I hear that some of the commercial boats use a residential unit and mount on
top of cabin with better success than marine grade heat pumps.

What brands are best for marine grade? Is this a project that the average
boat owner can handle?

The cost to go with a residential is much less but I am concerned that the
marine products would be better.

thanks for help,
marshall

The main difference other than seawater condensers rather than forced air is
that the domestic unit's sheet metal (drip pans, covers etc) is mild steel
rather than stainless.

Medium size commercial boats like ferries do use domestic type A/C units but
that is because when you get into the 10 to 20 ton range it is cheaper to
replace them every couple of years than invest in a true marine system that
a similar size megayacht would use. Also noise is not normally a factor.
In the 3/4 to 1.5 ton sizes typical of most under 60' boats it is far
cheaper to get a marine unit that will last 7 to 8 years rather than a
domestic unit that only last two seasons and water cooled marine A/Cs are
much quieter.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"MarshallE" wrote in message
...
I hear that some of the commercial boats use a residential unit and mount
on
top of cabin with better success than marine grade heat pumps.

What brands are best for marine grade? Is this a project that the average
boat owner can handle?

The cost to go with a residential is much less but I am concerned that the
marine products would be better.

thanks for help,
marshall

On Sun, 18 Jun 2006 23:00:52 GMT, "MarshallE"
wrote:

I hear that some of the commercial boats use a residential unit and mount on
top of cabin with better success than marine grade heat pumps.

What brands are best for marine grade? Is this a project that the average
boat owner can handle?

The cost to go with a residential is much less but I am concerned that the
marine products would be better.

thanks for help,
marshall

Hi,

The biggest problem would be galvanic corrosion within the condenser's
aluminium fins and copper tubes from salt spray and salt/humidity
laden air. Similarly the evaporator from salt in the air and condensed
water.

Ways to minimise this would be having a louvred cover for the
condenser, and spraying the condenser/evaporator fins with a thin coat
of cold galvanizing spray, then a corrosion inhibitor like boeshied
etc.

Also if the condenser is on rubber mounts, the connecting pipes need a
bit of care so they don't work harden and break from vibration and
movement. Flexible pipes of the right type for the refrigerant might
be a better way to go.

Try asking on alt.hvac (don flame suit first!)

cheers,
Pete.