Even though it’s not preferable, it is perfectly possible to have an open fire with a heat recovery ventilation (HRV) system. Total Home Environment would still specify a ceiling terminal within that room supplying fresh air even though the HRV in that room would be reduced and more uncontrolled because of the natural air exchange between the HRV system and the fire’s chimney. However, if you could possibly bare to get a room-sealed wood-burning stove (WBS) instead of an open fire, you would lose far less heat up the chimney and it would indeed make the HRV system more effective. (NB: If the WBS was over 5kW you would need an external air supply directly feeding the WBS – under 5kW wouldn’t need one.) Hope this helps.

Clarissa