Water Softener recs for maximising flow rate

[Adam2]

Seems hard to get real info on this topic so asking you enlightened people ?

 

Manufacturers eg BWT quote things like max flow rate but don't say what the input flow rate needs to be to achieve that meaning you can't easily compare the options.

 

Is there likely to be much difference across Harvey / BWT / Kinetico in terms of their impact on flow rates? Should I just go for one with min 22mm connections. Or, would a single vs double chamber one have an impact on flow rates?

 

I'd like to maximise the flow rate from my mains supply so looking at softeners with larger connections eg BWT WS555 model with 22mm connections that seems quite good value and is stated as suitable for 4+ bathrooms. Only £645 which seems pretty good but flow rate says up to 22.7l/min vs others stating up to 57/80l/min such as Kinetico Maxi and Harvey XL1

 

 

 

 

 

[tonyshouse]

Twin cylinder, first or last for me, if you need  more flow get two in parallel 

[Dan F]

29 minutes ago, Adam2 said:

Seems hard to get real info on this topic so asking you enlightened people ?

 

Manufacturers eg BWT quote things like max flow rate but don't say what the input flow rate needs to be to achieve that meaning you can't easily compare the options.

 

Is there likely to be much difference across Harvey / BWT / Kinetico in terms of their impact on flow rates? Should I just go for one with min 22mm connections. Or, would a single vs double chamber one have an impact on flow rates?

 

I'd like to maximise the flow rate from my mains supply so looking at softeners with larger connections eg BWT WS555 model with 22mm connections that seems quite good value and is stated as suitable for 4+ bathrooms. Only £645 which seems pretty good but flow rate says up to 22.7l/min vs others stating up to 57/80l/min such as Kinetico Maxi and Harvey XL1

 

Also look at https://greatwater.co.uk/. Couple of models with 1-inch connections and pretty good flow rates.  Cheaper than Harvey and Kinetico AFAIU.

 

 

[Nickfromwales]

Twin cylinder just keep soft water flowing during regeneration, whereas a single will give hard water through to the house whilst regenerating. 

[Adam2]

3 hours ago, Dan F said:

Also look at https://greatwater.co.uk

Cheers will do

[Adam2]

4 hours ago, tonyshouse said:

Twin cylinder, first or last for me, if you need  more flow get two in parallel 

Ha ha ha - they are so expensive ? but I like the thinking. I'd be happy just having real stats eg 3 bar at 30l/sec will deliver 3 bar at 28l/sec - it's not so hard is is ( well aside from the water of course ? )

[Adam2]

3 hours ago, Nickfromwales said:

Twin cylinder just keep soft water flowing during regeneration, whereas a single will give hard water through to the house whilst regenerating. 

Which if is the only benefit of a twin tank I guess a small amount of hard water isn't such a big deal if it means it's a lot cheaper to get single

[tonyshouse]

I don’t see the softener as the limiting factor, noses, taps and elbows will all slow flow so use 22mm full bore isolators 28 or 22mm short as pos hoses or plumb in with 28mm tube

what size is the mains and distribution pipe work 

[Nickfromwales]

15 hours ago, Adam2 said:

Which if is the only benefit of a twin tank I guess a small amount of hard water isn't such a big deal if it means it's a lot cheaper to get single

If you buy one with an electronic brain vs hydro-mechanical, you can move the regen to 03:00 so it's done when you're fast asleep  

[Adam2]

38 minutes ago, tonyshouse said:

I don’t see the softener as the limiting factor, noses, taps and elbows will all slow flow so use 22mm full bore isolators 28 or 22mm short as pos hoses or plumb in with 28mm tube

what size is the mains and distribution pipe work 

Yes we've tried to keep that all as big as reasonably possible hence not wanting to potentially undermine those efforts with the softener. From meter it's 35mm into plant room then 28 then 22 for most distribution of any importance with 28 going to top floor (furthest away from plant room) before getting smaller. UVC with 28 fittings. 

[tonyshouse]

Nice, how long is the 35mm pipe run?

 

can you do a flow test on the installed pipe work. Basically open a tap for 90 secs, while running shove bucket under it and time to full gives flow rate , volume of bucket/time = l/s 

[jack]

Be careful to note your unit's installation details.

 

I didn't check ours until long after the plumber had left, and his team didn't follow the instructions.

 

If you have high incoming water pressure, then the trick is to put a first PRV before the softener to bring the pressure below the softener's maximum operating pressure, and then a further one after it to bring the pressure down to what the house is designed to operate at. 

 

For example, we have nearly 6 bar incoming. We should have a ~5 bar (6 bar being the max the softener runs at) PRV on the incoming main, and then a 3 bar PRV after the softener.

 

Even if your pressure isn't that high, you should still put the main PRV after the softener, not before.

 

Here's the picture from the manual:

 

 

 

Unfortunately, we have only a 2(!) bar PRV on the incoming before the softener, which does leave us with sub-optimal water pressure if there's a shower on, the washing machine is refilling, and the water softener decides to regenerate at the same time. 

 

When I asked why they installed such a low bar PRV, I was told that they wanted to make sure the water pressure didn't look too powerful if the building control guy turned the taps on!  

[Adam2]

From the street meter it's about 25m to the plant room - gentle curve in the pipe downhill where we end up with 3bar static pressure

Good idea now to do the flow rate test and I guess we could easily enough do a dynamic pressure test as well - plumber is back in tomorrow.

 

I saw on the GreatWater website that they claim 31 l/min at 1bar on the 1400 model and 45l/min at 1 bar on the 2300 model - see what pricing is like for them, looks like electric operated so can get recharge outside of normal shower times.

 

@jack thanks for that - yes that sucks. As we have 3 bar and the softener we're looking at (probably like others) is OK with 5bar incoming I'll see what the plumber says- either no PRV or just a 3bar one after the softener. Actually having said that we have our hard water supplies of course before that so may be useful to have a PRV on the incoming or on the hard water manifold. 

 

The plumber enjoyed making my manifolds - he didn't like my Hep2O idea in the plant room and wanted it to look sharper - above ceiling level copper transitions to plastic so we can have nice ceiling cut-outs around the straight pipes.

 

 

[fezster]

On 08/02/2022 at 16:21, jack said:

Be careful to note your unit's installation details.

 

I didn't check ours until long after the plumber had left, and his team didn't follow the instructions.

 

If you have high incoming water pressure, then the trick is to put a first PRV before the softener to bring the pressure below the softener's maximum operating pressure, and then a further one after it to bring the pressure down to what the house is designed to operate at. 

 

 

What is the advantage in doing this? I'm not trying to be facetious here - but based on my understanding, having 2 PRV's like this is pretty pointless, and in fact detrimental because the pressure drop across the PRV itself is significant, so you're compounding that by having two of them.

 

Taking your example of 6 bar incoming (I assume this is static?) with a 5 bar PRV before the water softener. When you open outlets, the dynamic pressure will reduce as the flow rate increases, depending on pipe size. Let's say it drops to 4 bar (which would be significant at > 20 L/min, but for arguments sake). The pressure drop across your water softener takes this down to 3.5 bar. Your second PRV at 3 bar after the water softener would reduce this down to 3 bar. So you have 3 bar going to your outlets at 20 L/min.

 

Now let's remove your 6 bar incoming PRV and replace it with a single 3 bar PRV (remove the PRV after your softener). At 20L/min, your incoming pressure is 4 bar. The 3 bar PRV will reduce this down to 3 bar. You have a 0.5 bar loss through your water softener, but the 3 bar PRV will maintain 3 bar, because you have sufficient pressure behind it to do so. So you have 3 bar going to your outlets at 20 L/min.

 

The end result is the same - except you're not losing additional pressure through a second (unnecessary, highly restrictive) PRV.

 

Of course, the PRV itself, in either scenario, should be as large bore as possible to maintain adequate flow rates.

 

[fezster]

On 07/02/2022 at 17:55, Adam2 said:

Seems hard to get real info on this topic so asking you enlightened people ?

 

Manufacturers eg BWT quote things like max flow rate but don't say what the input flow rate needs to be to achieve that meaning you can't easily compare the options.

 

Is there likely to be much difference across Harvey / BWT / Kinetico in terms of their impact on flow rates? Should I just go for one with min 22mm connections. Or, would a single vs double chamber one have an impact on flow rates?

 

I'd like to maximise the flow rate from my mains supply so looking at softeners with larger connections eg BWT WS555 model with 22mm connections that seems quite good value and is stated as suitable for 4+ bathrooms. Only £645 which seems pretty good but flow rate says up to 22.7l/min vs others stating up to 57/80l/min such as Kinetico Maxi and Harvey XL1

 

I have a Tapworks AD11. It has 22mm inlets/outlets and I believe they quote >50L/min. Having a dual chamber seems unnecessary to me, given the softener recharges overnight, with no outlets running.

[jack]

1 hour ago, fezster said:

Taking your example of 6 bar incoming (I assume this is static?) 

 

Yes.

 

44 minutes ago, fezster said:

What is the advantage in doing this? I'm not trying to be facetious here - but based on my understanding, having 2 PRV's like this is pretty pointless, and in fact detrimental because the pressure drop across the PRV itself is significant, so you're compounding that by having two of them.

 

The manufacturer is pretty clear about positioning the 3 bar PRV after the softener, even if you don't have 6 bar incoming:

 

51 minutes ago, fezster said:

Now let's remove your 6 bar incoming PRV and replace it with a single 3 bar PRV (remove the PRV after your softener). At 20L/min, your incoming pressure is 4 bar. The 3 bar PRV will reduce this down to 3 bar. You have a 0.5 bar loss through your water softener, but the 3 bar PRV will maintain 3 bar, because you have sufficient pressure behind it to do so. So you have 3 bar going to your outlets at 20 L/min.

 

My understanding is that if you have a 3 bar PRV on the incoming, then it's trying to maintain a maximum of 3 bar at its output - that is, between it and whatever restriction is downstream of it.

 

In the scenario you set out above, the 3 bar provided by the PRV will be reduced at the softener's output, rather than maintained as you suggest. Assuming a nominal 0.5 bar loss through the softener, then the most you'll get at its output is 2.5 bar. 

 

My understanding could well be wrong though.

[fezster]

1 hour ago, jack said:

My understanding is that if you have a 3 bar PRV on the incoming, then it's trying to maintain a maximum of 3 bar at its output - that is, between it and whatever restriction is downstream of it.

 

In the scenario you set out above, the 3 bar provided by the PRV will be reduced at the softener's output, rather than maintained as you suggest. Assuming a nominal 0.5 bar loss through the softener, then the most you'll get at its output is 2.5 bar. 

 

My understanding could well be wrong though.

 

The PRV will try and maintain 3 bar regardless. The pressure at any given point in the system with water flowing through it (notwithstanding pressure loss due to change in height), should be the same. So in your example, if there is 0.5 bar pressure loss due to the softener, but the incoming mains can provide 3.5 bar, then the PRV will open to maintain 3 bar downstream of it.

 

It is odd, though, that the manufacturer instructions say otherwise.

[dpmiller]

PRV will control dynamic pressure at it's point of fitment. The softener's restriction is dynamic, not static. So static pressure will be the same for all past the PRV yes, but once there is flow then you'll lose some part of that 0.5 bar everywhere after the softener

[fezster]

I'm not an expert, so happy to be corrected. However, I have done a lot of reading on this topic and my testing on my own setup as well seems to suggest (to me!) what I described above. 

 

As an example. My incoming static pressure is up to 5 bar during off peak. Measured using a gauge at an outside tap. My prv (with gauge) is set to 3 bar. If I run a shower (approx 15 to 20 l/min), the gauge drops to 2.5 bar dynamic. If I increase my prv to 4 bar, I still get 2.5 bar dynamic. If the pressure loss was downstream only, I'd have expected the prv to have a fixed drop across it (ie. 0.5 bar). 

 

However, my understanding of it may be incorrect. That's what I've posted - to get input from more knowledgeable people. 

[Adsibob]

The twin tank is a lot of marketing nonsense in my opinion. With a good single tank system, you can set it to regenerate at 3am. So for 20 minutes at 3am you will have no water softening. You will still have water though! 
This is the system I went for:

https://www.eastmidlandswater.com/water-softener-ems15-blue-meter-controlled-eco-water-softener-ems15/424

 

not cheap, but with the 1” fitting option gives you a very high flow rate. This should be higher than the Harvey’s or Kinetico range at this price point.

 

 Yes it dos have to be plugged in, but uses very very little power.

 

 

[Gone West]

12 hours ago, Adsibob said:

With a good single tank system, you can set it to regenerate at 3am.

I had a similar softener to that many years ago. We used to have a lot of power cuts and unfortunately it lost the time setting with every power cut. If I didn't remember to reset the time it would regenerate unexpectedly. It was less than half the price of yours though so I expect yours has a rechargeable battery in it.

[Dan F]

@fezster Is your PRV dynamic or static?

 

The 2.5bar dynamic pressure you see is due to losses either before or through PRV. The best way to confirm this would be to test dynamic pressure just before PRV.

 

The fact your dynamic pressure doesn't increase above 2.5bar when you increase PRV to 4bar simply points to a limitation in dynamic pressue of supply IMO.

 

The pressure drop in the PRV is dynamic pressure before - dynamic pressue after, not the difference between static and dynamic values.

[Adsibob]

25 minutes ago, Dan F said:

Is your PRV dynamic or static?

I didn’t know there was an option to have a dynamic one. What are the pros and cons?

[Dan F]

1 hour ago, Adsibob said:

I didn’t know there was an option to have a dynamic one. What are the pros and cons?

If your supply is 5 bar and you have a 3 bar static PRV then dynamic pressue after PRV will be impacted by pressure loss through PRV and be lower than 3 bar.  On the the other hand, if you have dynamic PRV set to 3 bar then, as long as supply can support it, dynamic pressure  after PRV will be 3 bar regardless of the flow rate.

 

Dynamic PRV's sound better, but the downside is that static pressure isn't limited and can creep up so they aren't suitable for some applications.

 

(That's how i understand it anyway)

[fezster]

My PRV is "drop tight", so the static pressure won't creep up. I'm not sure what a "dynamic prv" is? Mine is a Reliance 28mm Predator 315i.

 

I do agree with your point that the dynamic pressure may be limited by the incoming supply pipe.

 

What I'm not sure about is whether the dynamic pressure can ever differ anywhere in a pipe run - ie. If you have a 100m pipe with 20l/min flowing through it, then surely the dynamic pressure is the same at any point in that pipe run? If that is true, then having a prv at any point in that pipe run will surely not matter. The pipe run itself has a pressure loss, just as any fitting or water softener has losses, and therefore a prv before or after a fitting/softener shouldn't affect the overall dynamic pressure the pipe run is capable of providing. Not sure if I've explained that very well, but that's how I make sense of it in my head.