Looking After a 24V Diaphragm Pump Through the Year

A diaphragm pump is easy to forget once it's in and working. I'd rather not find out about a problem when a tap goes dry, so I keep a set of limits, a few quick checks for when it misbehaves, and a seasonal checklist for frost. This is all of it in one place.

Duty limits I respect

The pump is rated for intermittent duty, not running all day, so I don't use it for jobs that would keep it going continuously. It is meant for clean water only: pH 5.0 to 7.5, with solids at no more than 0.1 %. A strainer always sits on the inlet in my setup.

The motor must never be submerged. I mount it high and dry, on its rubber feet, where a spill or a full bilge can't reach it.

When it won't behave

• Pump runs but nothing comes out: is the strainer clear, and is every hose clip tight enough to stop air leaks?
• Won't self-prime: is a tap open so air can escape? The stated self-prime is up to 3 m, so I check the lift isn't more than that.
• Keeps running with taps closed: is the pressure switch reaching its 40 PSI, 2.8 bar shut-off, or is there a leak downstream?
• Nothing at all: is the fuse intact, and are red and black on positive and negative?
• Noisier than usual: have the mounting screws been over-tightened so the rubber feet can't absorb vibration?

I start with air leaks. A loose clip on the inlet side is the simplest thing to rule out, and the instructions single out clipping the hose for that reason.

Electrical limits

It is a 24 V DC pump drawing 132 W and 5.5 A. I only feed it from a 24 V battery or a matching 24 V adapter, always through a fuse. I won't try it on a 12 V system, and I don't use a UK mains supply without the right adapter, which doesn't come in the box.

Frost and storage checklist

1. Before a cold spell, switch off at the fuse.
2. Open a tap to release pressure.
3. Drain the pump so no water is left inside to freeze.
4. Clean the inlet strainer while it's off.
5. Check every hose clip before switching back on.
6. Open a tap first when restarting, so it can prime.

Draining before frost is the one step I never skip.

The clean-water and duty limits are set out on dcautom.co.uk, so it's worth checking them against your own setup.