Re: How do RV pumps work?

On this Sat, 16 Nov 2024 12:46:29 -0500, Clare Snyder wrote:

I'd explain it but you probably wouldn't understand .

 If the restriction causes 43PSI backpressure it won't pump. Valve
closed, pressure over 43psi - pump off. Valve open, pressure below
43psi, pump turns on.
  For your use you really want a "pony pump" but the RV pump can be
made to work

Thanks for the explanation that if the pump sees at least 43psi on the
outlet side it shuts off, otherwise it pumps water from the inlet side.
The unit came with a cigarette-lighter socket also for use in vehicles.
That's kind of neat as it can also be used as a portable outdoor garden
hose for watering plants which are far away from the house that you can
truck the water to in ten gallon containers (or whatever size you carry).
Looking up what a "pony pump" is, I'm surprised I never heard of them.
https://www.google.com/search?q=what+is+a+pony+pump
 "Pony Pumps are famous for their compact portable flexible   impeller utility pumps and their versatile line of small submersible
  pumps. Pony pumps are non-submersible, self-priming nickel plated   brass transfer pumps with Buna-N impellers. These lightweight,   pumps can be used to empty waterbeds, drain water heaters or aquariums,
  pump out a basement, transfer water to an RV, pump boat bilges, pump   out stock tanks, and in other applications where water needs to be   transferred. Intermittent duty is 15 minutes ON and 45 minutes
  OFF. Two extra impellers and gaskets included."
  https://store.waterpumpsupply.com/ponypump.html
I wonder how they differ from the other liquid-transfer pumps though.
For example, this is billed as a 12VDC "self-priming diaphragm" pump.
https://www.amazon.com/dp/B0DF7B1VYD
And this is billed as a 12VDC "fuel transfer" pump.
https://www.amazon.com/dp/B0DFCRH64R
And this is billed as a 120VAC "water transfer" pump.
https://www.amazon.com/dp/B0D9W3VQNB
And this is billed as a 120VAC "submersible water draining" pump.
https://www.amazon.com/dp/B0D9B3MQB9
I'm not sure which pump I need for my application which is to have a
solar-powered spa heater that pumps water in the summer from the spa
through a few hundred feet of black hose back to the (now warmer) spa.