Boost a Main

[tomcoleman]

12 hours ago, fezster said:

 

Yes, a pump can be used to increase the static pressure. I thought you were saying you increased the pipe size to the road and saw no increase in static pressure - you wouldn't expect to. Sorry if I misunderstood. 

sorry mate - not enough coffe inside me !! HAHA

 

im going for accumlator + pump to increase pressure. i did increase the pipe from the road already to MDPE but made no difference.

[fezster]

I've been considering an accumulator for quite a while (albeit, not pumped, as my static pressure is 4-6 bar incoming).

 

The question I can't seem to answer, though, is whether my internal pipework is good enough to benefit and be able to run multiple showers. I'm certain there must be a way of determining this without "just trying".

 

Who is fitting your kit? And have you found them to be knowledgeable on the product?

[tomcoleman]

1 hour ago, fezster said:

I've been considering an accumulator for quite a while (albeit, not pumped, as my static pressure is 4-6 bar incoming).

 

The question I can't seem to answer, though, is whether my internal pipework is good enough to benefit and be able to run multiple showers. I'm certain there must be a way of determining this without "just trying".

 

Who is fitting your kit? And have you found them to be knowledgeable on the product?

 

I had a guy come over from boost-a-main to have a look, wasn't a sales guy more technical and talked me through some options, i also discussed some other products on the market.

 

My internal plumbing is mainly John-Guest 15mm, i have a flow device which showed my taps pushing around 8lp/m which is rubbish and a inbound street static pressure of 2bar.

 

Im going to fit the kit myself im a DIY'er and its not that hard, couple of connectors etc.

 

The pump will then pressurize the unit and i can adjust the output to the unvented megaflow which should be an opertional bar of 3bar but i'll do 3.5 to account for 0.5 loss of transport.

 

I should have this kit in april so can always report how i got on.

 

on 15mm pipe the max flow rate is 18l/min so more then enough,.

 

 

[fezster]

Interesting. What kind of pressure drop do you get when running a shower? (I presume the intent is to increase shower performance?).

 

My understanding of an accumulator is that it maintains working pressure whilst boosting flow. So - for example - if your internal pipework resulted in a pressure drop of 1.5 bar whilst running the shower (at say 10 litres/min), you'd only have 0.5 bar working pressure.

 

The accumulator (obviously charged via a pump in your case) would initially output max flow rate at 3 bar (eg. the shower can run at 20 litres/min) , and the working pressure would slowly drop to 0.5 bar until the accumulator is depleted. During this process, the mix of water from accumulator + mains would start by being heavily weighted to accumulator -> then 50:50 -> and finally all mains (i.e. back to 10 litres/min), once the accumulator depletes.

 

It's the amount of flow rate achievable during this process I'm trying to understand. I'm sure there must be a way to calculate it.

 

[tomcoleman]

from my understanding the shower will be fed from the accumlator and when that depletes it goes back to mains.

 

As the accumlator is pushing out to the megaflow at (whatever bar is set ) and when empty its flow & pressure is no more so mains takes over.

 

Mind you i have gone for a 300L version so should hold more then enough water for showers....

 

I'll let you know how i get on.

 

I dont know what pressure drop i get all i know is mains in is 2bar and showers arent dribbling they just arent lovley.

[tomcoleman]

ok boost a main all installed.

 

Mains in which is MDPE goes into 22mm copper with a check-valve, this then goes into 22mm>28mm into the inlet of the pump.

 

From the pump i have a 28mm > 28mm connection to the accumulator tank.

 

The outlet of the pump is then 28mm out reduced to 22mm which connects onto existing 22mm PRV which then goes off to feed megaflow and balanced cold.

 

Pressure on PRV gauge used to be 2-2.5bar and now reads 3.5bar (this is what i set it to)

 

 

[fezster]

On 26/05/2021 at 09:55, tomcoleman said:

ok boost a main all installed.

 

Mains in which is MDPE goes into 22mm copper with a check-valve, this then goes into 22mm>28mm into the inlet of the pump.

 

From the pump i have a 28mm > 28mm connection to the accumulator tank.

 

The outlet of the pump is then 28mm out reduced to 22mm which connects onto existing 22mm PRV which then goes off to feed megaflow and balanced cold.

 

Pressure on PRV gauge used to be 2-2.5bar and now reads 3.5bar (this is what i set it to)

 

 

 

 

I missed this post.

 

What is your shower performance like now?

 

Any pics of the pipework / prv / pump setup?

 

[tomcoleman]

shower performance has gone up by around 30% 

 

my PRV is set to 3.5Bar

 

the mains comes in from the street via a MDPE pipe which then goes into 28mm copper which then feeds directly to the accumulator pump.

 

The pump then pressurizes the black storage tank (as seen in photo) upto 6bar.

 

The pump is on a timer and set to come on 3 times a day (as its noisy even with damper matts and sound proofing)

 

It has made a difference as i said around 30% but its not worth the £3000 it cost.

 

The pressure of the storage vessel drops very quickly im trying to speak to the manufacture to see if it can be set to go upto 7-8bar so i have more pressure for longer.

 

On the top floor shower i renewed the pipe work from 15mm to 22mm this made no difference as the thermostatic mixer i guess still reduces everything to 15mm.

 

Dont get me wrong the shower "feels" stronger i just wish it lasted longer, in the rest of the house no real major difference on taps etc 

[fezster]

What's the pre-charge on the vessel? They are usually set to 1.5 bar below the charge pressure. The higher the pre-charge pressure, the less volume of water you'll have in the accumulator.

 

Out of interest, why not set it to 1.5 bar pre-charge/3 bar PRV? This should still give you plenty of dynamic pressure and should increase the volume of water available.

[tomcoleman]

On 23/07/2021 at 11:22, fezster said:

What's the pre-charge on the vessel? They are usually set to 1.5 bar below the charge pressure. The higher the pre-charge pressure, the less volume of water you'll have in the accumulator.

 

Out of interest, why not set it to 1.5 bar pre-charge/3 bar PRV? This should still give you plenty of dynamic pressure and should increase the volume of water available.

 

ive been emailing the manufacture for weeks on how to set the pressure via the pump. Theres no controls and says its "pre set" act factory i presume if i took the cover off there would be some type of USB connector but would need the software to adjust. Out the box its set to come on and charge at 4.0bar and switch off at 6.0bar thus storing 6bar of pressurized water in the vessel. 

 

The pressure drops rapidly from the vessel, for example on a full charged (charged to 6bar) if i have a shower for around 5-8mins it will drop below 4 bar then pump will turn on and try to start charging the vessel again if im showing in the window when the timer plug for the pump is on. 

[fareedboda]

Hi - just joined the forum. I'm using a Boost a main and yes, little information about them out there so I thought I would share some. 

I'm using a 250l GWS tank with it. It's fitted before a Harvey filter. I precharged to 2 psi below the cut in as per most web resources. Found that once I had exhausted the water there would be some hammering whilst it dropped to 1.7bar, my normal non boosted house pressure. 

 

Called the manufacturer and was told to put to 2.8bar pre charge to leave a 3.2 bar differenial. Did that and it's better but the water does exhaust in around 8 mins of a rain shower. But maybe that's accurate. Around 125l of water from my acc, 8x15l or so from the rain shower and I'm back to boost. 

 

Overall, pressure seems better and flow too. But I want to try a Dab, Stuart turner. The water doesn't blast out of the shower like a hotel. Combi boiler set up old 15mm pipework so maybe that explains it. 

 

Let me know your situation and we can get better and optimal performance. Thanks 

 

 

 

 

[GaryM]

On 28/08/2021 at 23:53, fareedboda said:

Hi - just joined the forum. I'm using a Boost a main and yes, little information about them out there so I thought I would share some. 

I'm using a 250l GWS tank with it. It's fitted before a Harvey filter. I precharged to 2 psi below the cut in as per most web resources. Found that once I had exhausted the water there would be some hammering whilst it dropped to 1.7bar, my normal non boosted house pressure. 

 

Called the manufacturer and was told to put to 2.8bar pre charge to leave a 3.2 bar differenial. Did that and it's better but the water does exhaust in around 8 mins of a rain shower. But maybe that's accurate. Around 125l of water from my acc, 8x15l or so from the rain shower and I'm back to boost. 

 

Overall, pressure seems better and flow too. But I want to try a Dab, Stuart turner. The water doesn't blast out of the shower like a hotel. Combi boiler set up old 15mm pipework so maybe that explains it. 

 

Let me know your situation and we can get better and optimal performance. Thanks 

 

 

 

 

There are some interesting systems here, as mentioned I just went for this simple DAB systems, DAB E.Sybox Mini 3.

It works really well to improve water pressure  for the whole house. It's very simple to install, just put  in your main water supply.

 

I had low flow around 10 ltr /s and low pressure 1.1 bar. It seems to help flow a little (although in theory it shouldn't )  but pressure is fantastic, I have at 2.5 bar and it instant as soon as you turn the tab.

 

I use a combination boiler  and now have great showers.   I've been using it for three years and highly recommend it.

 

[Adsibob]

On 30/08/2021 at 11:28, GaryM said:

I had low flow around 10 ltr /s and low pressure 1.1 bar. It seems to help flow a little (although in theory it shouldn't )  but pressure is fantastic, I have at 2.5 bar and it instant as soon as you turn the tab.

I'm now having to research this as we finally did a dynamic pressure test and my pressure drops from 2.8 bar to about 1.2 bar as soon as second tap is turned on. Plumber brought a little cup with him to measure flow rate and reckons it's only 11L/min which I found odd because I did an old fashioned test (using a 6L bucket) before we did our building works and got around 17L/min.

I'm also considering DAB systems, but my plumber has recommended one that comes with a 480 litre tank, called DAB E.Sytank. It's actually quite compact for a tank that size, because it's cuboidal rather than cylindrical and housed within some soundproofing casing, so the advertised dB is only 45dB. Expensive, but almost £2k less than boost a main. My builder is concerned that we don't have the structural strength in the floor to support something so heavy given that the unvented HW cylinder is going nearby and it is about 400kg. I need to double check, but I think the posis which support the HW cylinder are not the same posis that would support this E.Sytank. If I'm right about that, then he must be worried about the wooden beam that is attached to the wall from which the posis are hung, but that just seems odd. Now need to speak to structural engineer to see if he can find a solution, as not sure I have space for it elsewhere. 

Edited September 16, 2021 by Adsibob

[tomcoleman]

On 17/09/2021 at 00:21, Adsibob said:

I'm now having to research this as we finally did a dynamic pressure test and my pressure drops from 2.8 bar to about 1.2 bar as soon as second tap is turned on. Plumber brought a little cup with him to measure flow rate and reckons it's only 11L/min which I found odd because I did an old fashioned test (using a 6L bucket) before we did our building works and got around 17L/min.

I'm also considering DAB systems, but my plumber has recommended one that comes with a 480 litre tank, called DAB E.Sytank. It's actually quite compact for a tank that size, because it's cuboidal rather than cylindrical and housed within some soundproofing casing, so the advertised dB is only 45dB. Expensive, but almost £2k less than boost a main. My builder is concerned that we don't have the structural strength in the floor to support something so heavy given that the unvented HW cylinder is going nearby and it is about 400kg. I need to double check, but I think the posis which support the HW cylinder are not the same posis that would support this E.Sytank. If I'm right about that, then he must be worried about the wooden beam that is attached to the wall from which the posis are hung, but that just seems odd. Now need to speak to structural engineer to see if he can find a solution, as not sure I have space for it elsewhere. 

i was also concerned about weight as mega flow is next to vessel in the end it was on a load bearing wall and joist are new and thick, builder said it was ok so did it, been fine ever since.

[Nickfromwales]

On 24/07/2021 at 18:44, tomcoleman said:

 

ive been emailing the manufacture for weeks on how to set the pressure via the pump. Theres no controls and says its "pre set" act factory i presume if i took the cover off there would be some type of USB connector but would need the software to adjust. Out the box its set to come on and charge at 4.0bar and switch off at 6.0bar thus storing 6bar of pressurized water in the vessel. 

 

The pressure drops rapidly from the vessel, for example on a full charged (charged to 6bar) if i have a shower for around 5-8mins it will drop below 4 bar then pump will turn on and try to start charging the vessel again if im showing in the window when the timer plug for the pump is on. 

Accumulator vessel is undersized. 
A pre-charge of 1.5bar vs 6bar cutoff will see the diaphragm being exercised a heck of a lot further than I would ever specify in a design for any of my clients installations tbh. The upshot of this is a lot more % of stored pressurised water vs redundant air space in the accumulator, but it will massively shorten the lifespan of the diagram ( aka bladder ) too. 
I never fit less than 300L in a family home with a poor cold mains, and set it to accept 50-60% water ( max ) to give the vessel / bladder as long a life as possible.

The reason you run out of water so quickly and the pump starts up again under duress is down to incorrect specification alone. I would add at least another 1x accumulator of Dili mar or slightly bigger size to improve things.
The pump also has a limited lifespan and this cycling will ultimately see that needing changing sooner too. 
FWiW I have never fitted a charge pump to a mains, even ones where I can p**s quicker than the water mains, instead just fitting much bigger acc’s and leaving them to be pressurised off the static head of the cold mains instead. Works extremely well. 

In my experience of over 2 decades of installing these devices on multi-occupant dwellings with poor to very poor cold mains, I have not once fitted a pump to the cold mains, instead it’s just been down to specifying the correct size acc’s and the results have been excellent. 

[Adsibob]

4 hours ago, Nickfromwales said:

I have not once fitted a pump to the cold mains, instead it’s just been down to specifying the correct size acc’s and the results have been excellent. 

But surely the accumulator can only accumulate the pressure one has coming in from the mains supply? 

[dpmiller]

... which is the ultimate static pressure.

[Nickfromwales]

1 hour ago, Adsibob said:

But surely the accumulator can only accumulate the pressure one has coming in from the mains supply? 

Yup. The mains peaks out at around 04:00 and the use of a non return valve captures the available potential, usually north of 2.5bar sometimes as high as 4bar and that’s sat there ready to utilise for the days needs. What matters, is how much of it you stored.

 

[Adsibob]

2 hours ago, Nickfromwales said:

Yup. The mains peaks out at around 04:00 and the use of a non return valve captures the available potential, usually north of 2.5bar sometimes as high as 4bar and that’s sat there ready to utilise for the days needs. What matters, is how much of it you stored.

 

Okay, that definitely is a selling point of an accumulator. But what still confuses me is whether the DAB E.Sytank (details here), which is a 480L tank together with a clever pump is an accumulator plus a pump or is it not an accumulator at all? Because whilst an accumulator will give you really good mains static water pressure of about 3 to 4 bar all day (or at least until you use up the water in the accumulator) as far as I can tell, an accumulator will do absolutely zero for your dynamic water pressure if you are already dealing with a very low flow in the property. That's why I was looking at pumped systems. The DAB E.Sytank has a tank that appears to boost flow rates by 12 L/min, though I'm not entirely sure. It incorporates a pressure and flow sensor and an inverter. My understanding is that the pump inverter maintains a constant and stable pressure in the system by varying the speed of the pump motor to deliver the same pre-set pressure at the outlet regardless of how many outlets or appliances are in use, up to the maximum capability of the pump. So isn't something like the DAB E.Sytank going to be more effective than an accumulator of the same size tank?

[Nickfromwales]

OK, the DAB unit you linked is simply a pump that sucks water out of a A>B break tank ( a barrel basically ). Barrel runs dry, outlets 100% cease to flow. Major issue. 

Cold mains fills the tank via a float valve, so the same way water refills your WC, and the only water you can get is what is stored in the unit and then that's it.....zero ( until the very slow fill rate of the float valve refills the unit to the point where there is a useful amount of water back inside it so prob about 15-20 mins to recharge before the unit restores 'power' after depletion. Of course, you would train yourself to not get to that point eg understanding these restrictions and attenuating life accordingly, as you'd realise that still being covered in Timotei with not even a dribble coming out of the shower head is less than great...........let alone the subsequent 5 / 10 mins wait, or more, stood there in your birthday suit waiting for the magic to happen. That scenario is caused by that fact that the cold mains is actually then disconnected from your house plumbing and you are solely reliant on the rate that the float valve can refill that tank, the bigger system = longer wait for this "recovery". No ta.

 

With a 'passive' cold mains accumulator arrangement you always remain connected to the cold mains, regardless of however crap it may be, so even after the water stops blasting out you can still wash away the Timotei  

 

If you are a complete and total creature of habit the pumped systems can work, and for some obviously they do, but given you have to pay a lot more for the pumped system, plus you have to segregate the household plumbing to suit, ( WC's, outside taps, appliances etc should be teed directly off the mains with a system that can 'run dry' plus you want to reserve the stored water for bathing only, ideally ), then a retro-fit is a logistical nightmare. Either that, or you have to size the pump / tank system to deal with everything wet plumbed being connected to it, and completely reliant on it. No ta.

 

I fitted 2x 180L acc's into a house situated deep into the greenbelt, where you could literally pee faster than the water came out of the hot taps, and again the results were staggeringly good. I swapped out their UVC to a Vaillant 937 hi-flow combi, and they were over the moon with it. Even when the acc's ran very low, they could still realise that was going downhill and finish up in the shower sharpish, whereas with the pumped systems the water just completely stops and you're done. Some pumped systems feature a small acc so have a little bit of a warning but not much, and they are of course still reliant on the float valve fill rate which ( if this is a dwelling with crap cold mains flow, hence the system needed fitting to resolve that issue ) that can be some time indeed.

 

On another 6 bed dwelling, with 3 bathrooms ( 2 large electric showers and 1 thermostatic mixer, plus 1 bath ) utility, kitchen etc plus cloak WC, I fitted a 300L acc to the cold mains ( segregation observed ) and demonstrated to the client how effective the system was. They reported never being able to turn the 10.5kW electric shower up to the max setting due to it being so massively reliant on a strong, maintained cold feed, so they often used that on setting 1 out of 3. They said there was never a day when they cold use the two electric showers simultaneously.

For my demonstration, I allowed the acc to charge overnight and then walked the customers through the house with both of the electric showers running on max settings, then I flushed each WC in each of the bathrooms, electric showers remained 100% unaffected, then I left those running and we went to the master bathroom where I removed the 3rd electric shower and converted it to a wet unit. THat was also running throughout my demonstration. They were completely gobsmacked. "Result!"

 

THEN......drumroll please.......I left all that running, time elapsed was about 3 -4 mins at this time from starting the demo, showed them the kitchen taps worked full blast also, then the utility, and then showed them that the cold mains stopcock was shut OFF during the demo  We got to nearly 7-8 mins before the acc started to give up. Even with the 2 electric showers then shutting down, the mixer shower still gave hot water output sufficient to get the job done. The DHW device was a thermal store.

 

Consultation, specification and correct design ans execution guarantee results, simples ?  

[fezster]

On 18/09/2021 at 23:56, Adsibob said:

an accumulator will do absolutely zero for your dynamic water pressure if you are already dealing with a very low flow in the property

 

That's not right. Boosting dynamic pressure (and therefore flow rate) is precisely what an accumulator does (it accumulates water and releases it as required).

[Adsibob]

1 hour ago, fezster said:

 

That's not right. Boosting dynamic pressure (and therefore flow rate) is precisely what an accumulator does (it accumulates water and releases it as required).

Maybe I didn't express myself very well. The point I was trying to make is that if your maximum pressure is X, storing it in an accumulator won't increase that. All it will do is make sure you don't fall below X whilst there is still water in the accumulator tank, in theory at least. But in practice, that sounds dodgy to me. Once water is released from the accumulator tank, won't Boyle's law dictate that the pressure will fall as essentially the extra space created by the release of water will result in extra volume for the remaining water. Now of course one needs to take into account that the space can be refilled by the mains water as it is being used. But without a pump, that will only be coming into the accumulator tank at mains pressure. So if mains pressure is 3.5 bar in the middle of the night, but 2 bar during the peak usage times in the day, then whilst the accumulator can accumulate pressure at 3.5 bar in the middle of the night, if usage in the house is a couple of showers at 7am (time of peak demand in my street) then whilst those showers are running and the accumulator is emptying, it will only be refilling at 2bar, not 3.5 bar. So overall, won't the pressure of the accumulator tank fall to a weighted average of the pressure in the tank before the showers and the mains pressure at the time the tank is refilled (weighted by reference to the proportion of the tank that is being refilled).

I'm probably missing a lot of important details, but that's my take on it as layman who thinks he understands how Boyle's law works.

Edited September 21, 2021 by Adsibob

[fezster]

I think your thinking is on the right lines, but I'd add the following:

 

1. Overnight (or during day if you have a high static mains all day) the accumulator will equalize with the static mains pressure (eg. 3.5 bar). The volume of water in the accumulator will be dictated by the difference in pre-charge and static mains.

 

2. When an outlet is running, the dynamic pressure from the mains will drop, depending on the flow rate available and the pipe run to the outlet. Eg. from 3.5 bar to 1.5 bar.

 

3. The accumulator pressure now exceeds the dynamic pressure, so water will exit the accumulator boosting the dynamic pressure initially to 3.5 bar. This will be a curved graph where initially the boost is much bigger and then slows over time, until eventually the accumulator pressure matches the incoming mains dynamic pressure, and you no longer get any additional flow rate.

 

4. So in the above, your outlets will gradually decrease from 3.5 bar down to 1.5 bar, depending on the flow rate required and the capacity of water in your accumulator. This should be sufficiently sized to give adequate flow rate for the duration of one or multiple showers.

 

 

[Nickfromwales]

11 minutes ago, fezster said:

I think your thinking is on the right lines, but I'd add the following:

 

1. Overnight (or during day if you have a high static mains all day) the accumulator will equalize with the static mains pressure (eg. 3.5 bar). The volume of water in the accumulator will be dictated by the difference in pre-charge and static mains.

 

2. When an outlet is running, the dynamic pressure from the mains will drop, depending on the flow rate available and the pipe run to the outlet. Eg. from 3.5 bar to 1.5 bar.

 

3. The accumulator pressure now exceeds the dynamic pressure, so water will exit the accumulator boosting the dynamic pressure initially to 3.5 bar. This will be a curved graph where initially the boost is much bigger and then slows over time, until eventually the accumulator pressure matches the incoming mains dynamic pressure, and you no longer get any additional flow rate.

 

4. So in the above, your outlets will gradually decrease from 3.5 bar down to 1.5 bar, depending on the flow rate required and the capacity of water in your accumulator. This should be sufficiently sized to give adequate flow rate for the duration of one or multiple showers.

 

 

Spot on. 

[Nickfromwales]

1 hour ago, Adsibob said:

Now of course one needs to take into account that the space can be refilled by the mains water as it is being used. But without a pump, that will only be coming into the accumulator tank at mains pressure.

Nope. 
The mains ‘passes’ the accumulator and goes direct to the outlet. The potential stored in the accumulator exits the vessel to fortify flow. When the outlet closes, mains starts to recharge the accumulator again. 
Mains will never enter the accumulator until it’s own potential is lesser than the stored potential. 
Trust me, this works very well. You just need to size the accumulator for your specific requirements. 
For the rotund Welsh tenor, Paul Potts, we fitted 2x 500’s to suit the demand. They went in the garage with a 500L UVC. With the job I mention above with the electric showers I fitted a 300L in the attic.