Plumbing for power shower

[emlrdag]

Hi,

Just found this fantastic site, so here goes for my second question.

I am installing a Mira Extreme power shower (the type where the pump is integral to the shower unit). I had intended to re-use the old pipework for a gravity fed mixer shower where the cold water is fed from the tank in the loft, and the hot feed comes from a spur from the top of tank, up into the loftspace, across for 2-3 metres and and then down into the shower cubicle.

Then I read the installation manual and it states then this installation is incorrect and will not work as airlocks can form in the top-fed hot water pipe, which sounds reasonable. The manual states that the hot warer feed should run down from the tank, along the floor and up to the unit.

This is difficult for me to acheive, so instead I re-used the hot feed for the sink which was running along at floor level, and then took the hot feed for the re-positioned sink from the (un-used) bidet.

Now I am thinking I did the wrong thing, and would have been better off using the top fed pipe and taking the risk of airlocks (which could have been cured with a Surrey flange)

I am about to tile this shower cubilce, so need to make any changes quite quickly.

Does anyone have any views - is re-using the hot feed for the sink a bad thing and if so why?

Thanks

 

[kymer]

Hi,

I've just been re-doing our bathroom and have asked about a million similar questions of the patient fellas at my local plumbers' merchants. It annoys me that the manufacturers rarely explain *why* you shouldn't install their products in certain ways so you can make up your own mind!!

Anyway - here's what I think I know:

- Running the shower off the old hot feed to the sink shouldn't be a problem save for the possibility of: (a) getting air bubbles in the feed, which you can fix by installing a Surrey/Essex flange as you've said; (b) assuming the feed is a common one for all the hot water in the house, you may get a reduction in the flow to your shower should someone turn on a hot tap.

- Running off the pipework in the loft would probably work fine too provided that you installed the Surrey flange (which has the added benefit of effectively giving the shower a dedicated hot feed), put an "anti gravity loop" in the supply (which basically means bending the pipe downwards by a foot or so after it leaves the flange before sending it up into the loft again), popping an air vent on the top corner of the pipework in the loft so you can bleed those airlocks off, should they occur, and insulating the whole run in the loft.

On balance, given that you've already done the work, I'd probably leave the setup as you have it!