Operating Guide
Termix VMTD-I with complete insulation
VMTD-I insu IHPT Functional description
District heating substation for direct heating and instantaneous domestic hot water with flow-compensated temperature controller. Designed for wall-mounting.
Application
The Termix VMTD-I is a complete solution with built-in water heater and a differential pressure controlled heating system. Termix VMTD-I is applicable for single family houses and for decentralized systems.
District heating (DH)
The substation is prefabricated with a differential pressure controller, a fitting piece and sensor pockets for insertion of an energy meter as well as strainer. The display of the energy meter is to be mounted on a bracket underneath the substation.
Heating (HE)
The heating circuit is designed for direct generation of heat.
The differential pressure control sets the optimum operation conditions for radiator thermostatic valves in order to enable individual temperature control in each room. In order to enable a time – depending temperature control program, a zone valve with actuator is included, and a room thermostat can be included as an option.
Domestic hot water (DHW)
The domestic hot water is prepared in the heat exchanger and the temperature is regulated with a flowcompensated temperature controller with integrated differential pressure controller. The heat exchanger – which is insulated – cools the DH water very efficiently, thereby creating an excellent operating economy. The IHPT valve ensures a stable hot water temperature by varying loads, supply temperatures and by high and varying differential pressure without the need for readjusting the valve. This protects the heat exchanger against overheating and lime scale formation. Furthermore the IHPT valve has an integrated idle temperature controller, which keeps the house supply line warm. This shortens the waiting periods during summer when the heating system is in reduced operation, which is ideal where high comfort is requested. A WRAS approved non-return valve is fitted in the cold water supply.
Safety notes
3.1 Safety Notes– general
The following instructions refer to the standard design of substation. Special versions of substations are available on request.
This operating manual should be read carefully before installation and start-up of the substation. The manufacturer accepts no liability for damage or faults that result from non-compliance with the operating manual. Please read and follow all the instructions carefully to prevent accidents, injury and damage to property.
Assembly, start-up and maintenance work must be performed by qualified and authorized personnel only.
Please comply with the instructions issued by the system manufacturer or system operator.
Corrosion protection
All pipes and components are made of stainless steel and brass.
The maximum chloride compounds of the flow medium should not be higher than 150 mg/l.
The risk of equipment corrosion increases considerably if the recommended level of permissible chloride compounds is exceeded.
Energy source
The substation is designed for district heating as the primary source of energy. However, also other energy sources can be used where the operating conditions allow it and always are comparable to district heating.
Application
The substation is designed to be connected to the house installation in a frost-free room, where the temperature does not exceed 50 °C and the humidity does not exceed 60%. Do not cover or wall up the substation or in any other way block the entrance to the station.
Choice of material
Choice of materials always in compliance with local legislation.
Safety valve(s)
We recommend mounting of safety valve(s), however, always in compliance with local regulations.
Connection
The substation must be equipped with features that ensure that the substation can be separated from all energy sources (also power supply).
Emergency
In case of danger or accidents – fire, leaks or other dangerous circumstances – interrupt all energy sources to the station if possible, and seek expert help.
In case of discoloured or bad-smelling domestic hot water, close all shut-off valves on the substation, inform the operating personnel and call for expert help immediately.
REACH
All Danfoss A/S products fulfill the requirements in REACH.
One of the obligations in REACH is to inform customers about presence of Candidate list substances if any, we hereby inform you about one substance on the candidate list: The product contains brass parts which contains lead (CAS no: 7439-92-1) in a concentration above 0.1% w/w.
Storage
Any storage of the substation which may be necessary prior to installation should be in conditions which are dry and heated.
Authorized personnel only
Assembly, start-up and maintenance work must be performed by qualified and authorized personnel only.
Please observe instructions carefully
To avoid injury to persons and damage to the device, it is absolutely necessary to read and observe these instructions carefully.
Warning of high pressure and temperature
Be aware of the installation’s permissible system pressure and temperature.
The maximum temperature of the flow medium in the substation is 120 °C.
The maximum operating pressure of the substation is 10 bar. PN 16 versions are available on enquiry.
The risk of persons being injured and equipment damaged increases considerably if the recommended permissible operating parameters are exceeded.
The substation installation must be equipped with safety valves, however, always in accordance with local regulations.
Warning of hot surface
The substation has got hot surfaces, which can cause skin burns.
Please be extremely cautious in close proximity to the substation.
Power failure can result in the motor valves being stuck in open position. The surfaces of the substation can get hot, which can cause skin burns. The ball valves on district heating supply and return should be closed.
Warning of transport damage
Before substation installation, please make sure that the substation has not been damaged during transport.
IMPORTANT – Tightening of connections
Due to vibrations during transport all flange connections, screw joints and electrical clamp and screw connections must be checked and tightened before water is added to the system. After water has been added to the system and the system has been put into operation, re-tighten ALL connections.
Mounting
4.1 Mounting
Installation must be in compliance with local standards and regulations.
District heating (DH) – In the following sections, DH refers to the heat source which supplies the substations. A variety of energy sources, such as oil, gas or solar power, could be used as the primary supply to Danfoss substations. For the sake of simplicity, DH can be taken to mean the primary supply.
Connections:
- District heating (DH) supply
- District heating (DH) return
- Heating (HE) supply
- Heating (HE) return
- Domestic hot water (DHW)
- Domestic cold water (DCW)
Connection sizes:
| DH+ HE: | G ¾” (int. thread) |
| DCW+ DHW: | G ¾” (int. thread) |
Dimensions (mm):
With insulation:
H 610 x W 540 x D 345
Weight (approx.): 15 kg
Authorized personnel only
Assembly, start-up and maintenance work must be performed by qualified and authorized personnel only.
The pipe placement can deviate from the shown drawing. Please note the markings on the station.
4.1.1 Installation
Mounting:
Adequate space
Please allow adequate space around the substation for mounting and maintenance purposes.
Orientation
The station must be mounted so that components, keyholes and labels are placed correctly. If you wish to mount the station differently please contact your supplier.
Drillings
Where substations are to be wall-mounted, drillings are provided in the back mounting plate. Floor mounted units have support.
Labelling
Each connection on the substation is labelled.
Before installation:
Clean and rinse
Prior to installation, all substation pipes and connections should be cleaned and rinsed.
Tightening
Due to vibration during transport, all substation connections must be checked and tightened before installation.
Unused connections
Unused connections and shut-off valves must be sealed with a plug. Should the plugs require removal, this must only be done by an authorized service technician.
Installation:
Strainer
If a strainer is supplied with the station it must be fitted according to schematic diagram. Please note that the strainer may be supplied loose.
Connections
Internal installation and district heating pipes connections must be made using threaded, flanged or welded connections.
Keyhole for mounting.
4.2 Start-up
Start-up, Direct heating
The shut-off valves should be opened and the unit observed as it enters service. Visual checking should confirm temperatures, pressures, acceptable thermal expansion and absence of leakage.
If the heat exchanger operates in accordance with design, it can be put to regular use.
After water has been added to the system and the system has been put into operation, re-tighten ALL connections.
Re-thighten connections
After water has been added to the system and the system has been put into operation, re-tighten ALL connections.
Design
5.1 Design
Your substation might look different than the substation shown.
Design description
B Heat exchanger, DHW
N Circulation connection
9 Strainer
14 Sensor pocket, energy meter
31 Differential pressure controller
41 Fitting piece, energy meter
63 Sieve
74 IHPT controller, DHW
5.2 Schematic diagram
Your substation might look different than the schematic diagram shown.
Schematic description
B Heat exchanger, DHW
1 Ball valve
9 Strainer
14 Sensor pocket, heat meter
31 Differential pressure controller
39 Connection closed
41 Fitting piece, energy meter
63 Sieve
74 IHPT controller
DHW: Domestic Hot Water
DCW: Domestic Cold Water
DH Supply: District Heating Supply
DH Return: District Heating Return
HE Supply: Heating Supply
HE Return: Heating Return
5.2.1 Technical parameters
Technical parameters
Nominal pressure: PN 10 (PN 16 versions are available on enquiry)
Max. DH supply temperature: 120 °C
Min. DCW static pressure: 1.0 bar
Brazing material (HEX): Copper
Heat exchangers test pressure: 30 bar
Sound level: ≤ 55 dB
Controls
6.1 Heating circuit
6.1.1 Differential pressure controller
The differential pressure controller smooths out the fluctuations in pressure arriving from the district heating network. The operating pressure in the substation is thus held steady.
6.2 DHW temperature control
DHW temperature control
There are various types of DHW temperature control used in Danfoss substations.
DHW temperature should be adjusted to 45-50 °C, as this provides optimal utilisation of DH water. At DHW temperatures above 55 °C, the possibility of lime scale deposits increases significantly.
6.2.1 IHPT 90 controller (45–65 °)
IHPT is a self-acting flow-compensated temperature controller with integrated differential pressure controller.
The IHPT operates at its best at DH supply temperatures of up to 100 °C.
By turning the handle for temperature setting in (+) direction the setting is increased, by turning it in (-) direction the setting is decreased.
| Turns* | Scale | DHW Temperature Setting [°C] |
| 0 | 7 | 64 |
| 1 | 6 | 61 |
| 2 | 5 | 58 |
| 3 | 4 | 55 |
| 4 | 3 | 52 |
| 5 | 2 | 48 |
| 6 | 1 | 44 |
| 7 | 0 | 43 |
*Start position: Handle turned fully in (+) direction.
The values are intended as a guide.
6.3 Other
6.3.1 Safety valve
The purpose of the safety valve is to protect the substation from excessive pressure.
The blow-off pipe from the safety valve must not be closed. The blow-off pipe outlet should be placed so that it discharges freely and it is possible to observe any dripping from the safety valve.
It is recommended to check the operation of safety valves at intervals of 6 months. This is done by turning the valve head in direction indicated.
6.3.2 Strainer
Strainers should be cleaned regularly by authorized personnel. The frequency of cleaning would depend on operating conditions and the manufacturer’s instructions.
6.3.3 GTU Pressure Equalizer
The GTU Pressure Equalizer absorbs the expansion on the secondary side of the Termix water heaters and can be used as a substitute to the safety valve.
Furthermore the pressure equalizer absorbs a possible increase in pressure, so a discharge outlet is omitted.
The GTU Pressure Equalizer may not be applied in systems with hot water circulation.
6.3.4 Fitting piece
The substation is equipped with a fitting piece for energy meter.
Assembly of energy meters:
- Close ball valves
Close the ball valves on DH Supply and DH Return, if there is water on the system. - Loosen nuts
Loosen the nuts on the fitting piece. - Remove fitting piece
Remove the fitting piece and replace it with the energy meter. Do not forget the gaskets. - Tighten connections
After mounting of the energy meter remember to check and tighten all threaded connections.
Sensor pocket, energy meter
The sensors of the energy meter is mounted in the sensor pockets.
6.4 Extras
6.4.1 Circulation pipe
The circulation pipe set is mounted directly on the controller.
The set includes circulation pipe, single check valve and fitting.
When mounting the hot water circulation directly on the controller the hot water circulation temperature will be equal to the idle temperature. The idle temperature is a few degrees lower than the set domestic hot water temperature.
6.5 Mounting plate for energy meter display
Bracket for the display of the energy meter delivered loose with the District Heating substation.
Mount the wall clip for the display onto the bracket.
Fix the bracket onto the pipe clips using a pair of pliers.
Slide the display of the energy meter on the clip.
The display is now neatly positioned below the District Heating substation.
6.6 Maintenance
The substation requires little monitoring, apart from routine checks. It is recommended to read the energy meter at regular intervals, and to write down the meter readings.
Regular inspections of the substation according to this Instruction are recommended, which should include:
Strainers
Cleaning of strainers.
Meters
Checking of all operating parameters such as meter readings.
Temperatures
Checking of all temperatures, such as DH supply temperature and DHW temperature.
Connections
Checking all connections for leakages.
Safety valves
The operation of the safety valves should be checked by turning the valve head in the indicated direction.
Venting
Checking that the system is thoroughly vented.
Inspections should be carried out minimum every two years.
Spare parts can be ordered from Danfoss. Please ensure that any enquiry includes the substation serial number.
Authorized personnel only
Assembly, start-up and maintenance work must be performed by qualified and authorized personnel only.
Troubleshooting
7.1 Troubleshooting in general
In the event of operating disturbances, the following basic features should be checked before carrying out actual troubleshooting:
- the substation is connected to electricity,
- the strainer on the DH supply pipe is clean,
- the supply temperature of the DH is at the normal level (summer, at least 60 °C – winter, at least 70 °C),
- the differential pressure is equal to or higher than the normal (local) differential pressure in the DH network – if in doubt, ask the DH plant supervisor,
- pressure on the system – check the HE pressure gauge.
Authorized personnel only
Assembly, start-up and maintenance work must be performed by qualified and authorized personnel only.
7.2 Troubleshooting DHW
| Problem | Possible cause | Solution |
| Too little or no DHW. | Strainer in supply or return line clogged. | Clean strainer(s). |
| DHW circulation pump out of order or with too low setting. | Check circulation pump. | |
| Defective or clogged non-return valve. | Replace – clean. | |
| No electricity. | Check. | |
| Wrong setting of automatic controls, if any. | To adjust an electronic controller for DHW, pls. note enclosed instructions for electronic controller. | |
| Scaling of the plate heat exchanger. | Replace – rinse out. | |
| Defective motorized valve. | Check (use manual function) – replace. | |
| Defective temperature sensors. | Check – replace. | |
| Defective controller. | Check – replace. | |
| Hot water in some taps but not in all. | DCW is being mixed with the DHW, e.g. in a defective thermostatic mixing valve. | Check – replace. |
| Defective or clogged non-return valve on circulation valve. | Replace – clean. | |
| Tap temperature too high; DHW tap load too high. | Thermostatic valve adjusted to a too high level. | Check – set. |
| Temperature drop during tapping. | Scaling of the plate heat exchanger. | Replace – rinse out. |
| Larger DHW flow than the substation has been designed for. | Reduce DHW flow. | |
| Thermostatic control valve does not close | Temperature difference between DH supply and DHW set point too low. | Lower the set point temperature or increase the DH supply temperature. |
| Idle temperature too low (for stations equipped with IHPT). | Set point too low. | Turn thermostat in (+) direction. |
7.3 Troubleshooting HE
| Problem | Possible cause | Solution |
| Too little or no heat. | Strainer clogged in DH or HE circuit (radiator circuit). | Clean gate/strainer(s). |
| The filter in the energy meter on DH circuit clogged. | Clean the filter (after consulting the DH plant operator). | |
| Defective or wrongly adjusted differential pressure controller. | Check the operation of the differential pressure controller – clean the valve seat if required. | |
| Sensor defective – or possibly dirt in the valve housing. | Check the operation of the thermostat – clean the valve seat if required. | |
| Automatic controls, if any, wrongly set or defective – possibly power failure. | Check if the setting of the controller is correct – see separate instructions. Check the power supply. Temporary setting of motor to “manual” control – see instructions on automatic controls. |
|
| Pump out of operation. | Check if the pump is receiving power and that it turns. Check if there is air trapped in the pump housing – see pump manual. | |
| The pump is set at too low speed of rotation. | Set the pump at higher speed of rotation. | |
| Pressure drop – the pressure drop on the radiator circuit shows lower than recommended operating pressure. | Fill water on the system and check the functioning of the pressure expansion vessel if required. | |
| Air pockets in the system. | Vent the installation thoroughly. | |
| Limiting of the return temperature adjusted too low. | Adjust according to instructions. | |
| Defective radiator valves. | Check – replace. | |
| Uneven heat distribution in building because of incorrectly set balancing valves, or because there are no balancing valves. | Adjust/install balancing valves. | |
| Diameter of pipe to substation too small or branch pipe too long. | Check pipe dimensions. | |
| Uneven heat distribution. | Air pockets in the system. | Vent the installation thoroughly. |
| DH supply temperature too high. | Wrong setting of thermostat or of automatic controls, if any. | Adjust automatic controls, – see instructions for automatic controls. |
| Defective controller. The controller does not react as it should according to the instructions. | Call automatic controls manufacturer or replace the regulator. | |
| Defective sensor on self-acting thermostat. | Replace thermostat – or sensor only. | |
| DH supply temperature too low. | Wrong setting of automatic controls, if any. | Adjust automatic controls – see instructions for automatic controls. |
| Defective controller. The controller does not react as it should according to the instructions. | Call in automatic controls manufacturer or replace controller. | |
| Defective sensor on self-acting thermostat. | Replace thermostat – or sensor only. | |
| Wrong placement/fitting of outdoor temperature sensor. | Adjust location of outdoor temperature sensor. | |
| Strainer clogged. | Clean gate/strainer. |
| Too high DH return temperature. | Too small heating surface/too small radiators compared to the total heating requirement of the building. | Increase total heating surface. |
| Poor utilization of existing heating surface. Defective sensor on self-acting thermostat. | Make sure the heat is distributed evenly across the full heating surface – open all radiators and keep the radiators in the system from heating up at the bottom. It is extremely important to keep the supply temperature to the radiators as low as possible, while maintaining a reasonable level of comfort. | |
| The system is single pipe loop. | The system should feature electronic controls as well as return sensors. | |
| Pump pressure too high. | Adjust pump to a lower level. | |
| Air in system. | Vent the system. | |
| Defective or incorrectly set radiator valve(s). Single pipe loop systems require special one-pipe radiator valves. | Check – set/replace. | |
| Dirt in the motorized valve or in the differential pressure controller. | Check – clean out. | |
| Defective motorized valve, sensor or automatic controller. | Check – replace. | |
| Electronic controller not adjusted correctly. | Adjust according to instructions. | |
| Noise in system. | Pump pressure too high. | Adjust pump to a lower level. |
| Heat load too high. | Defective motorized valve, sensor or electronic controller. | Check – replace. |
7.4 Disposal
Disposal
This product should be dismantled and its components sorted, if possible, in various groups before recycling or disposal.
Always follow the local disposal regulations.
Declaration
8.1 Declaration of conformity
Category 0 without electrical equipment
Danfoss A/S
DK-6430 Nordborg
Danmark
CVR nr: 20 1657-15
Telefon: +45 7488.2222
Fax: +45 7449 0949
EU-DECLARATION OF CONFORMITY
Danfoss A/S
Danfoss District Energy Division
declares under our sole responsibility that the product(s)
Small substations – type:
Termix VMTD-F-B, Termix VMTD-N-B, Termix VMTD-F-I, Termix VMTD-I, Termix VMTD-Q.
Termix Distribution unit.
Covered by this declaration is in conformity with the following directive(s), standard(s) or other normative document(s), provided that the product is used in accordance with our instructions.
Machinery Directive 2006/42/EC
DS/EN 60204-1/A1:2009. Safety of machinery Part 1-
General Requirements.
DS/EN 12100:2011, Safety of machinery – Risk assessment.
Category 0 with electrical equipment
EU-DECLARATION OF CONFORMITY
Danfoss A/S
Danfoss District Energy Division
declares under our sole responsibility that the product(s)
Small substations – type:
Termix VMTD-F-B, VMTD-N-B, Termix VMTD-F-I, Termix VMTD-I, Termix Distribution unit.
With zone valve and/or Domestic hot water pump
Covered by this declaration is in conformity with the following directive(s), standard(s) or other normative document(s), provided that the product is used in accordance with our instructions.
Machinery Directive 2006/42/EC
DS/EN 60204-1/A1:2009. Safety of machinery – Part 1 – General Requirements.
DS/EN 12100:2011, Safety of machinery – Risk assessment.
Low Voltage Directive (LVD) – 2014/35/EU
DS/EN 60204-1/A1:2009.
Safety of machinery – Part 1 – General Requirements
EMC-Directive – 2014/30/EU
DS/EN 61000-6-1:2007
Electromagnetic compatibility (EMC). Generic standards. Immunity for residential, commercial and light-industrial environments DS/EN 61000-6-2:2005.
Electromagnetic compatibility – Generic standard: Immunity industry.
DS/EN 61000-6-3:2007, Electromagnetic compatibility – Generic standard: Emission for residential, commercial & light industry.
Danfoss only vouches for the correctness of the English version of this declaration. In the event of the declaration being translated into any other language, the translator concerned shall be liable for the correctness of the translation ID No. LUK30003
Revision No. 01
503N0014A03
1ª issue
Substations Category 0 2014-02
Printed copy for reference only
Property of Danfoss District Energy Division
Gemina Termix A/S Member of the Danfoss Group
heating.danfoss.com +45 9714 1444
E-Mail: mail@termix.dk
Danfoss can accept no responsibility for possible errors in catalogues, brochures and other printed material. Danfoss reserves the right to alter its products without notice. This also applies to products already on order provided that such alterations can be made without subsequential changes being necessary in specifications already agreed. All trademarks in this material are property of the respective companies. Danfoss and all Danfoss logotypes are trademarks of Danfoss A/S. All rights reserved.
24 Danfoss | 2019.05
VM.IE.C3.02 / LUK40143
Documents / Resources
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Danfoss VMTD-I Heating Controller [pdf] Instruction Manual VMTD-I Heating Controller, VMTD-I, Heating Controller, Controller |