What your hot air costs, and what it could cost

01What fires your hot air generator today

02Your air duty

What 1,000 kcal of delivered heat costs you

Fuel spent up to that year. The green line is what you have saved by then.

This is a fuel comparison only — equipment cost, installation and replacements are not included. Ask UDBT for a delivered price against your duty.

Method and assumptions

Heat duty

Q = air mass flow × specific heat × (hot air temperature − inlet air temperature), with Cp = 0.2382 + 0.0000297 × mean air temperature kcal/kg·°C.

Fuel

Firing rate = duty ÷ (efficiency × blend calorific value). Calorific value, price and CO₂ factor are weighted by mass; the first fuel takes the share you set and the second takes the remainder.

Efficiency

80% for the CFHAG under-bed fluidised combustion with flue gas recirculation, against 72–75% for a conventional solid fuel unit, or 85% indirect and 98% direct for oil and gas. Stack temperature suggests a baseline at 0.04 points per °C above reference.

Modes

Oil and gas is a fuel-only comparison. Solid fuel runs the full life cycle: CFHAG capital 20% above your unit, and a major replacement at 10% of your capital cost every 3 years on yours and every 5 on ours.

Calorific values

Typical as-received values for the fuel selected. CO₂ factors follow IPCC 2006 Guidelines Vol. 2 Table 1.4; biomass is shown as zero because biogenic CO₂ is reported separately under the GHG Protocol.

Currency and units

Changing the currency changes the symbol and number format only, so enter every price and equipment cost in the currency you have selected. Direct-fired units put combustion products into the process air; a CFHAG delivers clean indirect air.