Running a village heating network is a daily routine of tending the fire to the weather, a weekly check of three logged numbers (fuel burned, return temperature and pump hours), and a yearly cycle of start-up, winter operation and summer shutdown. For the 30-house reference village the boiler burns 37.8 kg of seasoned wood an hour at peak and 15.1 kg at the season average, a season needs about 89 t, and every added metre of trench costs 133 kWh of heat per season, which is the price to weigh before adding houses.
Part of District Heating
What running a village heating system involves day to day and over the year, and the rule for growing it.
The Daily Routine
In the 30-house reference village, at the 120 kW peak, the boiler takes 37.8 kg of wood an hour, so 907 kg a day, about nine loads of 100 kg. At the season-average 48 kW it takes 15.1 kg an hour, 363 kg a day, between three and four loads. The operator’s work follows the weather. The wood rate and its derivation are in Heat Source; the carrier page puts the tending at 2 to 3 hours a day for wood. The season total of about 89 t is derived in Fuel Consumption Estimates.
Each morning and evening:
- Check the expansion tank level and the pump (running, quiet, no leaks).
- Read the supply and return temperatures at the plant.
- Load the boiler; note the number of loads.
- Walk the boiler house for smell, smoke and heat at the flue.
What To Log
| Reading | Why it matters |
|---|---|
| Loads of wood (or other fuel) per day | Gives the season’s fuel use; compare with Fuel Consumption Estimates |
| Supply and return temperature at the plant | Return rising with supply fixed means too much flow or houses that waste heat |
| Expansion tank level | A falling level means a leak; see Building Connections |
| Pump hours | Wear, and the pump’s energy use |
| Outdoor temperature | To relate fuel to weather |
A weekly look at the log is the cheapest fault detection a network has: a step change in fuel with no change in weather means wet insulation or a leak, the failure modes in Insulation Methods.
The Yearly Cycle
- Autumn start-up. Test the pump and its spare, check vents, safety devices and the expansion tank, fill and vent the system, and fire the boiler in steps.
- Winter. Keep the plant staffed at the worst weather; the plan for a pump stop or an outage is in Wood-Fired Boiler Design. If the loop could stand cold in a freeze, drain the sections above the frost line.
- Spring shutdown. Decide the summer regime: the network off, with hot water made locally, as set out in Domestic Hot Water Takeoff.
- Summer maintenance. Clean the boiler and flue, replace worn parts, inspect trench lines for sinking, stack the next season’s wood to dry.
The Scaling Rule
Adding a house on a spur costs heat in proportion to the trench it needs: 27.7 W per metre for the supply-and-return pair over a 4,800-hour season is 133 kWh per metre. A house that needs 7,680 kWh a season is served efficiently on a 5 m spur (665 kWh, 9% of its demand) and wastefully on a 100 m spur (13,300 kWh, 173%). The full arithmetic is in Expanding the Network.
Common Mistakes
- No log. Without numbers a leak looks like a cold winter.
- Running at full supply temperature all season. Loss is paid every hour; lower the supply in mild weather.
- Adding houses until the pump or boiler struggles. Check each against the plant’s headroom.
Safety
The operator is the safety system
A boiler operator is the person who notices a pump stop, a low tank, carbon monoxide or a hot flue. Train at least two people, keep a written emergency procedure at the boiler house door (pump stop, low water, fire in the flue, burn), and never leave a fired boiler unattended unless a damper and vent protect it automatically.
What’s Next
- Learn next: Fuel Consumption Estimates — the season’s tonnes
- Combine with: Expanding the Network — growth in detail