Shower pump problem

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Hi all.
I've got a problem with a shower that is powered by a salamander ct50 pump. A bar mixer valve that we'd used for years stopped working properly and gave one temperature regardless of where the temp was set to.

I bought a new mixer, a one with an overhead rainfall spray, I fitted it and it didn't work very well. The shower kept stopping and starting when on the ordinary showerhead but worked continuously when the rainfall thing was used. Stopping the shower and leaving it a short while resulted in it not starting again. It did occasionally start on the rainfall setting though. Putting it on full cold got it going then you could set the temp you wanted. Leaving it a long time though and it didn't work in any position unless I climbed into the loft and bled the pipes.

The pump sits on a shelf just above the hot water cylinder in a cupboard on the first floor. The outgoing pipes in 22mm go from the pump go up into the loft along the loft floor for about a metre and then reduce to 15mm to drop down into the bathroom to the shower. The short 15mm pipes in the loft have air bleeds on each one at the highest point. The cold water tank in the loft is raised up off the floor about 5inches and the cold shower supply is taken off this.
In the cupboard the hot take off from the top of the cylinder is a 22m pipe that is soldered into an immersion heater blanking plug and this pipe goes into the cylinder I think about 5 inches or so. So hot water comes out then drops down the side of the cylinder through an anti gravity loop about 10inches before going up to the pump. I'll take some picture tomorrow if they will help.

This new valve is thermostatic, I don't think the previous bar valve was but I can't be certain. The only problem I ever had with the last valve was the pump would very occasionally switch on and then off fairly rapidly.

I'm guessing air is a problem or maybe a lack of pressure when the valve is set to it's central marked temperature of 38 degrees c. That's why putting it on full cold will sometimes get it working whereas with part hot and cold there isn't enough pressure on either switch to kick it into life.

My setup is similar to the diagram apart from my pump is just above the cylinder, my hot water take off the cylinder is out of the top and I don't have the non return valve fitted.

Any suggestions most welcome, thanks.
 
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Are you certain you bled all the air out. It sounds like an air lock, sometimes the only way to be sure is connect a mains hose and gently reverse pressure it until you stop hearing the bubbles coming out the expansion tank.
 
I've bled them a few times and always till jets of water come out of the bleed nipples. I'd have thought though that once the shower was working that any air would be pushed out through the shower head and I wouldn't have to bleed it again.

My previous valve didn't need any bleeding which was just as well as there was originally no bleed points. I added them last week after having this problem After any disconnection with the old valve I just operated the shower on full cold then full hot untill any air stopped coming out and that was it till next time.
 
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With the pump turned off what kind of flow through the shower do you get? May be too high a resistance to activate the pump.

Also If there are problems with the NRV's or they aren't installed then air may also be entering the pipework as the shower pipes are emptying when the shower's turned off, does the shower drip for a little when it's shut down?
 
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The rainfall overhead thing drips for a while after switching it off. The flow is close to non existent when the pump isn't running.
It didn't work again this morning so I bled the pipes in the loft and a very small amount of air came out. The shower still wouldn't operate so I opened the nipples again with the shower switched on and left them running water out for about 30 seconds. The pump then kicked in and it worked. 10 minutes later and again it didn't work but putting it on full cold got it going again.
 
I am not any kind of expert in shower pumps but if your drawing is correct then you have a single ended pump, I think you need a double ended pump for shower valves, the single ended is designed for electric showers not mixer valve showers.

SHOWER PUMPS EXPLAINED CONTINUOUS RATING All Salamander pumps are continuously rated. A pump that is continuously rated, can effectively run for as long as the user chooses, without the need for the pump to shut down, to allow the pump to cool. With a large family in a household this is particularly important, many competitor pumps are not continuously rated, and will automatically shut off for 20 to 45 minutes to allow the pump to cool. TWIN ENDED These pumps pump both hot and cold water supplies with one end for hot water and the other for cold. Each end then goes on to supply the outlet, which is most commonly a shower valve. SINGLE ENDED These pumps operate with a single impeller to pump either cold, hot or blended water. Typically, single ended pumps can be used to supply electric showers, taps, combination boilers, unvented cylinders or washing machines, but all of which must be supplied via a header tank to the pump. WARRANTIES The CT Xtra and CT Bathroom ranges come with a 2 year warranty which can be extended to 3 years if the pump is registered by phone immediately after installation. The CT Force range comes with a 5 year warranty
 
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Putting the shower onto fully cold opens the thermo valve up to its max increasing the flow through the shower and ergo the pump, allowing the flow switches to activate ..... pump kicks in.
You need a min of 2l/Min through the shower to activate the pump.

The air getting into the pipework can be from several different areas.
F feeding back through the shower at the time when it's being turned off I.e. when you're turning the shower off but just before the valve shuts fully & the pump deactivates, creating a slight draw.
There's a slight weep somewhere allowing the pipework to drain back to the cylinder
Aanother hot outlet that's drawing on the cylinder that's then pulling on the shower pipework.

NRV's are important where pumps are concerned, either as part of the shower or independently fitted to stop backflow.
 
I am not any kind of expert in shower pumps but if your drawing is correct then you have a single ended pump, I think you need a double ended pump for shower valves, the single ended is designed for electric showers not mixer valve showers.

SHOWER PUMPS EXPLAINED CONTINUOUS RATING All Salamander pumps are continuously rated. A pump that is continuously rated, can effectively run for as long as the user chooses, without the need for the pump to shut down, to allow the pump to cool. With a large family in a household this is particularly important, many competitor pumps are not continuously rated, and will automatically shut off for 20 to 45 minutes to allow the pump to cool. TWIN ENDED These pumps pump both hot and cold water supplies with one end for hot water and the other for cold. Each end then goes on to supply the outlet, which is most commonly a shower valve. SINGLE ENDED These pumps operate with a single impeller to pump either cold, hot or blended water. Typically, single ended pumps can be used to supply electric showers, taps, combination boilers, unvented cylinders or washing machines, but all of which must be supplied via a header tank to the pump. WARRANTIES The CT Xtra and CT Bathroom ranges come with a 2 year warranty which can be extended to 3 years if the pump is registered by phone immediately after installation. The CT Force range comes with a 5 year warranty
Doh. I posted the wrong image I didn't notice that diagram had a single end pump. I've removed it now.
 
Putting the shower onto fully cold opens the thermo valve up to its max increasing the flow through the shower and ergo the pump, allowing the flow switches to activate ..... pump kicks in.
You need a min of 2l/Min through the shower to activate the pump.

The air getting into the pipework can be from several different areas.
F feeding back through the shower at the time when it's being turned off I.e. when you're turning the shower off but just before the valve shuts fully & the pump deactivates, creating a slight draw.
There's a slight weep somewhere allowing the pipework to drain back to the cylinder
Aanother hot outlet that's drawing on the cylinder that's then pulling on the shower pipework.

NRV's are important where pumps are concerned, either as part of the shower or independently fitted to stop backflow.
I'll fit a nrv and see what that does. I think my problem is flow rather than air because the amount I get out is tiny, just a hiss then water. The bleed nipples are on 6" long vertical pipes so the air isnt in the main pipework. Keeping the bleed nipples open got it all flowing and activaved the pump.
Can you tell me what the anti gravity loop does? I can't see what it does to be fair.
 
The gravity loop is there when a pump is installed above the hot water cylinder, it's there to stop bubbles from the cylinder getting into the pump impeller.

You may find the gravity flow is reduced now with your new shower - narrower waterways and the thermo cartridge to get through, especially if your old one wasn't a thermo type. Basically there isn't enough flow to activate the pump now, measure how much water you get from the shower over a min, when on normal temp. Min 2L/Min.
 
I checked to see how much water came through the shower without the pump running.
I disconnected the shower hose from the bottom of the valve, set the temp to the middle and switched it on. Nothing came out at all. Back into the loft opened the bleeders the cold quickly flowed out the nipple but the hot took about 5 seconds before anything came out. Back in the bathroom turned the shower on and it filled a 1 litre jug in 14 seconds. So I've got plenty of flow but getting it started is a problem
 
After doing the flow test I reconnected the shower hose and tried the shower. With the temperature in the centre I switched it on and the pump operated fine. I moved the flow control (which isn't a separate valve but on the left hand end of the bar) to the rainfall setting and it stopped working. Moving the temp control to full cold the rainfall worked, I could then move it to the middle temperature and it kept going.

There wasn't time for any air to build up so why would it stop when I moved to the rainfall position? The rainfall outlet is higher up than the normal shower head but other than that it makes no sense.

I'm starting to think the bar mixer is faulty and I might be better off just buying a cheap non thermostatic valve and using that instead. Either that or keep climbing into the loft every time somebody wants to use the shower. It'll be good for my fitness I suppose.

Some pictures of the pump, it's connections and the loft pipework. Are there any glaring errors? The grey plastic pipe out of the water tank goes directly to the pump below. It then comes back to the loft along the floor and reduces to 15mm. Before going down to the shower. The other grey pipe in the loft is from the hot side of the pump and does the same thing, reducing, etc.
IMG_20181227_194331.jpg IMG_20181227_194318.jpg .IMG_20181227_194053.jpg IMG_20181227_194038.jpg
 
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I disconnected the shower hose from the bottom of the valve
Is that how you start/run the shower usually? A true test would do it at the height that the shower is normally is at with the shower head on, that gives you an accurate representation of L/Min in normal use

Your hot water supply is the problem here, the thermo valve when opened starts with mostly hot to first and then starts to add cold as the hot supply heats up until up to temp. If there isn't enough flow at that point, from the shower head, then it won't start the pump.

The only thing that's changed here is the shower itself, so that's where your problem lies. If you had a bar mixer before chances are it was a thermo too but we'll never know. No or faulty NRV's can allow the pump to drain back to the cylinder when another hot outlet is opened but they can restrict the flow a little too as @steve32 mentions, removing them may allow the flow to increase enough but could also exacerbate the air issue in the hot supply, which is what you are suffering from.

If you can try this test too. Turn off the power to the pump, turn on the shower, turn the pump back on, does it run and keep running?
 

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