Mahe 36: Air Conditioning

[Scott730]

Jef
I have a similar set up to JC's, I have 2 reverse cycle 110 volt units (each supplys 12,000 BTU's for AC ), each one sits under each side of the settee, duct work runs from each unit to feed half the salon and one hull, they draw about 9 amps for AC each, haven't used them for heat yet but i'm told they would supply 6000 BTU's each. I have a NextGen generator mounted in the starboard engine compartment above the muffler that supplies 30 amps, at half load it consumes 1/4 gallon an hour of diesel.
Don't know if this helps you.

Scott

[Captain Bill]

Keep in mind that water cooled/heated reverse cycle systems freeze up in water temps below about 4 C. They work great in the tropic or subtropics but are probably not appropriate above about 35-40 degrees lat except in the summer. I have reverse cycle heaters in North Carolina (35N) but they are quite marginal here in the depth of the winter when our water temps get down to around 5 C.

[Cotemar]

Jef,
I have done a bit of research on these diesel heaters in the past.
They are pretty small. I have the installation pdf manuals, which are a big help for planning out your installation.
I have attached the Webasto_AT 3500.pdf This is a 12,000 btu model also.
Just e-mail me and I can send you the Espar airtronic D4 Manual.pdf
and Espar D4 diesel heater.pdf both if which cover the Espar 12,000 btu model.
I do not own a Mahe yet, so can not give a best place to install one on the Mahe.
Mark

[Clipperton]

My Mahe is equipped with 3 AC units (shore power 110v). One in each hull (AC unit under) the beds and the saloon's under cushions. It will be used in NY. Will tell you the results of it. In particular how it behaves with cold water.

[Clipperton]

hello,

Some feedback on this reversible AC system. it works great and surprisingly, it works as well with water temperature at 3.7°c (sorry i don't know too much about farenheit). last night was -7°c and i was still able to have 12°c in each hull and 18°c in the saloon. Not bad. I was about to buy a regular electrical heater to help but I figure out that this is not really needed and now that the winter is ending, it will wait next winter I guess.
This AC system runs on 30AMP is stand alone from the general system (30 AMP as well).
The three units are controlled via a digital command very similar to a car.

[1rkghost]

I am considering air conditioning for my mahe but first i need to replace my inverter. Can any one recommend an inverter brand model and watt amount enough to handle ac and every day items like phone chargers radio computer etc.

[Scott730]

1rkghost
Why use an invertor for the AC? First you do not have enough battery capacity to run the AC and secondly, my AC units draw 9 amps when running and at least 15 amps to start, this is all alternating current. If you want to run AC away from the dock you will absolutely need a generator. I have a 30 amp generator that handles both my AC units with no problem. I use small invertors to run my TV, charge my lap top, Ect...
I hot Florida my 2 12K BTU AC units work wonderfully.

Scott

[1rkghost]

What kind of generator?

[Scott730]

NexGen 3.5 Made in Jacksonville Florida. I installed it in the starboard engine hold with a sound enclosure

[1rkghost]

Do you have a pic

[Michelhhhebert]

I have a 5,500 btu reverse cycle unit than runs from a puresine 1800 watt inverter or 2,000 watt Yamaha generator, all located behind the fridge (except the genny) , with 520 watts of solar panels and 720 amps of house batteries, all this is sufficient, never needed the AC in the Bahamas, only used it in marinas (rarely), but used the reverse cycle to warm up more... the AC cost only $1,100, so not too expensive otherwise not worth it, unless you spend a lot of time in 85f or more locations... and even then the 5,500 btu would be sufficient to "cool down" the saloon just enough... IMO

[Scott730]

Having sailed in tropical climates for over 10 years, and owning a Mahe since 2007, there is no way a 5.5K A/C unit will cool a Mahe comfortably. No way. You may get off with cooling one berth. I personnally would not own a boat without reverse cycle A/C aboard in a tropical climate.
As to your solution for powering the unit. Will it work sure, is it the most effcient use of your batteries and inverter no. Your inverter losses effciency by converting from DC to AC so you will use more power from your batteries, in addition, you are putting more strain on your batteries and charging system. If you watched the actual power draw in DC amp hours everytime the unit cycles you would see the strain you are putting on your batteries, which then has to be made up by your generator and battery charger. I would suspect you will be replacing those batteries much sooner than I will.
If you want to cool your boat to your satisfaction at anchor, you needed a 3000 watt genset minimum and run the a/c directly from the generator.
Just my 2 cents.

[DtM]

..... and a good two cents at that.

[roetter]

Originally Posted by Michelhhhebert

I have a 5,500 btu reverse cycle unit than runs from a puresine 1800 watt inverter or 2,000 watt Yamaha generator, all located behind the fridge (except the genny) , with 520 watts of solar panels and 720 amps of house batteries, all this is sufficient, never needed the AC in the Bahamas, only used it in marinas (rarely), but used the reverse cycle to warm up more... the AC cost only $1,100, so not too expensive otherwise not worth it, unless you spend a lot of time in 85f or more locations... and even then the 5,500 btu would be sufficient to "cool down" the saloon just enough... IMO

I am trying to do the same (powering AC by inverter and solar) on a Lagoon. I am installing 1800W solar, 700Ah LiFePo batteries and two Victron Multi 12/3000 inverters. The LiFepo can handle the huge DC power demands no problem. With lead acid batteries this can be problematic. On my previous boat with 840Ah lead acid even one Multi 3000 gave them near heart attacks (voltage drop under 200A+ load down to 10.5) when powering a toaster or cappuccino maker and they were only down to about 70% SOC. The Nexgen genset will remain on the back burner until I know I really need it.

[Michelhhhebert]

In rebuttle to Scott, i offer my own experience adapted for MY cruising ground. North East to Bahamas. After 5 years of this setup my batteries are still "happy", and we have needed to use the AC in the afternoon only, when the sun is high and the batteries are full, so we use the "otherwise lost" energy from the solar panels, about 25 amps, with a potential of 40, the inverter indicates that the peek demand is 45 amps with 23 amps running, so we do not drain the batteries that much, now it is true that we are not in 90 degrees plus weather, but the saloon is cooled enough. Funny enough we have used the AC more in the North than in the Bahamas...

When i will replace my batteries i will put in at least 1,000 amps, not only for the AC but to have ample reserve, for cloudy days. The 2,000i generator has been just what we need for most of our needs, everything has to be in balance: 40 amp/hour charger with 1,000 watt water heater works within the 1,600 watts generated. The AC at 5 amps is within the power generated by the genny. If you need more AC then everything needs to be increased.... My 3 cents...