[Gary Mabbott]

Hi Guys,
Need a little advice. Been WFP for years making do with the Old Merlins to fill up my onboard 500 tank.
I have a psi of 45 & a mains TDS of 320, typical South East. Use 500 litres a day.
Need to upgrade as impending water meter & a 1 to 5 pure to waste is stupid to say the least. Was thinking of a Merlin PRF from Gardiners or pay a bit more & get a HF5 ultra low pressure 4040 set up. The only thing is I have been told that because of my hard water I would still get a high pure to waste ratio with the 4040?
Any advice appreciated,
Gazza

[lozsing]

I have very similar circumstances to you and use a low pressure 4040 running at 60/40 split.

[Gary Mabbott]

Thats good to know, is yours using just tap pressure or have you a booster pump as well.

[andyM]

I have a tap TDS of around 280ppm and use a 4040 HF4 membrane  with a Clarke booster pump.
I'm on a water meter so run mine at 50/50.

[lozsing]

Thats good to know, is yours using just tap pressure or have you a booster pump as well.

tap pressure
membrane lasts me 2.5/3 years

[Gary Mabbott]

That's pretty good how long would it take to fill 500 litre and what membrane is? it heard the h5 is pretty good

[mjm]

hi gary     I have the     hf5     2400 gpd   pumped system from pure freedom  iam on a metre    and the tds is 300    the machine is in a garage   an the tap pressure is 30 to 40 psi    15meres  away from the machine    it fills my static 250 tank in 10/15mins     
waste 50/50 pure    the good thing  is about the hs5  is you can use it with low pressure and high pressure  iam moving soon so I don't know the pressure in the new place     if you don't  want the 2400    get the 900  pumped  I have had the system a week    going from 450 pumped  is a shock  at first 

[Gary Mabbott]

Hiya,
I see that Lotzing doesn't use a pump with his low pressure system, how long to fill a 500 tank this way?
At the moment it takes me about 8 to 10 hours to fill my tank with my merlin with a lot of waste!

[lozsing]

Hiya,
I see that Lotzing doesn't use a pump with his low pressure system, how long to fill a 500 tank this way?
At the moment it takes me about 8 to 10 hours to fill my tank with my merlin with a lot of waste!

about 6 hours to fill a 400l tank

[Gary Mabbott]

Thanks for the advice guys. I will probably go for the pumped system as the difference in the fill rate is amazing.
I presume if it only takes 30 minutes to fill a 500 tank don't really need a shut off solenoid as easy to monitor. At the mo I have a ballcock in the tank which cuts the merlin when full, saying that for some reason the waste water still flows!!!

[p1w1]

Thanks for the advice guys. I will probably go for the pumped system as the difference in the fill rate is amazing.
I presume if it only takes 30 minutes to fill a 500 tank don't really need a shut off solenoid as easy to monitor. At the mo I have a ballcock in the tank which cuts the merlin when full, saying that for some reason the waste water still flows!!!

I very much doubt your gonna fill a 500 lt tank in half and hour with 1 40-40 membrane and a booster pump, you need to be making about 16lt a min of pure alone not taking into account your waste ratio.
You can run a 40-40 at any waste ratio you like but you need to find the balance of making the pure water and not overworking your membrane to make it last and get the best out of it.
At 320ppm from the tap you definitely dont really want to be going any lower then 50/50 if it was me i would be running it at 60/40 waste to pure.
My tds averages at about 570-590 and i run a bit less than 70/30 my membrane has been running for 15 months now and it still produces 14ppm before di vessel (the same as when i first installed it) making about 500lt-600lt of pure a day( i am not on a water meter).
Ideally you also need to check your tap flow rate first when using a booster pump as most need a minimum flow to work properly, having said that most mains flow are good enough but best to check first to be on the safe side.

[Spruce]

Thanks for the advice guys. I will probably go for the pumped system as the difference in the fill rate is amazing.
I presume if it only takes 30 minutes to fill a 500 tank don't really need a shut off solenoid as easy to monitor. At the mo I have a ballcock in the tank which cuts the merlin when full, saying that for some reason the waste water still flows!!!

It will be an issue with the shutoff components inside the Merlin.

My 4040 with a HF5 membrane at 50 psi and 50/50 pure to waste ratio delivers 2 liters of pure per minute, no booster.

Once you go to booster pumps then you have to buy an expensive contoller that will switch the booster off at the same time as the solenoid valve is triggered off.
Or you need to invest in a Machine Mart booster pump that has a electronic controller which shuts the pump of when the flow to the booster is cut.

https://www.machinemart.co.uk/p/cbm240e-1in-multi-stage-230v-booster-pum/

It gets rather complicated and expensive.

[andyM]

If you're getting a Booster Pump then why not get a HF4 membrane?
The (Axeon) HF4 is around £50 cheaper than the HF5.

[martinw]

you will get around 4lpm  from boosted 4040 to 100psi. 60/40 waste/pure 8-9ppm hf4 from 320 ppm ish  input
Merlin will need booster pump anyway to get the best out of it.