Water pump adjustable pressure?

John.G

John.G wrote: »

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.?

Should have made this a new post.

Sleeper12

John.G wrote: »

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.?

I originally set my shower to the desired showering temperature ( not at its hottest) because thats how many litres per minute my shower puts out when I shower. I was asked to measure how many litres per minute on cold only so I measured that. If you ask me how many litres per minute my shower puts out its 23 As i rarely shower in cold only or hot only

metricspaces

John.G wrote: »

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

Any input is helpful, as I really want to solve this problem. Thanks.

John.G wrote: »

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.

I'll give this a go tonight. But for sure when I turn off the pump the flow rate is even worse. I haven't measured, so this is just from visual. But I will measure flow rate tonight with pump off.

Is it just the flow rate from hot tap in kitchen with pump off that you are interested in?

John.G wrote: »

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.?

I didn't realise it was thermostatically controlled. I thought as you move from coldest to hottest setting it just closed the cold valve more and opened the hot valve more. I've been testing all along with no hot water. I'll heat the water and test again.

As it is thermostatically controlled though, I wonder why the Mira Atom valve jumps to almost 20 l/min (from 13-14 l/min) when I go for temperature setting 3 to 4, and then drops back to 13-14 l/min when I go back to setting 5.

Another thing to keep in mind too is that my main priority is solving this problem in the ensuite and not the main bathroom. All the recent figures are from the main bathroom. The ensuite has a diverter valve and I couldn't figure how at the weekend how to get it off the wall to put on the Mira one for testing. As you can see in my previous post my original shower valve was giving a whopping 7.9 l/min in the ensuite (compared to 10 l/min in main bathroom). So I would imagine the 13-14 l/min I'm seeing from Mira valve in main bathroom will translate to less than this in the ensuite, so this valve alone will not solve my problem.

John.G

metricspaces wrote: »

Any input is helpful, as I really want to solve this problem. Thanks.



I'll give this a go tonight. But for sure when I turn off the pump the flow rate is even worse. I haven't measured, so this is just from visual. But I will measure flow rate tonight with pump off.

Is it just the flow rate from hot tap in kitchen with pump off that you are interested in?



I didn't realise it was thermostatically controlled. I thought as you move from coldest to hottest setting it just closed the cold valve more and opened the hot valve more. I've been testing all along with no hot water. I'll heat the water and test again.

As it is thermostatically controlled though, I wonder why the Mira Atom valve jumps to almost 20 l/min (from 13-14 l/min) when I go for temperature setting 3 to 4, and then drops back to 13-14 l/min when I go back to setting 5.

Another thing to keep in mind too is that my main priority is solving this problem in the ensuite and not the main bathroom. All the recent figures are from the main bathroom. The ensuite has a diverter valve and I couldn't figure how at the weekend how to get it off the wall to put on the Mira one for testing. As you can see in my previous post my original shower valve was giving a whopping 7.9 l/min in the ensuite (compared to 10 l/min in main bathroom). So I would imagine the 13-14 l/min I'm seeing from Mira valve in main bathroom will translate to less than this in the ensuite, so this valve alone will not solve my problem.

You might measure the Flowrate (pump off) in both the ensuite and the kitchen please.

Re ensuite shower and its 7.9 LPM flow, this means that the 2 bar pump (if operating to spec) will be running with a 1.7 Bar head. If you require 16 LPM from each end of a pump then based on the above, the head required, 1.7*(16/7.9)^2, 6.97 Bar (so forget it). 12 LPM will require 1.7*(12/7.9)^2, 3.9 Bar would require a 4.5 Bar pump, if you would settle for a flowrate of 11 LPM then the head required, 1.7*(11/7.9)^2, 3.3 bar, is fairly comfortably covered by a 4 bar pump.

re thermostatic showers (or even mixer showers) I dont have any experience of them so dont know that if its set to maximum flow and say with a temperature setting of 40C will just add the 7/8 lpm required to mix it and give the required temperature (assuming 60C hot and 8C cold water) or if it starts throttling the hot water flow while increasing the cold water flow, so its just maybe possible that you can end up with a mixed flowrate of 18/19 LPM but personally I would think that there has to be some form of throttling to get mixing especially as both hot&cold are at the same pressure.
Sleeper12 has posted that he gets 16/17 LPM cold and 23 LPM hot, if one assumes the same conditions as above, then with no throttling the mixed flowrate would theoretically be 26 LPM so based on that there is very little throttling as the indicated flowrate of 23 LPM shows.
So if you are happy with a ensuite flowrate of around 18 LPM at 40C then the 4 bar pump should achieve this, I cant recall if you measured the ensuite flowrate with the showerhead on, if not you might do so (with pump on)

If it was my house, I would make up of get it made up, a fitting with a gate valve and a pressure gauge fitted to the discharge end of the cold then hot end of the pump and measure the flowrate (into a bucket) at a few different pump discharge pressures and compare them with the pump spec. I think that is the only certain way of ruling out any problems at that end, be it either the pump or the plumbing arrangement.
There may be a tapping point on the pump discharge(s) to enable the fitting of a pressure gauge, if so only a pressure gauge is needed and the flowrate can be measured anywhere, (better again).

metricspaces

John.G wrote: »

You might measure the Flowrate (pump off) in both the ensuite and the kitchen please.

Re ensuite shower and its 7.9 LPM flow, this means that the 2 bar pump (if operating to spec) will be running with a 1.7 Bar head. If you require 16 LPM from each end of a pump then based on the above, the head required, 1.7*(16/7.9)^2, 6.97 Bar (so forget it). 12 LPM will require 1.7*(12/7.9)^2, 3.9 Bar would require a 4.5 Bar pump, if you would settle for a flowrate of 11 LPM then the head required, 1.7*(11/7.9)^2, 3.3 bar, is fairly comfortably covered by a 4 bar pump.

Thanks! I will take some more measurements and post over coming days.

I would not be happy with 12 LPM in the ensuite. That is lower than I am getting in the main bathroom with the Mira Valve (13/14 LPM), and I am not happy with that.

See an image below of my house, the shower valve for the main shower and the ensuite are on the same wall and about 2 meters apart at most. Surely it should be possible to get almost identical pressure at both shower valves? Dropping from 10.x LPM down to 7.9 LPM seems odd?

Does this point at something "strange" with my plumbing that is reducing the pressure so much between these two valves? If I run separate pipes from a new pump up through the attic and split them off in the wall holding the two shower valves, then would I be guaranteed almost identical pressure in each valve?

GreeBo

You could have a ridiculous number of elbow joints, each will reduce the flow.

But a 2 bar pump should be fine, I installed one in my house a few years ago (also a ST monsoon from UK) and had no issues with shower or bath pressure.

John.G

metricspaces wrote: »

Thanks! I will take some more measurements and post over coming days.

I would not be happy with 12 LPM in the ensuite. That is lower than I am getting in the main bathroom with the Mira Valve (13/14 LPM), and I am not happy with that.

See an image below of my house, the shower valve for the main shower and the ensuite are on the same wall and about 2 meters apart at most. Surely it should be possible to get almost identical pressure at both shower valves? Dropping from 10.x LPM down to 7.9 LPM seems odd?

Does this point at something "strange" with my plumbing that is reducing the pressure so much between these two valves? If I run separate pipes from a new pump up through the attic and split them off in the wall holding the two shower valves, then would I be guaranteed almost identical pressure in each valve?

Two meter difference should make little or no difference except as stated above that there is a ridiculous amount of elbows etc BUT you are talking about two different showers so the only way that you can rule out that short piece of plumbing is to move one shower, lock stock and barrel, onto the other location and then compare the flowrate at that location to its previous one, one type of shower might give a flowrate of say 10 LPM at say 1 bar maintained pressure and another type might give 15 LPM at the same maintained pressure, it all depends on what they are designed for.

John.G

Some/most of bar mixer showers would appear to restrict the outlet flowrate to 8 LPM by having a regulator installed on the mixing bar where the hose is connected, it might be worth checking the ensuite shower for this, or there may be restrictors fitted to the hot/cold connections, if you know or can find out the make/model of your shower it would help a lot, logically, it is hard to accept that the 2 bar pump just feeding this unit with everything else turned off will not give more than 8 LPM??..

GreeBo

John.G wrote: »

Some/most of bar mixer showers would appear to restrict the outlet flowrate to 8 LPM by having a regulator installed on the mixing bar where the hose is connected, it might be worth checking the ensuite shower for this, or there may be restrictors fitted to the hot/cold connections, if you know or can find out the make/model of your shower it would help a lot, logically, it is hard to accept that the 2 bar pump just feeding this unit with everything else turned off will not give more than 8 LPM??..

I've certainly seen restrictors and filters fitted between hose and shower head that will impact flow but typically it's only an issue with a gravity fed shower, 2 bar pump should be lashing the water out. You should be complaining that the tank is emptying too quickly!

If taps have same issue, check for aerators fitted to the sprout. They should unscrew easily.

The other possibility, since its new plumbing, is that you have a blockage. I assume you have isolating valves on the inlets to the pump?
Might be worth checking the filters on the inlet pipes to the pump, if they are clogged them there is nothing your pump can do.

John.G

GreeBo wrote: »

I've certainly seen restrictors and filters fitted between hose and shower head that will impact flow but typically it's only an issue with a gravity fed shower, 2 bar pump should be lashing the water out. You should be complaining that the tank is emptying too quickly!

If taps have same issue, check for aerators fitted to the sprout. They should unscrew easily.

The other possibility, since its new plumbing, is that you have a blockage. I assume you have isolating valves on the inlets to the pump?
Might be worth checking the filters on the inlet pipes to the pump, if they are clogged them there is nothing your pump can do.

Agree, but if everything has been checked out then I would then do that pressure/flow test that I suggested a few posts ago, its relatively cheap and depending on results, one can move on.

metricspaces

GreeBo wrote: »

I've certainly seen restrictors and filters fitted between hose and shower head that will impact flow but typically it's only an issue with a gravity fed shower, 2 bar pump should be lashing the water out. You should be complaining that the tank is emptying too quickly!

Thanks! I'm testing the flow rate with the shower head off. So that rules out anything in between hose and shower head.

GreeBo wrote: »

If taps have same issue, check for aerators fitted to the sprout. They should unscrew easily.

My taps have no aerators. I only tested the kitchen tap for flow rates. But I will check some of the others.

GreeBo wrote: »

The other possibility, since its new plumbing, is that you have a blockage. I assume you have isolating valves on the inlets to the pump?
Might be worth checking the filters on the inlet pipes to the pump, if they are clogged them there is nothing your pump can do.

I'm getting 40 LPM from bath with both taps open. Wouldn't that rule out a blockage near the pump?

metricspaces

John.G wrote: »

Some/most of bar mixer showers would appear to restrict the outlet flowrate to 8 LPM by having a regulator installed on the mixing bar where the hose is connected, it might be worth checking the ensuite shower for this, or there may be restrictors fitted to the hot/cold connections, if you know or can find out the make/model of your shower it would help a lot, logically, it is hard to accept that the 2 bar pump just feeding this unit with everything else turned off will not give more than 8 LPM??..

Unfortunately there is no make\model information on my valves - but the ensuite valve is identical to the valve in the main bath apart from the fact that it is a diverter valve for a "rain shower" head.

I couldn't figure out how to unscrew the ensuite fixings holding the vertical pipe coming out of the valve, it looks like it needs a special screw bit. When I figure this out I will take the valve off in the ensuite, put the Mira one on, test and post up some figures.

This evening I will check (1) the kitchen tap on hot with pump off (2) a tap upstairs (3) main bathroom shower with hot water in the tank.

GreeBo

metricspaces wrote: »

Thanks! I'm testing the flow rate with the shower head off. So that rules out anything in between hose and shower head.



My taps have no aerators. I only tested the kitchen tap for flow rates. But I will check some of the others.



I'm getting 40 LPM from bath with both taps open. Wouldn't that rule out a blockage near the pump?

There could still be something (a filter) between the hose and the tap itself, so I would check that too.

If you are getting 40 LPM, whats the issue?
Is it just the drop off once you add the shower head in?

John.G

metricspaces wrote: »

Thanks! I'm testing the flow rate with the shower head off. So that rules out anything in between hose and shower head.



My taps have no aerators. I only tested the kitchen tap for flow rates. But I will check some of the others.



I'm getting 40 LPM from bath with both taps open. Wouldn't that rule out a blockage near the pump?

Re the restrictor location, if fitted, I have seen pictures of them fitted in the mixer barrel itself, when you remove the shower hose you then have to prise out the restrictor or use a needle nose pliers to extract it.

Bath tap flowrates: you are getting 20 LPM/Tap, my bathroom (3/4 ins) taps are each flowing 17 LPM on a gravity head of 0.3 bar, if I stuck a 2 bar pump in the system I would expect to get at least 30 LPM/Tap.

metricspaces

GreeBo wrote: »

There could still be something (a filter) between the hose and the tap itself, so I would check that too.

If you are getting 40 LPM, whats the issue?
Is it just the drop off once you add the shower head in?

Yep, the main issue for me is the flow rate from the showers. I want it close to 20 LPM in both ensuite and main bathroom showers.

metricspaces

John.G wrote: »

Re the restrictor location, if fitted, I have seen pictures of them fitted in the mixer barrel itself, when you remove the shower hose you then have to prise out the restrictor or use a needle nose pliers to extract it.

I will check the valves this evening. But if you look at the graph of the Mira valve for pressure\flow rate, do they not suggest that they are not restricting the flow? So if my LPM is on the low side with the Mira valve it would suggest either the pump is under performing or a the plumbing is restricting the flow (either too many bends or a blockage)

GreeBo

metricspaces wrote: »

Yep, the main issue for me is the flow rate from the showers. I want it close to 20 LPM in both ensuite and main bathroom showers.

Just to confirm, you are getting 40 LPM with the head off but it drops below 20 LPM with the head on?

metricspaces

GreeBo wrote: »

Just to confirm, you are getting 40 LPM with the head off but it drops below 20 LPM with the head on?

Sorry I probably wasn't clear. See the figures in the chart below.

I get 40 LPM with both bath taps fully open.
I get 13 LPM from the shower hose (head off), using Mira valve
I get 10 LPM from the shower hose (head off), using my existing valve (which I don;t know what brand it is)
I haven't measured the flow rate from the shower head.

Sleeper12

metricspaces wrote: »

Sorry I probably wasn't clear. See the figures in the chart below.

I get 40 LPM with both bath taps fully open.
I get 13 LPM from the shower hose (head off), using Mira valve
I get 10 LPM from the shower hose (head off), using my existing valve (which I don;t know what brand it is)
I haven't measured the flow rate from the shower head.

The bath is 3/4 inch pipes so you'd expect great flow.


Are you sure you are heating the water hot enough? You usually have 2/3 hot & 1/3 cold mixed to shower in warm water. You should be getting the 13.2 hot plus 5 or 6 more cold mixed in with it.



Your Mira figures don't make sense. You can't be getting less mixed (both hot & cold on at the same time) on level 7 (13.1) than you are getting with only hot (13.2) or only cold (13.4)
The other valve (I believe it to be a Triton but could be wrong) could have the flow regulators still in & the Mira without.


I would think if the water was hotter you'd get 15 lpm or more with the mira mixed & the same with the other valve if regulators removed

John.G

metricspaces wrote: »

I will check the valves this evening. But if you look at the graph of the Mira valve for pressure\flow rate, do they not suggest that they are not restricting the flow? So if my LPM is on the low side with the Mira valve it would suggest either the pump is under performing or a the plumbing is restricting the flow (either too many bends or a blockage)

Can you post the link to the above please as I cant locate it easily.
The above would seem to imply that 2.0 bar is the pressure required to give a flowrate of 20 LPM with the shower head on and in "handset" mode?. If this is correct then one will also have to add I would suggest a minimum of 0.3 bar for pipeline losses etc so you would require a 4 bar pump to give you a cold shower as all the water will have to be supplied from one end of the pump (cold end). If you are happy with a mixed flowrate of 20 LPM at 40C which is around 12 LPM from the cold & 8 LPM from the hot end so a 3 bar pump would do the job.
I would do the test especially on the Mira with the showerhead in place and in "handset" mode as otherwise it is meaningless. Again if your system/2 bar pump is performing as specified then even with the showerhead in place you should be getting 15 LPM but you are not getting this even with the showerhead off!.

John.G

Sorry if I've asked this question before Sleeper12 but do you know the make/model of your shower.

Sleeper12

John.G wrote:

Sorry if I've asked this question before Sleeper12 but do you know the make/model of your shower.

Mine is definitely a triton. I would have removed the flow regulators when I installed it.

GreeBo

metricspaces wrote: »

Sorry I probably wasn't clear. See the figures in the chart below.

I get 40 LPM with both bath taps fully open.
I get 13 LPM from the shower hose (head off), using Mira valve
I get 10 LPM from the shower hose (head off), using my existing valve (which I don;t know what brand it is)
I haven't measured the flow rate from the shower head.

My fault, I assumed the shower was separate to the bath.

Ok, so if you are getting 40LPM from the same pipes that you then get 10LPM, your problem is how the mixer sends water to the shower.


What height (head) do you have from the pump to the shower heads?
Could this be a negative head issue?

John.G

Sleeper12 wrote: »

Mine is definitely a triton. I would have removed the flow regulators when I installed it.

Here's a Triton Dove showing the (a) flow regulator, page 6.

https://www.wolseley.co.uk/wcsstore7.00.805.1036/ExtendedSitesCatalogAssetStore/images/products/AssetPush/DTP_AssetPushHighRes/std.lang.all/ti/on/Triton_DoveEcoMixer_Installation.pdf

metricspaces

John.G wrote: »

Can you post the link to the above please as I cant locate it easily.

I actually got this mailed to me by Mira. I couldn't find it online either.

John.G wrote: »

I would do the test especially on the Mira with the showerhead in place and in "handset" mode as otherwise it is meaningless.

Thanks. I will test this scenario also and update with results.

GreeBo wrote: »

What height (head) do you have from the pump to the shower heads?
Could this be a negative head issue?

When I am testing this the shower hose head is about the same height as the bath taps and the pump would be at the level of the bathroom floor. So 0.5m or less from head of pump to shower hose.

Sleeper12

metricspaces wrote:

When I am testing this the shower hose head is about the same height as the bath taps and the pump would be at the level of the bathroom floor. So 0.5m or less from head of pump to shower hose.

Head height is from the bottom of the cold water tank in the attic. The higher the tank the more head height

John.G

metricspaces wrote: »

I actually got this mailed to me by Mira. I couldn't find it online either.



Thanks. I will test this scenario also and update with results.



When I am testing this the shower hose head is about the same height as the bath taps and the pump would be at the level of the bathroom floor. So 0.5m or less from head of pump to shower hose.

stuart turner state: ""For a Gravity (Vented) 'Low Pressure System' where the flow from the shower head due to gravity (no pump fitted) is less than 1 litre/min, a 'negative head' situation exists and a 'Universal' pump type must be used""

This minimum flowrate is necessary to start the pump and generally I would think that because in most houses the cold water header tank is located in the attic space and gives a adequate head to give the minimum flow to activate the pump flow switch.

John.G

Sleeper12 wrote: »

The bath is 3/4 inch pipes so you'd expect great flow.


Are you sure you are heating the water hot enough? You usually have 2/3 hot & 1/3 cold mixed to shower in warm water. You should be getting the 13.2 hot plus 5 or 6 more cold mixed in with it.



Your Mira figures don't make sense. You can't be getting less mixed (both hot & cold on at the same time) on level 7 (13.1) than you are getting with only hot (13.2) or only cold (13.4)
The other valve (I believe it to be a Triton but could be wrong) could have the flow regulators still in & the Mira without.


I would think if the water was hotter you'd get 15 lpm or more with the mira mixed & the same with the other valve if regulators removed

Here is a great explanation of thermostatic control.

metricspaces

Sleeper12 wrote: »

Head height is from the bottom of the cold water tank in the attic. The higher the tank the more head height

Standard two story semi-d setup. Cold water tank is sitting a few centimeters off the ceiling joists in attic, and then room below is standard 2.4m height and the pump is sitting on this floor.

metricspaces

I measured the hot tap in the kitchen with the pump turned off. Flow rate was 3.3 LPM. How does this sound?

I want to get the old valve off the ensuite to test with the Mira valve, but there are two screws in the bracket holding the vertical pipe in place and it looks like I need a special screw bit to take it apart. Anyone have any ideas?






I didn't get time to fully test both valves in main bathroom with hot water. I'll do that at the weekend at post up complete set of figures.

One problem I noticed though is that my hot\cold pipes are the wrong way around in the main bathroom, so I had to turn the valve upside down to get it to work. Other than being a bit of a pain as you can't read the settings on the valve now as they are upside down, will this cause me any problem?