scary said:

I'm buying a 1976 Hatteras 48 LRC two of the four Cruise air units are not working. This boat has been in the Pacific North West for at least the last 20 years and I suspect the Ac units have not had much use. The owner used the resistance heat and portable baseboard heaters for heat. I will be using this boat in a hotter environment as well and I currently use Dometic units to heat and cool my 4788 Bayliner. The owner is responsible for having these units serviced and made to work as part of our sales conditions. I like the quite operation of the remote compressors when compared to my Dometic units but these don't seem to put out as much cold air. What can I expect out of these units in life span and performance.…That's really hard to say since they are already what ? 36 years old… Should I push for new compressors or evaporators if these units are losing refrigerant.…Those condensing units (if original) had low pressure switches so they at least have not run without freon…But the air handlers at that age are subjet to many leaks at the hundreds of solder joints that hold them together…The units not working are the ones servicing the pilot house and the master stateroom. How much differential should I have between the ambient air temp and the out put at the duct...15 to 18 degrees The owner has kept good maintenance records and it appears he had these serviced 10 or so years ago. Since I'm planning on keeping this boat long term, can I expect these units to last years into the future if rebuilt and maintained by a qualified tech or am I peeing in the wind.

Obviously it's hard from here to see the systems & their overall condition…But look for dark or black spots on the units around where copper tubes are joined (solder joints)…Black is an indication of galvanic action eating away at that joint…solder is a dis-similar metal, and any problems will show there first…Oil around that black joint is an indication that it is in fact already leaking…

If it were me…I would at least plan on new air handlers first…The new models are much better anyway in that they are quieter & move more air.

Leaky solder joints on the condensing units in the engine room are easier to pinpoint & re-solder than the ones in the air handlers…

The air handlers usually need to be removed (for access) to repair anyway, and they also have much thinner wall copper tubing so it's easy to melt thru that copper while doing solder joint repairs….Often times you create another leak just by heating an adjacent joint as the heat transfers to the other one that has a marginal seal…At this point it's best to replace the whole thing because leaks will continue to surface fairly often in other joints.

Also saw your post on HOF…No these system are not like cars with any kind of rubber hoses or shaft seals…R-22 will permeate any kind of rubber…They should not need charged seasonally.

Steve~

If you have Honeywell T-Stats and two knob controls…Which I think I remember the Hatt 48 LRC having…I don't think you will be very happy with the temp differential of the cabin/s…That setup provided a 5 degree swing at best, because the Honeywells used a Bi-Metal disc or coil to sense temp (can't use mercury on a rocking boat)

Folks always complained they were either too cold, or too hot with those thermostats.

Today's digitals are capable of keeping the temp as close as 1/4 a degree of where you set it, but 1.5 to 2 degrees is usually a standard swing we set them to that most won't notice the change.

Yes Air handlers are readily available… http://www.dometic.com/enus/Am…..taid=89269 

Be sure to click on the yellow print "TurboVap spec sheet"

Steve~

Your assumption on the hardware store t-stats is not entirely true…While they can be made to work in a marine system…They were not designed to work with a marine system…

Marine systems use full line voltage, and the home type t-stats are designed to work with the stepped down voltage of residential systems…Home systems have a step down transformer that drops control voltage to 24 VAC…Marine systems do not…

Home T-stats can't carry any load…They can only trigger a contactor (compressor) & relay (fan) that does carry load…They also only provide for one fan speed where your marine units are variable speed.

Lastly…Hardware t-stats are not ignition protected as per USCG regulations…

Here is a link to a dealer locator for Dometic products (Cruisair/Marine Air) http://www.dometicenviro.com/d…..hp?l=water 

And a link to the controls offered by Cruisair…. http://www.dometic.com/enus/Am…..red-Water/ 

I would look at the SMXir & the SMXht….

Steve~ 

Yes…Sunny West Coast of Florida    In St Petersburg…That's about as far west as I get… 

Steve~