400 for 2 bar and just under £500 for 3bar from Screwfix but it is superb. I would go 3bar.
It is on internet for as little as circa £430 if you look

 

[Deleted member 93861]

No, if you had to replace your existing pump you would need a twin pump similar looking to what you have at present. You can get them in negative head which have a small expansion vessel on them. I actually think your pump should work as the head of water to both cold and hot is what starts your existing. If you have a shower handset attached to a shower hose (not fixed) and lower the handset every time you want the shower pump to start, you might find it works.
Otherwise a negative head pump is the answer and will always start as there is a pressure charge in the outlet pipes with it.
The Monsoon negative head is about £400 for 2 bar and just under £500 for 3bar from Screwfix but it is superb. I would go 3bar.
It is on internet for as little as circa £430 if you look

Thanks will talk to owner when back from holiday
cheers

 

[ShaunCorbs]

also wheres your s flange?

 

[64degrees]

Spot on as usual Corbs, could end up with an expensive burnt out pump if the hot feed isn’t piped correctly from the cylinder. Get your G3 and go with an unvented, admittedly it’s more money upfront, but the customer will be happy, and you won’t get called back

 

[Deleted member 93861]

also wheres your s flange?

Looks like its been T'd off on top of tank -first image

 

[ShaunCorbs]

Looks like its been T'd off on top of tank -first image

Yes that's wrong it needs the correct kit

 

[SalamanderPumps]

If you need any assistance our technical team are here to help! Give us a call on 0191 516 2002. Thanks

 

[Deleted member 93861]

also wheres your s flange?

I'll check it tomorrow to make sure I thought that looked odd
cheers

 

[Deleted member 93861]

If you need any assistance our technical team are here to help! Give us a call on 0191 516 2002. Thanks

Good to know cheers

 

[Deleted member 93861]

Hi as to the flange I checked it today it's t'd off on top of the hot water tank ,I know it should have its own dedicated flange but this is not my work- I've just been ask to sort the shower out .Owner's back soon see if she go's for new pump or just leave the shower head low that's working stop gap (thanks Best )
cheers

 

[Welder]

The teeing off is not really a prob. The point of a flange is to reduce air ingress and having it teed as is minimises air hugely. What IS wrong however is no dedicated CW feed from the tank.

Gate valves often calcify and cause reduced flow (especially on the hot) so my own first port of call would be replace those with full bore lever and to test flow rates before replacing the pump wholesale. I would also check the showers filters at the time of the valve changes to try to maximise flow as is.

IIRC those pumps had a negative head kit avail AND could be rebuilt but I'd want to know Why? first.

 

[Best]

Agree with above ^^ - make sure all filters clean and valves full flowing before you make a decision.
Some pumps will not start on hot until cold is first selected due to filters partially blocked on hot supply.