All,
In a conversation with Don we discovered that the link to the 12V water pump in the original post above had gone bad. I have corrected that link, but while doing so I ran across an interesting variation on the same idea that I thought was worth adding to the discussion.
SEAFLO offers a 33-Series 12V water pump and accumulator tank system that combines the same basic 3.0 GPM / 45 PSI pump concept with a small pre-pressurized accumulator tank:
What caught my attention is the accumulator tank.
With the pump by itself, opening a faucet causes system pressure to drop and the pump cycles on to restore it. With an accumulator, there is a pre-pressurized air cushion behind a diaphragm. The pump first compresses that air while putting water under pressure in the tank. When you subsequently open a faucet—particularly for a small amount of water—the compressed air can push some of that stored water into the plumbing without requiring the pump to start immediately.
That provides several useful benefits in an emergency/off-grid installation:
Less pump cycling — the pump does not have to start and stop for every small demand for water.
Reduced battery use — fewer motor starts are particularly attractive when your water system is being powered from a 12V battery/solar setup.
Longer pump life — reducing frequent starting and stopping reduces wear on the pump.
Smoother water flow and pressure — the accumulator acts as a cushion between the pump and the faucet.
Quieter operation — particularly useful in an RV, cabin, or improvised emergency water system.
Less pressure shock in the plumbing — the air cushion helps absorb pressure fluctuations rather than transmitting every pump start and stop directly into the plumbing.
The package is also already assembled with the pump, strainer and accumulator tank on one mounting plate. The 12V version is rated at 3.0 GPM, with the pump switching on at approximately 35 PSI and off at 45 PSI.
For the sort of emergency system we were discussing earlier in this thread—stored water, a 12V battery, perhaps solar charging, some hose or PEX and a faucet or shower—this strikes me as a particularly nice refinement. It gives you something much closer to the behavior of a conventional household pressurized water system while still operating entirely from 12V DC.
The accumulator is not a huge water-storage tank; its value is in storing pressure and supplying those brief or low-flow demands without unnecessarily cycling the pump. That is especially useful when every amp-hour in the battery matters.
I thought it was an interesting addition to Don’s original preparedness ideas and worth passing along.
73,
Phillip Beall (W5EBC)