FoxESS + Vaillant

What Zerofy can do with FoxESS and Vaillant

In practice

• Hot water is the simplest heat store: Autopilot can use the hot-water boost of your Vaillant heat pump to heat water in hours with surplus.
• Zerofy can also change the room temperature and flow temperature of your Vaillant heat pump, so space heating can shift into sunny hours.
• A heat pump draws roughly 1–3 kW while running, which a typical FoxESS home system (2.5–15 kW) can cover on sunny days.
• Zerofy gets new FoxESS data every 5 minutes. Heat pumps shouldn’t switch often, so set a minimum runtime in Autopilot.
• Zerofy also shows your FoxESS battery, so you can see whether surplus goes into the battery or into the heat pump.
• The boost is a one-time cylinder charge up to the hot-water setpoint you set in the myVAILLANT app (Zerofy can’t change that setpoint for Vaillant), so set it a few degrees higher than you strictly need if you want the tank to soak up more midday solar.
• The Zerofy integration for Vaillant is in beta.

What FoxESS and Vaillant offer on their own

FoxESS: FoxESS has its own R290 heat pumps (HP Series monobloc, HP BOX hydro module), controlled in FoxCloud 2.0, which lists a solar heating feature. The three-phase H3 Pro can switch an SG Ready heat pump through its dry contacts when feed-in exceeds a set start power.

Vaillant: Vaillant has no PV energy manager of its own; instead the heat pump talks EEBUS over the VR 920/921/940f internet module to external energy managers, and Vaillant’s cloud API is opened to partner services. Both need a VRC 700(f) or VRC 720(f) controller and a hot-water or buffer tank to store surplus as heat. Vaillant lists Zerofy among the partners on its smart-interfaces page.

Zerofy connects the two: it reads FoxESS production and controls your Vaillant heat pump to match, together with your other devices in one app, with dynamic tariffs and forecast-based Smart mode.

Setting up FoxESS and Vaillant in Zerofy

1. Connect FoxESS

Zerofy connects to the FoxESS cloud: you log in with your FoxESS Cloud account and authorize access on FoxESS’s own screen.

1. Make sure your inverter is online and registered in the FoxESS Cloud app.
2. In Zerofy, choose FoxESS and log in with the FoxESS Cloud owner account.
3. Confirm your devices on the FoxESS authorization screen.

Good to know: Use the owner account of the device. Installer and agent accounts don’t own the devices, so FoxESS shows “No Devices” and the connection fails.

Step-by-step guide for FoxESS

2. Connect Vaillant

Zerofy connects through Vaillant’s cloud using your internet gateway’s serial number and shows a Space Heating and a Hot Water Tank device; you can adjust room and flow temperature, and Autopilot triggers the hot-water boost.

1. Make sure the system runs on a supported gateway (myVAILLANT connect, sensoNET, eRELAX) and is online.
2. Copy the gateway serial number from the back of the gateway or from the myVAILLANT app under Status > Gateway.
3. In Zerofy, add a Vaillant device and enter the serial number.
4. Enable Autopilot (Solar or Smart mode) for the Hot Water Tank.

Good to know: The Vaillant integration is in beta. Supported controllers are eRELAX, E7C, VRT-350, VRC-720, VRC-710 and VRT-380; Autopilot currently steers only the hot-water tank, space-heating control is coming.

Step-by-step guide for Vaillant

3. Turn on Autopilot

In Zerofy, open your Vaillant heat pump, turn on Autopilot and choose Solar – or Smart to also use dynamic tariffs and forecasts. Set the priority, activation threshold and minimum runtime.

Dynamic tariffs

Zerofy can also run your Vaillant heat pump on dynamic electricity prices (EPEX Spot or Nord Pool, e.g. Tibber or aWATTar) or on a fixed time-of-use tariff. Smart mode combines those prices with forecasts of your household consumption and your FoxESS solar production.

Learn more about Smart Mode

About FoxESS and Vaillant

FoxESS – Fox ESS is a Chinese inverter and storage maker founded in 2019 and headquartered in Wenzhou. Homes typically have the single-phase H1/AC1 (2.5–6 kW) or KH (7–10.5 kW) hybrid inverters or the three-phase H3 Smart (5–15 kW), with EP, EQ or ECS batteries. Monitoring app: FoxCloud 2.0.

Vaillant – Vaillant is a German heating manufacturer from Remscheid. Most homeowners have an aroTHERM air-to-water heat pump or an ecoTEC boiler, run by a sensoCOMFORT/multiMATIC controller (VRC 700/720) and connected to the internet with a myVAILLANT connect or sensoNET module. Products: aroTHERM plus, aroTHERM Split, flexoTHERM exclusive, flexoCOMPACT exclusive, recoCOMPACT exclusive, versoTHERM plus, ecoTEC boilers.

Manufacturer information last checked: October 2026.

All devices that work with FoxESS