Improvised low energy A/C - Here's the plan...

[steve_cronin]

Improvised low energy A/C - Here\'s the plan...

Now I used to have a portable A/C unit which effectively conditioned my office (5m X 5m X 2.75m) but which we junked (in working order) when we had a full system installed a few years ago.

Our boat is in Greece and we suffer in the summer having to choose between being a free "local" for every mossie and sand fly in the Ionian or melting to oblivion, overnight. Daytimes are fine and you can just jump into the sea if you're too hot.

Now, lurking downstairs here is a virtually unused de-humidifier. This machine only consumes 300 watts. The portable A/C used 1500.

Now, considering that a de-humidifier is basically an A/C unit where the warm outlet from the condenser and the cold air from the evaporator are just allowed to re-mix (since lowering of temperature is unimportant for a dryer) and not kept seperate as in an A/C unit, it SHOULD be possible to seperate the two with some cunning re-arranging of the ducting (Innit?)

Since 1500 watts kept the volume of this office cool and dry, then surely 300 watts (we have a v. quiet genny) will keep one sleeping cabin conditioned. There is a suitable unused locker in the next cabin immediately through the wall of ours.

We'll also have a good supply of distilled water too - although the Boschs don't use all that much.

Cunning plan, in the best traditions of "Practical Boat Owner-ship"??

Steve Cronin

 

[jeremyshaw]

Re: Improvised low energy A/C - Here\'s the plan...

Sounds like a good wheeze, but a lot of work for an unpredictable result.

I think you may find you need rather more BTUs than you'll get out of that machine, given the high amibent temperature.

FWIW on our 43 cat when we are in marinas we plug in a box type aircon unit through one of the hatches - cost a couple of hundred dollars somewhere. The 8000 btus reduces the humidity wonderfully (the main issue in the Caribbean) but makes only a small dent in the daytime ambient temperature which I would have thought more of an issue in the Med. It will reduce it by several C during the night though.

So I'd suggest you get something 'proper' rather than do all that work for an unexpected outcome. There are split portable systems around now which would help with space.

Or get some fly screens!

 

[pvb]

Not enough coolth...

It's cunning, but you'll find that 300W won't generate enough cooling to make much of a difference in Greece. But if your generator really is quiet enough, you might consider building in a little portable air conditioner. B&Q do this 9000BTU one for £200, and on its lowest fan speed it'd probably do the trick. All you need to do is pipe the outlet hose outside.

 

[Avocet]

Re: Not enough coolth...

Your boat probably won't be anything like as well insulated as your office so the rate that heat is being transferred into it will be vastly greater. Car aircon systems tend to be much more powerful than house ones for the same reason.

 

[catmandoo]

Re: Improvised low energy A/C - Here\'s the plan...

Why dont you use the difference between wet and dry bulb temperatures . For a small amount of energy you can use it to power a small sea water pump to trickle water over your top decks and with a reasonable wind blowing the evaporation should cool your hull by a degree or two

 

[ytd]

Re: Improvised low energy A/C - Here\'s the plan...

I think you will find that the de-humidifier's design is not optimised for cooling and you would do better with a fan. Before you spend too much time installing it in the boat why not test it at home by measuring the input and output temps with some cardboard ducting. I have seen a few boats with caravan style air cons temporarily mounted over the main hatch for use in port. They are stored below at sea.

 

[steve_cronin]

Re: Improvised low energy A/C - Here\'s the plan...

Humidity is a very important issue in the med too. Also, as I said, it is the night time temp that is the issue.

I could easily install any of the suggested "off the shelf" systems but power consumption is a major factor and I can't justify running the generator full bore in the vicinity of other craft all night - although, in one Greek port, Katakolon, I once got frog marched to the Port Police office in handcuffs for daring to complain about the genset on a dodgily registered motor yacht which had the berthing master in it's pay, filling our boat with diesel fumes all night.

As to flyscreens, unless something elaborate is made for the main hatchway (top & back) the little sods still get in and as I'm sure you are aware, it only needs one! Also, the minute sandflies we get are able to get through the mesh on commercially available screens which at the prices rutgerson charge, would also cost a fortune to equip all ten portlights. We find that bridal veil net is best but it really restricts airflow and isn't too durable either.

I will of course do the "prototype development" here in the garage, in the UK.

Steve Cronin

 

[steve_cronin]

Re: Improvised low energy A/C - Here\'s the plan...

You are kidding of course?

You would need to rig up an overall spraying system for that to work.

Steve cronin

 

[steve_cronin]

Re: Improvised low energy A/C - Here\'s the plan...

[ QUOTE ]
I think you will find that the de-humidifier's design is not optimised for cooling and you would do better with a fan.

[/ QUOTE ]

That is only because of the ducting. Note that de-humidifiers collect as much water as A/C units, therefore they must be doing as much work, it is just the arrangement that needs altering. OF COURSE I will do the development here! I have far better facilities than on the boat.

Steve Cronin

 

[pcatterall]

Re: Improvised low energy A/C - Here\'s the plan...

Steve,
Tried all sorts on my house boat in the Nigerian delta.. very hot and humid. Eventually settled for net and fan, a bit of sweat on bare skin and a 12 volt fan works quite well.
We tried desert coolers which we had used with success in Saudi and similar but they dont work so well where the humidity is already high.
regards

 

[catmandoo]

Re: Improvised low energy A/C - Here\'s the plan...

Go the idea when washing decks with hose and noticing cabin cooler afterwards . Cheap moisture retaining blanket and perforated plant irrigation pipe from Dobbies tied flat onto deck like tarpaulin. Only needs to cover sleeping area Of course wont work in high humidity