Shower Pump Question.

[jonohanson]

First of all I would like to say Hi as I am new here, and secondly I have a question about a shower pump.

I am looking at getting this pump http://www.screwfix.com/prods/46231...-5bar?cm_re=SEARCHPROMO-_-SHOWER PUMP-_-46231

My question is that in the installation instructions it says your cold water storage tank has to be a minimum of 1.2m above the head of your hot water cylinder. Would this be ok with my set-up as my cold water tank is directly(30cm) above my hot water cylinder, I cant think of a reason it would need to be that much higher.

The pump will be used to feed a shower with cold from the cold water tank and hot from the cylinder, the reason I want to user a pump is that I will be installing a thermostatic shower and i'm guessing the pressure on the hot will not be there.

One thing to mention is that it will be replacing an electric shower so there is a mains coldwater feed in the bathroom(i'm pretty sure its mains and not from the tank) already would I be able to utilise this and have a single pump?

Any suggestions advice welcome.

Thanks in advance, Jon

 

[ChrisR]

No don't use mains cold.

The risk with the low cistern is sucking air down the vent pipe. The feed to the bottom of the CW cylinder is probably 22mm, it's much better 28mm.
Bigger pumps cause more problems. You would have to use a "lange" such as a Warix, Surrey or preferably Essex, to help.
Still a risk though.

 

[seco services]

it states 1.2m min as you need a min of 2 litres/m natural flow or it won't activate the flow switch and will never cut the pump in when shower turned on.
as for useing mains cold you will have to fit a prv to equal the pressure to the hot.

 

[jonohanson]

Thanks for the quick replies with regards to my cw tank being straight above the cylinder is there anyway I could use a pump with it gaining enough natural flow to initiate the pump??

Regards

 

[seco services]

you need a negative head pump not a positive head pump like the salamander esp cpv pumps

 

[jonohanson]

it states 1.2m min as you need a min of 2 litres/m natural flow or it won't activate the flow switch and will never cut the pump in when shower turned on.
as for useing mains cold you will have to fit a prv to equal the pressure to the hot.

So if I attach this PRV(http://www.screwfix.com/prods/63442/Plumbing/Radiator-Valves/Comap-PRV-With-Gauge-15mm-x-22mm) to the mains reduce it to the same pressure as the hot then have the reduced cold and hot going to the pump would this work??

Thanks

 

[seco services]

it easyer and better to run a cold feed from the cws than using mains with a prv.

 

[Breesey]

So if I attach this PRV(http://www.screwfix.com/prods/63442/Plumbing/Radiator-Valves/Comap-PRV-With-Gauge-15mm-x-22mm) to the mains reduce it to the same pressure as the hot then have the reduced cold and hot going to the pump would this work??

Thanks

If you reduce the mains px down to match the hot you could be back at the same problem of taking cold from the cws ie not enough flow to trigger the pump flow switch

 

[jonohanson]

Thanks for all your replys, I think I will give it ago. Worse case scenario the pump does not kick in and I have to move the CWS to the loft to create enough flow.