SanFran 12 Posted January 4, 2014 Share Posted January 4, 2014 We are wanting to upgrade to a 12v pressure water pump on our 32' keeler. There are various one on TM etc. Does any one know the average pressure that should be delivered? We want supply to the galley, and heads basin, and also a bit of small wash down after swim (not a full shower) in the cockpit area. TM listings show 35psi and 80psi ones, and we are looking at around 4lpm (not wanting to drain the tank in an afternoon). My (layman) thoughts/questions are: Is the pressure not dependant regarding the size and length of the pipes? And is the higher the pressure the better all round option? We dont want a fine high pressure spurt at the galley when we turn on the tap! I am aware of the issues about dry running, self priming etc which shouldnt otherwise be an issue. Any help appreciated. Link to post Share on other sites
wheels 543 Posted January 4, 2014 Share Posted January 4, 2014 I will start with your last comment first. These water pumps are diaphragm pumps and are happy running dry continuously, so don't worry about that. They have no metal parts in contact with the water, so can pump salt water as well as fresh. Being a Diaphragm pump, they have chambers and you will note that the common ones are either 2 or 4 chamber. 4 means a greater volume of water can be pumped than 2. Bigger volume often results in far more water used, because when you turn on the tap, it just flows out. What sets the pressure is a spring in the pressure cutout. Low pressure 20-35PSI pumps tend to be cheaper because they don't need such a grunty motor. Pressure comes at a cost of bigger motor, harder work which equals more current required from batteries. It also comes at a cost of even more water being used. High pressure pumps tend to be slightly lower volume pumps as in 2 chamber, because it takes a good body design to withstand the pressure over a larger diaphragm area. Pipe size will have an affect on water flow. But it is based on length and diameter of the pipe. So a short length can get away with 12mm, but a long length is going to be better with 15mm and so on. For a small boat like yours, I would suggest 15mm if you can possibly fit it, but 12mm would be fine. A small 2 chamber pump of 20-35PSI is fine. Gas water heaters will require 35PSI, so if you ever intend to fit one, you need to get a 35PSI pump. 80PSI pumps are overkill for most boats, but excellent as washdown pumps, especially if you want to wash mud off the anchor and chain. Link to post Share on other sites
SanFran 12 Posted January 5, 2014 Author Share Posted January 5, 2014 Hey that is fantastic information. Really appreciated. One last question.... if you can help? In relation to the tapware, is a standard kind of house sink tap ok, or is there something specifically made for boats? Im not intending to have any hot water mixer on board. (If she wants warm, it'll come from the solar shower!) Link to post Share on other sites
wheels 543 Posted January 5, 2014 Share Posted January 5, 2014 House stuff will work just fine, but Boat and Campervan stuff tends to be a little more compact and possibly cheaper anyway. Oh and make sure you install decent wiring to the pump. Many make mistakes here and when the motor starts to work, the pump can slow down too much and burn the motor out or just perform poorly. Oh and finally finally, you may or may not need an accumulator. Personally you will. Some pumps are advertised as not needing them, but I have found even those still perform better with one installed. It's a small tank fitted in the pressure line and simply uses air to act like a pressure spring and stops the fast cycling of the pressure switch, which would simply burn it out eventually and smooths out water flow instead of it pulsing through the tap when you open it. The only pump I have come across that does not truly need one, is the fully elctronically automated pressure controlled units, but I doubt you will want one of them, as they are very expensive and pump a heck of a lot of water. Link to post Share on other sites
Guest Posted January 5, 2014 Share Posted January 5, 2014 Do you realise how much your water usage will jump up once you fit a pump? A manual pump will us a LOT less water, a LOT. Do you have big tanks? Link to post Share on other sites
wheels 543 Posted January 5, 2014 Share Posted January 5, 2014 KM is absolutely correct. You could go another way if you want a pump. Use the little electric galley pump that id designed to drop into the internals of the water tank. They use a special little Galley faucet that has a switch on it's base to pump the water. So in other words, no water sitting under pressure ready to go, but if you want electrically pumped water and at the flow you are currently using with the hand pump, then there you have it. Link to post Share on other sites
Guest Posted January 5, 2014 Share Posted January 5, 2014 Just an interesting thing in regards to taps San Fran, I have a pump and also used to have a caliphont which I removed. Now the ceramic mixer taps, not having hot water connected , can be used to regulate the amount of water that comes out the tap when turned on fully. The more towards the hot water position the less water comes out so this could be used to conserve water when needed. Easier than using the tap handle to regulate the amount. Link to post Share on other sites
SanFran 12 Posted January 5, 2014 Author Share Posted January 5, 2014 All good info. Thanks to everyone who contributed. Like the idea of the in tank pump, but also want the cockpit connection for after swimming even though I may need the accumulator tank as well. It might be a bit utilitarian but I saw a gate valve arrangement for the galley in leu of a tap . just an idea. Link to post Share on other sites
rigger 47 Posted January 5, 2014 Share Posted January 5, 2014 Random thought - for the galley - have you tried a foot pump - I have found them to be a great alternative to hand or electric pumps. Link to post Share on other sites
Grinna 2 Posted January 5, 2014 Share Posted January 5, 2014 We have a pressure freshwater system (came with the boat) but we also have a foot pump in the galley and it's bloody handy. It's great to wash your hands when they're covered in gunk, you can still pump water to rinse your hands. It also means we use much less water and there's no noise, so if someone's sleeping or something then you can still get water without a pump buzzing away under the floor. It's also a way of getting water from your tanks if you ever have an electricity/electric pump failure or you're running short on battery power. Just a thought. Link to post Share on other sites
wheels 543 Posted January 5, 2014 Share Posted January 5, 2014 To take Grinna's post a step further, we have a saltwater pump over the Galley Sink as well. It is awesome for pre-washing the dishes. That same pump works as a deckwash as well. Link to post Share on other sites
rossd 16 Posted January 5, 2014 Share Posted January 5, 2014 I am with rigger here and have a Whale double acting foot pump and find it way better than hand pumps. The only thing I plan to do is get another one for salt water. Link to post Share on other sites
Steve Pope 243 Posted January 5, 2014 Share Posted January 5, 2014 Also second rigger, 2 foot pumps, fresh and salt, unless you have big tanks stick with hand / foot pumps. Link to post Share on other sites
banaari 27 Posted January 5, 2014 Share Posted January 5, 2014 You could go another way if you want a pump. Use the little electric galley pump that id designed to drop into the internals of the water tank. They use a special little Galley faucet that has a switch on it's base to pump the water. So in other words, no water sitting under pressure ready to go, but if you want electrically pumped water and at the flow you are currently using with the hand pump, then there you have it. Nooooo!!! I thought precisely that and installed such a unit... but it turns out they are in fact the worst of all worlds. They're not self priming, and are therefore a pest to install properly, and the fixed flow rate (there's no tap as such) was in my case a lot MORE than you typically want (more wastage). I have just ripped the cheap-and-nasty little thing out, and replaced it with a "proper" pressure actuated pump and faucet. Magic. Link to post Share on other sites
Grinna 2 Posted January 5, 2014 Share Posted January 5, 2014 Generally speaking, pumps are the bane of the boat owners existence (count how many pumps you have onboard, it'll surprise you). Simple is good. Foot pumps are simple. Link to post Share on other sites
Chewing Gum 17 Posted January 5, 2014 Share Posted January 5, 2014 I second the whale foot pumps - they are ultra reliable, we have 2 in the galley (one salt) and one in the head - electric pumps are noisy, use a lot of water and use battery. We do have an electric pump for the shower only. Link to post Share on other sites
Guest Posted January 5, 2014 Share Posted January 5, 2014 How did you plumb the whale footpumps in chewing gum? Do you have separate taps for the footpumps and the electric or do they go through the same tap? Link to post Share on other sites
too_tall 15 Posted January 5, 2014 Share Posted January 5, 2014 If your wanting to consider the water use, but still have a reasonable flow for the deck shower, consider fitting a small restricting tap below the galley top to limit the flow to the galley sink, and maybe also the hand basin. Then you can restrict these to a sensible flow without having to remind everyone not to turn the tap to full, whilst still getting a good flow on the deck outlet. We have a near domestic type of water reticulation system on the boat, 80psi, 28lpm pump ( its huge!. don't know why its so large, for some reason a prior owner thought they needed it ) and a 9l pressure accumulator/tank ( bladder type ). This is excellent, but as noted, can use significant amounts of water. Awesome showers. We get away with this somewhat by having over 800l of water storage and the ability to top them up on the fly. But we also have a salt water outlet ( pressurised again ) at both the galley and in the head basins, along with hot and cold fresh. We also have salt water soap at all, and find that the water storage, without running the water maker, is quite sufficient for up to a week away with sensible use of the water, and specially sensible use of the showers!. A cockpit shower is awesome. Specially a hot one to put nice warm water into wetsuits..... Link to post Share on other sites
Chewing Gum 17 Posted January 5, 2014 Share Posted January 5, 2014 The foot pumps have a little faucet - no tap is required Link to post Share on other sites
rossd 16 Posted January 6, 2014 Share Posted January 6, 2014 The foot pumps have a little faucet - no tap is required Generally yes, but in my case with the tank up behind the bunk it would siphon out when on the "wrong" tack. Had to have a little cork to stick up him. Since changed to tap type. Link to post Share on other sites
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