How to Read a Heat Meter: Display Values and Brand Guide

The Main Display Value: Total Energy (Meter Reading)

The main display that the heat meter shows by default is the total heating energy measured since the meter was commissioned. This value is called the meter reading (index) and it only increases; it shows the accumulated total, not the monthly consumption. To find the consumption for a period, subtract the reading at the start of the period from the reading at the end.

Example: If the reading is 12,345 kWh on 1 January and 13,105 kWh on 1 February, the consumption in January is 13,105 − 12,345 = 760 kWh.

Units: kWh, MWh and GJ

The unit depends on the model and the meter settings; it is written immediately to the right of the number.

On a meter that shows MWh, the three digits after the decimal point are kWh: 13.105 MWh means 13 MWh and 105 kWh, i.e. 13,105 kWh. When you note a reading, write down the unit as well; a figure such as 13.105 without a unit can be mistaken for either 13 kWh or 13,105 kWh.

What Do the Decimal Digits Mean?

Some meters show the reading in kWh with decimals (e.g. 19,051.9 kWh). The part after the decimal point is a unit that the meter has started counting but has not yet completed. Some models separate these digits from the main number with a frame.

At Novus Energy we record readings in kWh and use the integer part: the decimal part is not rounded, it is dropped. A reading of 19,051.9 kWh is recorded as 19,051 kWh. Rounding up would record consumption that the meter has not yet measured. The dropped fraction is not lost; it is counted in the next reading once that unit is completed. Since the start and end readings of a period are recorded with the same rule, the consumption calculation stays consistent. For meters that show MWh we first convert to kWh: 13.105 MWh is already 13,105 kWh.

Navigating the Displays with the Menu Button

All heat meters on our site with a published manual have a single button, and the logic is similar:

• Short press: Moves to the next value in the same menu; after the last value it returns to the start.
• Long press: Moves to the next menu or level. How many seconds to press depends on the brand.
• Waiting: If the button is not pressed for a while, the meter returns to the main display or switches the display off. This is normal; no data is lost.

Pressing the button does not affect the measurement. Do not open any part other than the button; do not touch the seals or cables.

Values You Will See on the Display

Consumption increases only when there is both flow and a temperature difference. It is normal for the reading not to increase while the heating or the radiator valves are off.

Month-End and Due-Date Values

Heat meters also store the values of specific days in their memory. The day selected for the annual record is called the target date (in manuals the due date or accounting date); most models also store monthly values. This way, even if the reading is taken a few days late, the value at the start of the period can be read back from the meter. Note: on the past-month display, some models show not the reading for that month but the consumption within that month. Which one is shown is stated in the brand sections below.

Where Is the Cooling Reading Shown?

Heating–cooling (combined) meters store the two energies in separate registers. Cooling energy is usually shown right after the main display, with a snowflake symbol. ZENNER's manual states that on a meter operating in a cooling circuit, the temperature difference and current power are shown with a minus sign. Heating-only meters do not have this line.

Reading Heat Meters Brand by Brand

The steps below are compiled from the manufacturers' manuals. The display order may differ slightly depending on the software version and order options.

Minol Zenner C5 IUF and C5 ISF

The Minol Zenner C5 family (the manufacturer ZENNER's zelsius C5 series) works with a single button and groups its displays into four levels. The energy unit is MWh as standard; kWh or GJ are options.

• Main display: Total heating energy. In MWh, the three digits after the decimal point are shown in a frame.
• Short press: Level 1 shows, in order, cooling energy (on combined models), display test, last due date, energy on that date, total volume, flow rate, supply and return temperature, temperature difference and current power.
• Holding the button: Moves to the next level. Level 2 shows consumption since the due date and since the start of the month; Level 3 shows the serial number, the year the battery life ends with EOb, and the error status with Err.
• If the button is not pressed for about 2 minutes, the meter returns to the main display.

Models: Minol Zenner.

Danfoss SonoSafe 10 and SonoSelect 10

These two Danfoss models use the same user manual and the same menu. The single-button displays are grouped into three loops. If no action is taken, the display switches off after a while; pressing the button switches it on.

• Loop 1 (Accumulated): alarm indicator, heating energy and volume; on combined models cooling energy and volume; operating hours. Advance with a short press.
• Loop 2 (Instantaneous): opens when the button is pressed for 2 seconds: power, flow rate, supply and return temperature, temperature difference, display test.
• Loop 3 (Historical): opens when the button is pressed for 5 seconds: the annual value on the accounting date and the values of the last 12 months.

The decimal digits are separated by a frame called the decimal highlighter in the manual; Danfoss's product record states that for the DN20 model with kWh units on our site, energy is shown without decimals. Models: Danfoss.

Honeywell (Resideo) EW700

According to Honeywell's user instructions for the EW700 series, pressing the button for 3 seconds switches between the A1, A2, A3 and A5 menus; a short press advances within a menu.

• A1: heating energy (flame symbol), cooling energy, current power, supply and return temperature, temperature difference, total volume, flow rate, operating and alarm times.
• A2: date, meter number, display test.
• A3: with a year-month label, the energy and water volume used within that month. These figures are monthly consumption, not meter readings.
• A5: time-stamped maximum power, flow and temperature values.

In the examples in the instructions, energy is shown in kWh without decimals. Models: Honeywell.

CEM CM-HR

According to CEM's user manual, the display is always on and shows the total heating energy. A short press of the single button advances within the menu, a long press moves to the next menu; after 1 minute without action the meter returns to the main display.

• Menu A1: heating and cooling energy, current power, supply and return temperature, temperature difference, total water volume, flow rate, operating times.
• Menu A2: date, serial number, display test, M-Bus address.
• Menu A3: past consumption data with a year-month label.

In the manual examples, energy is in kWh without decimals. Models: CEM.

Calmet PM02

According to the technical document of the manufacturer FNF Teknoloji, the PM02 has a single button and a backlit display; the display switches off after 4 minutes without action. A short press advances within a loop, a long press moves to the other loops.

• 1-USER: heating energy, cooling energy, total volume, flow rate, supply and return temperature, temperature difference, serial number, display test.
• 2-HISt: month-end dates of the last 24 months and the heating and cooling energy on those dates.
• 3-LOG: values on the 5th, 10th, 15th, 20th and 25th days of the previous month.
• 5-ERROR: the last 10 error records with date and time.

The energy unit and the number of decimals depend on the settings (e.g. kWh integer, kWh with one decimal or MWh with three decimals). Models: Calmet.

İntegral UK-PLUS, Novus Digitermo DTL and Large-Diameter Minol Zenner IUF

For İntegral UK-PLUS and Novus Digitermo DTL, the manufacturers have not published a user manual describing the display menu online. In DN50–DN300 Minol Zenner IUF sets, the display depends on the calculator unit supplied with the set. When reading these meters, note the value on the main display together with its unit; contact us for the menu steps.

Reading Without Entering the Apartment: Remote Meter Reading

Heat meters with M-Bus (wired) or wM-Bus (wireless) communication can be read remotely without looking at the display. This way nobody needs to enter the apartment on reading day, all meters are read on the same day and manual transcription errors are eliminated. Most models on our site have M-Bus; some models have a wireless option. For remote reading of the meters in your building and cost allocation, see our Remote Meter Reading and Billing page.

If the Value Looks Wrong

• If the display shows Err, a code starting with E or a warning triangle, you can find its meaning in our Heat Meter Error Codes guide.
• If the battery symbol is lit or the display is completely blank, see our Heat Meter Battery guide.
• Make sure you have not misread the unit: there is a factor of 1,000 between MWh and kWh.
• If the volume does not increase at all for a long time while the heating is on, inform the service provider. If you doubt the accuracy of the measurement, the meter can be re-verified at an authorized service; details on our Heat Meter Re-verification and Calibration page.