Help W/water tank pump pressure switch

SwampYankee

This is not a solar pump but pump related.

I currently have a 12V Jabsco 4GPM 60PSI Im using in my off grid camp. I do not have a pressure tank with the pump and this causes it to run quite a bit. I want to install a tank I have but am not sure about the pressure switch. I can't find a DC rated switch anywhere. I seem to remember a post on here talking about a AC rated Square D switch that would work with DC but need the specifics.

I know I can run a standard AC pressure switch off the inverter but I need to stay DC so I don't have to run the inverter all the time.

The pump has a built in pressure switch which I know have a chance of wearing out and failing. The question is should I just utilize the built in switch or go with a separate DC rated switch. Will there be any problem with the pumps internal switch and another working together? What PSI should my tank be at?

Im not sure of the PSI specs on the pumps built in switch but I sent Jabsco an email still waiting.

Thanks
Swamp

waynefromnscanada

Re: Help W/water tank pump pressure switch

Hi "Swamp",
Several things - -
You ask "what PSI should my tank be at?" That depends on where you want it to be and what your pump is capable of. You state that your pump is rated 60 PSI, I would suspect that to be the max if one is to expect a reasonable length of life for that pump. If that be so, than I would run it at a lower pressure, perhaps 20 to o40 PSI, or even lower if you don't need that much pressure. Lower pressure would also mean lower power consumption, assuming this is a positive displacement type pump.
Second: "Will there be any problem with the pumps internal switch and another working together?" - - - No, as long as the pressure settings of the external pressure switch is set lower than the pumps internal switch. That way, the internal switch will always stay on, and power to the pump will be controlled by the external switch.
Third: "I seem to remember a post on here talking about a AC rated Square D switch that would work with DC". This switch is likely the one spoken of: http://www.acehardware.com/product/index.jsp?productId=29000596 This switch has a very fast acting toggled mechanism that, depending on the amps demanded by your 12 volt pump, should result in the contacts lasting a long time. Since the double contacts in this switch open far enough and very fast, and with only 12 VDC to control, unless the pump's current draw is relatively huge, arcing won't be a problem. These switches have been known to withstand terrible abuse in 120 and 240 VAC service for years and still keep on working. While it may not be RATED for DC operation, I'd have no concern using it in your application if pump draw is less than 10 or 15 amps @ 12 VDC. It's also very easy to change it's pressure settings for much lower pressures, just adjust the nut that pre-loads the spring pressure exerted on the internal mechanism.

vtmaps

Re: Help W/water tank pump pressure switch

SwampYankee wrote: »

The pump has a built in pressure switch which I know have a chance of wearing out and failing. The question is should I just utilize the built in switch or go with a separate DC rated switch. Will there be any problem with the pumps internal switch and another working together? What PSI should my tank be at?

Use the built-in switch. The only reason to use an external switch is if you want lower pressure than the internal switch gives you. Whichever switch (internal or external) is set to the lowest pressure will be the one that controls the pump.

--vtMaps

SwampYankee

Re: Help W/water tank pump pressure switch

Thank you fellas!