Negative flow shower pump

[leeffrost]

HI

Im installing a new bathroom and I need a little advice on negative flow pumps.

I want to:

• Instal a negative flow pump in my upstairs tank cupboard (cold water header tank is a smilar height to the shower head)

• Only pump the hot water and leave the cold from the mains, its a decent pressure and its going to a thermostatic shower valve panel thingi

My plumber has said I should install a large cold water tank in the loft and install new piping direct to the bathroom and pump both the hot and the cold with a dual positive flow pump.

Im not keen on this as it seems a little old fashioned and a lot of hassel.

All advice gratefully received.

Thanks LEE

 

[Elkato531]

Sounds like your plumber knows what he's talking about. Mixer showers need balanced pressures and, if pumped, a large enough cold water store to ensure that the pump doesn't run dry.

 

[leeffrost]

HI

I've been thinking about this and really just need to know the best cause of action.

The options I have are

1) Put a large cold water tank (114 litres) in the loft and run a positive head twin impella pump for both hot and cold water to the bathroom.

2) Pump the hot water with a single negative pump and use water at mains pressure.

3) Install a unvented cylinder, but im not sure about the costs and its all a bit confusing as I read something that said these dont work with showers.

Id rip it all out and put a combi in it I hadn't replaced the boiler about 18 months ago.

Thanks again for all your posts and help

LEE

 

[picasso]

first choice would be the unvented cylinder if your mains pressure and flow are good enough (and budget) second would be replace the tank in loft but I doubt 114 litres would be enough stored water, 225 (50 gallon) would be the minimum I would use with a shower pump, you will have problems if you use a single pump and mains pressure, not a good idea for several reasons.