Danfoss HRU Operating guide

Operating Guide

HRU – Heat Recovery Unit

controlled with ECL Comfort 310 – P501.12 application

1	Classified as Business

Contents
HRU Unit with ECL Comfort 310 – P501.12 ........................................................................................	3
Primary function..............................................................................................................................	4
Function description P501.12 .............................................................................................................	5
Operation.........................................................................................................................................	5
Control .............................................................................................................................................	5
ECL operating mode....................................................................................................................	5
Regulation .......................................................................................................................................	6
Flow temperature........................................................................................................................	6
Sale of excess heat.......................................................................................................................	6
Energy monitoring ......................................................................................................................	6
Alarms ..........................................................................................................................................	7
Sensor overview ..............................................................................................................................	7
Configuration guide: ...........................................................................................................................	8
Heating circuit: ................................................................................................................................	8
REMEMBER...................................................................................................................................	8
Flow meter F1, F2 and F3 configuration.........................................................................................	9
Configuration parameters for flow temperature from the HRU unit (S3) ...................................	10
Configuration parameters for the return temperature controller...............................................	11
Configuration parameters for optimisation .................................................................................	12
Reg. parameter 1 applies to M1 controls......................................................................................	13
Reg. parameter 2 applies to M2 controls......................................................................................	14
Circuit 1, heating circuit ................................................................................................................	15
Circuit 1, schedule 1 ......................................................................................................................	16
Tank temperature..........................................................................................................................	17
Compensation T. ...........................................................................................................................	18
Reg. recovery. ................................................................................................................................	19
Control par., export .......................................................................................................................	20
Boost. .............................................................................................................................................	21
Circuit 2, schedule 2.......................................................................................................................	22
Circuit 3, tank temperature. ..........................................................................................................	23
Circuit 3, schedule 3.......................................................................................................................	24
Connection of ECL 310 to ECL portal............................................................................................	25
Integration with the cooling plant................................................................................................	27
Configuration of heat requirement signals from HRU unit .............................................................	27
Safety function...............................................................................................................................	27

2	Classified as Business

HRU Unit with ECL Comfort 310 – P501.12

Versions A1A4

Versions A6A7

3	Classified as Business

Primary function

Utilisation of excess heat from CO2 refrigeration plants.

The unit prioritises heating of own plant before any sales to e.g. district heating suppliers.

In order to balance different usage patterns (temperatures and heating requirements) on the heating side and the production of excess heat on the cooling side, the unit has been designed as a buffer charging circuit.

This results in very stable and uniform charging, also ensuring a long service life for the CO2 heat exchanger.

The flow temperature from the HRU unit is controlled by the building requirements (heating, hot water or ventilation), either via signals from other ECLs or via Modbus from an existing SCADA system.

In the event of possible sale of excess heat to the district heating supplier or other buyers, this can be managed in such a way that a constant temperature is supplied to these buyers.

The HRU unit can send a reference signal to the cooling plant indicating how much heat can be accumulated.

A safety function has been embedded to protect against boiling over on the water side.

4	Classified as Business

Function description P501.12

Operation

The system is configured and monitored via the ECL Comfort 310 regulator or a PC/Mac/mobile via the ECL portal.

Link to the ECL portal: ecl.portal.danfoss.com (Internet connection required)

Control

ECL operating mode

The mode of operation of the unit can be selected:

: AUTO The unit switches between comfort/saving mode via a time program.

Or this can be done via a heating request from a slave regulator (ECL Comfort 310)

The mode of operation for this application must be AUTO.

5	Classified as Business

Regulation

Flow temperature

The flow temperature can be controlled using the following principles:

1.Fixed flow temperature or flow temperature based on the outdoor temperature from the HRU unit

2.Determined by external reference (via Modbus)

3.Determined by references from other ECL 310 regulators for domestic hot water, heating or ventilation units via ECL 485 bus communication

The control intelligence ensure that predominantly heat from buffer tanks is used. If, during certain periods, this is not adequate, auxiliary heat can be added from external heating sources such as district heating or boiler systems, etc.

The charging temperature is controlled in accordance with the desired buffer temperature and the cooling plant load, so that maximum energy is transferred from the cooling plant at all times. This ensures that minimal energy is discharged from the gas cooler on the roof.

Cooling circuit

A signal is transmitted to the cooling plant about how much energy can be accumulated so that, during periods without the possibility for accumulation, energy is not transferred from the CO2 exchangers to the buffer charging system.

Sale of excess heat

In the event of sale or export of excess heat, energy is pumped out via the same supply connection used to buy heat using a frequency-controlled booster pump controlled by the differential pressure and the desired sales flow temperature.

Energy monitoring

If desired, consumption data can be collected via the ECL 310 from heat, water and electricity meters via M-bus connections. The data is transferred to Danfoss' ECL portal.

The energy data is logged on an hourly basis and can also be retrieved for use with third-party energy management systems, in which it may be possible to create an overview of the total energy consumption, corrected for heating degree days, allowing for comparison of the energy consumption of buildings in connection with energy management.

6	Classified as Business

Alarms

Flow failure in charging circuit

An alarm can be configured so that, in the event of a flow failure in the charging circuit (flow meter F3), can stop the circulation pump P3, and at the same time 0V will be transmitted to the cooling plant so that the three-way valve on the CO2 side leads the gas directly to the gas cooler on the roof.

The alarm is given in accordance with the configured time delay.

Sensor overview

Sensor ID	Sensor description
S1	Outdoor temperature
S2	Return temperature, CO2 to gas cooler
S3	Flow temperature from HRU to the heating
	circuit
S4	Charging temperature to accumulation tank
S5	Return temperature to district heating
S6	Top temperature in the accumulation tank
S7	Return temperature from the heating circuit
S8	Bottom temperature in the accumulation tank
S9	Flow temperature, sale of excess heat
S10	Return temperature from the accumulation
	tank
S11	CO2 temperature from the cooling
	compressor

7	Classified as Business

Configuration guide:

Heating circuit:

The mixing circuit (M1) operates in three phases:

1:100% use of recovered heat

2:mixture of recovered heat and auxiliary heat

3:100% use of auxiliary heat

Note: in the event of 100% use of recovered heat, mixing takes place via the purchase exchanger with a closed M2 valve.

REMEMBER

The return temperature from the heating plant (S7) must always be as low as possible, as only five degrees lower could have a major impact on the utilisation of CO2 heat recovery. For radiator heating, the return temperature at S7 should ideally be around 30-35 degrees, and for underfloor heating it should be 20-25 degrees.

It is therefore crucial to the utilisation of excess heat that the heating circuit is optimised and correctly configured.

The mixing circuit (M1) is configured as an ordinary mixing circuit. The desired flow temperature from the HRU unit (R3 reference) can be configured as a fixed temperature or a flow temperature based on the outdoor temperature. It can also originate from another ECL 310 or via Modbus from an existing SCADA system.

Remember to configure night setback in the heating system. This means that less energy is used from the accumulation tanks at night. Several refrigerators are now also covered at night and, in such situations, less energy is generated for heat recovery.

8	Classified as Business

Flow meter F1, F2 and F3 configuration

Menu -> Settings -> Flow temperature

•The M-bus from flow meters is connected to the terminals 37 and 38 in the ECL 310.

•All flow meters must be configured in settings. Flow meter F1 must be configured as Energy meter 1, flow meter F2 must be configured as Energy meter 2 and flow meter F3 must be configured as Energy meter 3.

•Energy meter F3 - shows how much energy is being recovered.

•It is important to ensure that the Baud rate has been set to 2400 for all connected meters.

9	Classified as Business