Under construction.
This details the installation of a seawater pro single membrane 12VDC watermaker.
The seawater pro water maker is essentially a kit of parts, with separate membranes, water filters, pumps. It was well priced and I viewed it as a benefit to be able to choose where each of the bulky components was to be mounted.
The decision to add a watermaker was made after the purchase of the 1800w inverter, which was not adequate to support an ac-powered watermaker. (3500w would have been appropriate). So, I elected to use a dc-powered unit.
The addition of a large dc motor requires the addition of heavy cabling and protection. Fortunately the claimed wattage (600) of the seawater pro unit is less than that of the windlass (1000w) so the water maker could be supplied by the windlass feed, provided the two were not used concurrently.
The windlass is a 12v model, so I selected a 12v motor for the watermaker.
The most logical location for the watermaker and its various parts is in the sail locker, near both the windlass and the plumbing in the forward head.
Upon receipt I noticed the motor supplied with the seawater pro unit is rated at 80A. (1040w at 13vdc) we shall see how it works in practice.
Threads and fittings
The fittings in the kit are all imperial, the boat is not. It is very difficult to locate imperial fittings in Martinique, and to make matters more complicated seawater pro does not provide a table specifying the style of fitting used.
So, I asked them, and was assured. that their larger fittings are all 1/2” NPT. ( The ‘T’ means tapered, this is how the parts make a tight seal when assembled) However the system uses several male to male fittings to connect female threaded (FNPT) components, and this fitting has parallel (not tapered) threads, and includes o-rings. Clearly this is not an NPT thread.
After about an hour of measuring and research, it appears that the thread is 1/2” BSPP on this ‘custom’ part. 14mm thread pitch, 20.8mm thread OD, no taper. Not sure why they mixed thread styles in the kit, one of which is made in-house. Maybe they should include two rolls of Teflon tape.
NPT pitch is 14tpi, tapered.
BSPP fitting measured diameter at the outer threads is 21mm (20.8mm per standard) , 14tpi no taper.
They will engage but will not seal as-is.
Hoses and barbs
Attempt should be made to standardize all fresh water hose and fittings at 16mm/5/8” ID. This appears to be the most reliable cross between metric and imperial and is most prevalent in the ovni’s existing plumbing.
Seawater supply tubing (to pre-filters then pump) supplied is 1/2”, push on type.
Treated water (output) tubing supplied is 3/8”.
Threaded fittings are typically 1/2” NPT. (A few smaller)
Rinse filter will need to be connected with flexible hose- 16mm Fittings. Use valve instead of rinse timer?
Pex fittings will work. Should pex hose also be used ?
Required parts -
brine hose 3/8” ID to sink drain: 3/4” id T or y and run larger hose up to water maker.
Join to tanks - 16mm T-fitting at companionway, and hose to white supply tubing. Ideally valve remains in pump area.Push-on 3/8 (white) to 1/2” NPT female to adapt at valve.
Seawater supply from fridge strainer 16mm T fitting and shut off valve.with 16mm barbs., 16mm barb to 1/2” FEMALE NPT at pump. Existing push-to-connect to NPT female at pump. (Or straight. This continues to push-to connect at filters.
Straight 1/2” NPT female to 1/2” PUSH (option for existing)
Push to connect splices for 3/8 and 1/2” OR straight hose approx 8.5-9m each
Are push fittings to 16mm (5/8”) hose barbs available? Necessary for adapting to new pump in future.
Existing hoses
20
22
26.
*13mm hose is approx 18mm od.
Imperial od
3/4 (19.5mm) is approx 26mm OD (3mm wall)
5/8 (15.9mm)is approx 22mm OD (3mm wall)
Tubing as supplied appears to be
1/2” x .37” water filter hose, LLDPE (Same dimensions as 3/8” PEX)
3/8” OD x.25” ID marked DMtube 3/8” Same as 1/4” PEX
http://www.dmfit.com/eng/company/contactus.html
https://www.ifanbrass.com/info/pex-pipe-size-chart-get-a-grip-on-dimensions-a-84419707.html
