Premix Burner Technology - CleaverBrooks CFC ClearFire User Manual

Model CFC
Full Modulation
Designed For
Heating
Applications
Dual Return
Combined with a variable speed fan, this technology provides very low emission
levels, exceptionally safe operation, and nearly 100% combustion efficiency.
The variable speed fan provides modulated firing for reduced on/off cycling,
excellent load tracking, and reduced operating costs. The burner does not require
mechanical linkage connections between the fuel input valve and air control.
Instead, the microprocessor control positions the fan speed in accordance with
system demand, and this determines the fuel input without mechanical device
positioning - that is, linkage-less fuel/air ratio control. This eliminates linkage
slippage, minimizes burner maintenance, and provides control repeatability. This is
shown schematically in Figure B5-3.
Figure B5-3. Premix Burner Technology
The pressure vessel is designed for 125 psig MAWP (Max. Allowable Working
Pressure) and is constructed of durable ASTM Grade Steel and Stainless Steel
materials. Figure B5-4 shows the counter flow heat exchanger design that gives
optimal heat transfer. The design also prevents hot spots, does not require a
minimum flow for thermal shock protection, and does not require a minimum return
water temperature. In fact, the design carries a 20-year thermal shock warranty.
Because of its design characteristics, the Model CFC is well suited for applications
utilizing indoor/outdoor reset controls, radiant floor heating, snow melt systems,
ground source heat pump systems and systems that utilize variable speed
circulating pumps. It may also be employed in standard hot water systems that
require higher heated water at colder outdoor temperatures but then require
minimum temperatures during warmer heating days, realizing fuel efficiency savings
over traditional hot water boilers.
While the design does not lend itself to the direct supply of potable water, a separate
storage tank with an internal heat exchanger can be employed, as the
microprocessor control permits domestic water programming. Therefore, the Model
CFC can service both hydronic heating and domestic water source heating.
Two return pipes - high and low temperature - allow condensing performance with
as little as 10% return water at condensing temperature.
ClearFire Commercial Boilers
4 Rev. 05-2012