Water pump adjustable pressure?

metricspaces

Hmmm...I guess the relationship betwee
flow rate and pressure are not linear. So if sleeper12 dropped from a 3bar to a 2bar pump, his flow rate would not drop linearly. So my example is wrong? I don't know the equation to work it out correctly.

Sleeper12

metricspaces wrote:

So the pumps sold in UK (for way cheaper) are not the same spec as the ones sold in Ireland?

Modern Plant is the Irish agent for Stuart Turner. If you buy a Stuart Turner pump from the UK or Screwfix.ie then it hasn't gone through Modern Plant. If it doesn't go through them then they don't make any money on the pump. If Modern Plant don't make any money on the pump then they won't repair it under warranty. They only offer a warranty on pumps they sell. Buy a pump from the UK & you don't get the 5 years warranty. This is the case with any product from the UK with an Irish agent. Triton, Aqualisa, Salamander etc are a few more examples

metricspaces wrote:

If sleeper12 is getting 23 l/min with a 3bar, then if he stuck in a 2bar pump you'd expect roughly 15 l/min ? (3bar is 50% more pressure than 2 bar, 23 l/min is 50% more than 15 l/min).

Everything being equal. There can be many variations on setup. If one attic tank is higher than the other it will make a difference. Every elbow on the run slows it down.

When I tested mine I had the shower mixer valve halfway bet hit and cold to allow as much water through as possible. You can test it on cold only then hot only then both together. This might give you an indication that there's a problem with one pipe. Sometimes valves being fully open on the outside does not mean that they are fully open inside the valve. Sometimes you get faulty valves

There will be filters on the pump and on the hot & cold inlet on the shower itself. These need to be totally clean.

Sleeper12

metricspaces wrote:

Hmmm...I guess the relationship betwee flow rate and pressure are not linear. So if sleeper12 dropped from a 3bar to a 2bar pump, his flow rate would not drop linearly. So my example is wrong? I don't know the equation to work it out correctly.

If you have a half inch pipe & valve. The water pressure is let's say 2 bar. If you half close the valve you will reduce the flow rate but the pressure will still be 2 bar

K.Flyer

metricspaces wrote: »

I don't understand why previously you mentioned it was ok the I got almost 9 l/min with shower head off?

Because it was close to what the label said you should get.

Surely with the shower head off I should be expecting a lot more than the minimum output of the pump?
The pump is approximately three metres from the shower.

You will loose flow rates through pipes and shower valves, especially with fine strainers fitted.

The 3bar pump also says 9 l/min at 2.5bar. So I really don't understand why I should only be expecting 9 l/min on my 2bar pump.

So surely I should be expecting more than 9 l/min with shower head off?

As I said it comes down to resistance in pipework and valves.

Might be worth disconnecting one of the outlet pipes from the pump, preferably the cold one, and rate the water flow straight off the pump to see what the difference might be.
Also the feed hoses to the pump have strainers, I would double check them for any debris as well.

So the pumps sold in UK (for way cheaper) are not the same spec as the ones sold in Ireland?

Comparing the label on my pump to the info on the Stuart Turner website my pump looks identical.

I would agree that they are identical with the exception of the connection hoses, 3/4" and not 22mm.
They even say on their data sheet that the only difference is the hoses. So I imagine its market protection more than anything else.

metricspaces

Sleeper12 wrote: »

Modern Plant is the Irish agent for Stuart Turner. If you buy a Stuart Turner pump from the UK or Screwfix.ie then it hasn't gone through Modern Plant. If it doesn't go through them then they don't make any money on the pump. If Modern Plant don't make any money on the pump then they won't repair it under warranty. They only offer a warranty on pumps they sell. Buy a pump from the UK & you don't get the 5 years warranty. This is the case with any product from the UK with an Irish agent. Triton, Aqualisa, Salamander etc are a few more examples.

It's looking like I need to buy a new pump. The difference between UK and Irish price is a few hundred so I'm trying to weigh up my options.

If you buy from UK you must have some manufacturers warranty, same as buying any other product from UK/EU. Any idea what this is?

How would Modern Plant know you bought it outside Ireland? If a plumber buys and installs it for you you'd never know where he got it from?

Is it really a 5 year warranty? I mentioned that to someone and I remember vaguely being told it's really a 2 year warranty. I can't remember the details. Is there something particular about the warranty that means most people could not avail of it after two years?

metricspaces

Interesting. I just rang up Stuart Turner. They have told me that Modern Plant will come out to look at a Stuart Turner pump even if you bought the pump in the UK, the only requirement is that the pump has to be under warranty.

Does anyone have experience of Modern Plant refusing to look at a pump bought in the UK that is still under warranty?

Now, the person I was talking to from Stuart Turner said none of the online retailers in the UK would sell a pump with Irish fittings, and if I got the UK fittings separately afterwards it "may" invalidate the warranty.

Sleeper12

metricspaces wrote:

Does anyone have experience of Modern Plant refusing to look at a pump bought in the UK that is still under warranty?

Best option is to ring Modern Plant & ask. They won't know who you are so it won't effect any pump you might buy here or in the UK.

I can confirm that Triton definitely won't repair UK sourced showers. This includes triton models not intended for the Irish market but sold by Argos, B&Q, Screwfix and Homebase in Ireland. I also have emails from the Aqualisa agent stating that I have to provide an Irish receipt for any showers that I have fitted that needs repairing under the warranty. Up until recently my clients just showed them the receipt I gave.

Modern plant used to be the agent for Mira and never repaired UK mira showers. I'd be interested to hear what they say about UK Stuart Turner pumps

metricspaces

Sleeper12 wrote: »

Best option is to ring Modern Plant & ask. They won't know who you are so it won't effect any pump you might buy here or in the UK.

I rang Modern Plant and they said "Shower Doctors" are the ones that look after repairs (I didn't get around to calling them).

Whilst on to Modern Plant they gave me a price of 580e for a 4 bar monsoon pump. The UK price I have is 430e. A difference of 150e, guessing the 580e is retail price, trade I'm sure would be a little cheaper...so in the grand scheme of things it's not as big a saving as I was initially thinking.

K.Flyer

Spoke with M.P. about this..
If you phone up with a warranty issue call they will ask for the serial number and model code.
If the pump does not have ROI on the end of the model code number they will have to refer back to S.T. for authorisation to cover the warranty, which is at the discretion of S.T.
If the U.K. flexible hoses have been changed to Irish ones then most likely the warranty may be void as it has not been an authorised change to manufacturers specifications.
So..
If you are going to buy and fit a Stuart Turner pump sourced from the UK or N.I. make sure you fit the original hoses that come in the box to the pump.
But, Make sure you use 22mm copper pipe (or 15mm for the smaller plastic pump) to connect to the Stuart Turner hoses.
Then use whatever adaptors are required to connect back from this pipe to your original pipework.
There is no guarantee that S.T. or M.P. will cover the warranty, but at least with the correct hoses (which must be fitted almost dead straight up!!) they can't use the hoses against you to void the warranty.
Hope that somewhat clears up the question

metricspaces

I took at look at my pump and it does not have ROI at the end of the serial number. It also has a plastic attachment on the between the silver pipes of the pump and the copper pipe work. The end of the attachment connected to copper pipes has 22mm marked on it and the other end connected to the sliver pipes going into pump has 3/4 marked on it. Do I have a UK pump and and UK pipe work in my house (22mm)?

metricspaces

I just got a response back from Stuart Turner and they checked my serial number - my pump is a UK pump. Which I guess is good news as I can order a cheaper pump from the UK and fit it without any additional work required

Are there any potential negatives for me in the future with the house in general due to the fact that the builder used UK 22mm sized pipe work?

K.Flyer

metricspaces wrote: »

Are there any potential negatives for me in the future with the house in general due to the fact that the builder used UK 22mm sized pipe work?

Not really no, once you are aware of it you can mention it to anyone coming to do work for you.
There may sometimes be a small delay sourcing a component in metric, but adapters etc are available and a lot of parts come into the country with metric connections.

metricspaces

Fantastic. The only slight negative is it may be difficult for me to sell my current uk pump. Unless there's someone in ROI that has 22mm pipes, or is willing to adapt their 21mm pipes to fit my pump.

Of course I can stick on ebay and hope for a buyer up north or uk!

Sleeper12

metricspaces wrote:

Fantastic. The only slight negative is it may be difficult for me to sell my current uk pump. Unless there's someone in ROI that has 22mm pipes, or is willing to adapt their 21mm pipes to fit my pump.

I thought it wasn't working properly?

metricspaces

Sleeper12 wrote: »

metricspaces wrote:

@Sleeper12 you mentioned previously that a 2.0 bar pump should be putting out 14 l/min? But K.Flyer said my pump (based on the photo I shared of the label on it - see below) should only be putting out 9 l/min. That's obviously a big difference of 50%.

I was wrong. I was surprised myself when K.Flyer said 9 litres per minute but I don't for a second doubt his knowledge. I deal with self contained power showers and electric shower. I rarely deal with stand alone pumps

@Sleeper12 based on above I understood you were saying my pump putting out 8.6 l/min was working as expected?

Sleeper12

metricspaces wrote: »

@Sleeper12 based on above I understood you were saying my pump putting out 8.6 l/min was working as expected?

My fault. I thought you were replacing it because it was faulty. I'm mixing this with another thread

metricspaces

I did some more testing of the flow rate of bath\taps\shower in my house. Shower flow rate is extremely low. Does it look like I've a problem between the pump and the shower hose?

How I tested:

• Shower tested with shower head off.
• Cold\hot tested separately but no difference in flow rate.
• Left tap\shower running for a minute, then filled a bucket to 4 litre mark. Repeated 3 times (figures were almost identical each time).

In the main bathroom the flow rate of the bath is 66% faster than the shower. Surely something wrong here?

If I understand correctly, both the shower and the bath have the same diameter flexi pipes coming from the water pump. Copper piping is just added on at the T junction to connect up the tap\shower regulator - so the actual amount of copper pipe is a only a small fraction of the piping between the pump and the tap\shower? So how could the flow rate be so drastically different?

The ensuite shower is even worse again. It has almost the same flow rate as the mains coming into the kitchen cold tap. The ensuite is directly beside the main bathroom yet it drops 2 l/min flow rate?

If I could get my showers at the same flow rate as my bath, then I wouldn't need a new water pump I think.

K.Flyer

The bath taps will have a 3/4" connection and when the tap is fully open there is very little restriction on the flow rate. By comparison, shower connections will reduce down to 1/2" and usually have a gauze strainer and sometimes small little non-return valves to further reduce the flow rate.
The outlet of the shower is 1/2" and then its further reduced to the internal diameter of the hose.
So if the pipework is all exactly as it should be, then the flow rate from bath taps will always be higher due to the lesser restrictions.
You also find kitchen and basin taps fitted with small bore flexible connection hoses have much lower flow rates compared to older taps with 1/2" connections.

metricspaces

Thanks. So possibly these figures are ok? Even the drop of 2 l/min between the main bathroom shower and ensuite shower? Main bathroom is closer to the pump, the ensuite shower is about a further meter away.

I have someone coming to look at gauze strainers to see if they are blocked, so I'll see what that shows up.

They suggested that putting in a higher bar pump for the entire house may not be a great idea. The pressure in my taps is already high enough, but there is not enough copper pipe coming to my taps to put in pressure reducing valves, so would need to extend the piping on feeding every tap to give space to fit in the valve.

The extended pipes would be hidden, but it'll be messy and take up limited space I have in units under the taps. The pump is feeding 5 sinks, so 9 values in total.

The best job they said would be to run separate pipes to both the showers and run them off a separate pump. Bathrooms are tiled already, so I'm guessing this means ripping up at least the floor?

metricspaces

I got a Mira Atom shower valve to see if it made any difference. I see an increase of 27% in flow rate (from 10.4 l/min up to 13.2 l/min). But the end result from the shower head is not massively different. (There's no name on my valve, so no idea what brand it is)

Observed Flow Rates

Here are the results below from various tests. They are with the shower head off and max flow setting on the valve. Same hose used for both shower valves.



Expected Flow Rates of Mira Atom

Here is the expected flow rate of a Mira Atom EV valve. Based on this I'm seeing about 0.8bar at my shower hose (or maybe worse, as this graph is showing figures for the handset and I have the shower head off).


Mira Atom 19.6 l/min

One interesting thing with the Mira valve is when I put it at temperature setting 4 I see a flow rate of 19.6 l/min (temperature settings go from 1 to 10; where is 1 lowest cold and 10 max hot). I didn't notice this behaviour with my current valve.

I guess at temperature setting 4 the Mira valve is letting through full flow from both hot and cold. If I got this flow rate throughout the temperature settings I would be happy. But it drops off immediately back to the 13 l/min as soon as I move the setting up to level 5.

How to get close to 20 l/min?

To get close to the 20 l/min it looks like I would at least need to double my pressure? I currently have a 2 bar pump so that would mean going to 4 bar.

Looking at the pressure\flow rate chart from Mira.
* A flow rate of 13 l/min equates to about 0.8 bar
* A flow rate of 20 l/min equates to about 1.8 bar

So if I double the pressure of my pump, I hopefully double the pressure at the shower valve which would bring me from 0.8 bar at the valve to 1.6 bar, this would get me close to 20 l/min

Sleeper12

I think Your shower looks like the Triton bar mixer in the photo. The photo of the manual shows you where the filter is & where the flow regulator is. I would bin the regulator

Sleeper12

2nd photo

I have a bar mixer like this. Just tested 16 / 17 litres per minute on just cold. 23 on hot & cold

metricspaces

Sleeper12 wrote: »

2nd photo

I have a bar mixer like this. Just tested 16 / 17 litres per minute on just cold. 23 on hot & cold

Thanks! This measures up quite well:

• I get 13-14 l/min with 2bar
• You get 16-17 l/min with 3bar

So a 4 bar would hopefully get 19-20 l/min

Sleeper12

metricspaces wrote: »

Thanks! This measures up quite well:

• I get 13-14 l/min with 2bar
• You get 16-17 l/min with 3bar

So a 4 bar would hopefully get 19-20 l/min

Pumps aren't my field but 4 bar might be overkill. You'd usually only require 4 bar for showers with jets.

I get 23 litres per minute of warm water

metricspaces

Sleeper12 wrote: »

I think Your shower looks like the Triton bar mixer in the photo. The photo of the manual shows you where the filter is & where the flow regulator is. I would bin the regulator

Mine doesn't have the little handles on the levers like in the photo. My filter definitely comes out, should the flow regulator come out too? I'll take a look this evening.

If I'm understanding you correctly, you are suggesting taking it out the flow regulator and leaving it out all together right?

Sleeper12

metricspaces wrote:

If I'm understanding you correctly, you are suggesting taking it out the flow regulator and leaving it out all together right?

If there is a flow regulator, it's restricting the flow. I'd try it without it

John.G

metricspaces wrote: »

Thanks! This measures up quite well:

• I get 13-14 l/min with 2bar
• You get 16-17 l/min with 3bar

So a 4 bar would hopefully get 19-20 l/min

These Monsoon Pump curves are helpful, select "performance" to see them when the link is opened.
http://www.stuart-turner.co.uk/products/monsoon/s20-bar-twin/

If I am interpreting it correctly you are stating that you are getting say 13 LPM with a "2 Bar" pump, this, from the pump curves means that the pump is then operating at a 1.6 Bar (16 Meter) head. If you require 16 LPM then your head requirement is 1.6*(16/13)^2, 2.42 Bar (24 meter) but even a "3 Bar" pump wont achieve this, it will only have a flowrate of 10 LPM at this head. A "4 Bar" pump will have no problem as it can achieve a flowrate of 27 LPM at 2.4 Bar. A flowrate of 18 LPM requires (1.6*(18/13)^2, 3.06 Bar which the "4 Bar" pump can just about achieve.

metricspaces

John.G wrote: »

These Monsoon Pump curves are helpful, select "performance" to see them when the link is opened.
http://www.stuart-turner.co.uk/products/monsoon/s20-bar-twin/

If I am interpreting it correctly you are stating that you are getting say 13 LPM with a "2 Bar" pump, this, from the pump curves means that the pump is then operating at a 1.6 Bar (16 Meter) head.

Thanks. Yes I've seen these curves and it would be good to understand what i might get in theory if i increase the pressure.

John.G wrote: »

If you require 16 LPM then your head requirement is 1.6*(16/13)^2, 2.42 Bar (24 meter) but even a "3 Bar" pump wont achieve this, it will only have a flowrate of 10 LPM at this head.

I don't understand this bit here. It sounds like you are saying that a 3 bar pump will only have a flow rate of 10 l/min at the shower hose. But I'm already seeing 13-14l/min with my 2 bar and another poster sees 16-17 l/min with their 3 bar. (These flow rates are just based on one supply not the pump taking both hot & cold)

John.G

metricspaces wrote: »

Thanks. Yes I've seen these curves and it would be good to understand what i might get in theory if i increase the pressure.



I don't understand this bit here. It sounds like you are saying that a 3 bar pump will only have a flow rate of 10 l/min at the shower hose. But I'm already seeing 13-14l/min with my 2 bar and another poster sees 16-17 l/min with their 3 bar. (These flow rates are just based on one supply not the pump taking both hot & cold)

If I explain it another way, if you disconnected the discharge hose from one end of the pump ie the cold end and fitted it with a 3/4 ins gate valve and opened it fully, discharging to a open drain, you then start the pump, you will get a massive flowrate approaching 55 LPM (2 Bar pump) because there is little or no back pressure and the pump discharge pressure will read practically zero. If you now keep shutting it that 3/4 in valve until you get a flowrate of 13 LPM, you will now find that the pump discharge pressure will read 1.6 Bar, you now want say 18 LPM with the valve throttled at the same position, the only way to increase the flowrate is obviously to increase the pressure and the required pressure is now 1.6*(18/13)^2, 3.06 Bar. neither the 2 bar or 3 bar pump will give the required head under these conditions but a 4 bar pump will. your system or anyones system will have a certain restriction caused by pipe diameter and length, any valves etc in the system causing pressure losses and for any given flowrate will require a certain pump discharge pressure. I would try and fit a pressure gauge as close to the pump discharge and see what the pressure is at different flowrates, I would also as suggested above, remove the flow restrictor from the shower unit.
One other point that was mentioned above re pressure and flow, they are not linear, Flowrate is proportional to the Sq.root of pressure and as above pressure is proportional to the square of the flowrate.

Re someone else getting 16 LPM with a 3 bar pump, the 3 bar pump curve shows a pressure of 2.3 Bar for that flowrate. your flowrate is 13 LPM at 1.6 bar ( with 2 bar pump) so the pressure required to increase the flowrate to 16 LPM is 1.6*(16/13)^2, 2.4 bar which isnt far away from the 2.3 bar which means that your system isnt too far removed from his. In other words if you had a 3 bar pump then your flowrate would be close to 16 LPM as well.

John.G

metricspaces wrote: »

I got a Mira Atom shower valve to see if it made any difference. I see an increase of 27% in flow rate (from 10.4 l/min up to 13.2 l/min). But the end result from the shower head is not massively different. (There's no name on my valve, so no idea what brand it is)

Observed Flow Rates

Here are the results below from various tests. They are with the shower head off and max flow setting on the valve. Same hose used for both shower valves.



Expected Flow Rates of Mira Atom

Here is the expected flow rate of a Mira Atom EV valve. Based on this I'm seeing about 0.8bar at my shower hose (or maybe worse, as this graph is showing figures for the handset and I have the shower head off).


Mira Atom 19.6 l/min

One interesting thing with the Mira valve is when I put it at temperature setting 4 I see a flow rate of 19.6 l/min (temperature settings go from 1 to 10; where is 1 lowest cold and 10 max hot). I didn't notice this behaviour with my current valve.

I guess at temperature setting 4 the Mira valve is letting through full flow from both hot and cold. If I got this flow rate throughout the temperature settings I would be happy. But it drops off immediately back to the 13 l/min as soon as I move the setting up to level 5.

How to get close to 20 l/min?

To get close to the 20 l/min it looks like I would at least need to double my pressure? I currently have a 2 bar pump so that would mean going to 4 bar.

Looking at the pressure\flow rate chart from Mira.
* A flow rate of 13 l/min equates to about 0.8 bar
* A flow rate of 20 l/min equates to about 1.8 bar

So if I double the pressure of my pump, I hopefully double the pressure at the shower valve which would bring me from 0.8 bar at the valve to 1.6 bar, this would get me close to 20 l/min

This is a old thread but may have some significance as one poster mentions a "flow restrictor built into the head".

https://www.boards.ie/vbulletin/showthread.php?p=98012784

Edit: I dont want to beat the thread to death but I'd hate to see you buying another pump and find that it still mightn't fix your problem so I've been looking again at the posts. You said that the pump serves everything in the house bar the kitchen cold tap, you measured the kitchen hot water flow rate at 6.7 LPM, if this is fed from the hot water end of the pump then the 2 Bar pump should give a 1.7 Bar head, if you then add the static head of say 0.6 bar you end up with a total head of 2.3 Bar but yet end up with a very poor flow of 6.7 LPM, my own hot water tap flows 5.3 LPM from just the static head of 0.6 Bar. My cold tap, coincidentally, from a mains pressure of 2.3 Bar flows 10.6 LPM. You might just consider switching off the pump from its MCB or whatever and then measure the flowrate again as somethings dont add up here.
You also say (and Sleeper12 says something similar about his shower) that Mira cold flows 13.4 LPM, Mira Hot 13.2 LPM, Level 4, 19.6 LPM & Level 7, 13.1 LPM. How do (both of you) measure "hot only" if its a thermostatically controlled shower.?