OK. It's
project time!
This should be a good one. We need
air conditioning. I've read all the 'you don't need it, you want it' comments in other threads but the fact is, Hayley is in
Miami, in May, in a marina and pregnant. The last 10 months we have lived off
anchor and despite a couple of nights where it was slightly too warm, on the whole, as long as it's not raining then the breeze is plently cool enough.
Next year however, we will spend much more time in
marinas. Partly due to the bubba on the way but also because I will be working more often (the last 9 months off
work has left us nearly bankrupt) so
single parent,
dinghy runs with baby just isn't happening. Like I said: we need AC.
The beauty of not having it installed by
Lagoon is I can now install exactly what we want (need). So what do I want?
AC in the 3 cabins plus
saloon. Do, I need it in the
saloon or will the cool air from each
hull provide sufficient
cooling upstairs?
My thinking is to fit 2 separate units. (I had thru huils put in prior to launch).
Unit 1 can chill master
cabin and saloon.
Unit 2 can chill the 2x port side cabins.
I'll fit separate pumps and controls so that they are completely independant. Often we won't need the port side unit running.
The under seat
storage in the corner is hardest to access so this will be home for 1 unit. Can i fit both in there?
Today I've been reading up on air con unit
power requirements because I'm thinking that once we're all used to sleeping in AC in a marina we are going to want it out on
anchor. Obviously I'm no expert (yet) but here's a few calculations I've done with an eye on running it on
inverter. These are approx and I've rounded up or down for ease:
6,000btu = 5a
8,000btu = 6a
10,000btu = 7a
12,000btu = 9a
I read today that there's a 10x
rule for AC / DC. Basically, the 6 amps that the 8k unit draws will use 6 x 10 = 60 amp hours from my
batteries. I'll use 10 hours run time for simplicity which is obviously 600ah. (a lot!) But, the
compressor doesn't run flat out all the time so you can assume 80%. 600 x 0.8 = 480ah
Here's the calculations for all the units:
6,000btu. 5 x10 = 50ah x 10hours = 500ah x80% = 400ah
8,000btu. 6 x10 = 60ah x 10hours = 600ah x80% = 480ah
10,000btu. 7 x10 = 70ah x 10hours = 700ah x80% = 560ah
12,000btu. 9 x10 = 90ah x 10hours = 900ah x80% = 720ah
This is all a very simplified version of reality but it gives an idea of what is feasible. I've not gone into only being able to use 50% of your banks amp hours as some have huge lead acid banks and others are on
lithium and using 80% DOD. We are currently on the standard
Lagoon LA's with 840ah so at present it's not possible but this has highlighted the sweet spot and I think the 8,000btu unit is a go!
In a years time I could be installing a
lithium bank or I might have even bought someones 6 LA's who's swapping out their bank for lithium. I could probably get another 6x 140ah
batteries for £500 and put them under our port side
bed. My point is the 8,000btu unit should be cool enough for us? and should be future proof.
To run off
inverter you also need a soft start to reduce the
current spike on starting the
compressor. I've been researching the Dometic Turbo self contained units which have an optional Smart Start that takes care of the spike.
Of course we can simply run it all off
generator but I'd rather not. I've found our
solar has our
current bank fully charged by lunchtime so if we double our bank we would need more
solar, however, we do tend to run the genset most evenings 5-6pm for an hour to make
water so this ensures our bank is at 100% and of course there's time spent motoring too. All things considered, I think it will
work for us most of the time.
I've waffled more than usual there so what do you guys think? Please correct me if there are any huge glaring errors there?
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