Home made air conditioner?

[stuhaynes]

We've been roasted in the last couple of days on board. High temperature and very high humidity. It got me to wondering whether anyone had converted a small aircon unit from a car, to work on their boat. Even the smallest commercial units seem to cost a fortune compared to the short time (in the UK) that they would actually be used.

 

[lustyd]

In theory you could extend the "sock fridge" theory posted on here recently. Place a sheet, or several sheets, over the boat and wet them then close the hatches. I've not tried this but if you can keep them wet then in theory the boat temp should go down a few degrees.

 

[Giblets]

In theory you could extend the "sock fridge" theory posted on here recently. Place a sheet, or several sheets, over the boat and wet them then close the hatches. I've not tried this but if you can keep them wet then in theory the boat temp should go down a few degrees.

Ahh yes, the good old "evaporative cooling" theory. SWMBO uses this trick on the dog van on very hot days. Flannellete sheets are best as they hold lots of water. Hope you get to any before I do as they are very good for mopping up water from plumbing leaks!!

 

[Twister_Ken]

We've been roasted in the last couple of days on board. High temperature and very high humidity. It got me to wondering whether anyone had converted a small aircon unit from a car, to work on their boat. Even the smallest commercial units seem to cost a fortune compared to the short time (in the UK) that they would actually be used.

If you consider the interior volume of a family saloon car and compare it to a family yacht, a car sized system is going to struggle. Plus it will gobble power. Rather, the first thing is to keep direct sunlight off the decks and coachroof - a big awning, covering as much boat as possible.

Then ventilation - hatches open, dorades turned to windward, wind sails rigged, fans below.

Finally, cold beer or G&T helps.

 

[Csail]

We've been roasted in the last couple of days on board. High temperature and very high humidity. It got me to wondering whether anyone had converted a small aircon unit from a car, to work on their boat. Even the smallest commercial units seem to cost a fortune compared to the short time (in the UK) that they would actually be used.

Why not just buy one..ours second hand was free.

 

[KellysEye]

I don't know what you call expensive but we have one of these and it works well on a 38 foot boat. http://www.hawthornshop.co.uk/index.aspx?S=category&id=1613
It's first dehumidifier down the page UKP 153.06, there is a more expensive one further down.

 

[Bassplayer]

Best answer is to use a portable home unit. I am about to do this on my boat. You could use the heating pipes to distribute the cold air.
I reckon I will try out the unit this weekend to see if it works. Then I will dismantle the cabinet to build it into a locker. Either change the motor for a 12v or run it off the inverter which already runs the 'fridge.
Look out for news later....

 

[pcatterall]

In theory you could extend the "sock fridge" theory posted on here recently. Place a sheet, or several sheets, over the boat and wet them then close the hatches. I've not tried this but if you can keep them wet then in theory the boat temp should go down a few degrees.

This 'desert cooler' idea will work well where the humidity is low ( like in the desert!!) where the humidity is high there is not enough evaporation.

To get a bit more mechanical you need avery small pump to spray the water onto the 'sacking' and a fan to blow the air through the sacking. Not as effective as ac but less power consumed. I used them a lot in Saudi.

Other wise keep the sun off use any breeze, avoid heat from cookers fridges instruments etc.

 

[Avocet]

I think a car system would be fine in respect of its cooling capacity. Boats are bigger than cars, but they're generally white on top, sit in water rather than over hot tarmac, don't need a massive airflow rate through them, and don't have the glass area of a car.

However, a typical car AC pump will need a couple of HP from the engine. You'll also have to sort out how to drain the condensation from the evaporator (possibly into the bilge?) and how to get the condenser cooled. Car ones are air-cooled by the airflow over them as the car moves (or by the engine cooling fan when its not). I'd have thought it would be more sensible to cool a yacht condenser with seawater - but a car one wouldn't last 5 minutes in those conditions!

 

[DownWest]

Guy I knew in Sevilla used to install evaporative systems in bars and other places were high air transfer was not a problem (and cost was). AFAIR, he used vertical mesh boxes filled with wood chips which were kept wet with a spray bar. Air was driven through by a fan and the humid cool air kept the customers happy. Problem for a boat was the power for the fan, his were 1 to 2 hp. (his main business was standard aircon systems). Sevilla can get up to 50C and retains the heat at night.... Pretty humid too.
So for a boat, a car system might be OK. Not so much glass to build the heat, but still need the engine running, or a genset.
A

 

[lenseman]

I don't know what you call expensive but we have one of these and it works well on a 38 foot boat. http://www.hawthornshop.co.uk/index.aspx?S=category&id=1613
It's first dehumidifier down the page UKP 153.06, there is a more expensive one further down.

I think you might have misread the original question?

The Originator was asking about Air-Conditioning Units, not dehumidifiers?

 

[rob2]

If you consider the interior volume of a family saloon car and compare it to a family yacht, a car sized system is going to struggle. Plus it will gobble power. ...Finally, cold beer or G&T helps.

I used to work for a manufacturer of car aircon systems. For our summer barbecue, we used to use a massive van with a cooler system to store the meat and beers. You had to warm the beer up before drinking! The van system was driven by the usual car compressor, which takes about 2hp. As said by others, you have a possible problem disposing of the condensate from the evaporator and need to find a suitable condenser.

I agree about the G&T!

Rob.

 

[William_H]

Airconditioning

Your OP suggests that humidity is your problem. Only refrigerated aircon will remove the humidity.
For operation away from mains power only an engine driven compressor is practical and as said it will take several horsepower. Small cars here have a throttle nudger to open throttle at idle with a/c on and have an a/c cutout for when throttle is wide open. (Max performance required.) so they do take significant power from the engine.
A car is a real challenge often being dark coloured and huge glass areas closed up when parked. A yacht would be easy to cool by comparison.
If it was a case of dry and hot then an evaporative system would work well but it just stops cooling with high humidity. But I reckon that good fans would be the first step for hot weather in UK. I reckon you should celebrate being hot by doing nothing but drinking long cold drinks.
I wonder how a small water pump spraying water over the cabin top would work to cool the boat. After all the water is always cold in UK.
Anyway don't fret the posts will turn to eberspacher questions before you know it. olewill

 

[nimbusgb]

Just a word of caution. Systems that spray mists of water that operate from around 30° and higher are the perfect breeding ground for Legionaires disease. At 35° you hit the sweet spot for the breeding cycle.

 

[lenseman]

. . . . . Anyway don't fret the posts will turn to eberspacher questions before you know it. olewill