- Heat pumps
- Air-to-water heat pump
E112
Viessmann E112 on a Vitocal 100-AW heat pump: anti-freeze protection
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
On the Vitocal 100-AW AM2V, E112 is the outdoor unit anti-freeze protection. Viessmann links it to insufficient water flow or outlet water that is too cold. Confirm the notification on the display and call an authorised service centre.
Safety first
Stop and check this first
- E112 is a freeze protection for the water circuit. Do not cut power to the heat pump in freezing weather without talking to the technician first.
- The Vitocal 100-AW outdoor unit contains flammable R32 refrigerant. Viessmann warns that some PCB components stay live after the power is switched off and requires waiting at least 4 minutes before removing covers. Do not open the unit: installation and service are for a licensed professional.
Safe checks you can perform
- Exact code: E110, E111 or E112
- Water temperature set value
- Flow and outlet temperature
Leave these tasks to a qualified professional
- Do not attempt this professional task: Set value change with justification
- Do not attempt this professional task: Check flow before changing the set value
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Set value change with justification
What they doIf flow is normal, the technician raises the water temperature set value.
They must show youthe old and new set values.
In writingthe adjustment and the test without E112.
Check flow before changing the set value
What they doThe technician applies Viessmann's flow steps before changing the temperature set value.
They must show youthe clean filter, the venting done and the pump running.
In writingwhether flow was the cause and what was corrected.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Exact code: E110, E111 or E112
- Who:
- you.
- How:
- read and confirm the notification on the display and note the code shown or given by the technician.
- Result that matters:
- E110 and E111 are waits for cold inlet water; E112 points at flow or outlet temperature.
- If it is E110 or E111:
- Viessmann only says to wait for the inlet water temperature to rise.
- If it is E112:
- flow and set value need checking; call the service centre.
- Evidence to keep:
- a photo of the display and the outdoor temperature.
Evidence: Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
Water temperature set value
- Who:
- you, from the controller.
- How:
- check the water temperature set value and heating curve on the controller, which Viessmann lists among user checks.
- Result that matters:
- whether the water set value is very low.
- If it is very low:
- tell the technician; Viessmann says to raise it if the outlet water was too cold.
- If it is normal:
- the set value does not explain E112; flow remains.
- Evidence to keep:
- a photo of the settings screen.
Evidence: Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
Flow and outlet temperature
- Who:
- a licensed professional.
- How:
- they apply steps 1 to 5 of water flow protection, pump, venting, circuit resistance, valves and filter, and review the outlet temperature logged before the protection.
- Result that matters:
- whether flow was low or outlet temperature was.
- If flow was low:
- a hydraulic cause is confirmed.
- If flow was normal and outlet very cold:
- they adjust the set value.
- Evidence to keep:
- a job sheet with what was checked and the final set value.
PCB components stay live after power off: wait at least 4 minutes before removing covers. Licensed professional only.
Evidence: Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Heat pumps
- Brand
- Viessmann
- Product type
- Air-to-water heat pump
Known code variants
- Viessmann heat pump E112
- Viessmann Vitocal 100-AW E112
- Vitocal E112
What it means
Viessmann defines E112 as anti-freeze protection in the outdoor unit of the Vitocal 100-AW AM2V, a North American model. It lists two causes: insufficient water flow and outlet water temperature too low. For flow it refers to steps 1 to 5 of water flow protection, E18; for temperature it says to raise the set value. E110 and E111, primary and secondary anti-freeze, are different: they only require waiting for the inlet water temperature to rise.
Warnings and stop conditions
- Higheditorial warning
E112 is a freeze protection for the water circuit. Do not cut power to the heat pump in freezing weather without talking to the technician first.
Evidence: Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
- Highsource verified
The Vitocal 100-AW outdoor unit contains flammable R32 refrigerant. Viessmann warns that some PCB components stay live after the power is switched off and requires waiting at least 4 minutes before removing covers. Do not open the unit: installation and service are for a licensed professional.
Evidence: Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
Symptoms and causes
Probable causes · in order
- Insufficient water flowCommon
Pump, air, circuit resistance, valves or filter: the same five steps Viessmann gives for E18. Measuring flow separates it.
Evidence: Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
- Outlet water too coldPossible
If flow is normal, Viessmann checks whether outlet temperature before the protection was too low and says to raise the set value.
Evidence: Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
Virtual technician
Does E112 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Viessmann Vitocal 100-AW AM2V installation, service and operating instructions 6221389-11
Viessmann · 2026 · manual
Was this entry useful?