Stuart turner Trent ClydeCharger MJ2

[texas]

Hi i am not sure if anyone can please help.

 

I have low pressure coming into the house around 1.1 bar.

We have 3 story terrace. The boiler and the Stuart turner accumulator and mainsboost are in the loft. 

 

When it works it is great. We get really powerful showers. Only one person can shower at the same time though. It will also lose pressure after about 10 mins of a shower. 

 

This is ok in parts. However it has so many alarms go off and i have to go up and restart the MJ2 accumulator. It is frustrating. 

 

A few questions.

 

 

There are numerous settings. I have tired to fiddle about with them but its a bit trial and error. 

 

The settings are as follows and also next to them the factory preset

 

 

"set point" 3 bar
"Diff pressure" 0.5 bar
"Low pressure" 0.2 bar
"High pressure" 4.5 bar
"Pump run timer" 180 mins
"Pump number" NPM2 (do not tamper)
"CRE Setting" 0

Do you know what i should have these above on ideally? 

 

I am not sure what "Low pressure" means does it means it kicks in if it goes below that? Does it mean it alarms if it goes below that? 

 

I get LPR low pressure cut out PRT (pump run time) and HNT High temp cut out alarms. 

I am a bit fed up of it. 

 

Does any one have any tips. My tank is pretty big its a vertical tank about 6ft tall. 

 

Any tips on settings to make it work better would be gratefully recieved.

 

 

Also

I have done some googling and have seen this DAB ESYBOX and ESYTANK Cold Water Booster Set and Tank | Complete Pump Supplies 

Do you think this is any better and will fix my problems? The person on the phone implied it will give me 3 times as much pressure and as such i will be able to have multi showers on the go at the same time. I am not sure if i am being sold a bit of an expensive dream. 

 

Many thanks in advance

 

 

[sharpener]

If you can post a link for the actual product that would be good. Nearest I can find on the web in a quick search is this so I will assume it is something like that. See also this guide.

 

If so it has a pump which boosts the incoming supply and stores the resulting water under high pressure in an accumulator partly filled with air. When it reaches the set point of 3 bar it will stop. The 0.5 bar will be the amount the pressure has to drop before the pump cuts back in, this is to stop it going on and off all the time. The max run time is a limit to how long the pump will run to try and refill the vessel up to the set point. I am surprised it ever takes as long as 3 hours, that is a flow rate of only 1 litre/min so it must be really struggling for water.

 

I am assuming it works on cold water only so I am guessing the high temp limit is a measurement of the motor winding temp to prevent it burning out, I am not surprised this is triggered if it is struggling.

 

The stored volume of water is only 174 litres so that is the max you can get out at the boosted pressure, which should be enough for maybe three 5 min showers, after that you will only get the flow rate that the pump can manage from the mains alone which is very feeble. You could try increasing the set point as much as you can before you get to the 4.5 bar h.p. warning level to give you the maximum storage volume.

 

The 0.2 bar is a warning level, presumably the pump needs at least this on the suction side to function correctly, so you do not have this all the time.

 

However if the pump is up in the attic with the rest of the plant and the incoming mains pressure is only 1.1 bar (is that static or with any flow and if so how much?) then it can only lift the water to a height of 11 metres. If the mains pressure is not sufficient at a reasonable flow rate to get the water high enough for the pump to be able to function properly without cavitation the pump will struggle to pressurise it any further, I think this is likely to be what is happening. Check what suction head the pump is designed to achieve.

 

In which case the solution is to re-install the pump (or a different pump) at ground floor level so it is flooded on the suction side and will perform better.

 

DAB pump sets are I think well regarded, comparable with or better than Stuart Turner IMO, but the one in yr link works differently. It has a tank storing 500 litres at the incoming mains pressure and then a pump to provide the supply to the house. If you want 3 showers at once you need (a) enough stored volume (b) sufficiently large diameter pipework to minimise pressure drop and (c) enough pressure, 3 bars should be adequate as that is what unvented cylinders usually work at. This DAB pumpset will provide 80 litres/min at 3 bar so enough for 4 rain showers at once.

 

But it relies on the mains pressure to fill the tank to begin with and so could not be installed in the attic if the underlying problem is that the mains pressure will not lift the water that high, and it will not solve the problem.

 

[texas]

Thank you for such an amazingly detailed response. 

 

I am going to send a photo of what i have and will come back regarding the points you have made. 

 

Thanks

 

 

[texas]

[texas]

[texas]

[texas]

On 11/02/2025 at 17:05, sharpener said:

If you can post a link for the actual product that would be good. Nearest I can find on the web in a quick search is this so I will assume it is something like that. See also this guide.

 

If so it has a pump which boosts the incoming supply and stores the resulting water under high pressure in an accumulator partly filled with air. When it reaches the set point of 3 bar it will stop. The 0.5 bar will be the amount the pressure has to drop before the pump cuts back in, this is to stop it going on and off all the time. The max run time is a limit to how long the pump will run to try and refill the vessel up to the set point. I am surprised it ever takes as long as 3 hours, that is a flow rate of only 1 litre/min so it must be really struggling for water.

 

I am assuming it works on cold water only so I am guessing the high temp limit is a measurement of the motor winding temp to prevent it burning out, I am not surprised this is triggered if it is struggling.

 

The stored volume of water is only 174 litres so that is the max you can get out at the boosted pressure, which should be enough for maybe three 5 min showers, after that you will only get the flow rate that the pump can manage from the mains alone which is very feeble. You could try increasing the set point as much as you can before you get to the 4.5 bar h.p. warning level to give you the maximum storage volume.

 

The 0.2 bar is a warning level, presumably the pump needs at least this on the suction side to function correctly, so you do not have this all the time.

 

However if the pump is up in the attic with the rest of the plant and the incoming mains pressure is only 1.1 bar (is that static or with any flow and if so how much?) then it can only lift the water to a height of 11 metres. If the mains pressure is not sufficient at a reasonable flow rate to get the water high enough for the pump to be able to function properly without cavitation the pump will struggle to pressurise it any further, I think this is likely to be what is happening. Check what suction head the pump is designed to achieve.

 

In which case the solution is to re-install the pump (or a different pump) at ground floor level so it is flooded on the suction side and will perform better.

 

DAB pump sets are I think well regarded, comparable with or better than Stuart Turner IMO, but the one in yr link works differently. It has a tank storing 500 litres at the incoming mains pressure and then a pump to provide the supply to the house. If you want 3 showers at once you need (a) enough stored volume (b) sufficiently large diameter pipework to minimise pressure drop and (c) enough pressure, 3 bars should be adequate as that is what unvented cylinders usually work at. This DAB pumpset will provide 80 litres/min at 3 bar so enough for 4 rain showers at once.

 

But it relies on the mains pressure to fill the tank to begin with and so could not be installed in the attic if the underlying problem is that the mains pressure will not lift the water that high, and it will not solve the problem.

 

I've attached the pics above. The manual dial is the pressure of the water coming in. I think its showing 1.4 at the moment but it can fluctuate. I have shown a pic of a tank called an aquasystem I have no idea if this is linked to the situation but have added it anyhow.

 

I play about with the numbers and as thing stand i have not had an error for a while using the following ( i forget what they were on before i wish i had noted them down)

 

SP 2.2

Dif 1.5 

LPR 0.5

PR2.8

PRT 180

Npn 2

going on what you have suggested above i feel maybe i reduce the Dif to 0.8 or something? 

 

I believe you are correct in that it works on the cold water. 

You say 174 litres. I am not sure if this is correct. How do i check this? You say set the set point high i am concerned this may lead to it trying to achieve this and over heating? 

You ask me regarding the pressure and if its static or flow reading. The readings vary but at the moment static ( as in no water flowing) is 1.4 when ive just ran the tap the 1.4 stays the same. I am not sure if this is what you are asking me though. Regarding the 1.1 (it was on the day i posted initially but today it is 1.4) that is the reading i have in the attic. I am not sure how to test it downstairs? 

 

"Check what suction head the pump is designed to achieve" how do i check this please? 

 

 

 

Regarding the DAB i am concerned that 500 litres of water will weigh a lot would a loft be able to support that size of tank weight? google implies it would weight around 500kg! seems a lot. We have nowhere really other than the loft to store this product due to the layout of our house. 

 

Any help with the above would be gratefully received. 

 

 

 

 

 

[Nickfromwales]

On 07/02/2025 at 21:11, texas said:

Does any one have any tips. My tank is pretty big its a vertical tank about 6ft tall. 

It's just maths, and not an issue with your currently installed equipment.

 

The amount of water you are consuming, between each event of 'recovery', exceeds the capacity of the system that you have installed.

 

Yes, fit a bigger system and the problem will go away. Simple maths  but remember the "gotcha" which is that it is illegal to create a negative pressure on the incoming cold main supply. A prosecutable offence, no less.

[John Carroll]

On 14/02/2025 at 14:24, texas said:

I've attached the pics above. The manual dial is the pressure of the water coming in. I think its showing 1.4 at the moment but it can fluctuate. I have shown a pic of a tank called an aquasystem I have no idea if this is linked to the situation but have added it anyhow.

 

I play about with the numbers and as thing stand i have not had an error for a while using the following ( i forget what they were on before i wish i had noted them down)

 

SP 2.2

Dif 1.5 

LPR 0.5

PR2.8

PRT 180

Npn 2

going on what you have suggested above i feel maybe i reduce the Dif to 0.8 or something? 

 

I believe you are correct in that it works on the cold water. 

You say 174 litres. I am not sure if this is correct. How do i check this? You say set the set point high i am concerned this may lead to it trying to achieve this and over heating? 

You ask me regarding the pressure and if its static or flow reading. The readings vary but at the moment static ( as in no water flowing) is 1.4 when ive just ran the tap the 1.4 stays the same. I am not sure if this is what you are asking me though. Regarding the 1.1 (it was on the day i posted initially but today it is 1.4) that is the reading i have in the attic. I am not sure how to test it downstairs? 

 

"Check what suction head the pump is designed to achieve" how do i check this please? 

 

 

 

Regarding the DAB i am concerned that 500 litres of water will weigh a lot would a loft be able to support that size of tank weight? google implies it would weight around 500kg! seems a lot. We have nowhere really other than the loft to store this product due to the layout of our house. 

 

Any help with the above would be gratefully received. 

 

 

 

 

 

 

A few basics about any accumulator.

Its important that the precharge pressure (air end pressure with no pressure at the water end) is set to just slightly less than the minimum required pressure, if, for example, the minimum required pressure is  1.5bar, then the precharge pressure should be set to 1.3bar, if the pump SP pressure is set to its design? pressure of 3.0bar then the available water vol per 100L of accumulator capacity is 34.5L, if the precharge pressure, for whatever reason is set to only 0.5bar then the available water vol in falling from 3.0bar to 1.5bar is only 22.5L, important to bear this in mind. You have the pump SP at 2.2bar , assuming the precharge pressure is 1.3bar then the available water vol in falling from 2.2bar to 1.5bar is 28L (per 100L of accmulator vol), I would definitely suggest checking that precharge pressure and set it slightly below your required minimum pressure and reducing the diff to 0.8 bar, as you suggested, Can you also post the pump inlet and outlet pressures with a big demand.

Also the the indexed setting in the window of that ABV?, automatic bypass valve, located between the two pressure gauges.

[John Carroll]

This is probably very similar to your pump, your pump has a higher closed valve head of 3.98bar. It should really have no problem in reaching a cut out SP of 3.0bar when the demand finishes, as long as the inlet pressure is > than 0.7bar. How long is it running for before it cuts out at 2.2bar?

You might also measure the accumulator circumference with a tape, can then get a good idea of its capacity at 6ft? high.

 

Edited February 15 by John Carroll

[sharpener]

On 14/02/2025 at 14:24, texas said:

You say 174 litres. I am not sure if this is correct. How do i check this? You say set the set point high i am concerned this may lead to it trying to achieve this and over heating? 

 

As suggested upthread, measure the diameter and height and calculate the apparent volume of yr cylinder, though I am surprised there is not a capacity label/rating plate somewhere on it.

 

If you mean overheating of the pump motor, I don't think it would make much difference and it says it has a thermal cutout anyway.

 

If you are getting 1.1 or 1.4 bar pressure at the level the pump is installed at i.e. in the loft then some of my earlier remarks do not apply. Though it doesn't explain why it takes such a long time to refill/re-pressurise. I think the main problem is simply the setup is too small for your usage pattern as @Nickfromwales states.

A simple answer may be to fit aeration-type shower heads - by drawing air into the water flow these are supposed to give the sensation of a bigger shower while using less water. They are alleged to work though I haven't tried them myself.

[John Carroll]

3 hours ago, sharpener said:

 

As suggested upthread, measure the diameter and height and calculate the apparent volume of yr cylinder, though I am surprised there is not a capacity label/rating plate somewhere on it.

 

If you mean overheating of the pump motor, I don't think it would make much difference and it says it has a thermal cutout anyway.

 

If you are getting 1.1 or 1.4 bar pressure at the level the pump is installed at i.e. in the loft then some of my earlier remarks do not apply. Though it doesn't explain why it takes such a long time to refill/re-pressurise. I think the main problem is simply the setup is too small for your usage pattern as @Nickfromwales states.

A simple answer may be to fit aeration-type shower heads - by drawing air into the water flow these are supposed to give the sensation of a bigger shower while using less water. They are alleged to work though I haven't tried them myself.

I would get that pump looked at for a start.

If that was operating as designed then it should have no problem in achieving 3.0bar could  give a 71% increase in the accumulator output, refilling time for a 175L accumulator should still only be 11 ninutes or so.

Accumulator 175L Calcs Rev 0.xlsx

[texas]

Thank you for all the above responses. I am a little unsure on a couple of points but will come back to the parts i can find out 

Regarding the parts i don't understand

"it is illegal to create a negative pressure on the incoming cold main supply. A prosecutable offence, no less" 

 

What does this mean. What am i doing or suggesting to do that could lead to this? Or am i already doing it? 


"Its important that the precharge pressure (air end pressure with no pressure at the water end) is set to just slightly less than the minimum required pressure, if, for example, the minimum required pressure is  1.5bar, then the precharge pressure should be set to 1.3bar, if the pump SP pressure is set to its design?"

 

How do i modifythe precharge pressure? Is this not hte factory set "Factory pre charge 1.4 bar" that is written on my tank?

 

When you talk about minimum required pressure what do you mean by this? As in minimum that i need to have a nice shower or is it something more technical in terms of what my pump or tank need to run correctly? If so how do i find this please? 

 

pressure of 3.0bar then the available water vol per 100L of accumulator capacity is 34.5L, if the precharge pressure, for whatever reason is set to only 0.5bar then the available water vol in falling from 3.0bar to 1.5bar is only 22.5L, important to bear this in mind. You have the pump SP at 2.2bar , assuming the precharge pressure is 1.3bar then the available water vol in falling from 2.2bar to 1.5bar is 28L (per 100L of accmulator vol), I would definitely suggest checking that precharge pressure and set it slightly below your required minimum pressure and reducing the diff to 0.8 bar, as you suggested"

 

Im a bit lost above i dont really follow what you are saying but appreciate this is important so is it possible you could explain a bit more please. 
 

"Can you also post the pump inlet and outlet pressures with a big demand.

Also the the indexed setting in the window of that ABV?, automatic bypass valve, located between the two pressure gauges."

 

I think you want me to run a lot of water as in a lot of taps to be open at the same time? If so i will do this. But before i do what measures do you want me to show. Is it these 3 things? ive attached 3 pics in the follow up to this post. I am not sure if they are accurate as one seems to be stuck on 1.4 whenever i look at it. If it is not these can you let me know. Once i know ill run the taps to capacity and post. 

Thank you all for such detailed help. I really appreciate it. 

 

 

[texas]

Is it these? NB I’m not running the taps I just want to be sure it’s these you talk about before I run the taps and monitor, 

 

 

[texas]

"This is probably very similar to your pump, your pump has a higher closed valve head of 3.98bar. It should really have no problem in reaching a cut out SP of 3.0bar when the demand finishes, as long as the inlet pressure is > than 0.7bar. How long is it running for before it cuts out at 2.2bar?"

Hi do you want me to time how long it takes it to get to 2.2 bar from a standing start? Do you suggest i turn the pump off and allow all the water pressure to be exhausted then turn the pump on and time it? 

 

"You might also measure the accumulator circumference with a tape, can then get a good idea of its capacity at 6ft? high."

 

Which bit is this? Is this the tall vertical tank you want me to measure the circumference of? 

[texas]

"As suggested upthread, measure the diameter and height and calculate the apparent volume of yr cylinder, though I am surprised there is not a capacity label/rating plate somewhere on it."

Do you want me to measure the diameter/circumference of the bit vertical tank? and when you say height do you mean the height of the actual tank or a guide to how far from the ground floor the tank is?

"A simple answer may be to fit aeration-type shower heads - by drawing air into the water flow these are supposed to give the sensation of a bigger shower while using less water. They are alleged to work though I haven't tried them myself."

 

Thanks i will look into this. 

[texas]

"I would get that pump looked at for a start.

If that was operating as designed then it should have no problem in achieving 3.0bar could  give a 71% increase in the accumulator output, refilling time for a 175L accumulator should still only be 11 ninutes or so."

 

Thanks for this i have opened the spreadsheet and note you have some numbers in yellow. Are these numbers i can change? I am not sure what i am supposed to do with these. If you could explain i would be very grateful


Sorry for coming across a bit thick i just have limited understanding of this world. 

 

But am super grateful for all your knowledge. 

 

Thanks

 

 

[John Carroll]

No problem.

 

First, you know yourself what the minimum pressure you require to give you the minimum acceptable flowrate, so change (cell) D16 "End Pressure" (present setting 1.5bar) to whatever the minimum operating pressure is or should be.

Then change D7 "Precharge Pressure" to the D16 setting minus 0.2bar, if you set D16 to say 1.8bar then set D7 to 1.8-0.2, 1.6bar.

Change D9 & D18 (both) "Charged Pressure" to whatever your pump is cutting out at, present setting, 2.2bar OR whatever you think it should be capable of.

D6 "Accumulator Capacity" present setting 175litres, leave or change it to whatever the actual capacity is, if not known, get a tape and measure the circumference, and the height, post back and a good estimation of the capacity can be arrived at, also state the insulation (if any) thickness.

 

Also check for a schrader type valve (like a car type) on top of the accumulator, if there is one, check that pressure with the cylinder fully drained, it should be at or set to whatever D7 is set to (Charged pressure - 0.2bar).

[John Carroll]

"Also check for a schrader type valve (like a car type) on top of the accumulator, if there is one, check that pressure with the cylinder fully drained, it should be at or set to whatever D7 is set to (Charged pressure - 0.2bar)." Should be set to the precharged pressure, D7.

[Nickfromwales]

23 hours ago, texas said:

it is illegal to create a negative pressure on the incoming cold main supply. A prosecutable offence, no less

Hi. 
 

If you have a pump connected directly to the cold mains, and you are consuming water faster than the mains flow rate, then you’ll be “sucking” on the mains supply aka applying a negative pressure. 
 

A lot of plumbers will speak to a sales rep or some guy behind the counter in the merchant and sell the plumber some kit, the plumber will fit it, and no one ever checks if it’s all ok / compliant as they both just want paying.

 

These systems should be designed after a survey, I say this all the time particularly where an accumulator is the intended solution; this way, when I install expensive equipment and disrupt someone’s lives to do it all, it works afterwards (as intended / promised) and has a great service life.

 

If you have sub 11 lpm flow at the main the 1st advice should be to petition your water authority to see if you can get the local supply uplifted slightly; sometimes there’s just been another 30-40 new homes built and they’ve done nothing to maintain your existing supply, other instances could be that the tapping into the main in the street is furred up (I always ask the neighbours if I can test at their outside taps too to ensure it’s not an isolated issue).

 

If you have a system that fills an A>B break tank then you can’t ‘suck’ on the cold mains supply as the system will be hydraulically separated by an air gap in the break tank. These systems should pump would just be sucking that break tank bone dry faster than the incoming mains can refill it.

 

Some very poorly installed systems will see next doors supply drop to zero whilst the pump is pulling. The water authority do NOT take well to that because of reverse contamination issues.

[Nickfromwales]

@texas

 

If you click on someone’s text and highlight it you’ll see a box appear saying “quote selection”   

 

To ‘mention’ another user just type the @ symbol and then the first couple of letters of their username and you’ll see a drop box appear below that you can select their name from. Like I’ve done with you at the top of this post. 
 

May save you some typing lol 😉👍

[Nickfromwales]

The quick and simple solution here is to add a second, similarly sized accumulator to boost the stored capacity. After this your issues will be solved. 
Put the second vessel the opposite end of the attic to put the additional weight away from where the current one is. 
 

Ideally these should have had some timbers under them run perpendicular to the attic joists, so maybe do that for the second vessel to be sure to spread the weight.

 

This all needs proper, methodical thought and planning, or, do what I have done previously, use a metal cradle mounted to an external masonry wall to sit the second vessel on. 
 

Link the 2 vessels together with MINIMUM 35mm pipe (which every plumber on the planet will tell you is completely overkill / unnecessary) and this solution will allow you to close the door on this.

 

You can’t really improve on this I’m afraid, as it exists, without either a) installing a couple of ‘coffin’ sized break tanks for the pump to suck on, or b) (the best solution and to stay fully potable) fit the second accumulator.

 

I’ve done bucketloads of these types of installs, mostly in HMO properties and massive student accommodation conversions; one example had 14 ensuite shower rooms, 2 full bathrooms with baths, and 2 kitchens + utility running off 1 x 15mm cold mains, and all still in and working after over a decade of service.

 

 

You can’t squeeze any more juice out of this lemon  You need to add capacity. Simples.

[marshian]

7 minutes ago, Nickfromwales said:

<snip>

 

I’ve done bucketloads of these types of installs, mostly in HMO properties and massive student accommodation conversions; one example had 14 ensuite shower rooms, 2 full bathrooms with baths, and 2 kitchens + utility running off 1 x 15mm cold mains, and all still in and working after over a decade of service.

 

That's pretty damn impressive on a 15mm mains

 

 

7 minutes ago, Nickfromwales said:

You can’t squeeze any more juice out of this lemon  You need to add capacity. Simples.

 

Love that ^

 

One of the reasons I still have a CW tank in the loft and vented system - yes unvented would allow me to ditch the pumps I have on the showers but then I'm totally reliant on the mains pressure and it can be a bit patchy here!!!

 

[Nickfromwales]

25 minutes ago, marshian said:

That's pretty damn impressive on a 15mm mains

5x 50 gal CWS in the attic, all series  linked with 35mm copper x2, all WC’s on gravity, 300L gravity fed open vented HWC and 8x gravity mixer showers with 6x triton T80si pumped electrics (over 3 phases).

 

Just about every other plumber walked away from the job saying it cannot be done. lol. 
 

Massive floor standing gas boiler already there (in good nick) so reutilised that for heating and W plan DHW; (large nursing home converted to student HMO). Had to put heat loss on the DHW loop though, big old boiler that threw a lot of flow / heat out, and that was after using a solar cylinder so I could put the 2 coils in series for rapid recovery. Could have tried doing the coils in parallel but I thought that may not ‘be cricket’ in such a tall cylinder.

 

Cold mains went to the F&E (I fitted 2 x float valves set at 4 lpm each, one at the lead CWS and one at the lag) plus the outside taps and kitchen & utility sinks / appliances only.

 

New owners couldn’t / wouldn’t (?) get gas and water upgraded so I went with lots of stored capacity. We put a LOT of supporting timbers in the attic, but thankfully the internal walls were all brick rising from founds through 3 storeys to the attic so I could traverse those.

 

Was a while back, and still makes me cringe with how much work we did there !
 

As above, design for the task, add 30% redundancy for times of duress, sleep well. 🛌 💤. 

[John Carroll]

On 18/02/2025 at 09:25, texas said:

Is it these? NB I’m not running the taps I just want to be sure it’s these you talk about before I run the taps and monitor, 

 

 

 

I only saw this photo today.

 

Can you switch off the pump and open a few taps to give a good flow ~ 15LPM and note the two pressures, switch on the pump and note the pressures again, shut the taps and note the pressures as the pump stops.

Also check to see where the pump discharge (outlet) pipe is teed in to the system.