Tiny heat pump, with benefits

I've blathered on about our heat pump enough that by now all of you should know how they work:  They use electrical energy to move heat.  Of course, this means that there has to be a heat source.  Eolian's heat pump extracts heat from sea water.  And household heat pumps typically extract heat from the outside air.

But here's a heat source you may not have thought of:  condensing water.  A dehumidifier removes moisture from the air by condensing it.  Annnnd... condensing water releases  970 BTU/lb, 1010 BTU/pint.  So is that a lot of heat?

Dehumidifier capacity is typically rated in pints/day.  Ours is a small one, rated at 25 pints/day, or a little better than 1 pint/hr.  Using the numbers above, our little heat pump will deliver 1052 BTU/hr.  It does that while drawing 1.6 amps - that energy (about 600 BTU/hr) also gets delivered into the boat.

So let me put all that into clear perspective for you:

Our little tiny dehumidifier, which draws only 1.6 amps, is the equivalent of an 484 watt electric space heater.

We keep the dehumidifier in the head; this explains why it gets so warm in there when we take a shower.

Of course, these numbers assume that the dehumidifier is working at capacity, and that only happens when the air is very humid, like it is in the head when someone is showering.  At other times, the heat output will be less.  But like all heat pumps, the efficiency will never fall below 100%.

So think of that dehumifier as a tiny heat pump with these side benefits:

• It keeps the boat interior dry
• It provides an apparently never-ending onboard source of distilled water

I consider ours to be one of the best $125 we've ever spent.

Tiny heat pump, with benefits