A condensing boiler gains higher AFUE/thermal efficiency by recovering latent heat. This requires the return water temperature to be in what relation to the flue-gas acid dew point (conceptual)?
Choices
- (A) Always above 80°C in all burners
- (B) Low enough (within material limits) to allow condensation of water from products of combustion, increasing sensible+latent recovery
- (C) Equal to wet-bulb of tower
- (D) Matches slab expansion joint width
Correct answer: (B)
Low enough (within material limits) to allow condensation of water from products of combustion, increasing sensible+latent recovery
Explanation
Return below dew point: condense flue; condensing design vs material corrosion controls.