Shower pump plumbing conundrum...

[Mattox]

Evening all. Just signed up to the site for some assistance as I'm a rank amateur (with a reasonable amount of DIY sense I think) who is about to embark on a project to refit my bathroom.

I'm having to do much more than I envisaged at first as I've been told I need to rip out pretty much all of the existing pipework as it is the original, galvanised steel, imperial pipes that have no place in a fresh installation in 2019 apparently ..

So the multi tool will be coming out and its all going. I'm going to replace with both copper and speed fit pipe work. All appliances are moving to different positions so there's a lot to do.

My main conundrum at the moment is to do with the pipework for the shower pump that I want to fit. My setup is as follows:

Vented gravity fed system
Cold tank in loft
Hot cylinder downstairs
New shower in bathroom upstairs
Previously only had a bath

What I'd like to do is have the pump under the bath in the bathroom (head end where there's room under the slope of the bath). I want to do this so that the noise of the pump won't be heard in the living room (where the airing cupboard is).

I'm told I need to have an anti gravity loop (250mm drop) straight out of the Surrey flange. Is this right? Am I then OK to go straight up through the floor boards to the bathroom (bath directly above hot water cylinder) and in to the pump? Does the hot feed from the Surrey flange to the pump need to also pick up the vent? I don't think so but have seen that mentioned somewhere by someone whose pump has stopped working.

My flow of both hot and cold is reasonably good I think. Will I be ok to install a twin impeller, 1.5 to 1.8 bar pump in this location (below cold tank but above hot cylinder)?? Will be so many other issues as I progress with the project. But this is the one currently troubling me.

Any help gratefully received, thanks in advance...

 

[ericmark]

I did my mothers shower, it was not originally my job, but bathroom fitters ran off in middle of the job. The problem with a power shower is it can't be connected to mains as it could suck dirt into the system if the water fails. And second is you must ensure even if the water supply fails any immersion heater will still be in water.

Pipe dimension matters, a 22 mm pipe from top of cylinder would clearly allow the pump to draw air rather than empty the cistern, but flow rates and length of pipe run will also affect what happens, I am sure there is a formula, but I simply tested, turned off the water, and immersion heater then run the shower until it stopped and checked the cistern was still full.

Then after all that work, dad had a new combi boiler and the power shower had to be removed. With a heater tank in the loft likely you don't need the pump, however heater tank for dad was just above the cistern, so not enough head. Having to take the cold water from the heater tank resulted in an extra cold pipe feed.

 

[Mattox]

Hi there. I have already pre installed a separate feed for the new pump from the cold tank in the loft and it will also have its own hot fed via the Surrey flange from downstairs. The cold feed is 22mm speed fit tank connector (fitted to the bottom of the tank), 22mm pipe down in to bathroom and will then be reduced to 15mm before the pump (most are 15mm connections I think?)

Salamander have told me there shouldn't be any more than 4m of pipe from the pump to the shower head which is all the more reason to place it upstairs if possible

 

[foxhole]

Tank must be large enough to supply pump with pipe work a low as possible from tank or you risk it emptying the tank and sucking in air .