Emerson AE4-1395 manual Scroll Temperature Protection, Crankcase Heaters, Oil Type and Oil Removal

Application Engineering
B U L L E	T	I	N	AE4-1395

bar) for R-407C & R-22 to prevent evaporator coil icing. The cut in setting can be as high as 180 psig (12.5 bar) for R-410A and 105 psig (7.2 bar) for R-407C & R-22 to prevent rapid recycling in case of refrigerant loss.

For heat pumps, a cut out setting no lower than 20 psig (1.4 bar) is recommended for R-410A and 10 psig (0.7 bar) for R-407C & R-22.

Scroll Temperature Protection

Most digital scrolls do not have internal discharge gas temperature protection. In order for the Emerson controllers to operate properly an NTC sensor must be attached to the compressor discharge line as close as possible to the compressor discharge fitting. For best response the sensor should be insulated. See Table 1 of AE8-1328for thermistor temperature vs. resistance values. Refer to Table 4 for part numbers of discharge line thermistors. Figure 7 illustrates the two different types of discharge thermistors.

The ZRD61 through ZRD81KC compressors have a discharge thermistor that is inside of a well in the top cap of the compressor. If this thermistor ever needs to be replaced, it should be replaced with either 985-0199- 00 or 085-0204-00 as listed in Table 4.

Crankcase Heaters

A crankcase heater is required if the system charge exceeds the system charge limits listed in Table 2. For more information regarding regarding heater part numbers and installation location please refer to the equivalent non-digital scroll Application Engineering bulletin listed on Page 4.

Oil Type and Oil Removal

Mineral oil is used in the ZRD*KC compressors for R-22 applications. Polyolester (POE) oil is used in the ZRD*KCE and ZPD*KCE compressors for R-22

&R-407C and R-410A applications respectively. See the compressor nameplate for the original oil charge. A complete recharge should be approximately four fluid ounces (118 ml) less than the nameplate.

It is an approved practice to use ZRD*KCE compressors with POE to replace ZRD*KC compressors with mineral oil in R-22 service applications. R-22 has been approved for use with both mineral and POE and some mixing of these oil in the system is acceptable.

If additional oil is needed in the field for POE applications, Copeland™ Ultra 32-3MAF, Lubrizol Emkarate RL32-3MAF, Parker Emkarate RL32-3MAF/ Virginia LE32-3MAF, or Nu Calgon 4314-66 (Emkarate

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Printed in the U.S.A.

RL32-3MAF) should be used. Copeland Ultra 22 CC, Hatcol EAL 22CC, and Mobil EAL Arctic 22 CC are acceptable alternatives.

If additional oil is needed in the field for mineral oil applications, Sonneborn Suniso 3GS or Chevron Texaco Capella WF32 should be used.

CAUTION

POE must be handled carefully and the proper protective equipment (gloves, eye protection, etc.) must be used when handling POE lubricant. POE must not come into contact with any surface or material that might be harmed by POE, including without limitation, certain polymers (e.g. PVC/CPVC and polycarbonate).

Power Factor

During the loaded state the digital scroll compressor operates at full capacity and the power factor is the same as a standard scroll. However, when the scrolls are unloaded, the power factor is much lower. If power factor is an important consideration, the correcting capacitors should be calculated using the full capacity data to avoid problems associated with over correction. See AE9-1249for more information on power factor correction.

Tandem Applications

Tandem compressors follow the same application guidelines as single compressors outlined in this bulletin. The refrigerant charge limit for tandem compressors is shown in Table 2. A tandem circuit with a charge over this limit must have crankcase heaters applied to both compressors.

Tandem compressor assemblies are available for purchase from Emerson. In lieu of purchasing the assembled tandem, the OEM has the option to purchase the tandem-ready compressors to assemble the compressors into a tandem configuration in their manufacturing plant. Drawings of the tandem manifolds are available by contacting your application engineer. Figure 9 illustrates a typical tandem compressor assembly using 3 through 7.5 ton scroll compressors. Note that only one compressor in the tandem assembly is a digital scroll compressor. Customers that choose to design and build their own manifolds for tandem and trio compressor assemblies are ultimately responsible for the reliability of those manifold sets.

For more information on tandems, please refer to the non-modulating compressor Application Engineering bulletins listed on Page 4.