DIY air conditioning install on 43 DS

[Renaissance]

Hi everyone,

I have started to casually consider installing an air conditioning unit on our 43 DS. If we do it, I plan to install it myself. We are in US PNW and don't need AC very frequently but it is occasionally needed and when it is needed it gets really bad. Also we eventually plan to sail south to Southern California and Mexico so want to have some options.

That being said, I have a bunch of limitations. I can only install a small unit. First of all, we only have a portable generator and don't want to use it for air conditioning. So planning to use it on shore power or in limited capacity on solar and batteries. We have 960 watts of rigid solar panels, which can pump in easily 65 amps on a sunny day when AC will be needed (controller is a Victron 150/70, so capped at 70A). We also have 600 Ah LifePo4, with an option to upgrade to 700 Ah. So a small unit, running either on shore power or for ~6 hours on anchor is the goal. We have a Magnum 2800 watt pure sine inverter. While planning to change it to a bigger Victron, it is not an immediate goal. So needs to work with this setup. 

Size and space is also another consideration. We have a Webasto hydronic heater (more of a necessity in PNW!) with 4 blowers and it takes a fair bit of space. 

These are obviously some significant restrictions, the only practical option I found is a Webasto FCF-6000. It is rated at 115V/ 4.7 Amps with a starting Surge: 21 Amps. The next bigger unit is FCF-1000 but starting surge is 34 amp, which is even exceeding our shore inlet of 30A, and the capacity of our inverter which is a no go. FCF-6000 would draw around 540W on average with a peak of 2415W. Average usage is acceptable for us and peak is within the limits of our inverter. If I go with this, I plan to install it under the wine cabinet, on the port side. We already have an unused thru hull previous owner installed, so want to take advantage of that. 

Now obviously, 6000 BTU is a pretty small unit for a boat like 43 DS which has good big windows (which we love).

I have two questions: Is this worth the effort on my side? Or is 6000 practically useless? If we could bring the temperatures a bit down it would help.

Also, is this something that can be a DIY install or will I be taking too much on? I am reasonably handy, having installed all electronics, lithium batteries with adjusted chargers, alternator protector, solar panels, Webasto forced air heater etc on our current boat (and the previous boat). But this is a more complex install and electrical wiring will be more complicated with grounding etc. 

Any thoughts, suggestions?

Thanks much in advance!

[zaphod]

6000 BTU is pretty small, but it will have some effect. It will likely run continuously in hot weather. That's a continuous 45a draw on your DC system. It sounds like you have enough solar to support it.

Keep in mind that the inrush current is only momentary, and shouldn't trip your breaker even if it exceeded 30a. You may be able to get away with a bigger model.

If you did all of your battery, inverter and solar wiring you should be able to wire in the ac unit. It is pretty basic stuff. If you are unsure, then pay a marine electrician to check your work.

The most difficult part will be routing the ductwork to get good air distribution and adequate return air to the unit.

[Don Reaves]

I have a 9000 BTU A/C installed on my SO35, and it's barely adequate. I would suggest that 6000 BTUs, if installed on your boat, should be restricted to a specific space, like the cabin you sleep in. It would be adequate in that case.

That said, even the reduction in humidity would be helpful in a larger space. That makes it much more comfortable even if the temperature is still fairly high.

[Renaissance]

Thanks for the input. Reading the manuals of Webasto AC units, it looks like these need to be installed above the waterline. I don't have that option really as space is already quite tight and the best place I can put it slightly below the waterline. 

Where do you all have your units installed?

[Don Reaves]

I don't know for sure, but I expect my A/C is at least partly below the waterline. The input hose definitely loops up above the waterline, but there's no anti-siphon valve involved.

[andreshs1]

Hi there

I would go for a full DC Aircon unit, Mabru makes a very good one, and there is also the unit that is developed by Clark, from the www.emilyandclarksadventure.com/AC (this one seems to be a winner price and performance wise, the DC draw is minimal

Cheers

[rxc]

Just noticed this post. I have two Webasto units on my 43DS, dual heating/cooling units that have been in place for 17 years and work well, in spite of all sorts of trials and tribulations. The one up forward is the 16K BTU unit, which sits under the settee just to stbd of the mast. The circ pump is in the bilge, and the unit has outlets into the main cabin and the fwd cabin (I have the 2-cabin 43DS). There is a smaller 7K unit in the bilge inboard of the stove/cooker, with an outlet to the large aft cabin.

They work well, as long as you provide them with a good source of cooling water. I recently spend nearly 2 weeks trying to figure out why they were not getting water, and eventually had to dive on the inlet, to find a large, balled-up plastic bag tangled up in the clamshell thru hull.

If you are in the PNW, you might appreciate the heat - we did when we sailed in NW Europe, and now we appreciate the AC in Florida.

[sailbaum]

You should take a look at the Velair units.  They have no inrush current and ramp up slowly.  I have a 16k unit and it draws 9amps on full power and you can limit it to 1/2 power at about 1/2 the draw.  When on solar, you can limit the current for battery life and dehumidification and when on shore power you have the full capacity available. 

I bought mine from the Yacht Rigger (https://theyachtrigger.com) with great support to help me self install.  No affiliation just a satisfied customer. 

[zzmeyer]

My cruising grounds are SoCal and Pacific Mexico. I very rarely need aircon at anchor but often do at the dock where there is shore power. I’d size your unit to the cooling requirement and not battery capacity.

[andreshs1]

Jun 15, 2022 6:57:10 GMT sailbaum said:

You should take a look at the Velair units.  They have no inrush current and ramp up slowly.  I have a 16k unit and it draws 9amps on full power and you can limit it to 1/2 power at about 1/2 the draw.  When on solar, you can limit the current for battery life and dehumidification and when on shore power you have the full capacity available. 

I bought mine from the Yacht Rigger (https://theyachtrigger.com) with great support to help me self install.  No affiliation just a satisfied customer. 

Hi there, but you are referring to 9amp @ 115v, right? Isn’t that roughly 100 amp/h?

cheers

[sailbaum]

Yes, that's right and about 50 amps (12VDC) at 1/2 power.  I wouldn't recommend and don't use it regularly on battery but it is possible (depending on bank capacity and charge source).

They are great units and because they are variable speed can maintain a more consistent temp - they aren't all or nothing like many of the others.