Which size of salamander shower pump do i need

[jb1468]

Have done a little reading around choosing the right pump for my mira thermostatic mixer shower. I am happy with a salamander but unsure what size I should go for. Showering performance is very important to me and my partner so i don't want to get this wrong. I have a plumber coming tomorrow so please advise before then would be great.

Choice is between the RSP 50 (1.5bar) and RSP 75 (2.0 bar). I hope to fit on the floor by the hot tank which is at same level as bathroom up through to the loft and across and down into concealed pipework for mixer shower. There is about 3 metres between hot tank and shower (straight line of course). cold tank is in the loft.

I am used to the performance from a decent power shower and would like as close if not the same performance.

I measured my current flow rates - please be kind - I have little idea how to do this correctly (hoping I got it right). At the moment when I measure my flow from the shower head (mixing cold and hot) I get about 3L per minute. From the shower water outlet (don't know the proper language to describe - where water comes out when I unscrew the shower hose of) I get 6.5 L per min and cold on its own - 4.5 lpm - hot on its own 5.5 lpm.

Lastly I see the smaller pump uses 15mm connectors and the larger 22mm. Do I need to be using 15mm piping with the smaller and 22 with the larger or what are my options to maximise performance or does it matter. Some of my 15mm pipework is concealed behind the false wall for the shower. Even if someone suggests I use 22 mm for either or both pumps would I loose much performance by converting to 15mm just before I get to the concealed 15mm. don't fancy ripping a wall down to change all to 22mm.

So given all that to get a performance similar to what I'm used to (power shower) is the 1.5 bar enough?. Thanks ever so much for anyone who can help put me straight and at ease with choosing a way forward.

 

[jb1468]

any thoughts anyone? ta

 

[kevplumb]

if you want more water use the RSP 75

 

[qaz]

I am in a similar position, except my hot tank and pump are on the floor below the shower with the cold tank above the shower. I wondered how you got on with the 15mm pipework in the wall. Did you get plenty of pressure? I can't work out whether 22mm or 15mm makes much difference if you are only running the one shower off a 1.5 Bar pump. I'm getting the Grundfos Nile STR-1.5C Twin 1.5 bar pump.

 

[jb1468]

I am in a similar position, except my hot tank and pump are on the floor below the shower with the cold tank above the shower. I wondered how you got on with the 15mm pipework in the wall. Did you get plenty of pressure? I can't work out whether 22mm or 15mm makes much difference if you are only running the one shower off a 1.5 Bar pump. I'm getting the Grundfos Nile STR-1.5C Twin 1.5 bar pump.

I did get the larger pump (2.0bar), however in hindsight I'm sure I didnt need it. The power is unbelievable and I restrict it through the shower controls. I did install 22 mm where I could easily reach but connected it to 15 mm already there........as i said I was worrying about nothing. The pressure is fantastic and I.m sure this is due to the pump and the combination of 15/22 mm has little to do with it.

So if you are running one shower the pipework I feel makes no difference. I hope your choice of pump is as good. I dont know it. The only thing I would say is the noise is more than I expected and from feedback the salamander were suppose to be quiet. If you have opportunity to soundproof a little I would take it

Good luck

 

[qaz]

Thanks for the reply. That's good. Now I'm wondering whether to use plastic or copper pipe. I'm not capable of soldering anything so I think plastic with short copper runs at each end is probably the same as far as water flow/restriction is concerned - there will be four right angle turns between pump and shower head over a distance of about six mtrs and the joins between copper and plastic. I think if plastic is fitted properly and secured at regular intervals it is probably just as reliable as copper. Thoughts anyone?

 

[persiamomolti]

A couple of things to remember: some pump manfactrers advise to upgrade 22mm feed to cylinder to 28mm.
The cold supply from header tank in loft must be connected on the opposite side to where your cold fill/ballcock is to prevent a `vortex` being formed between cold in/cold out.
Your hot supply to your pump must be fed correctly from your cylinder using an approved method ie, surrey/essex/warix/york flange. These are either fitted at top of cylinder or from side.
Don`t allow plumber to simply `tee` off pipe coming out of top of cylinder otherwise you will have the problem of air being drawn into pump and uneven temp and spluttering at the shower head.
Finally, I would suggest using 22mm pipe definitely for your supplies into shower pump then 22mm up into loft then reduce to 15mm.
I use copper where it is on show because plastic looks bulky and ugly, it also sags when temp is very hot but it`s up to you really.
Don`t forget to get gate valves fitted x 4 on all legs in/out of pump to isolate easily for servicing or if you need a repair carrying out.
Non return valve also required on hot pipe out of pump and lag all pipes in loft.

 

[Richard C]

I would never use anything other than soldered copper. 22mm is important on the delivery side of the pump but the length of runs after it will affect delivery rate & pressure if you drop down to 15mm; personally I always run in 22mm right up to the mixer valve. Only use full flow isolation valves (gas lever type) in the pump lines; most gate valves will restrict the flow. Be carefull with up & over loops; regardless of where you sight the pump, if the loops are closer than 600mm to the bottom of the CWS tank you may be in a negative head situation; many have initially bought the wrong pump! You will also need air vents at the top of the loops or they will fill with air & airlock the pump.

Read the pump manufacturers installation guide & stick to it (they are mostly the same though) & have a look at specific archive posts on shower pump problems; the biggest cause of system problems is poor pump sighting & incorrect installation.

 

[bathstyle]

I am in a similar position, except my hot tank and pump are on the floor below the shower with the cold tank above the shower. I wondered how you got on with the 15mm pipework in the wall. Did you get plenty of pressure? I can't work out whether 22mm or 15mm makes much difference if you are only running the one shower off a 1.5 Bar pump. I'm getting the Grundfos Nile STR-1.5C Twin 1.5 bar pump.

More info needed!

- Length of run between pump and shower valve
- Height of Cold storage Cistern in loft area
- Height between shower head and bottom of Cold cistern
- Route to Shower valve
- Type of shower valve (minimum operating pressure)

It sounds like in your situation it has to be 2 bar with 22mm pump connections, your Cylinder is in the floor below your Bathroom??

 

[Lower]

I have a RSP50 feeding a rain type shower head but with the changeover valve to also supply a normal type shower head. Pump is at the base of the hot water tank fed from the tank in 22mm with 15mm then feeding the shower mixer.

The RSP50 supplies good flow to the rain type head and works very well. But the pressure from the normal type shower head is not dissimilar from the pressure we had from our old mains pressure electric shower.

Perfectly adequate for us and we're happy with pump. But if you're looking for more 'power shower' type pressure then i'd say you need the RSP75.,

 

[qaz]

More info needed!

- Length of run between pump and shower valve
- Height of Cold storage Cistern in loft area
- Height between shower head and bottom of Cold cistern
- Route to Shower valve
- Type of shower valve (minimum operating pressure)

run - 4.5 mtrs
cistern - 6 mtrs above hot tank
head-cold cistern - 1 mtr
route - pump on grnd flr, up to next flr, 4.5 mtrs with 4 elbows.
type - Aqualisa classic aquavalve

I've bought 15mm copper and the Grundfos Nile 1.5 Bar. I think this will be fine for pressure as it is only pumping to the one shower head. I was more worried about mixing 15mm and 22mm pipework. I thought there might be imbalances of pressure that might cause problems. The trickest bit will probably be connecting the 15mm to the 22mm flexible pushfit outlets from the pump. I think I might need to use 15mm to 22mm and a short piece of 22mm copper as I don't see any flexible 15mm to 22mm connecting hoses in B&Q.

 

[bathstyle]

You need a 22mm pump or at the very least 22mm pipe up to the Pump. I would've specified a 22mm 2 bar pump in this instance with the run changed to 15mm 1m before the valve.

In fact I would've scrapped the idea of a pump and a seperate shower valve and fitted a digital shower, installation cost are greatly reduced, no need to run pipework all the way downstairs for the pump and a guaranteed decent shower which will be in the region of 1.5 bar depending on manufacurer.

Also, as the pump for these showers is in the loft above the Bathroom, the whole house won't get disturbed when someone has a shower as it will with the siting of your pump next to HW Cylinder.

 

[qaz]

I have 22mm hot and cold supplies. I see 22mm recommendations all over the fora but, having looked closely at the pump and flexible connectors, the channels through which the water flows is only about 10mm. This is also the case with inserts for plastic pipe, which I am not using. This leads me to believe that 15mm pipe from the pump to the shower head is plenty. Just got to hook the pump up today.

 

[Richard C]

You’re conclusion is incorrect; local restrictions should be avoided, hence the recommendation for full flow valves & bends rather than elbows but they are not the same as reducing the whole pipe run down to 15mm! This causes additional resistance which will restrict flow, the longer the pipe run the greater the resistance & reduction in flow rate.

 

[qaz]

You’re conclusion is incorrect

I understand that 22mm would be preferable. But there isn't room for it unless I make detours, start hacking flooring about. So 15mm it is. I've managed it with only 3 right angles and a bit of pipe bending over the 4.5 metre run (<4 vertical) between pump and shower head. I have yet to put the shower cubical panels and doors on, after which I shall give the thing a proper test. But all looks well so far. Plenty of water at the head and no leaks. It would be interesting to do it all again with 22mm but...