Fireplace with a water heat exchanger

A fireplace with a water heat exchanger heats the room it stands in and, at the same time, water in the exchanger. That water flows into the heating system or a buffer tank, so the heat also reaches other rooms - radiators, underfloor heating or hot water. A wood-burning fireplace is usually a supplementary source next to a gas boiler, an electric boiler or a heat pump.

Mandatory cleaning, inspections and revisions

• Chimney: under Decree No. 34/2016 Coll., the flue of a solid-fuel appliance up to 50 kW used all year is cleaned three times and inspected once a year; in seasonal use (up to 6 months a year) it is cleaned twice and inspected once a year. The owner may clean it themselves; the inspection is done by a chimney sweep.
• A flue revision is required, for example, before a new chimney is put into service, when the fuel changes or before the appliance is replaced with a different type.
• Technical inspection: if the fireplace or insert is connected to a water-based central heating system and its nominal heat input is 10 kW or more, a competent person trained by the manufacturer must check it at least every three years (Section 17(1)(h) of Act No. 201/2012 Coll.).

According to the Ministry of the Environment, the ban on old solid-fuel boilers that has applied in homes since September 2024 does not cover appliances also designed to heat the room where they are installed, including stoves with a water heat exchanger.

Frequently asked questions

How do I know if the three-year inspection applies?

What matters is the nominal heat input, not the output. It is in the manufacturer's documentation, or it can be calculated as output divided by efficiency. The ministry's example: an insert with 4 kW to water and 4 kW to the room (8 kW in total) and 70% efficiency has an input of 8 / 0.7 = about 11.4 kW, so it is covered.

What should I ask for when buying a house?

The latest flue cleaning and inspection report, the revision report (if the chimney was built or altered or the appliance replaced), the technical inspection record for an insert connected to central heating, and the manual or data sheet showing the heat input. The connection to the heating system should follow the design and manufacturer's instructions, including overheating protection.

How does a fireplace affect the EPC?

Decree No. 264/2020 Coll. gives firewood a non-renewable primary energy factor of 0.1, compared with 2.1 for electricity and 1.0 for natural gas. Heat from the fireplace can therefore improve the rating in the energy performance certificate.