Hoval PV-Heater

07.07.2026 In connection with Modbus TCP and networks or routers from AVM / Fritz Box: There is currently a technical problem that leads to varying degrees of problems with the heating element. The Hoval PV-Heater times out and constantly reboots! The previous Multi-DNS issues with AVM's Fritz Box routers and Loxone can be resolved by updating the electric heating insert to the latest software version.

The following steps must be performed: 1. Update the electric heating insert to the latest standard software version. If you encounter any problems with the software update, please contact Askoma Support directly. 2. Select the Loxone integration in the commissioning menu on the Askoheat+ web interface 3. Integrate using the Loxone library template "Hoval PV-Heater" with the correct transmission cycles

Why the Hoval PV Heater compared to conventional cheap Direct Heaters?

- The Hoval Photovoltaic Heater is available in Screw-in (1½") and Flange version (180mm), each versions in three different Power-Sizes (3,5kW up to 9,0kW) . The Hoval PV Heater is thus prepared for Installation in a Register Hot Water Storage Tank or a Heating Buffer (Hot water or heating). - For Hoval Storages there is a selection table in the Project planning guide, but the Hoval PV-Heater can also be installed in any other black steel, enamel and stainless steel storages. (Independent of manufacturer) - The PV heating element has an integrated Electricity Meter, from which Current Power and total Energy can be provided using the Loxone Config! - The Hoval PV Heater are available in 7 Stages (3,5kW; 4,4kW; 5,2kW & 5,8kW) or in 3 Stages (7,5kW & 9,0kW). This means that for example the minimum Stage (Stage 1) of a 3.5kW PV-Heater, for example, is divided by 7 stages = 500 watts. or e.g. the 5,8kW Heater is 830W at every stage. - The Hoval PV Heater has a Webinterface for parameterizing minimum and maximum temperatures and of course for activating Modbus TCP or RTU. (How exactly? You will find out in the course of the use case example in this template). - The Hoval PV Heater also has the option of Analog control (0-10V), a Digital request contact for Full power or the option of setting a Legionella time program. - The Hoval PV Heater is always protected against overheating! The first setpoint is the maximum default temperature of 70°C (adjustable!) set in the Webinterface, the second Switch-Off Value is the temperature controller on the rotary wheel located on the housing of the Hoval PV Heater, this should be always at Maximum (85°C) by operate with Modbus over Loxone! If both temperature controllers fail, in the worst case the Safety temperature Limiter ensures the locked Switch-Off (95°C). - The Hoval PV-Heater is not connected to the CAN bus of the Hoval TTE and can therefore only communicate with the Hoval Source via Modbus TCP, RTU, Analog or Digital.

Hoval Helpcenter: Do you have problems with the Hoval PV heating rod not working properly, occasionally hanging up and requiring a restart or even a factory reset?

- Please make sure that you have installed the latest software/firmware for the Hoval PV Heater. - Please make sure that you are also using the “Repitition Interval” in the Loxone Config Sample File (cyclical sending of the setpoint).

If the heating element does not regularly receive a setpoint value from Loxone, there is a risk that the heating element will close the communication for self-protection and a restart will be necessary.

Data should be in the interval between 1000 and 8000 milliseconds! Intervals greater than 10000 milliseconds lead to a timeout and an error message.

If there are any problems, please contact the following telephone number, the service is excellent. +41 62 958 70 99

1.Hoval Screw-In PV-Heater using Modbus TCP

2.Hoval Screw-In PV-Heater using Modbus RTU with Loxone Modbus Extension

3.Hoval Screw-In PV-Heater using Modbus RTU with a Loxone Modbus Air.

Depending on variation of your project you can choose between Miniserver, Miniserver Go or Miniserver Compact

The choice of paring Hoval PV-Heaters with Loxone offers the possibility of:

- Active integration in interaction with e.g. PV-Systems in a Loxone Energy Management - Load management in areas where the building's electricity connection is low - Using flexible electricity tariffs with the Spot Price Optimizer. - Use statistics or individual notifications - Create individual system schematics. - Reduce cycles and operating hours of your Hoval Sources e.g. Belaria or BioLyt - Combining hybrid solutions e.g. Heatpump and PV- Heating element in your Hot Water Storage - Grid management according to §14a ENWG in Germany - Blackoutsafe! Switch off the PV-Heater if the Grid power fails e.g. emergency power is active to safe battery capacity. - Use the flexible ways of reading electrical & thermal meters via e.g. M-Bus or IR readers and the thermal or electrical visualization in the Loxone Energy Flow Monitor. For e.g. Contractors. - Increased security through leakage detection or activation of IP cameras in the plant room. - Use demand-based decision logics in connection with presence, weather forecast or schedules.

Example UseCase: Integration of a Hoval PV-Heater into Loxone Energymanagement: When using Modbus, the Hoval PV-Heater can be controlled with three different variants and thus offers maximum flexibility:

1. Heater Steps (Register 200): The individual Stages can be specified by the Loxone Energy Manager (Stages 0-7). 2. Positive Load Setpoint (Register 201): The setpoint in [Watt] is statily specified by the Loxone Energy Manager. The Hoval PV-Heater selects the correct level for setpoints in between for e.g. 2800W and regulates to the adjustable default temperature of 70 degrees (adjustable). 3. Negative Load FeedIn (Register 202): You give the Hoval PV-Heater the available excess power in [Watt] at the Grid connection point and the heating element automatically selects the correct Stage according to demand until it has reached the default temperature of 70 degrees (adjustable).

Please take a look on the Loxone Config Sample file in the Library download area. You can find the complete Modbus data point list under the following link: Modbus data point list .

1.Installation in a Register Hot Water Storage: (Temperatures up to 60-70°C)

- In this case, the temperature depends on the Water Quality of the Location. Because a higher temperature increases the risk of lime failure. - Scald protection must be restored at high temperatures with a thermal mixing valve in the drinking water side.

2.Installation in the hot water buffer tank: (Temperatures up to 85°C)

- The maximum temperature of 85°C can be exhausted, because the fresh water station mixes the supply temperature for transfer to the drinking water heat exchanger and thus avoids limescale failure.

General information using the Hoval PV-Heater with Storages/Buffers: It is often discussed whether the use of direct PV power due to the 1:1 power makes sense because a Heatpump can provide the energy more efficiently. Loxone can regulate any order or decision of principle, always keeping the following aspects in mind:

- The PV-Heater can avoid switching on sensitive Heat Sources such as Heatpumps or Biomass Boilers for e.g. small demand like Hot water Production and therefore protects the Lifetime of your Source! - The PV-Heater creates temperatures of up to 85°C in a Heating Buffer tank, so Energy can be stored more Energy than in a Heatpump. Example: Heat 1000L by 35°C (from 40 - 75°C) x 1.16 = 40kWh. - The PV-Heater is a very fast and easy to control consumer, a heat pump has minimum running times and is therefore somewhat more bearable.