Air-con

[Graham_Wright]

I wonder if any of you enterprising lot have converted a vehicle heater for boat heating?

Engine heat is free and I have seen one commercial model advertised but expensive.

If that is too easy, how about the same for cooling? In France, vehicle air-con seems almost standard and a compressor and its associated bits could be available for a song recovered from the scrappies.

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[Robin]

Will you be running your engine 24/7 then?

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[Talbot]

I have looked at the possibility of aircon from a vehicle style system. My chosen donor worked out at 6,5 kW with a resultant cooling of 22178 BTU/h. Now that is more than adequate for most boats, however it is a massive power requirement from the engine (and anyway, who wants to run the engine just to get aircon) It is way outside the power abilities of a danfoss fridge compressor, so I have parked this concept in the useless ideas department. However, heating is a different matter, as a lot of people would be happy to heat up their boats when coming into harbour. Not only is this feasible, but has actually featured in PBO. Furthermore it is the same concept that is used to top up the calorifier in those boats that are fitted with them. Didnt bother myself cause I have a 4kw eberspacher which works nicely.

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[steve_cronin]

Heating.

I did hear of someone who used the heater from a Reliant Robin! Apparently it is a uniform rectangular box with integral blower and the inlet/outlet water hoses situated in a convenient place. Also the demister outlet hoses are 2" diameter making it suitable for connection to normal marine heating outlets.

Sounds like a great idea to me and on our boat quite easy to accommodate as the hoses to the calorifier run just behind the fixed bottom step of the companionway, the area below which could be easily boxed in to accomodate the unit. This could be very neatly controlled by a Drayton thermostatic radiator valve protruding out from the box. The diverting type used as a domestic hot water cylinder controller might be more suitable as you could then get a boost of heat by closing off the calorifier feed from the circuit and directing all the flow to the heater matrix. If using a secondhand heater shut offs are essential to avoid loss of coolant should an aged matrix spring a leak.

AirCon.

Well pre-cooling just one stern cabin with an engine run compressor and evaporator from an elderly Jaguar, BMW or a Mercedes might just work so long as your engine is at least 50hp, you run on re-cycle mode and you keep all the portlights and hatches to that cabin closed. However I think that you just might get tired of the noise.

In our marina in Gouvia, Corfu, quite a few boats have one cabin A/C'ed using a portable A/C unit hooked up to the shorepower with it's elephant trunk vent hose sticking out of a convenient portlight.

It isn't the heat so much as the humidity of mid-summer so we find that air movement over the skin is the priority and a few low power fans - computer ones are very good but a "Ring" brand battery fan running on 4 D cells lasts a whole season in my wife's cabin (yes we sleep alone on the boat in the summer - it's too darned hot!)

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Graham_Wright]

I have a problem with credibility with that.

In France I hired a Smart car (Daimler-Chrysler;- don't ask about the parentage but not at all like the Mercedes variety) which had very effective air-con that had to be run at minimum to avoid freezing us (with an outside temp. of 28°C) and switching on the compressor resulted in no detectable engine noise. Previously I have hired a Fiesta which did blink slightly at the compresor load when the air-con was activated.

Those experiences are at odds with the quoted 50h.p.

Please continue with the debate!

<hr width=100% size=1>GBW

 

[Talbot]

1. You missed the decimal comma for power (6,5 Kw = approx 8.7 hp)
2. Information copied directly (including the comma) from email from Vauxhall motors tech department.
3. Your smart car had a 50 or 60hp engine, it would also have had a MUCH smaller aircon than that fitted in an Omega, and in any case would probably shown more in mpg than engine load.
4. Your engine in the colvic is probably much nearer 25hp, thus a 8.7 hp use is a respectable load.


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[Talbot]

not sure why you think that the air con from a big car is going to be so feeble. Reports from Florida on aircon for a Prout Snowgoose have shown that 12,000btu make a respectable difference, and that 16,000 btu is more than adequate. The aircon on my Omega is rated at 22,000 btu (according to Vauxhall)

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[philmarks]

I plan to use a portable aircon unit for the aft cabin, run off generator or shore power. It seems to me that you only need to run it during the late afternoon/evening to prepare the cabin for sleep, and then switch it off before turning in. It does also depend on crusing area - i sailed from GIB to Canaries and back via Azores this summer, and ther were probably not more than 5 nights when aircon was desirable. MY boat is steel with a dark blue hull. I realise that the tropics will be much more humid and hotter, but reckon that my approach will suit me. A friendly aircon engineer offered to install a quiet compressor and aircon (also connected to my fridge and freezer). I was afraid to ask the cost after he said "we just fitted one out in a new yacht in <a well known Hamble boatyard> cost them £40k for the work it did!!

<hr width=100% size=1>Rgds
Phil

 

[Ric]

Whenever I look at fitting an Eerspracher or other such diesel heater, I ask myself whether it wouldn't be cheaper and easier to fit a diesel generator, and then a reversible electric aircon/heater system.


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[steve_cronin]

where did I say "feeble"?

Steve cronin

<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Talbot]

didnt have the space for the generator, and wouldnt want to run one as a permanent solution. Too noisy, and much more difficult to install in my boat than the eber.

However, if you were starting the build of the boat from scratch, the concept of a diesel generator providing the overall power including motive does have some advantages.

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[Talbot]

<<where did I say "feeble"?>>
<blockquote><font size=1>In reply to:</font><hr>

Well pre-cooling just one stern cabin with an engine run compressor and evaporator from an elderly Jaguar, BMW or a Mercedes might just work so long as your engine is at least 50hp, you run on re-cycle mode and you keep all the portlights and hatches to that cabin closed.

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That was my interpretation of your statement. I think you will find that the average Prout Snowgoose has 5 main compartments which are cooled by a 16,000btu aircon in Florida, whereas the Omega aircon is rated at 22,000 btu. I would imagine that the mercedes is even larger. This size uses abt 8hp to run, so could be run off a 35 hp engine (which a single engined Prout Snowgoose Elite normally has as standard). Notwithstanding this, I rejected it as a concept because it did not meet the requirement that I had.

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[timentide]

I am sitting at this moment in air-conditioned saloon on my Prout 34.We use a standard window model 110-240v plugged into 240v shorepower when available. It is rated 12000 BTU and is very adequate for this size of boat here in the tropics. When anchored off we find that we have not needed to run it off a generator as we always seem to have a nice flow of air through the boat. It is placed above the main 500x500 hatch with the hatch open and covered with reflective sided canvas to make a trunking. The only problem I can forsee on a monohull is that of storage whilst underway, on the cat it goes on the rear deck along with the Yamaha 90cc motor bike!!!! To sum up then the advantage of a mobile unit is that no custom permanent fittings within boat and it can use shorepower in marina, out on the hook you probably won't need it. Disadvantage is storage and initial cost.

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[William_H]

Horsepower required for a car airconditioner. Here in oz all small cars less than 2000cc have a throttle nudger to increase idle revs with A/c on and some have an A/C cutout to disconnect A/C compresser when full throttle is requested. Most 6cyl cars don't bother with these concerns so horsepower required is significant. A/C in a boat. It would be a shame to waste the under hull cool water resource for cooling the condenser. If you used a sea water heat exchanger the eficiency of fridge or aircon should be vastly better than air cooling the condenser. This however pushes price up as it must be installed. Reverse cycle would be ideal for heating. The boat engine is an ideal source of power for A/c however you probably don't want to run it when requiring aircon unless it is just for an hour in the evening. 240 volt AC means you can run it from shore power or if necessary a generator so would probably be a better bet. So you would probably get a domestic A/C cos they are so cheap. Here last summer split medium power types were on sale for 200quid.
My own opinion is that on the water you don't need A/C as the boat never gets really hot and even if it does you shouldn't be doing anything strenuous. Don't know about heating. regards will

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[jfkal]

Technically it should be viable to use a car aircon unit provided you have suitable front PTO option on your engine. Dunno whether it is an DIY job but one of the aircon manufacturers should be able come up with a marinized version of it. I am sure that there are modifications needed on the heatexchanger side of it (size, space, heat ransfer). I went a different avenue:
Got a 13000 BTU marine air unit in my 38 ft Sunshine. I wanted to get actually a 220V engine driven system to generate the juice without dealing with 200A DC. However there do not seem to be commercial systems on the market which provide the clean tru sine supply as required.
Final solution was to upgrade the alternator to 140A and install a 3KV true sine inverter. Some alternator cooling challenges aside the system does indeed work and also provides virtual limitless supply of AC power (once the aircon is off [I admit]. I am happy to share the technical details (PM me).


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[Benbow]

Re: Air-con - why bother

I have spent most of my working life in the tropics and I personally am convinced that aircon is a really bad idea because you never get acclimatised. If I am staying more than a few days in a hot spot I never sleep in an airconditioned room. I am quite convinced that you do become acclimatised, so unless you can spend all of you time in air-conditioned environment, I believe you are better off suffering the initial pain.

However, I am sure this is a very personal view, I would be interested to hear what others think.



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[Graham_Wright]

The engine in my Countess is 36h.p. I imagine that there is quite a lot left over when on cruising revs but I'm way out of my depth here. There is space ahead of the engine to tack on a few driven accessories. I'll put it in the "Future" box!

Very rewarding responses;- thanks to all who reacted.

<hr width=100% size=1>GBW

 

[steve_cronin]

I posted a lengthy reply but the forum lost it.

To summarise, 8.5hp out of the output of a 35hp engine running at cruising revs (say around 18hp) will result in a 45% loss of power. You will notice that. Also the bigger engines being auto derived will be much more straightforward to adapt.

Personally, having a boat that is currently sitting in water at 23C, surrounded by air at 29C moving gently at 6mph (which will die to <2 overnight) we consider air movement more important. Fore and aft hatches wide open and sleeping naked under a single sheet do the job nicely.

Steve Cronin

<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[ashley]

There's a heat pump on ebay at the moment starting at £495.
quite reasonable-ish if it does not get to crazy
here; <A target="_blank" HREF=http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2492672133>http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2492672133</A>

simpler, efficient with fresh water cooling so uses less power and not affiliated with me in any way

<hr width=100% size=1>Live life to the fullest... think of all the people on the Titanic who passed up chocolate dessert.

 

[frilaens]

Re: Air-con - why bother

I agree with that; I spent 2 summers in North Africa one with and one without the AC on. We had some problems with the electricity and I opened up one of the units to try and clean it up a bit and make it more effective. One look at the crud my air was being filtered through was enough! The second benefit was the reduced noise from the fans which cannot be good for your hearing over longer time.

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