Engine-Driven Compressors

[tartanss]

Hi everybody, as usual the fridge freezer has packed in and the compressor a Yorke is making one hell of a raquet and not doing a thing. Am in Indonesia and will replace compressor but wondering wether to buy another York or go with a rotary type. The Yorke was original Grunert system but was very clunky but if I'm going to spend the money might as well update to the best. Anybody got any views

[Richard Kollmann]

There can be infant mortality failures of engine driven refrigeration compressors in the first 30 days but after that failures can be attributed to system design, refrigerant used or compressor’s speed. Excessive noise on Tartan’s compressor can be caused by a lose clutch or clutch bearing failure. Rocking compressor’s center shaft back and forth and hearing a clanging sound would indicate a rod or crankshaft failure.

Thirty years ago when Crosby and Grunert two of the pioneers in pleasure boat holding plate refrigeration first developed engine driven refrigeration understood the importance of refrigerant and oil flow. Some of these systems are still in use today. The secret to these older systems success was slower compressor speeds and reduced or metered liquid refrigerant return flow to compressor. What may have contributed to their compressor’s longevity success was diesel engines then operated at much lower engine Rpm’s than today’s marine diesels. Their designs also included heat exchangers between liquid line and suction line to insure suction line liquid changed back to a gas before interring compressor. Suction line accumulators separated oil and any liquid refrigerant slowly metered it to compressor.

If an engine driven refrigeration compressor fails it can be contributed to one or more of the following conditions:
· Excessive start up compressor Rpm when refrigerant has migrated in to cold holding plates. After compressor is stopped for a while refrigerant and oil will migrate into colder holding plates and collect there as a liquid. If compressor clutch is energized with liquid in low side of system it will quickly cause liquid slugging of a compressor that is only designed to pump gas. The restriction in this system that prevents this bulk liquid refrigerant flooding on start up is the refrigerant flow control device Thermo Expansion Valve (TXV). On a compressor’s restart if TXV’s sense bulb is detecting a temperature above normal partially frozen plate temperature TXV orifice will be at its full wide open capacity. If plate’s eutectic solution’s weight is less than 37 pounds for that TXV its capacity should be rated 1/3 of a ton or less to reduce possibility of compressor liquid slugging.
· Engine drive Rpm is the key to compressor longevity. There are many boaters that believe a 1 ½ ton capacity compressor must be turned fast in order to freeze a 20 pound holding plate that requires 2900 Btu to complete the solution’s phase change to ice in less than an hour. The fact is that reducing Compressor Rpm on Tecumseh HG 1000 or York compressors to 1200 Rpm, and Swash plate compressors reduced to maximum of 1600 Rpm is better. These lower compressor speeds will result in lower daily engine running time except on first days warm solution pull down that may add 10 additional minutes. Lower compressor startup RPM also reduces refrigerant flow velocity back to compressor giving it time to convert back to a gas.
· Not enough or contaminated oil, when a replacement compressor is purchased is a problem. Most new compressors come with oil recommended by compressor manufacturer. The volume of oil is assumed to be adequate for automobile air conditioning and may not be adequate or compatible with your holding plate refrigeration system design. Oil and refrigerant must be miscible at very low temperatures in order for oil to move through system and return to lubricate compressor. R22 and maybe some blended refrigerants are not good candidates for holding plate refrigeration.

There are never two boat refrigeration systems the same so if you are concerned about over stressing compressor do to liquid feed back because of excessive speed and or over capacity TXV’s then follow the operating instructions given to bare boat charter captains. Before turning on the engine driven compressor reduce engine Rpm to below 1000, then let compressor run for 5 minutes before increasing engine speed.

As to the question of York or Tecumseh versus Sanden multi piston compressors every one has an opinion. Glecier Bay spreads the story that compressors designed for automobile air conditioning are not suited for boat refrigeration. Others thought the two ton cast iron compressor was the best choice. For twenty years I sold all three types of compressors but only provided warranty on Sankyo SD508 now Sanden type multi piston compressors. Many charter boats are equipped with the smaller SD505 compressor. The original 1978 model of SD508 was still operating in my sailboat last year when I sold it. I placed no operating restrictions on my system. It was fully automatically controlled by thermostats and a low pressure switch. The three TXVs in my system were fitted with .02 ton orifices. I believe the reason these compressors lasted over 25 years on my designs is engine drive pulley was only four inches in diameter with a 5.25 inch pulley standard on SD508 compressors.
I prefer SD508 compressors but I have seen many boats with York and Tecumseh shaft driven compressors in use for twenty years.

There are technical differences between the two cylinder vertical compressors and five cylinder axial flow Sanden compressors this originally help me decide on the SD508. Two cylinder compressors develop much greater pulse vibration than the five piston compressors reducing shaft seal damage. Shaft side loading is another problem with the two cylinder vertical compressors as side loading of clutch is inside compressor. Modern compressors like Sanden support belt tension clutch side loading sealed bearing in center of clutch assemble. The two cylinder units are more exposed to valve failures do to possible return super saturated refrigerant interring top of compressor.

[tartanss]

hi richard and thanks again. have decided on looking at the 30 od year old compressor which has always been noisy to remove and change over to a sanden compressor. can you say which model would be the best for the least amont of changing pipe work and which gas 134a or r12 and as the oil accumulator has been removed do i need to fit a new one for this compressor. i believe all the other parts are good so which compressor and should it have service connections fitted although i think the original grunert bolt on the bulkead pakage may contain service ports.
many thanks we are searching suppliers in bali but if no luck sanden have place in singapore

[Richard Kollmann]

If you change from a York to a Sanden it would be a major project as mounting bracket and hose connections are different. The real problem I think is size of engine drive pulley and this may also be a problem for Sanden compressors. The SD508 has now been replaced by Sanden with a newer model. Grunert made the conversion to Sanden a few years back so they would be the best source for conversion parts. The SD508 is probably available where you are under the Sankyo SD 508 model number. Suction line accumulators should be available every where, it is important that it be sized for one half to one ton capacity.

[ibdcatt]

i have a oceanis 505 Moorings beneteau. 1997. The motor driven compressor dropped a bracket bolt, which caused the whole unit to twist and break the bracket mounts on the unit. Welders can't fix it.
Who made this compressor? Other than Beneteau where do you find the compressor used or refurbished?
Thanks
Ibdcatt

[Richard Kollmann]

Manufacturer of SD 505 engine drive compressors were Sankyo and Sanden. There are no small engine driven compressors produced for these boat refrigerators, all were designed for automobile and industrial equipment air conditioning. The SD 505 was used on mostly small cars like VW’s . Large SD compressors like the SD507, SD508 and SD510 were used in larger cars, farm equipment and trucks.
The SD 505 is available from many parts companies but all SD505’s are not the same so identify the configurations of your unit first:
1. The line connections are either Flared or use O ring fittings.
2. Refrigerant servicing connections are on top in front of lines or there are no servicing connections on compressor.
3. The electrical clutch coil is either 12 volt or 24 volt. If your boat is 12 volt make sure the compressor you buy is 12 volt.
4. The other SD compressors would work except they are longer in length and will not fit in your mounting bracket.
www.RParts.com has new SD505 compressors and good picture links to the above differences in the 505 configurations.
SCS Frigette Headquarters in Fort Worth Texas has new and remanufactured SD compressors.
JC Whitney also may have SD 505 compressors.

[JimM]

I am seriously considering a boat with a Grunert engine driven frig model. Would it
be expensive/difficult to convert this to a battery powered unit? The boat will be used primarily for weekend cruising.

[Richard Kollmann]

Originally Posted by JimM

I am seriously considering a boat with a Grunert engine driven frig model. Would it
be expensive/difficult to convert this to a battery powered unit? The boat will be used primarily for weekend cruising.

JimM,
Generally the reason why present refrigeration is engine drive instead of 12 volt is to reduce engine daily running time. Twelve volt refrigeration requires a major boat DC electrical power grid upgrade if refrigerated box is larger than 4 cu ft when south of Latitude 30N. In order to give a more precise answer I would need more information:

· Size of box to be refrigerated in cu ft or inside dimensions.
· What temperatures do you want to maintain inside box, Cooler, Refrigerator or ability to freeze?
· What will be normal Latitude you plan on cruising in now and future?
· How much time will boat be connected to shore power?
· Do you plan on living aboard at anchor?
· If you have an AC generator describe its size and if there are currently uses for it such as A/C or?.
· What is size of house battery bank.?
· What size battery charger? Its capacity and is it what is known as a smart charger?
· What type and size alternator is mounted on engine Standard or with smart charging?
· Do you have alternative energy such as Wind or Solar? If so size?
· Do you plan on installing unit yourself?

[JimM]

Richard,

I can't answer all of your very good questions now -- I am just in the negotiating stage. I am asking now because, for that very negotiating, I would like to have a sense of coming expenses. I can tell you that there are two
rather ordinary house batteries, a 50 amp (probably not very smart) alternator, and I will have a 100+ watt solar panel on a bimini, I hope. I want to use the boat weekends with 3-4 weeks/year cruising in the Chesapeake & up (home is NJ). Just frig, no freezer. I'd rather have battery powered frig
for the obvious reason that I would like to keep things on board during the
week -- and find them cold when I get on -- whenever I get on. As for doing
the work myself, I am fully aware of my considerable limits.

I appreciate your help!

Thanks, JimM

[robgoh]

Originally Posted by Richard Kollmann

If an engine driven refrigeration compressor fails it can be contributed to one or more of the following conditions:
· Excessive start up compressor Rpm when refrigerant has migrated in to cold holding plates. After compressor is stopped for a while refrigerant and oil will migrate into colder holding plates and collect there as a liquid. If compressor clutch is energized with liquid in low side of system it will quickly cause liquid slugging of a compressor that is only designed to pump gas. The restriction in this system that prevents this bulk liquid refrigerant flooding on start up is the refrigerant flow control device Thermo Expansion Valve (TXV). On a compressor’s restart if TXV’s sense bulb is detecting a temperature above normal partially frozen plate temperature TXV orifice will be at its full wide open capacity. If plate’s eutectic solution’s weight is less than 37 pounds for that TXV its capacity should be rated 1/3 of a ton or less to reduce possibility of compressor liquid slugging.
· Engine drive Rpm is the key to compressor longevity. There are many boaters that believe a 1 ½ ton capacity compressor must be turned fast in order to freeze a 20 pound holding plate that requires 2900 Btu to complete the solution’s phase change to ice in less than an hour. The fact is that reducing Compressor Rpm on Tecumseh HG 1000 or York compressors to 1200 Rpm, and Swash plate compressors reduced to maximum of 1600 Rpm is better. These lower compressor speeds will result in lower daily engine running time except on first days warm solution pull down that may add 10 additional minutes. Lower compressor startup RPM also reduces refrigerant flow velocity back to compressor giving it time to convert back to a gas.

Hi Richard, I now have Sanden SD5S11 engine driven compressor on board. It has a rated max rpm of 7000. I have been told by the previous boat owner that I should run my compressor no more than 1000rpm (the replaced compressor was a Tecumseh). QUestion, after running the compressor at start up at 500rpm for 15 minutes (say), can i run it at 2000rpm, the cruising rpm of my boat? I have never tried that as I dont really understand how the entire system works. Any advice that you can give would be most appreciated. Thanks,