Shower Pump Quandry

[rdo1104]

Good Morning

My system is gravity fed and everything is in the loft (headers, cylinder etc.) I have just had a new 22mm feed fed to my new bath, a 22mm feed fed towards my first shower which reduces to 15mm prior to a salamander 1.5 bar pump, the 15mm pipes are then split to feed a second salamander 1.5 bar pump for shower 2.

Since having an upgrade to 22mm towards the showers the pressure flow in shower 1 is worse than before and temperature fluctuates which has never happened before. (Problem 1)

Problem 2 is that due to the tap in the new bathroom being a 15mm inlet fed ceramic disc type (not sure what I'm on about here but am quoting information from another source) this needs to be pressure fed.

So to summarise, what is the best approach if I started from scratch to feed 2 showers (negative head) and increase the pressure to the bath. It is not an option to change the tap at present so need to conside what pump options I have and if I need a Surrey Flange or similar fitting.

I know this is a long topic but hopefully we can break it down into stages. This is seriously beginning to damage my health

Thanks in advance - Rhys

 

[Gunslinger]

i'm having trouble visualising your layout here.... where you say

22mm feed fed towards my first shower which reduces to 15mm prior to a salamander 1.5 bar pump, the 15mm pipes are then split to feed a second salamander 1.5 bar pump for shower 2.

it alsmost sounds like you have 2 pumps connected one after the other ! ... what i think your getting at, is the 22mm T's off into 2 15mm feeds, one to pump/shower 1 and the second to pump/shower 2 ... is this right ?

you also dont say if these pumps are single ended, or twins, or what model they are ... although you did say negative head

need a little more clear description before i can get my head around it ... if you have a sketch of the layout or pics that would be good.

As a general rule i would try to get the pumps on to the circuit early, and have them 'push' the water around the bathroom, rather than late in the circuit where they have to draw (suck) on a restrictive supply.

 

[rdo1104]

Gunslinger - to continue (I will try and get a layout or pics on if the following does not help).

Both pumps are twin impeller 15mm fed salamander 1.5 bar shower pumps for negative head.

There is a 22mm hot feed from the cylinder which reduces to 15mm before pump 1 and is teed off to pump 2. The 15mm feeds then go to each pump. There are gate valves before the pumps.

Exactly the same principle for the cold feed which is also 22mm and then splits to 2 x 15mm feeds - one to each pump. I have added a diagram which will hopefully give you more idea.
Thanks
Rhys

Untitled

• rdo1104
• 30 Apr 2008
• 1

Untitled

• rdo1104
• 30 Apr 2008
• 1

 

[gas4you]

Firstly I'm no shower expert, I mainly work with gas.

To me, looking at you diagrams, the fundamental problem is that both shower pumps are being fed from the same hot and cold feed.

If I had installed these I would have had seperate independant cold feeds from the cold tank and seperate hot feeds, via essex flanges from the HW cylinder.

But then as said, I'm only a gas engineer

 

[Gunslinger]

.....the fundamental problem is that both shower pumps are being fed from the same hot and cold feed.

Bingo !

If I had installed these I would have had seperate indepent cold feeds from the cold tank and seperate hot feeds, via essex flanges from the HW cylinder.

But then as said, I'm only a gas engineer

That is one way to do it.


I have a basic question here, and i am assuming there is a reason for what you have done, so excuse the question if it seems dumb (but i cant "see" your room layout or restrictions)... but, why 2 pumps ?

The reason i ask is, because as pointed out, trying to run 2 pumps off one feed can cause all sorts of problems relating to supply starvation, you have to take into consideration the T's , bends, pipe lengths etc etc when trying this sort of setup.

It would seem more efficient and productive, and probably more effective if you were to do something like this.....

Tank (22mm) -- Pump (22mm) -- split to 2x15mm -- feed 1 to each shower

That example would obviously need the same setup for the other pump, so you would have a hot and cold 22mm, and then 2 hot and 2 cold 15mm feeds to the showers.



Hope this makes sense

 

[rdo1104]

Gunslinger

New to all this and not sure if I have managed to get my last reply through to you as it states that can only directly e mail my 'friends'

Can you help/
Ta
Rhys

 

[rdo1104]

Gunslinger

Further to last post, until i understand how to use this blessed technology I think that I need to get a new pump (maybe 3 bar) to feed the 2 showers. So effectively I would site the new pump as close to the outlets fo the hot and cold as possible then continue as far as possible in 22mm before splitting into 2 runs of 15mm - one to each shower.

Do you recommend the addition of a suitable flange? Once we get to the bottom of this, would you mind helping me with problem 2 which is the hot supply to the bath?

Yours in debt
Rhys

 

[Gunslinger]

ok, lets see if we can split this down a little bit, into the basics ...

Requirements
1. pump hot and cold to 2 showers
2. pump hot and cold to bath
3. operate in a negative head scenario.


Some basic guidelines (i wont say rules, as i am not an expert)
1. twin pumps are ok for showers where hot and cold will be drawn together, but unlikely seperate.
2. single ended pumps are better for pumping each supply (hot and cold) independently, usually from 2 separate storage tanks, but not necessarily
3. pumps are generally located nearer to the supply they are drawing from rather than closer to the outlets
4. bath cold supply is normally supplied from the cold mains, due to the volume of water involved.
5. hot stored and cold mains require check valves to prevent syphoning
6. hot stored and cold stored only require check valves to prevent back flow and unstable temps at the mixer
7. pump wiring should be done by a competent electrician if your are at all not sure, get someone to do it for you, better that than electrocute yourself trying to save a few pounds, because i guarantee you that your funeral costs will greatly outweigh what you might save on getting the wiring done correctly by someone !


Now, if you are seriously considering replacing those two pumps, then you could do a lot worse than to look to salamander, as they have excellent pre and post sales tech support and help, or if you prefer they will do the whole job for you i believe, or put you in touch with a recommended fitter.


Now, from what you have explained, here is what i would consider doing, bear in mind this is purely my opinion, and others may have better ideas, or step in to correct me if i get something wrong.


1. Ensure i have a a 22mm hot feed form the storage tank, connected in the manner the pump manufacturer recommends
2. Ensure i have a separate 22mm feed from the cold storage tank
3. Route a 22mm Cold mains feed to the bath cold supply, remembering about the check valve, or if you have separate hot and cold taps on the bath, no need for the check valves
4. either, and this is where some of us will disagree,

a. buy 2 new single ended pumps, of sufficient flow and pressure rates to do the job,
or
b. use the 2 pumps you have, one to feed the cold and one of rthe hot (i will explain how to connect them shortly)

5. feed 22mm pipes from the pumps to the showers, T'ing off into 15mm if that is what is required by the showers, if not then T the 22mm into 2 x 22mm feeds for the showers, feed the hot for the bath tap from the shower above the bath (i am assuming one shower is above the bath here) as you are unlikely to be running the bath tap and that shower at the same time


Now, how to use twin ended pumps as singles .... this is not exactly a recommended thing, some will frown upon it, some will say it is fine, it will certainly work in your case to ensure the setup works, before you go and buy more pumps.

Because a twin ended pump will always run both ends together, having one flowing water and one not can cause problems for the pump in relation to workload mis-balance, some pumps require a bypass or balancing link to be used if the pump is likely to be feeding hot (or cold) on its own, such as if separate taps are used.

now, what you can do is take your 22mm feed pipe, and split it into 2 (22mm) and then feed those 2 into the same pump, one at each end, then do the same on the otherside, joining the 2 outputs back into one, thus making it run as a single ended pump. BUT be aware of flow and pressure buildups, if you flow into a T piece from each end, then out in the middle, you may encounter problems by flowing the water against itself, look for fitting thats will give you the best flow pattern for what you require.

Do this for both pumps and you will effectively be using your twin ended pumps as 2 separate single ended ones..... now, if if works ok, you can then replace those pumps with proper single ended units, and this will be much tidier, and more efficient than bridging the 2 ends of the twin ended pump, and may actually result in better flow rates as well.


have a read through this, as there is some very useful information in it

http://www.salamanderpumps.co.uk/Download/instructions.pdf

 

[Gunslinger]

Forgot to say, yes the private messaging system only works if you add me to your friends list first, so go to my profile and select "add friend" and i should get a message about that and can then add you too, and then we can send messages through pm, but, while your knocking about ideas, it is sometimes best to do this in the main forum, so others can add their experience or knowledge to the thread