1.5 Bar shower pump, does this seem ok?

[shorn]

I have a Mixer tap on the bath which has connected shower. The pressure is not great. It is fed with a 22mm supply direct from cold storage tank, and 22mm feed from hot water cylinder (in the adjacent bedroom) I was thinking of locating a 1.5bar small shower pump, under the bath. This could then feed the supply to the mixer tap, and because the cold is a direct supply and the hot is tee'd off, the pump would not then be feeding the sink/toilet, merely just the bath mixer.

Does this sound OK?

 

[shorn]

I forgot to add...

The pipe work to the bath mixer is all 22mm pipe, yet the pump has 15mm connections, is it ok to reduce down to 15mm where it entered pump and then go from 15-22mm once it exits (and back to the mixer)?

Thanks!

 

[shorn]

Any ideas?

 

[Richard C]

Fitting a shower pump under the bath is never a good idea & not really a DIY option with the regulations governing electrical installations in bathrooms. Conventional shower pumps are designed to push water not pull it & all pump manufacturers recommend the pump be installed as close to the HW cylinder as possible with a maximum run from cylinder to pump of around 5m in 22mm pipe & 2m in 15mm pipe. You must also have an air free how water supply via a proprietary flange on the HW cylinder, using a conventional take of will cause air locks, cavitation & early pump failure. Pumps should always have a dedicated supply, fitting one into a common HW feed line as you describe will play havoc with the flow switch every time you turn on one of the other taps in the system & you cannot fit a one way check valve between the HW cylinder & the pump.

There are many archive threads on the forum regarding do’s & don’ts of fitting shower pumps, including a couple where they’ve been fitted under the bath as you propose & then the OP has been unable to get it to work properly. You need to do some more research of your own but by all means come back with specific questions as & when you need.

 

[Axel]

What he means is that you are supposed to drill a big hole in the side of your cylinder and rip the floors up to run new pipework, to keep the pump manufacturers happy and honour their warranty.

I do come across many pumps under baths and cannot comment on how this affects their lifespan in practice. I wouldn't create a new installation like this but have replaced faulty pumps under baths with new ones in the same location. Always I upgrade the electrical safety.

I am amazed at how many I come across that have the power lead for the pump connected to a non IP rated junction box that just dangles on the floor under the bath and has no RCD connected anywhere along the circuit. Whatever you do, it is vital to have the electrical supply safely installed, which means that if the pump lead won't reach outside of the bathroom, it must be joined to a longer lead via an IP68 rated junction box. The connection to a switched / fused spur must be outside of the bathroom, and this must have an RCD built in. You can buy these for less than £20. This is in addition to any RCD device in the main consumer unit.

Some may choose to ignore advice regarding a dedicated hot water connection to the cylinder and the pump may indeed not last as long. But often they are only used for a few minutes a day, and a replacement pump is only £100, so there is an argument that if doing it properly is a major upheaval and expense, some may wish to forego the pump warranty.

 

[Richard C]

What he means is that you are supposed to drill a big hole in the side of your cylinder and rip the floors up to run new pipework, to keep the pump manufacturers happy and honour their warranty.

A side fit Essex flange is always best & for obvious reasons is the preffered method by practically all the pump manufacturers but a Surrey or Warix flange will do; this can usually be fitted as a direct replacement to the top of the tank.

Some may choose to ignore advice regarding a dedicated hot water connection to the cylinder and the pump may indeed not last as long. But often they are only used for a few minutes a day, and a replacement pump is only £100, so there is an argument that if doing it properly is a major upheaval and expense, some may wish to forego the pump warranty.

Many do & with a dedicated feed it can work adequatly; but without a dedicated feed & with the pump fitted down stream of other taps/take offs, your very likely to get problems with the flow switches either not triggering at all or, under certain circumstances, hunting as the pump continually switches itself on & off. Biggest problem is the detrimental affect the length of the pump supply pipes (from the tanks) will have on pump performance until it gets to the point where there is little point in having the pump at all; depends on many factors including the static system head, the size/route of the feed pipe work & how far away the pump is from the storage tank.

All in all, it’s a cheap, nasty & naff way to install a shower pump that is likely to give hit & miss performance.

 

[shorn]

The reason I asked was that the bath mixer is on the end of a run, and by installing it there, the pump would literally just be supplying the bath mixer, albeit from a feed that tee'd off before that point for the basin. The cold is a dedicated feed so I just wanted to check with regards to the hot.
Electricity is fine as it would be connected in an adjacent room.

So when

I'm guessing it would be possible to fit a Surrey flange in the cylinder then take a hot feed up into the loft and go back down direct to the bathroom. Provided I can get the pipes down in the cavity!

 

[Richard C]

The reason I asked was that the bath mixer is on the end of a run, and by installing it there, the pump would literally just be supplying the bath mixer, albeit from a feed that tee'd off before that point for the basin. The cold is a dedicated feed so I just wanted to check with regards to the hot.

You didn’t read my post thoroughly or take into account what I’ve already said! Apart from that, you need to be aware of varying mains cold water supply pressure which will throw your shower mixer into hissy fits!

I'm guessing it would be possible to fit a Surrey flange in the cylinder then take a hot feed up into the loft and go back down direct to the bathroom.

A flange is good & going up & over is not a problem if it’s done correctly; but, in your case, it could complicate & compromise things even further.

Provided I can get the pipes down in the cavity!

Running pipes (or anything) within an external cavity wall is not only a really stupid idea, it is against Building Regulations. If your serious about wanting to make a success of your already compromised shower pump installation, I will do all I can to help but you need to do some more research, think sensibly & stop with the head in the sand suggestions; or you can just tell me to bu gger off & follow the advice of others.