# What should a Jamnagar brass unit check on its pit and billet furnaces, and how much heat does each gap cost?

Canonical: https://senseible.earth/answers/jamnagar-brass-furnace-heat-loss-checklist

The Bureau of Energy Efficiency (BEE) Jamnagar manual puts flue gas heat loss at about 35% of input for oil fired furnaces and 35 to 45% for coal pit furnaces. It says preheating the charge to 200 to 300 degrees saves 5 to 8%, and a poor air-fuel ratio costs 3 to 5% of efficiency.

## Coal and oil fired pit furnaces

- No heat recovery from the flue gas. Printed loss: about 35% of input for oil, 35 to 45% for coal.
- No charge or air preheating. Preheating the charge to about 200 to 300 degrees would cut use by 5 to 8%.
- Local firebrick of low alumina content wears quickly, and red brick is used as insulation, though it does not insulate. Coal melting furnace skin temperatures reached 110 degrees.
- Coal pit furnaces also lose 4 to 5% of the metal in melting and show uneven temperature between the top and bottom of the crucible.
- Oil fired pit furnaces add too little combustion space, locally made burners often leaking oil at the joints, and blowers and oil heating or pumping not sized for the job.

## Billet reheating furnaces

- Air-fuel ratio not right: the manual says it cuts furnace efficiency by 3 to 5%.
- Chimney in the middle of the furnace, so flue gas and billets exchange heat poorly; about 35% of input lost in flue gas.
- Skin temperatures as high as 100 degrees on walls and 130 on roofs, which the manual says radiation losses "sometimes" put "as high as 3-7 %" of the overall losses.
- Operators judge billet temperature by experience instead of a gauge.

## Habits

- Each cold start of a furnace uses 10 to 20% more energy than regular running and wears the refractory.
- Keep furnace gates shut except for material flow. For heat treatment furnaces the manual recommends digital temperature indicators, so nobody opens a gate to check temperature.
- Sand gravity moulding: 10 to 20% of castings rejected, and about 45 minutes of manual pouring that adds fuel and metal loss.

## What to write down this week

1. Fuel bought each month and tonnes cast or pressed.
2. Number of cold starts and shift length.
3. Skin temperature of wall and roof with a handheld meter, if you have one.
4. Rejection rate in the sand moulding line.

## Where 100 units of heat go in a billet furnace (example)

- Efficiency 17.59% from the manual's Table 3.2: 17.6 units reach the billet
- Flue gas loss about 35% of input, the manual's figure for oil fired furnaces: 35 units go up the chimney
- Remaining 47 units go to walls, roof, openings and other losses
- The manual's own new furnace reaches 28%, so even the fix leaves most of the heat unused

The 35% is a general figure from the manual's gap analysis, not a measurement of the furnace behind the 17.59%, so the split is only an example of the order of magnitude.

## What Senseible does here

Self-serve, Senseible reads fuel invoices and electricity bills into monthly records; furnace temperature and heat loss are custom, on request. The fuel bought each month sits beside your own production figures, and the checks above are done on site.

- [Green loan readiness check](https://senseible.earth/green-loan-check)
- [Four fixes for a Jamnagar reheating furnace](https://senseible.earth/answers/jamnagar-brass-reheating-furnace-four-fixes-compared)
- [Melting furnace swaps at 200 tonnes](https://senseible.earth/answers/jamnagar-brass-melting-furnace-swaps-at-200-tonnes)
- [Brass furnace thermocouples, three reports](https://senseible.earth/answers/brass-furnace-thermocouples-three-cluster-reports)

Sources: [BEE, Manual on energy conservation measures in brass cluster Jamnagar (Winrock International India)](https://sameeeksha.org/pdf/clusterprofile/Brass_cluster_Jamnagar.pdf)

Last reviewed 2026-11-06. Figures are from the technology gap analysis in BEE's Jamnagar manual, which prints no year on the pages used. The heat split in the example is the author's arithmetic.