Lol, OK, OK, but I've been busy Seffie. I've had a DIY LED rig, Driving lessons and extra days at work (amongst other things) to worry about as well.
Things to consider are how much water you will actually need and how long you are prepared to wait for it. Also, you need to consider that you will get only about 1/4 of the stated output most of the time unless you spend lots of £ on booster pumps and in-line heaters... Placement is important, they need to be near a mains water feed pipe, and they are bulky items, so placement can be a tricky one for those of us without much space beneath their sinks e.t.c
If possible, get direct from the manufacturer for new, as most sell to the public at a lower price than most LFS's/Ebay (in most cases) will offer them to you for. If ou are going second hand, look at Ebay, the Classifieds section of the forum, and any advertising site for fish stuff. Oh, don't forget the LFS's window adverts also
I'd always get one new, as you don't know the service history of the unit. It may be in full working order with all new filters, or the seller may just be saying that, or the membrane may have dried out... A full new set of filters for an average 4 stage 50GPD unit will be around £60-70 delivered from a cheap on-line dealer, when the units are about £90 delivered new... There are some second hand bargains out there, but a lot of lemons also
When buying second hand, you want to get one with all new filters ideally, or nearly new at least. Check the sediment pre filter for signs of use, along with the Carbon block filter, the DI resin (many change colour as they clog these days, nice and handy). Ask to see the unit running when you get there, compare the input pressure to the pressure going to the membranes (A good unit will have two pressure gauges, one on the feed line and one between the pre-filtration and the membrane) If there is a difference, the pre-filters as a minimum are going to need imminent replacement. Check the TDS after the membrane has finished with it also, and compare it to the source water TDS. The use needs to be 1/100th of the source at most to show a good membrane. If it's close to that or higher, the membrane either needs flushing or replacing. Which leads on to ensuring you have a flush-kit installed on you potential purchase.
Osmotics, New Era and my personal choice RO-Man are all good units, though the New Era ones don't allow access to any filter to visually check them. This is both a good and bad thing, as while you cannot visually check them, you cannot contaminate them either, something that is easily done with units where you have direct access to the filters
For extras, I'd ensure you have both the pressure gauges I mentioned, a spare set of replacement filters, a TDS meter and calibration fluid for it (yes, like refractometers, they need calibrating every few months to remain accurate), and you'll need a flush kit ideally. This said, the unit I use does not have half of that gear associated with it...
Usually you'll get a single pressure gauge included, and a flush kit with some manufacturers, but it's rare to get two pressure gauges unless you have two membranes, flush kits aren't always standard, you never get spare filters and often DI kits are missing. DI isn't essential though, when you get down to <10TDS, it's mostly carbon ions remaining, that are fairly harmless and a few argue they are beneficial. I sit on the fence with that one and personally would look to getting DI on a unit for me personally...
For a new 50GPD unit, budget £170-£180 for the unit, all the spares and extras that you will need. I would not pay more than £20 for a unit only at second hand price, streaching to maybe £100-£120 if they have the spares and extras on offer. A second hand unit deffinately isn't worth any more than a new unit minus a full replacement set of filters though, as you'll likely find yourself replacing them shortly after purchase
Hows that for a start? Can I get back to soldering now? GOOD
Rabbut
not heard that before, could it be the drinking water one?
