Shower pumps?

[dobbslc]

I'm looking at buying a second hand shower pump for temporarily supplying a shower but can't remember the difference between positive / negative pumps. The one I have in my existing house is a Salamander unit that has a cold and hot feed from tanks in loft & airing cupboard respectively.
Does that make it a positive feed? Thanks

 

[8ob]

Its to do with the switching, if the water storage tanks are lower than the appliance you will need a negative head pump. Positive head pumps only need a flow switch, negative head pumps have pressure switches that sense a drop in pressure. I have a pair of the negative head pumps feeding the whole house, they can fill a bath in about 20 seconds and will remove skin off you in the shower

Bob

 

[Kayos]

Most are positive head, negative are a lot more money

I have a Stuart Turner one I removed from a house when fitting a combi if you are interested?

 

[dobbslc]

Thanks.
I'm looking at a bunch of pumps on eBay and one is a Stuart Turner negative pump.

 

[dobbslc]

I have a pair of the negative head pumps feeding the whole house, they can fill a bath in about 20 seconds and will remove skin off you in the shower

That's what I want!

 

[Kayos]

The speed they work at doesn't matter if it's positive or negative, you will need the hot and cold water storage capacity to fill the bath as well

 

[8ob]

I have a pair of the negative head pumps feeding the whole house, they can fill a bath in about 20 seconds and will remove skin off you in the shower

That's what I want!

You wont regret it, any guests that stay over comment on the shower

If you do go down this route there are a few things to consider, water storage is one as @Kayos points out, our plumber fitted two 50 gallon storage tanks twinned together. You cant have any dripping taps because after two drips the pumps fire up to top up pressure which will drive you nuts in the night, our plumber fitted all taps with ceramic discs which solved that problem. Pumps need to be accessible and fitted with isolation valves and a spare pump kept to one side or at the very least a bypass valve arrangement fitted.

I keep a spare at all times, this one lasted about five years and then started blowing capacitors. Its probably salvageable but just for for a quick fix I swapped in the spare which gives me a chance to send it off for repair.

Bob

 

[dobbslc]

Good info!
I've already got a Twin outlet salamander pump for the shower that's pretty good.
Mine does to old on off on cycle if the shower hasn't been used for ages as I think it leaks a bit and the pressure drops, I was thinking of all sorts of potential problems until I just turned on the shower for few seconds!

 

[winchman]

I have a twin Stuart Turner one in the garage thats spare, well my mate asked me to Ebay it about two years ago!

 

[Kent]

No point pumping unless you have the tank size

 

[Pete.]

Its to do with the switching, if the water storage tanks are lower than the appliance you will need a negative head pump. Positive head pumps only need a flow switch, negative head pumps have pressure switches that sense a drop in pressure. I have a pair of the negative head pumps feeding the whole house, they can fill a bath in about 20 seconds and will remove skin off you in the shower

Bob

I'm sensing a small exaggeration there - unless your bath tap has a 2" outlet

 

[123hotchef]

he has a tin bath