STIEBEL ELTRON WPL 25 AC

Compatibility

Confirm WPM, ISG and point map before external reading

STIEBEL ELTRON lists WPL 15/20/25 A(C)(S) with WPMsystem or WPM 3 in its ISG compatibility table and marks building automation over Modbus for those rows. Confirm the installed WPM software, ISG model and firmware, and readable register set before planning an Edge monitoring connection.

WPL 25 AC order 236645, paired with its installed WPM. The May 2026 compatibility list includes WPMsystem and WPM 3, with a dated WPM 3 firmware condition for units built from July 2015. ISG Connect, ISG web and ISG plus are separate accessories; verify the applicable pairing and software. Do not reuse WPL 25 ACS, WPL 25 A, WPL 20 AC or newer WPL-A assumptions.

Models

Specifications

STIEBEL ELTRON identifies the WPL 25 AC as an outdoor air-to-water heat pump, order 236645, for heating and cooling. The current product page gives 7.84 kW at A7/W35, 12.86 kW at A-7/W35 and SCOP 4.76 at 35°C; these are different test conditions, not a continuous output range. A WPM wall-mounted heat-pump manager is required equipment.¹

Exact outdoor unit

WPL 25 AC, order 236645; outdoor air-to-water heat pump¹

Heating output

7.84 kW at A7/W35; 12.86 kW at A-7/W35 (EN 14511)¹

Seasonal rating

SCOP 4.76 at 35°C (EN 14825); not a site COP measurement¹

Required controller

Wall-mounted WPM, order 234727 on the German product listing¹

BMS interface

Compatible ISG accessory can present Modbus TCP; the outdoor-unit X43 is internal^2, 3, 4

SG Ready

WPL 25 AC is labelled SG Ready; WPMsystem inputs X1.13-1 and X1.13-3 are described in the ISG Connect manual^1, 3

Controller boundary

Confirm WPMsystem or WPM 3, ISG type, manufacturing date and minimum software before integration^2, 3

Interface

Documented measurements and integration boundaries for WPL 25 AC.

• The WPL 25 AC has no evidenced third-party Modbus socket on the outdoor unit. The documented building automation interface is on a compatible ISG connected to the WPM.
• The WPL 25 AC product page carries an SG Ready label. The ISG Connect manual describes two WPMsystem SG Ready inputs at X1.13 and potential-free relay contacts; commissioning belongs to a qualified installer.
• The outdoor unit wiring labels X43 as Modbus within the internal heat-pump control circuit. That terminal is not evidence of a third-party BMS interface.
• The ISG Connect manual also describes Modbus input signals for output control. Their existence does not authorize direct demand response, mode changes or setpoint writes from Edge.
• Internal heat-pump operating values are not a measured COP. Meter delivered heat and the complete electrical input boundary independently over matching periods.

Setup

1. Identify the whole heat-pump system

   Record outdoor nameplate 236645, manufacturing date, WPM version, any FES remote, ISG model and firmware. The compressor unit and controller/accessory are different equipment.

2. Check the compatibility row

   Use the current manufacturer ISG table for the installed WPM. The WPL 15/20/25 A(C)(S) family appears under both WPMsystem and WPM 3; the July 2015 WPM 3 row names minimum WPM and FES software.

3. Keep interfaces in their roles

   For BMS monitoring, use only a supported ISG local Modbus TCP service on a restricted network. The outdoor unit’s internal X43 bus and SG Ready contact inputs are not general third-party register ports.

4. Qualify the point list

   Obtain the current ISG Modbus map for the installed controller and firmware. Confirm read-only function codes, address base, data type, scale and unavailable-value behavior before polling. No worked read is given without that mapping.

5. Compare and meter

   Compare live temperatures and operating state with the WPM display, then meter full electrical input and delivered heat separately if COP or flexibility settlement is required. Keep SG Ready and output-control wiring with the commissioned heat-pump design.

Common questions

Does WPL 25 AC have a direct Modbus TCP server?

The manufacturer documents Modbus building automation through a compatible ISG accessory connected to the WPM. The outdoor-unit wiring label X43 is part of its internal circuit, not a third-party network endpoint.^2, 3, 4

Does the SG Ready label mean Edge may dispatch the heat pump?

No. SG Ready depends on the installed WPM and approved input wiring. The ISG manual describes potential-free contacts and separate Modbus control inputs, but this guide specifies no Edge writes or dispatch behavior.^1, 3

Can WPM 3 and WPMsystem use the same setup?

Both appear in the manufacturer’s WPL 15/20/25 A(C)(S) compatibility table. The WPM 3 row for units from July 2015 names specific WPM 390.03 and FES 417.02 versions; confirm the installed row instead of assuming the controllers are interchangeable.²

Can the product SCOP be used as measured site COP?

No. SCOP 4.76 is a standardised 35°C rating. A site COP needs independently metered delivered heat and complete electrical consumption over matching intervals.¹