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whole house pump - Stuart Turner Mainsboost Flomate MBF 12?

Discussion in 'Plumbing and Central Heating' started by Sup9, 14 Jul 2019.

  1. Sup9

    Sup9

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    I'm getting about 8L/m flow at the kitchen tap and for the shower, at peak hours it's only better than dripping. So I'm looking to install a whole house pump, ideally I can add the pump directly to the incoming mains so I don't have to use stored water.

    I had the gravity heating system then installed unvented cylinder so now the hot water is closed loop but for heating I still have a water tank in the loft.

    I'm looking at the ST Flomate MBF12 which is designed to draw 12L/m from the mains so legally it's oaky to install on to the mains directly.

    I was under the impression that if pump is installed as whole house pump, the pump flow will split for hot and cold water? so can I still expect 12L/m from shower head if nothing else is using water? If I add water softener, should I install before or after the pump and what impact on flow/pressure should I expect?

    Or would I be better off with the Flomate MBF 60/80 which comes with a pressure vessel?
     
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  3. Madrab

    Madrab

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    You had an unvented cylinder installed on an 8L/Min cold mains? That was a really bad idea and whoever installed that should be shot.

    A whole house pump will definitely help but it's still not the best. It will have better dynamic performance and it should sustaining the 12L/Min at multiple outlets better than the mains. The pump is installed on the mains where it enters the house so the pump supplies both hot and cold systems.

    You really need to upgrade your mains supply though, if it can be.
     
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  4. Sup9

    Sup9

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    Thanks Madrab! Your post got me thinking and I remembered that before the installation the guy actually tested the water flow from garden tap! So I measured it again, just now, from garden tap I'm getting 16L/m, kitchen tap 8L/m, bath tube tap 9L/m. Looks like my taps/shower head is high pressure type that restricted the flows, so the pressure is more of a problem I guess.

    ST MBF 12 would not be a good pump for me as it will restrict to 12L/m, and I think if the pump is capable of more than 12L/m I can not connect to mains directly (so I can't get a 16L/m pump just for pressure)?
     
  5. Madrab

    Madrab

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    If you are getting 16 L/min at least at the mains then no, a pump will not help. Regs dictate that there will be no more than 12 L/min at a domestic mains. The difference is that a pump would have enough torque to keep a dynamic pressure delivery at a higher rate.

    You'll probably have aerators on your taps that will reduce flow at the bath and sink as they don't really need much more than your getting.

    If those are typical deliveries though through the taps then I'd be looking at the shower's filters, head & hose first, then the shower itself as it should be delivering more than a trickle. If they're all ok then you'd need to work your way back through the system.
     
  6. Keithmac

    Keithmac

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    We fitted a Salamander Homeboost to our house (mains pressure down our whole street is poor!).

    Made a massive improvement to the shower.

    There flow and pressure to consider, maybe take some pressure measurements?.
     
  7. Sup9

    Sup9

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    Checked the shower head and took off the filter at the shower head inlet, also removed the non-return valve of the mixer's outlet (both hot and cold water inlet 's NRV are still there), bit better on the flow but making enough difference.

    But I checked the spec of my mixer and it's 25L/min at 3 bar, so I bought a new mixer and delivered today, it's 42L/min at 3 bar but when installed still not much difference, maybe 0.5-1L/m better.

    If I can't get a direct fitting pump maybe I should get one of these with a pressure vessel? I 'm also thinking of adding a water softener so I think a pump is probably still needed as I'd expect the water softener will impact the flow?

    Had a quick look of the Salamander pump and it looks like a similar product to the ST pump I was looking at, do you know what pressure are you getting after installed the pump? I bought a pressure gauge and I'm getting 2.4bar which I think is not too bad?
     
  8. Keithmac

    Keithmac

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    It says 1.5bar but I think this will be on top of supply pressure, basically it aims to supply 12l/min through any open tap/ showerhead etc.

    It's electronic/ solid state, has various sensors inside the unit. You can hear it adjusting the turbine speed depending on conditions.

    2.5 bar static pressure is good, depends what happens when the shower is in operation though?.

    I can't deadhead the Homeboost to check static pressure as it will shut down (assuming tap etc is turned off).

    You have pressure and flow rate to deal with when the bath/ shower etc is being used. A good flow through a large 3/4 bath tap is easier than being forced through a restrictive shower head (required more pressure to maintain the same flow rate as bath tap..).

    Our Homeboost has been faultess, very well engineered piece of kit (think we've had it 3 years now?).

    Put up with crap supply for 10 years and it's night and day different!.
     
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  9. Madrab

    Madrab

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    A whole home boost pump (regardless of manufacturer) will deliver a constant pressure and 12L/Min dynamic if the mains flow drops below that level. If the flow is higher than that the pump will not run

    You need to do a dynamic pressure and flow test 1st before going out and buying expensive bits to try and sort it. Static pressure isn't really relative to your issue. Run 1 then 2 outlets when the pressure gauge is connected, how much of a pressure drop is there? Then you need to test at the outlets open pipe to see what the difference is.

    You need to find out where the baseline of the system is before looking at what needs to be done to fix it.
     
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  11. Sup9

    Sup9

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    Garden tap is the only one have over 12L/m flow, all the rest is about 8-9L/m. That's because the garden tap is basically a ball valve, all other shower mixers and taps are more restricted.

    I only have the Silverline mains pressure gauge for all the testings:
    https://www.amazon.co.uk/gp/product/B06XY8WPYS/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

    I connected the gauge on the shower mixer outlet (closed), opened bath tap in the same room, then opened the shower mixer and I'm only getting 0.3 bar. Then I connected the gauge to the bath tap, opened the shower mixer, then bath tap, it's 0.2 bar at the bath tap.

    So if my measure method is correct for dynamic water pressure, then 0.2-0.3 bar is all I'm getting....:(

    So am I right thinking if I install a pump at the mains, it add 1.5 bar or what ever it's designed to add to my dynamic pressure, then will limit the flow at 12L/m at the pump. If the dynamic pressure it enough, can I expect 12L/m from my shower head too?
     
    Last edited: 19 Jul 2019
  12. Sup9

    Sup9

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    Thanks! I think the dynamic pressure is my issue, with current 8-9L/m from the shower head, if I can get 12L/m out of it with a pump I think it's quite a noticeable improvement. But will do more testing and questions before deciding what type of pump I'm getting.
     
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  13. snb

    snb

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    i have fitted loads of both these types of pump.
    the salamander is a little quieter. they will both still pump whenthe volume from the mains being drawn is over 12lt/per min and increase the pressure by about 1 bar. if the mains volume is below 12lt/min then they will suck in from the main and give you a minimum of 12lt/min. I have never experienced them switch off unless the flow rate has stopped or they have boosted the pressure above about 3.5bar.
     
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  14. Madrab

    Madrab

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    Apologies, wrong choice of words .... the pump won't stop, it goes into idle mode so it's doesn't restrict the mains flow. As the OP has mentioned there is 16L/Min @ the garden tap, then if he is getting at least that @ the main, the pump will stay in idle and won't actually boost the mains.
     
  15. SalamanderPumps

    SalamanderPumps

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    Good morning,
    Just reading through your post and wanted to pass my thoughts on, if you are getting 16L/m naturally through your outside tap yet only around half of this from internal appliances, I would assume that these are rather restrictive, in which case no matter what option you choose, it might not help considerably.
    However, I think you mentioned you were getting 2.4 bar standing pressure which falls dramatically as a working pressure (which is expected to a certain extent) so flow seems to be the main requirement here.
    Have you considered accumulators? There are two styles available, a pumped version and an unpumped version. The unpumped version stores mains pressure cold water at the highest achievable pressure at a period of low demand, typically overnight, which is held in the vessel by means of a non-return valve. The pressure is held against a pre-charged air pressure in the vessel, helping the water be forced out when demand occurs. This may be suitable for you if you are getting a standing pressure of 2..4 bar which would be enough to fill the accumulator. The other version, pumped, will use a pump to fill the AccuBoost vessel where sufficient pressure is not available at a rate of no more than 12 LPM.
    Both versions then discharge the water into the system at a higher pressure but also a higher flow. The down side is the space requirements for the units as they can be substantial depending on how much stored water is required to meet the requirements of the property. As a general rule, the quoted size is typically 50/50 air/water (slightly less water) so a 300 litre vessel would hold just less than 150 litres of water.

    Just some food for thought.

    cheers

    Ken
     
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  16. Sup9

    Sup9

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    Hi Ken,

    Thanks a lot for your reply, sorry for the late response as I just came back from holiday.

    I was also thinking that my system is somehow restrictive and I though it was the shower mixers so ordered the low pressure mixer but it was only marginally better. So not sure what is restricting the system.

    My original system was the gravity type so had a huge water tank in the loft, when I had the unvented cylinder fitted, I was surprised by the brown water from the bottom of the water tank so never wanted another in the system. I had a quick look at the pressured accumulator with pump, but I am very restricted in terms of space, would it help if I install one say 80L accumulator? It's about 40L pressured water maybe good for one quick shower? if the accumulator runs out of water I'd still get 12LPM at least so still best than my 8LPM?

    I'm thinking 80L accumulator because of the size but also 40L will be consumed quickly then recharge so it's like a huge pipe, less change of building up scales etc?
     
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