Dry peat burns slowly and steadily, builds a long-lasting bed of hot glowing coals good for overnight heating, and gives more smoke than seasoned wood, especially if it is not fully dry. At 30% moisture on a wet basis it gives about 12.9 MJ per kilogram, a little under air-dried wood at 20%, and it burns best in a stove with a grate and a good draught.
Part of Peat Harvesting
How dried peat behaves in a fire: burn rate, embers, smoke, ash and smell, and what controls its heat output.
What The Fire Does
The parent article gives the behaviour: a slow, steady burn with a long-lasting ember bed, good for overnight heating; fine, hot coals that hold heat for hours; more smoke than seasoned wood, especially when not fully dry, so it burns best in a stove with good draught; moderate ash; and a distinctive pleasant smell. Peat smoke has been used for centuries to flavour whiskey and smoked foods.
Heat Output Depends On Moisture
The heat from a kilogram of peat depends on how wet it is. Using the net-value formula worked through in BTU Content Compared to Wood with an assumed oven-dry value of 19.5 MJ/kg:
| Moisture (wet basis) | Net heat, MJ/kg |
|---|---|
| 20% | 15.1 |
| 30% | 12.9 |
| 40% | 10.7 |
| 50% | 8.5 |
The figures are derived from an assumption, not measured. At 30% the peat gives 12.9 MJ/kg, which is 90% of air-dried wood at 20% (14.3 MJ/kg).
Method: Burning Peat Well
Step 1: Burn it dry. Check by weight or by the knock and crust (see Drying Timeline).
Step 2: Use a grate and ash pan. Air passing up through the bed keeps the coals alive.
Step 3: Start with kindling. Light the fire with wood, then add a few blocks and build up to a bed.
Step 4: Feed in small pieces. Blocks broken into chunks burn faster and more cleanly.
Step 5: Keep the chimney clear. Peat gives tarry smoke; see Chimney Cleaning Schedule.
Common Mistakes
- Burning damp blocks. Heat goes to boiling off water, and the smoke is dense.
- Shutting the air right down overnight. The fire smoulders and gives carbon monoxide.
- Throwing in a full load at once. It smothers the fire.
Safety
Smouldering peat gives carbon monoxide
Peat banked low gives smoke and carbon monoxide (Carbon Monoxide Risks). Keep the air supply open enough to avoid smouldering, never sleep in a closed room with a banked fire, and keep sparks and embers away from stacks of dry peat and thatch.
What’s Next
- Learn next: BTU Content Compared to Wood — the numbers
- Combine with: Stove Compatibility — which stoves suit it