Mixer shower

[jasond77]

Hi All, excellent site!

I am after a liitle advice

I am soon to fit a mixer shower but there is currently no piping for it.

I am comfortable with fitting the pipes but my cousin (who I am fitting it for) just wants to run the pipe from the hot and cold feed to the bath, so how will the shower perform with no 'fall'? I suspect the pressure will be non existent, but will the shower be 'useable'?

Or will I def need to add a pump?

If so I am presming I should fit the pump under the bath, as the pipes are currently at the other end to where he wants the shower, so I will have a run of hot and cold along the length of the bath

 

[TicklyT]

Much depends on the characteristics of the hot and cold supplies. If both are gravity fed, and the mixer is designed for higher pressures, you are on a loser before you start.

For a gravity system, it is the height difference between the cold storage tank and the shower head that determines both the hot and cold water the pressure. The route of the pipework to the outlet is immaterial unless taken to extremes.

Using a low pressure mixer on a gravity system can deliver an adequate shower with very low water pressure without using a pump.

There is no need for a pump on higher pressure systems, such as a combi boilers or unvented cylinders. Their use on such systems is not approved anyway.

If you are installing a pump on a traditional gravity system there is more to it than just fitting it under the bath. You should consider modifying the hot cylinder outlet, whether the cold feed to the cylinder is adequate for the increased flow rate, and 'design out' any possibility of any trapped air in the system reaching the pump. Then there is the matter of supplying the electrical feed to the appropriate standard.

 

[Richard C]

As TiclyT for the explanation about static head & how that will affect shower performance but most tanks are placed on timber bearer just above the ceiling joists so the head will only be around 300mm, 600mm at most & it’s likely to be woefully inadequate & if your cousin has bought a high pressure mixer, you wont even get a dribble out of it.

If so I am presming I should fit the pump under the bath, as the pipes are currently at the other end to where he wants the shower, so I will have a run of hot and cold along the length of the bath

Assuming it's a gravity system, successfully installing a shower pump isn’t rocket science but it’s a bit more involved than just shoving a pump under the bath which is not the place to fit it anyway. It may work for a while but will struggle to give decent performance & will seriously shorten the pump life without an anti-aeration flange on the cylinder & you will almost certainly invalidate the manufacturer’s warranty. The pump should ideally be sited at the base of the HW storage cylinder with independent H & C water feeds from the storage tanks but within a maximum distance of around 5m using 22mm pipe work & just 2m in 15mm.