New Waeco CU95 Concerns

[Down2TheC]

Hey Shipmates... My old Danfoss BD2.5 went bad and rather than buy parts and reassemble and charge, I decided to get the latest middle tier to replace it. The CU95


Looked pretty similar but when it came, it's pretty tiny in comparison. The return line is the same size, but the line going to the evap is smaller than original install. The fittings certainly got smaller too.

I haven't measured my icebox on the T37 but now I'm worried that the BD35 on this thing isn't going to do the job. I foolishly didn't convert the 250 liters when deciding. 8.8 cu. feet doesn't sound like much. But the BD50 systems are mostly water cooled so I assumed that would be overkill.

Until I get to measure my icebox, can anyone tell me I didn't just toss $660? Anyone running this in a standard size 35-40ft sailboat icebox?

And if there's any refrigeration gurus, can I keep my big vertical evaporator from the old system despite the line size change on exit. That kind of worries me. I'd need to braze a union or braze on some connectors that match and then charge the system... so now I'm thinking I should have just purchased a BD50 and controller. Ugh!

It's not a yacht without a refer... hoping to upgrade from boat by the 4th.

[GordMay]

The refrigeration guru
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➥ KollmannMarine Boat Refrigeration Specialist

[Richard Kollmann]

Down, in this case larger shaped compressor is not better. The CU 95 has a BD50 compressor 40% greater capacity than your previous BD2.5 compressor. If you were satisfied with capacity of your old BD2.5 and its evaporator then this unit will produce the same results. WAECO’s CU 80 series uses the BD35 that would have equaled the BD 2.5’s performance if its speed is set to run near maximum.. Air cooling condensing units with Danfoss BD compressors are always a better choice if installed correctly in boat.

You face several problems by replacing only condensing unit and not evaporator as well:
· There will be no warranty on any part of system.
· With the original aluminum evaporator probably over 10 years old its service life is questionable.
· The 3/16 inch liquid line on old evaporator is not a problem, what is a problem is connecting old evaporator lines to new condensing unit as their line connectors are not compatible. The best solution for connecting these units is to use refrigeration flare nuts and a ¼ inch male union on suction line. Pressure line will need a new larger filter dryer. Soldering is extremely difficult on this small of a line do to wicking action of solder inside copper tube.
· There is no way to remove old mineral oil from evaporator do to small size of capillary tube.
· Another problem is while the condenser lines are open to atmosphere moist air may find its way into compressor’s new type Ester oil. Ester oil unlike the old wax free mineral oil does not release moisture easily, so do not leave refrigerant lines exposed to air more than a few minutes.
· After lines are connected system need to be leak tested then dehydrated with a good refrigeration vacuum pump.
· Your new compressor’s speed needs to be set to match capacity of the old evaporator by adding a resistor to thermostat’s wiring. With out a resistor compressor will run at minimum speed of 2000 rpm. Because this compressor is more energy efficient at slow speed I suggest you not speed unit up further until you see how it performs at the box temperature setting you desire.
· Servicing with refrigerant correctly is the final problem if you expect to achieve performance and an energy efficient system.

[Down2TheC]

Brilliant! Thanks for the tips. I'm going to consider all that and probably break down and purchase/install a new evap. I really like what I have, but opening both sides to get the join does give me pause.

And it's good to hear what I only hoped... that 20 years of advancement means smaller isn't always less. (It's less than half the weight!)

P.S. As you figured out, I typoed in the original post. I have the CU85 with the BD35F. The CU95 doesn't really seem to be out there yet. Old CU100s are in all the shops and internet stores.