[Adam]
I had a dehumidifier and was thinking about getting an automatic pump,
because I was tired of emptying the tank every day and because it
would fill up and shut off when I was away --- but the dehumidifier
failed recently, so I'm looking for an easy, low-maintenance solution!

On 2007-05-01, Lurch wrote:
You can get dehumidifiers with pumps built in, failing that though
an automatic pump is an easy addition. You just want a condensate
pump from a plumbers merchants.

I eventually found a dehumidifier with a built-in pump at a large B&Q.
It was £200, which sounds like a lot, but I thought it wasn't too bad
in comparison with the prices of a decent dehumidifier and a separate
pump, plus the work to fit the two together.

It's a "three-way" model: you can (1) unplug a drain hole in the back to
run the water away by gravity, (2) leave it as it comes to empty the
6-litre tank by hand, or (3) plug the inlet into the tank to get the
pump to run whenever a (presumably much smaller) tank inside fills up.

The pump has a maximum head of 1.65 m. I slightly underestimated the
height of the air brick I wanted to run the hose out through, so I
ended up putting the dehumidifier up on a heavy-duty shelf. It
mysteriously leaked a lot of water one evening right after I'd moved
it there (and let it settle for over an hour before plugging it back
in, although that's to protect the compressor rather than the pump,
AIUI). So I switched it off, looked to see if I could figure out
where it was leaking, gave up, and tried again later --- it has worked
fine since then.

The cellar is now drying out reasonably well after something like two
months of accrued damp with no dehumidifier. Unfortunately this
dehumidifier, which is rated at 60 litres/day, draws 600 W (and
increases the temperature down there by 2 or 3 C) when the compressor
and fan are running (I doubt the pump adds much more).

I've turned the humidistat back from "full blast" and will consider
running it on a timer for E7 too.