Hot Water Meters (Threaded, DN15–DN50)

A hot water meter measures the hot water used by each apartment in buildings with central systems, in cubic meters; the measured consumption is used to allocate hot water costs among the apartments. This category includes the Klepsan KVS-S series (DN15–DN50), rated up to 90 °C, and the DN20 Zenner ETWD, CEM KT13 and Polimeter PHW meters. For mains water, see the cold water meter category.

Where Are Hot Water Meters Used?

In buildings supplied by a central boiler or a shared domestic hot water system, hot water is distributed to the apartments through a common line. A hot water meter installed at the apartment entrance separately measures the amount of hot water drawn by that apartment and is usually used together with a heat meter that measures heating energy. Some heat meters have pulse inputs for water meters: hot and cold water meters can be connected to the three pulse inputs of the Minol Zenner C5 ISF in the mechanical heat meter category so that all of them are read over the same line.

What to Check When Choosing a Hot Water Meter

• Temperature class: The class on the meter label must cover the water temperature in the line: T90 is for water at 0.1–90 °C, T30/90 for water at 30–90 °C. The Klepsan KVS-S series is made for up to 90 °C, the Zenner ETWD for 0.1–90 °C and the Polimeter PHW for 30–90 °C; for hot water, the T90 or T30/90 version of the CEM KT13 is used.
• Body length: For DN20, lengths of 110 mm (Klepsan KVS-12S, CEM KT13), 130 mm (Zenner ETWD) and 190 mm (Klepsan KVS-2S) are available; the Polimeter PHW-20 is made in 110 and 130 mm lengths.
• Installation position: The Klepsan catalog specifies horizontal installation. The Zenner ETWD can be installed horizontally or vertically, the Polimeter PHW horizontally, vertically or inclined; for the CEM KT13, the R value depends on the installation position.
• Remote reading: To read meters in a central system without entering the apartments, check the module options. On our site, the Zenner ETWD can be selected with a 1 L pulse, M-Bus or wM-Bus module and the Polimeter PHW with an M-Bus module; for Klepsan, a pulse output is optional on the KVS-3S, KVS-2S and DN25–DN50 models.

Models: Size, Q3 and Body Length

Each model and size is listed as a separate product. By size: DN15 · DN20 · DN25 · DN32 · DN40 · DN50.

Values are taken from the manufacturers’ catalogs and data sheets. The maximum working pressure of the Klepsan, Zenner ETWD and CEM KT13 meters is 16 bar.

Re-verification of Hot Water Meters

Whether hot water meters must be re-verified or replaced at fixed intervals depends on national regulations, which differ from country to country and do not always treat hot water meters the same way as cold water meters. Check your local regulations for periodic re-verification requirements. For placing on the market, meters for heated water are also covered by the MID (2014/32/EU, MI-001); look for the CE and M marking on the meter. Because hot water costs are allocated based on the readings of these meters, faulty or unreadable meters should be replaced promptly. The meaning of the markings on a meter is explained on our Water Meters page.

Frequently Asked Questions

What water temperature can a hot water meter withstand?

It depends on the model: the Klepsan KVS-S series is made for water up to 90 °C, the Zenner ETWD for 0.1–90 °C and the Polimeter PHW for 30–90 °C. Check the temperature class on the meter label (e.g. T90, T30/90).

Do hot water meters have to be replaced at fixed intervals?

That depends on national regulations. Re-verification and replacement intervals for water meters are set nationally, and the rules for hot water meters are not always the same as those for cold water meters. Check your local regulations for periodic re-verification requirements.

What is the difference between a hot water meter and a heat meter?

A hot water meter only measures the volume of water passing through it (m³). A heat meter measures the flow together with the temperature difference between the supply and return lines and calculates the heat energy consumed (kWh). In central systems, the two are used together.

Can a hot water meter be read remotely?

Yes, with a module. On our site, the Zenner ETWD is offered with a 1 L pulse, M-Bus or wM-Bus module and the Polimeter PHW with an M-Bus module. A pulse output is optional on some Klepsan models; for the CEM KT13, the manufacturer offers pulse, M-Bus, wM-Bus/LoRaWAN and NB-IoT modules.