The crews of Annalee, Aquila, Contigo, Elsie's Phantasie, Kava Kava, Narsilion, Paisano, Pau Hana, Schatzi, Silent Running, Windrose and Windsprint gathered at Cutter's meeting room to participate in a discussion on refridgeration and air conditioning systems that we have on our boats.

Guest: Woody Sherrod of Sherrod Marine (Baltimore)
Sherrod Marine
1473 Stevenson St
Baltimore, MD 21230 - View Map
Phone: (410) 752-2870

The Frig/Freezer & A/C questions received and discussed were:

Refrigeration / Freezer
1) How do I determine if the unit is working properly?
Draws approx. 5 amps, if doesn't cycle off not working well. Avg. run time 50-90% of the time. Approx. 100amp-hrs per day. Rarely do thermostats go bay. Digital thermostats are expensive and can't override them.

2) The unit never cycles on / off.
Is this a thermostat problem?

3) How do I know if the unit is low on refrigerant?
Unit won't cycle. Should have a light sheen of frost all the way around and top to bottom. Uneven frost if it is low. There is only 10 oz of refrigerant in the system. If low, must have a leak. It is usually the screwed on quick connection. Look for oil under coupling. Approx cost is service call and a little refridgerant. Need gauges and can of 134a or 130a?? They stopped using r12 in mid 90's.

4) What is the best type of insulation to use for the frig / freezer box?
Not his expertise. Need to insulate inside and finish with glass. Generally box is ok, unless it is wet it will last forever. If freezer is overcharged, it will run all the time. Check temperature on the evaporator. It should read negative degrees (-10 degrees is good) after it has run a while. Capillary tube should be against the plate.
Refrigeration plate gets to 26 degrees. Two box spillover systems should have a second compressor. New plates have a fan in the middle.

5) How many amps per hour should the unit require?
4.5-5.5 amps, depending on how old the system is. R12 systems have high amp fans.

6) What is the best way to balance a two compartment / one compressor system?
Choose spillover fan possibly. A PVC pipe with fan will move the air around 24/7. It is best to have them blowing up.

7) What is the best way to prevent refrigeration compartment temperature stratification?
Use a fan to circulate the air in the box.

8) Does insulation deteriorate over time?
No. It will be OK until it gets wet.

9) What would be involved in making a new refrigerated ice box from scratch (replacement for the RV type installed on newer Hunter Sailboats)?
He does not do that. You would need a cabinet man. An option would be a top loading freezer or refrig. Really good boxes.
If there is no ventilation on your boat, adding some will help. Need hole under and top for hot air to go. Maybe a little pancake fan. It doesn't draw hardly any amps.

Air Conditioning

1) How cold should the air temp be coming from the outlet?
Should be 20 degree differential for cooling and 40 degrees on the hot side after warmed up.

2) How do I know if the unit is low on refrigerant?
Won't do its job. Easier to tell on the heat side. Less than 40 degrees. Depends on water temp. Do not run below 37-38 degrees water temp. Use electric heater if you don't have diesel. Add receptacle wired to AC circuit and use instead. It will use the second 30amp cord. Add oil filled radiator and possible fan only of system.

3) Can I add refrigerant?
No. Regulated sales. Really need to know what you need to do. Usually R22. 22 is more efficient. For 410a really need to know what to do. Usually only 17oz. He sells his at cost. It is a service call. $100 + refrigerant.

4) How easy is it to install a soft start capacitor?
Easy. $15-20. Dometic makes a box for 450-$500. Any down side? No, easy to install on run capacitor.

What size AC will run on portable generator?
12,000 maybe 16,000. Not all Honda generators are equal in power.

5) What is the expected differential between the return air temp and the output temp that should be expected? Do you use this method?
See above…Use the touch pad for return air. Everyone should have digital temp gun.

6) What is the best way to clear an ‘air lock’ on the ac water pump?
Trick to make priming easy is to install a plastic tee from WM (marine rated), petcock (or valve) from HD, put on the hose coming out of the pump. Air does not matter after pump. Strainer could be full of air. 1/2" tee, pet cock for ice maker, 1/2" to 3/8 reduced. Use ball valve instead. Tony cited possible surveyor issues with petcock.

7) What is the recommended disinfectant for an ac condensate pan?
No bleach. Condensation needs to get out of pan or will rust everything out.

8) What is recommended to use on the ac fitting rust to delay obsolescence?
CRC OR anything else.