Shower Pump Question

2 Dec 2010
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United Kingdom
Hi, ive recently started work on my bathroom to incorporate a thermostatic shower mixer as previously had an electric shower fed from mains.

I live in a flat but have a loft space above us which I have moved the cold water storage cistern into, this supplies the feed for the hot water storage cylinder only and all cold water is off the main. The hot water distribution pipes run under a screeded floor to feed the bathroom and kitchen which presumably tee off underneath.

My goal is to instal a monsoon S2.0 bar single pump to the hot water so that the new shower mixer will receive boosted hot and mains cold, therefore more balanced.

My problem is that the only space i have to locate the pump is under the bath which leaves me a little confused about how to supply the pump from the cylinder. I realise that the cylinder will need a flange installed but im not sure which one?

I wanted to boost the hot immediately as it entered the bathroom (therefore boosting the basin as well as the shower mixer) but how do i go about this without interferring with the feed to the kitchen? I know the easiest solution is to site the pump next to the cylinder and boost all hot water throughout the flat but there simply isnt any room unless it is above the cylinder, can this be done?

Any help will be much appreciated, cheers.
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Yes you can fit the pump above the HW cylinder or even in the loft but you need to install an anti-gravity loop on the supply from the cylinder, maintain a minimum of 600mm from the base of the CW tank & the pump & 100mm to the shower head or you will need a negative head pump; you may still need one if you can’t meet the minimum 0.6 litre/min flow rate necessary to trigger the pump flow switch. You must also ensure a minimum of 200mm from the surface of the cold water to the highest point on up & over pump loops or they will air lock; vents are usually necessary on these. A side fitting Essex flange is the preferred option by practically all pump manufacturers. You don’t say what size HW cylinder you have but it must have sufficient capacity as must the CWS tank in order to replenish it. You also need to consider that the CWS tank refilling will probably reduce mains pressure available to the shower causing system imbalance; might be difficult but your usually better off with a shower having both hot & cold water boost (from the CWS tank not from the mains). You cannot avoid boosting the kitchen HW if it’s on a common supply with the bathroom; pumped showers usually have dedicated, separate supplies to avoid this. This might be useful;
thanks Richard thats very helpful however what i really need is a solution to siting the pump under the bath without having to alter any pipework under floor.
Any suggestions?
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Can you not tee into the bath supply where it exits the floor? I assumed that's what you were doing with the CW mains! The only other way of achieving it is to run a separate, dedicated supply from a new HW cylinder flange to the pump & on to the shower head. But the pump can only deliver what the gravity section of feed pipe work will allow; the further away from the HW cylinder you position the pump, the lower the performance until you reach a point where there is little point in having the pump at all.

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