Makeshift aircon

[stranded]

Bear with me. Or shoot me down in flames if you want. We’ve got aircon on the boat but a. It’s a bit antisocial and b. It’s undersized so not terribly effective, though better than nothing. But retrieving a couple of bottles from the bilge where they are much cooler than ambient temperature had me wondering how I could make use of that free cooling. Obvious solution would be to experiment with a (or probably some) bilge fans to try to churn the cold air below with the hot air in the accommodation. Obviously would only work where sea temp is significantly cooler than air but If I could get the air churn right, could this make a noticeable difference£ Most obvious likely limitation is that it might be a one shot trick, which with our shallow bilges wouldn’t do much!at all. But worth a try or waste of time?

 

[Plum]

Bear with me. Or shoot me down in flames if you want. We’ve got aircon on the boat but a. It’s a bit antisocial and b. It’s undersized so not terribly effective, though better than nothing. But retrieving a couple of bottles from the bilge where they are much cooler than ambient temperature had me wondering how I could make use of that free cooling. Obvious solution would be to experiment with a (or probably some) bilge fans to try to churn the cold air below with the hot air in the accommodation. Obviously would only work where sea temp is significantly cooler than air but If I could get the air churn right, could this make a noticeable difference£ Most obvious likely limitation is that it might be a one shot trick, which with our shallow bilges wouldn’t do much!at all. But worth a try or waste of time?

Yes, you have a store of useful cooler air in your bilge but if you circulate that cooler air into the cabin so the warmer air in the cabin goes into the bilge, due to the limited surface area with the seawater beyond, the now warm air in the bilge will need to be in the bilge for an hour, maybe much more, to cool down before you can circulate it again. The heat transfer will be better in a metal hull, worse in a grp hull. Also, your warm air that is transferred to the bilge will have a higher moisture content which will then condense in contact with your hull. This added water content in your bilge may create other problems.

I assume the antisocial aspect of your heat-pump is the noise? Maybe focus on reducing that?

Www.solocoastalsailing.co.uk

 

[rogerthebodger]

You need to look ass where the noise comes from

I have a waer cooled aircon as ued in shopping centers.

These have a much lower air flow through the cooling fins that keeps th air flow noise low.

The compresser is a separate unit located in a closed cupboard and has sound insulation inside the compressor box which also keep the noise down

 

[stranded]

The unit itself can’t really be heard outside, it’s the tinkle of the water outflow that I imagine could be irritating to neighbouring boats without aircon - especiallly because they’re probably already feeling a bit grumpy because they’re too hot and of course have all the hatches open. Not that anyone has said anything, but then mostly we don’t do we, just grumble under our breath.

Anyway, in the light of morning, I can see my idea is not so bright as I thought - even if the cooling effect on the new warmer air is quicker than Plum suggests, from a rough visual guess I doubt the bilge volume is more than 5-10% of the cabin volume, and the temperature differential won’t often be much more than about 10 degrees, so I think its effectiveness would probably be firmly in the measurable but not feelable category.

 

[rogerthebodger]

The unit itself can’t really be heard outside, it’s the tinkle of the water outflow that I imagine could be irritating to neighbouring boats without aircon - especiallly because they’re probably already feeling a bit grumpy because they’re too hot and of course have all the hatches open. Not that anyone has said anything, but then mostly we don’t do we, just grumble under our breath.

Anyway, in the light of morning, I can see my idea is not so bright as I thought - even if the cooling effect on the new warmer air is quicker than Plum suggests, from a rough visual guess I doubt the bilge volume is more than 5-10% of the cabin volume, and the temperature differential won’t often be much more than about 10 degrees, so I think its effectiveness would probably be firmly in the measurable but not feelable category.

My unit is keel cooled (skeg actually) so no sound outside and I use freash water with corrosion inhibiter to prevent any damage to aircon

 

[Stemar]

Does anyone remember Dylan's flowerpot and candle heater? I reckon you could do something similar with an inverted terracotta flowerpot standing in water and a fan blowing on it. Turbocharge it with a wet tea towel on top when it's really hot...

 

[rogerthebodger]

Does anyone remember Dylan's flowerpot and candle heater? I reckon you could do something similar with an inverted terracotta flowerpot standing in water and a fan blowing on it. Turbocharge it with a wet tea towel on top when it's really hot...

Evaporative coolers are not very effective as they rely on the evaporation of water to cool the air . The real issue is as the temperature rises the due point temperature also rises which reduces the evaporation and thus the cooling effect

I had some in my office but replaced then with portable compressor air cons

 

[Stemar]

Dew point is the point at which water condenses. The higher the temperature, the more water vapour the air can hold, so the more evaporation. The other day, it was too warm to keep some food fresh for a few hours, so I put the container in a bowl of water in the shade with a wet cloth over it. I was surprised how cool it was. What stymies evaporative cooling is high relative humidity. As it approaches 100%, like before a thunderstorm, evaporation approaches zero, so my salad wilts almost as fast as I do.

 

[lustyd]

take a look at this channel, he's built out quite a sensible solution

 

[rogerthebodger]

take a look at this channel, he's built out quite a sensible solution

Interesting but who makes the compressor ?

 

[lustyd]

Interesting but who makes the compressor ?

Secop I expect, one of their new nano range

 

[rogerthebodger]

Secop I expect, one of their new nano range

New name for Danfoss.

I have Danfoss on my fridge and freezer.

As was said need a small spce well insulated and small windows.

The nano would not cool my wheelhouse or sleeping aft cabin even with 60 mm sprayed in insulation

 

[lustyd]

The nano would not cool my wheelhouse or sleeping aft cabin even with 60 mm sprayed in insulation

Not to fridge or freezer temperatures, no. But he's not trying to do that. Cooling an enclosed space by 5-10 degrees is entirely doable with those coolers assuming seawater cooling as well. The sea will be maybe 25 degrees, 30 in extreme circumstances and provides excellent heat transfer given how hot the refrigerant will be after compression.

 

[rogerthebodger]

Not to fridge or freezer temperatures, no. But he's not trying to do that. Cooling an enclosed space by 5-10 degrees is entirely doable with those coolers assuming seawater cooling as well. The sea will be maybe 25 degrees, 30 in extreme circumstances and provides excellent heat transfer given how hot the refrigerant will be after compression.

It all depends on the outside temperature and the amount of insulation

My fridge has a Danfoss db 35 compressor ans is water cooled. in the summer set at 5C would be on all the time nevr switch off until I added extra insulation to the fridge cabinmate

The outside temperature gets up to 35 and the sea temperature is average 28C summer and about 23 in winter

Can't remember the btu rating is but a lot higher than used in the video

This is my compressor unit

https://flic.kr/p/WYNLd4

Aft cabin outlet

https://flic.kr/p/WYQrPr

This is my air outlet unit

https://flic.kr/p/WVhPSh

 

[fisherman]

Wind scoop?
Shade and ventilation: How to keep your yacht cool and dry in the tropics

 

[geem]

We are in the Caribbean but don't have Aircon. What we do have is a mattress cooler. It uses evaporative cooling from a unit in the cockpit to cool a rubber sheet that goes under the top sheet of the bed. The rubber sheet has a matrix of water tubes that connect to the evaporative cooler by silicon pipes. Runs off 12v and uses 8w. I can't believe what a difference it makes when the air temperature doesn't drop below 28degC at night. A decent nights sleep without needing the fans on.