Converting Positive Head Pump to Negative

[It's me]

I plan to fit a shower pump as we have low water pressure. The flow is about 0.5 litres a minute through the shower head, so is unlikely to be enough to start a positive head pump.

I have read in another thread on here that you can buy add ons for pos.head shower pumps to be able to convert them to neg. head. However, they gave no actual details. Can anyone advise me on this, please? Positive head pumps are so much cheaper than negative head pumps that I would be interested in learning more.

Thank you.

James

 

[muggles]

Salamander made a conversion kit for the CT FORCE range of pumps but have discontinued it. It was about £130. Personally not a fan of Salamander anyway, Stuart Turner are much better. Not aware of any others that could be converted.

 

[ETAF]

I plan to fit a shower pump as we have low water pressure.

how big is your hot water tank, when i looked into this, my water tank was nothing like big enough for a pump , need to be about 225L 50 gallons - mine was a lot less than that 115L as its a combined cold & hot tank in a loft of a bungalow.

Just thought i would mention it, just in case

 

[Johntheo5]

I plan to fit a shower pump as we have low water pressure. The flow is about 0.5 litres a minute through the shower head, so is unlikely to be enough to start a positive head pump.

I have read in another thread on here that you can buy add ons for pos.head shower pumps to be able to convert them to neg. head. However, they gave no actual details. Can anyone advise me on this, please? Positive head pumps are so much cheaper than negative head pumps that I would be interested in learning more.

Thank you.

James

Not the perfect solution but you could probably wire in a "manual" start button to bypass (and in parallel with) the flow switche(s) until the pump starts, you could probably get a mechanical (or digital) type timer switch that stays on for say 30 secs to allow time to get the shower flow established, start button then deenergises and the flow switches will then continue to keep the pump running and then stop it once showering completed.

 

[It's me]

Salamander made a conversion kit for the CT FORCE range of pumps but have discontinued it. It was about £130. Personally not a fan of Salamander anyway, Stuart Turner are much better. Not aware of any others that could be converted.

That is a shame. Thank you.

how big is your hot water tank, when i looked into this, my water tank was nothing like big enough for a pump , need to be about 225L 50 gallons - mine was a lot less than that 115L as its a combined cold & hot tank in a loft of a bungalow.

Just thought i would mention it, just in case

It is a little small. It coped with the old power shower, supplying three consecutive showers. However, it is in need of replacement and I plan to fit a larger tank.

Not the perfect solution but you could probably wire in a "manual" start button to bypass (and in parallel with) the flow switche(s) until the pump starts, you could probably get a mechanical (or digital) type timer switch that stays on for say 30 secs to allow time to get the shower flow established, start button then deenergises and the flow switches will then continue to keep the pump running and then stop it once showering completed.

This is the sort of thing that I envisaged, but I can just imagine my wife's response to the idea. I suspect that I shall just have to bite the bullet and buy a new negative head pump.

James.

 

[Madrab]

There were 2 types, one that was a little pump that would provide just enough pressure to activate the flow switch(es). The other was just a remote power switch.

With most pumps, you can just wire in a manual power switch to turn the pump on. Most pumps prime themselves (spin up) when the power is turned on, so have a manual FCU powering the shower. Turning on the shower then turning the pump's power on is usually enough to kick start it, once it starts flowing it will keep running, then turning off the shower should shut the pump down as usual. You could probably also use a pull cord switch.

Not sure if that's the same as what @Johntheo5 suggested.

 

[It's me]

There were 2 types, one that was a little pump that would provide just enough pressure to activate the flow switch(es). The other was just a remote power switch.

With most pumps, you can just wire in a manual power switch to turn the pump on. Most pumps prime themselves (spin up) when the power is turned on, so have a manual FCU powering the shower. Turning on the shower then turning the pump's power on is usually enough to kick start it, once it starts flowing it will keep running, then turning off the shower should shut the pump down as usual. You could probably also use a pull cord switch.

Not sure if that's the same as what @Johntheo5 suggested.

Thank you for the explanation and for the suggestion. On balance, I shall be done with it and buy a new negative head pump. I had an informative call with Salamander and it seems that the CT80bu will be a good solution, especially with the restricted space that I have.

James.

 

[Johntheo5]

I see thats a regenerative type pump which Salmander themselves say are noisier than the centrifugal type but are more tolerant of any entrained air, you might enquire about the noise aspect.

 

[It's me]

I see thats a regenerative type pump which Salmander themselves say are noisier than the centrifugal type but are more tolerant of any entrained air, you might enquire about the noise aspect.

That is a good point and Salamander did mention that the CT Force 30 is quieter, but that it is also larger. The space on the airing cupboard floor is very limited and I am not sure yet whether the quieter one will fit. I shall need to do some careful measuring.