[john tomkins]

Hi,
I'm in the process of looking to buy all equipment for starting WFP, my question is should I go for a lower output RO Water Processor
and have it running all day or do any of you stump up for say a Merlin to get the job done in a few hours?
I'm assuming the say 300lpd figure is continuous running? but if its a van 250ltr system then you're not at home all day then you cant produce required amount or am I barking up the wrong tree.
Additionally should something go wrong and you find you dont have enough produced water at the start of the day do you have any back up for the situation?
Thanks for any answers.
John

[simbo]

Answers woul help me also, would ideally like to fill straight into van tank but have option of filling up on site if running low, what would i need for say 400ltr tank to start with bigger capasity if needed, this is a future question as bussines growing an need to keep upgrading
ps never thought i would use wf so much!!! simb0

[JM123]

Basically if you go for a merlin it will cost more - plus you need a di vessel as well.  The advantage of a merlin is that it will produce water very quickly.  Work out how much water you need (2ltrs per £earned) then go from there, your tap tds and pressure will affect output, don't settle for a very small ro as you'll find that even though it may claim 100gpd in effect you'll only get about 50gpd.

[john tomkins]

From a beginners point of view (ie mine) the "produced per day" figure would be much more helpful it it were "produced per hour" so then I/we could estimate how long to do a 250ltr fill, how does it work now then, do you divide figure by 24 to give hourly rate or is it much more complex?
Still need that back up answer to if you haven't got the required pure water produced please.

John

[D.Salkeld_Ltd]

John,

I have a 100gpd RO Man RO with a 275ml DI polisher and 3 200ltr Rain butts in my garrage. fills up once a week.  Produces about 200ltr per day in summer and about 150ltr per day winter.

[Morph]

You probably already know this, but when manufacturers give the gpd figure it is over 24 hours.  So 500 gpd sounds good but if you want that fast, forget it.
Just don't run short.

[Easyclean Windows]

Basically if you go for a merlin it will cost more

Cost more in which sense?

Merlin is a very very fast producer of "pure water" i have a tank in my van 700ltr which can be filled up from empty within 4 hours. The water cost to make 700 ltr with 900ltr waste is 98p per tank so thats not expensive.With all the correct hose and fittings etc you would only need to change your resin every 6-18 months depending on the size of your vessel.

A new filter every 6 months costs £12 and two new membranes every 2-3 years £160 so against what you could earn on residential only £200 per day then running a merlin is not expensive.And get the right commercial your laughing.Its mobile you dont need a garage or a shed and the costs are minimal.

Example one 700ltr tank 98p against 50 flats @ £20 each £1,000 get home after 3 hours refill ready to go again next day.

[paul mather]

I have a RO-MAN 200 gpd filling a 1000 litre IBC tank in the garage.. That's the theory. In practice it produces about 400 litres in a 24 hour period because my water pressure isn't great.

But I only have a 400 litre tank in the van so over each weekend I can build up a reserve

[JM123]

generally the productivity values of 200gpd etc are under these conditions:
water pressure of 100psi
water temp of 20c
tds of 50

If these are the conditions of your tap water then you must live on the far side of the moon

[Paul Coleman]

generally the productivity values of 200gpd etc are under these conditions:
water pressure of 100psi
water temp of 20c
tds of 50

If these are the conditions of your tap water then you must live on the far side of the moon

But there isn't any water there 
As people have said, the gpd figure is only under ideal operating conditions.
I get about 600 litres a day from a 300 gpd so the actual amount produced is around 130gpd - less than half of that produced under the ideal.  The water pressure isn't the best but it's OK.

[welmac]

the merlin is good but only if you have a good tap pressure. ones say you only need 40psi of pressure but in my opinion you need alot more. my tap pressure is 70psi which is very good, many have alot less, my tap ppm is 190, and my water comes out at 10-15ppm.

however if you were to run a smaller unit with a pump etc fitted, you would prob be producing water at 5ppm.

although small units only produce say a 1000ltrs per day, if you work on your own or with someone else, this should easily cover you if you have a static tank at home.

if you want to contact me feel free to do so, and i will try to help you if i can.

Thanks, gary- 07753 748650

[john tomkins]

Cheers Gary, my best solution would be to just use a tank in the van as I'm very limited spacewise at home, thats why I thought the Merlin would just fill up in a few hours as opposed to leaving it on  all night ( but obviously costing more initially.
Thats another thing - just using a van for water storage how do you link up the hoses without leaving the van open, same question when out and about, how can you leave the vehicle secure?

Thanks
John

[JM123]

welmac we run a merlin at 48psi, producing over 2000ltrs per day at 5ppm - you must be doing someything wrong - also our tap tds is 300-350ppm.  Have you backflushed recently?

[Paul Coleman]

Cheers Gary, my best solution would be to just use a tank in the van as I'm very limited spacewise at home, thats why I thought the Merlin would just fill up in a few hours as opposed to leaving it on  all night ( but obviously costing more initially.
Thats another thing - just using a van for water storage how do you link up the hoses without leaving the van open, same question when out and about, how can you leave the vehicle secure?

Thanks
John

Run the hose that will supply the pole to an outer part of the van and drill a hole through the floor (rear bumper area is a favourite). You can then put your hozelock style fitting on the end.  An alternative is to put a plate onto the bodywork like on a caravan and connect up to that.  Either way, you will need to pull your hosereel out of the van.  At least you will know if someone pinches it because you will immediately lose your water flow.

[john tomkins]

good idea about the overnight filling, but out and about seems a little risky, ok you might know about if they nick any part of your set up, but can still get at the radio etc  if you need to leave hose out.

[JM123]

Brodex do a very nice manifold for vans - it allows 2 operators to work from the van while filling, it also has a connection to allow the waste water out.  Its stainless steel, but is expensive (£200 approx.)

[Paul Coleman]

good idea about the overnight filling, but out and about seems a little risky, ok you might know about if they nick any part of your set up, but can still get at the radio etc  if you need to leave hose out.

But you can leave the hose out and leave the vehicle secure so long as the hose that feeds the hosereel doesn't go through any doors.

[Tristan R Clean]

You guys are getting phenomenal results with your Merlins.
My RO membranes are spent after half a year!
How often do you change your prefilter sediment membrane and pre RO carbon filter?
Tris

[JM123]

With the merlin we change the prefilter every 3 months, whether we think it needs it or not.  We run the tap water through a 20inch sediment filter first which we replace every 6 weeks or so.  We also backflush our merlin once a month.

[Easyclean Windows]

JM123
 could you please tell me how you back flush a merlin thanks

[freshwater]

Only go for the Merlin if you have good pressure. They run best at 70 to 80psi, but even at this pressure they will only acheive a maximum reduction in tds of 90%, which will mean using lots of de-min resin.

WARNING: The GPD rating of membranes is in US gallons (smaller than a UK gallon) also these rates a calculated with a water temp 25'C, on UK mains supply of about 5'C you can expext a reduct in production of abot 50%. And then there's the pressure, rates are usually quoted at 70 to 100psi.

Dont buy an RO just because the maker says it will make x thousand gallons a day, ask question, ask for references, ask for the names of other users. And don't buy it because its cheap, the only reason its cheap is because its cheap.