Danfoss VZH hybrid manifold Application guide

Application guidelines

Inverter scroll compressors

VZH hybrid manifold

R410A

http://cc.danfoss.com

Contents

GENERAL INFORMATION....................................................................................................	4
Scope.......................................................................................................................................................................................	4
Benefits...................................................................................................................................................................................	4
PRODUCT INFORMATION....................................................................................................	5
Oil management concept.....................................................................................................	5
System configuration........................................................................................................................................................	5
Dimensions............................................................................................................................	8
Tandem...................................................................................................................................................................................	8
SYSTEM DESIGN...................................................................................................................	9
Design pipe............................................................................................................................	9
General requirements.......................................................................................................................................................	9
Suction separator.............................................................................................................................................................	11
Oil equalization design...................................................................................................................................................	11
Design compressor mounting...........................................................................................	12
General requirements.....................................................................................................................................................	12
VZH178 Mounting feet....................................................................................................................................................	12
VZH208 Mounting feet...................................................................................................................................................	12
VZH257 / VZH278 Mounting feet................................................................................................................................	12
VZH301 Mounting feet...................................................................................................................................................	13
VZH350 / VZH410 / VZH465 Mounting feet............................................................................................................	13
VZH354 Mounting kit......................................................................................................................................................	13
Manage operating envelope.............................................................................................	14
Requirement.......................................................................................................................................................................	14
Manage superheat..............................................................................................................	15
Requirement.......................................................................................................................................................................	15
System evaluation............................................................................................................................................................	15
Test, criteria and solutions.............................................................................................................................................	15
Manage off-cycle migration...............................................................................................	17
Requirement.......................................................................................................................................................................	17
System evaluation............................................................................................................................................................	17
Refrigerant charge limit table......................................................................................................................................	17
Manage oil in the circuit.....................................................................................................	18
Oil management system for hybrid manifolding.................................................................................................	18
Oil management logic....................................................................................................................................................	18
Requirement.......................................................................................................................................................................	19
System evaluation............................................................................................................................................................	19
Test, criteria and solutions.............................................................................................................................................	19
Control logic.......................................................................................................................	20
Safety control logic requirements.............................................................................................................................	20
Cycle rate limit requirements.......................................................................................................................................	20
Defrost logic recommendations.................................................................................................................................	20
Pump-down logic recommendations......................................................................................................................	21
Assembly line procedure..................................................................................................	22
Handling..............................................................................................................................................................................	22
ORDERING INFORMATION...............................................................................................	23
Compressor ordering codes.........................................................................................................................................	23
Accessory ordering codes.............................................................................................................................................	23
Accessories.........................................................................................................................	24
Annex..................................................................................................................................	26

FRCC.PC.049.A3.02 3

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General information

Scope	The application guideline describes the operating
	characteristics, design features and application
	requirements for hybrid manifolding of the
	Danfoss SH fixed-speed compressor and the VZH
	inverter compressor in air-conditioning and heat
	pump applications.
	To ensure proper parallel installation and running
	conditions, the following recommendations must
	be followed:

•It is essential to respect all the instructions given in these guidelines; please refer to the instruction leaflet supplied with each

compressor and the application guidelines for single compressors.

•For additional system components related to specific application requirements, the supplier recommendations must always be respected.

Benefits	A parallel compressor installation refers to a
	system of interconnected compressors with a
	common suction line and a common discharge
	line. The technique of mounting compressors
	in parallel is also called manifolding. The hybrid
	manifolding in this application guideline refers
	to the manifolding of the Danfoss inverter
	compressor (VZH) and fixed speed compressor
	(SH), which has several benefits.

The main reason is reduced operating cost through controlling capacity and power consumption to a greater extent. This is achieved by both staggering the compressor switch-on sequences and regulating the speed of the inverter compressor which allows the parallel system to continuously match its power with the capacity needed.

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		Compressor n°1
		VZH 25-100 rps
	Compressor n°1	Compressor n°2
		xed speed SH
	VZH 25-100 rps

A second reason for manifolding the inverter compressor and the fixed speed compressor is improved part-load efficiency. In the variable speed+fixed speed parallel installation,

the system can run either only the inverter compressor at lower load or both the inverter and fixed speed compressors at a higher load with the fixed speed compressor operating at 100% load.

Therefore, it will be possible to achieve a higher part-load efficiency.

Thirdly, the capacity of the hybrid manifolding system can be widely regulated, for example 10% to 100%. The continuous capacity regulation allows for accurate temperature control and a comfortable indoor environment.

4 FRCC.PC.049.A3.02

Oil management concept

System configuration	Hybrid manifolding systems use the dynamic
	system for oil balance. The suction connections
	between the two individual compressors are
	interconnected by a special suction separator
	design that allows most of oil feed into variable
	speed compressors.

An optical-electrical oil level sensor fixed in a variable speed compressor monitors the compressor oil level.

If the oil level drops below the limit, the OEM main controller activates the oil management logic.

Drive	OEM main controller
	ModBus
Discharge line
VZH
SH
	Optical oil
	level sensor
Oil equalization tube Suction line	Suction separator

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Oil management concept

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	FS	VS
	Downstream	Upstream
		compressor
	compressor

Suction separator (Oil separator/gas restrictor)

The hybrid manifolding system uses the dynamic system for oil balance.

The suction connections of the two individual compressors are interconnected by a suction separator that integrates with the suction oil separator and the gas restrictor. The variable speed compressor (VS) is installed in the upstream position which appears first on suction line and fixed speed compressor (FS) is installed on downstream position.

The oil which clings back along the main suction line is separated by the suction separator which

returns most of the oil in the suction gas to the upstream compressor. The suction separator creates a slight pressure drop to ensure lower sump pressure between two compressors are well balance when fixed speed compressor

is ON and the inverter compressor is running at maximum speed. When the variable speed compressor runs at any frequency below

maximum speed, the sump pressure in the fixed speed compressor is lower than the variable speed compressor, and driven by the sump pressure difference, the excess oil from the variable speed compressor runs into the fixed speed compressor sump.

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Oil management concept

Approved hybrid tandem Different configurations of hybrid tandems are possible. All VZH models (high/low pressure ratio/ configurations and different voltage) could be manifolded with fixed speed compressors.

capacity range

Danfoss VSD : VZH compressor DriveTM 380-480 Volt

	Model	Description	FS: 50Hz, VS:100Hz		FS: 60Hz, VS: 100Hz
			kW	TR	kW	TR
	VZH178	VZH088+SH90	68.9	19.6	73.9	21.0
	VZH208	VZH088+SH120	77.7	22.1	83.7	23.8
	VZH257	VZH117+SH140	97.8	27.8	105.2	29.9
	VZH278	VZH117+SH161	101.6	28.9	110.1	31.3
	VZH301	VZH117+SH184	106.2	30.2	115.7	32.9
	VZH350	VZH170+SH180	137.5	39.1	147.4	41.9
	VZH354	VZH170+SH184	137.0	39.1	146.0	41.9
	VZH410	VZH170+SH240	151.9	43.2	164.9	46.9
	VZH465	VZH170+SH295	164.6	46.8	179.3	51.0
	TR: Ton of Refrigeration			Refrigerant: R410A
	Standard rating conditions: ARI standard			Evaporating temperature: 7.2°C		Superheat: 11.1k
				Condensing temperature: 54.4°C		Subcooling: 8.3k

Subject to modification without prior notification

Data given for motor code G compressor – for full data details and capacity tables, please refer to Coolselector2

www.coolselector.danfoss.com

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Dimensions
Tandem
	
H	H
D	D
L	L

	Tandem model	Composition	Outline drawing		Suction	Discharge	L (mm)	D (mm)	H (mm)
				number
	VZH178	VZH088 + SH090		8560108	1"5/8	1"3/8	1011	445	482
				8560109	1"5/8	1"3/8	810	445	482
	VZH208	VZH088 + SH120		8560104	1"5/8	1"3/8	1011	445	540
				8560105	1"5/8	1"3/8	811	445	540
	VZH257	VZH117 + SH140		8560106	1"5/8	1"3/8	1024	445	540
				8560107	1"5/8	1"3/8	811	445	540
	VZH278	VZH117 + SH161		8560106	1"5/8	1"3/8	1024	445	540
				8560107	1"5/8	1"3/8	811	445	540
	VZH301	VZH117 + SH184		8556183	1"5/8	1"3/8	1116	445	555
				8556184	1"5/8	1"3/8	811	445	555
	VZH350	VZH170 + SH180		8556181	2"1/8	1"5/8	1233	550	682
				8556182	2"1/8	1"5/8	953	550	682
	VZH354	VZH170 + SH184		8556188	2"1/8	1"5/8	1241	550	682
				8556189	2"1/8	1"5/8	890	550	682
	VZH410	VZH170 + SH240		8556181	2"1/8	1"5/8	1233	550	682
				8556182	2"1/8	1"5/8	953	550	682
	VZH465	VZH170 + SH295		8556181	2"1/8	1"5/8	1233	550	682
				8556182	2"1/8	1"5/8	953	550	682

Tandem configurations are achieved by assembling individual compressors

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Design pipe

General requirements	Proper piping practices should be employed to:
	1. Ensure adequate oil return, even under
	minimum load conditions (fixed speed
	compressor off, variable speed compressor
	at minimum speed, minimum evaporating
	conditions). If minimum refrigerant velocity
	cannot be reached, it is strongly recommended
	that an oil separator is used. For a validation test,
	the see section “Manage oil in the circuit”.

2. Prevent condensed liquid refrigerant from draining back into the compressor when stopped (discharge piping upper loop). For validation tests, see the section “Manage off-cycle migration”.

General recommendations are described in the figures below:

To condenser

	HP
0.5% slope	LP
4 m/s or more

max. 4 m

U-trap, as short as possible

8-12 m/s

max. 4 m

Evaporator

0.5% slope

4 m/s or more

U trap, as short as possible

Upper loop

HP

Condenser

LP

3D flexibility

3. Piping should be designed with adequate	on noise and vibration, see the section “Sound
three-dimensional flexibility to avoid excess	and vibration management” in the application
vibration. It should not be in contact with the	guideline for Danfoss VZH scroll compressors
surrounding structure, unless a proper tubing	(FRCC.PC.023).
mount has been installed. For more information

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Design pipe

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Suction on left

Suction on right

		Variable speed						Variable speed
				Fixed speed			Fixed speed
	Fixed speed		Variable speed	Tandem model	Suction direction	Hz of FS	Suction separator	Tandem accessory kit code
						compressor	code
						50	120Z0676	120Z0653 (with 24V oil level sensor)
								120Z0654 (with 230V oil level sensor)
	SH090	+	VZH088	VZH178	Left/Right
								120Z0653 (with 24V oil level sensor)
						60	120Z0675
								120Z0654 (with 230V oil level sensor)
						50	120Z0664	120Z0651 (with 24V oil level sensor)
								120Z0652 (with 230V oil level sensor)
	SH120	+	VZH088	VZH208	Left/Right
								120Z0651 (with 24V oil level sensor)
						60	120Z0658
								120Z0652 (with 230V oil level sensor)
						50	120Z0666	120Z0653 (with 24V oil level sensor)
								120Z0654 (with 230V oil level sensor)
	SH140	+	VZH117	VZH257	Left/Right
								120Z0653 (with 24V oil level sensor)
						60	120Z0665
								120Z0654 (with 230V oil level sensor)
						50	120Z0665	120Z0653 (with 24V oil level sensor)
								120Z0654 (with 230V oil level sensor)
	SH161	+	VZH117	VZH278	Left/Right
								120Z0653 (with 24V oil level sensor)
						60	120Z0674
								120Z0654 (with 230V oil level sensor)
	SH184	+	VZH117	VZH301	Left/Right	50 & 60	120Z0656	120Z0651 (with 24V oil level sensor)
								120Z0652 (with 230V oil level sensor)
	SH180	+	VZH170	VZH350	Left/Right	50 & 60	120Z0657	120Z0649 (with 24V oil level sensor)
								120Z0650 (with 230V oil level sensor)
						50	120Z0683	120Z0682 (with 24V oil level sensor)
							120Z0683	120Z0681 (with 230V oil level sensor)
					Left
							120Z0655	120Z0682 (with 24V oil level sensor)
						60
							120Z0655	120Z0681 (with 230V oil level sensor)
	SH184	+	VZH170	VZH354
							120Z0687	120Z0682 (with 24V oil level sensor)
						50
							120Z0687	120Z0681 (with 230V oil level sensor)
					Right
							120Z0687	120Z0682 (with 24V oil level sensor)
						60
							120Z0687	120Z0681 (with 230V oil level sensor)
	SH240	+	VZH170	VZH410	Left/Right	50 & 60	120Z0657	120Z0649 (with 24V oil level sensor)
								120Z0650 (with 230V oil level sensor)
	SH295	+	VZH170	VZH465	Left/Right	50 & 60	120Z0655	120Z0649 (with 24V oil level sensor)
								120Z0650 (with 230V oil level sensor)

Note:

The tandem accessory includes oil equalization kits and oil level sensor. For compressors that need a UL certificate, please order the accessory kit with the 24V oil level sensor.

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Design pipe

Suction separator The suction connections of the two individual compressors are interconnected by a suction separator, which is supplied as an accessory.

Suction separator

Oil equalization design	The two compressors are connected by a ½" or	and the seal gasket which were included in the
	¾" oil equalization pipe. To fix the oil equalization	tandem accessory kit.
	connection rotolock, use the adaptor sleeves
	½"	Model: VZH178-208-257-278-301/354
		(SH184 oil equalization line)
		Supplied with the compressor
		Included in tandem kit
		Not supplied
	Tightening torque 100NM

Model: VZH350-410-465/354 (VZH170 oil equalization line)

¾"

Supplied with the compressor

Included in tandem kit Not supplied

Tightening torque 145Nm

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