Transcript High Efficiency Rooftop

Engineer Presentation
Efficiency - GAS
Clamshell Heat Exchanger
80% Efficient
Typical two furnace unit
400 °F
1700 °F
Typical two furnace unit
70°F
20°F
80%
Efficient
120°F
75%
Efficient
Heat Exchanger
Air Stratification - Typical Heat
Exchanger
10-15 °F
ΔT
Tubular Heat Exchanger
82-83% Efficient
350 °F
1700 °F
Primary Secondary
93% Efficient
150 °F
1700 °F
91% Efficient
Sizing - Series
70°F
20°F
91%
Efficient
120°F
86%
Efficient
Sizing - Parallel
600 MBH input
300 MBH input
91%
Efficient
91%
Efficient
Heat
Exchanger
Heat
Exchanger
Air Stratification – High Efficiency
??? °F ΔT
Minimum Turn Down Limitation
• Single Stage VS Modulation
• The minimum turn down must be set to ensure
condensing in the secondary heat exchanger or
both heat exchangers must be made out of
stainless steel.
• The Power Venter/Draft Inducer’s airflow
directly affects the gas to air ratio at the burner.
The ratio must be set to keep Air Free CO below
400 PPM.
Why Hydronic?
• Minimize footprint while maximizing efficiency.
• Maximum efficiency at the widest range of ambient
& design conditions.
• Maximizing user comfort while minimizing operating
cost.
• VAV minimum CFM is now limited by the supply fan
instead of heat exchanger.
• No stratification issues.
• “Green” unit/minimize emissions
Xcelon w/ Integral Condensing
Boiler
90 °F
100 °F
140 °F
1700 °F
Hot Water Coil
Air Stratification - Heating
Constant Discharge Temperature
February 23th 2012
122
121.5
121
120.5
120
119.5
119
Performance
• 93% thermal efficiency per BTS2000. With a
discharge air temperature set at 70 degrees,
that efficiency increases to 98% efficient.
• Fully modulating gas valves.
– 10:1 turndown ratio
• Closed Hydronic Loop requiring no water
connections at the roof. Only connections are
gas, electricity and ductwork.
– 35% Glycol Mix protects the unit to -30°F
Performance
Xcelon Performance at Discharge Air Setpoint Temperatures*
100.0%
98.0%
System Efficiency, %
96.0%
94.0%
92.0%
70
90.0%
100
120
88.0%
140
86.0%
84.0%
82.0%
-40
-10
0
20
Outdoor Air Temperature, °F
40
60
65
The maximum allowed CO is 400 PPM
CO (Air Free)
• Variable speed power venter
• High fire should be between 8.5-9.5% for CO2
and below the maximum 150 PPM for CO.
• Low fire should be between 8.0-8.5% for CO2
and below the maximum 150 PPM for CO.
Efficiency - ELECTRICAL
Clamshell - Static Pressure
• A typical Clamshell Heat Exchanger can have
a static pressure drop of 1.12” per furnace.
• This can result in a total static pressure of over
3” through the furnace sections.
Xcelon – Hot Water Coil
• Regardless of the BTU input and CFM
selected, the hot water coil was carefully
selected to keep the air pressure drop below
0.5” of static.
• This can result in a reduction in motor horse
power by up to two sizes.
• Further adding to the electrical savings, all
units come with a VFD as standard.
Cooling Coil Bypass
Bypass Damper
• In cooling mode the
bypass damper is closed
forcing the air through
the cooling coil.
• When not in cooling
mode, the bypass damper
opens to reduce the
internal static pressure of
the unit.
Cooling Coil
Efficiency – Heat
Recovery
Heat Recovery Layout
VFD &
Transformer
Motor
Boiler
Pumps
This recovered waste heat increases the efficiency by 1+%
Additional Features
Cincinnati Fan
Piping
Condensate
• Integral condensate trap designed to drain in
the event of a power failure.
• Condensate
Neutralizer as a
factory installed
optional accessory.
• Optional Dedicated
heat trace power
supply for long
condensate runs.
Controls - Overview
1.
2.
3.
4.
Call for heat is received.
Dampers open and prove.
Burners turn on.
After glycol mix reaches temperature, VFD
slowly ramps up.
5. Glycol mix temperature is varied to maintain
constant discharge temperature.
6. (Optional) if the unit is unable to maintain
discharge temperature, it reduces the CFM until
discharge temp is satisfied.
Controls - Boiler
• The PID loop looks at the Propylene Glycol mix
temperature, the discharge air temperature and rate
of change.
• HRT Controls are configured to run the first burner
to 50% fire then turn on the second burner.
• True run time monitoring
Controls - Safeties
• Boiler – High Limit, Low Water Cutoff, Ignition
Control Fault and Software Operator Limit
Per code, unit complies with CSD-1.
• Air Side – VFD Temperature Status and Damper
Prove
Service
• Designed with ease of service in mind.
– Isolation valves for ease of boiler service
• Boiler is on a track for ease of repair.
– Service lights standard on all units.
– Optional Convenience Outlet available.
– Optional Clogged Filter Switch.
– External Control Terminal Strip on exterior of unit
for ease of Thermostat wiring.
Roof Cap
• The roof cap of the outdoor unit is sloped to
prevent standing water on top of the unit.
• It should be noted that underneath the roof cap is
that actual roof of the unit which is a same panel
construction as the walls (with the same R-value)
Performance
• Performance
– Max Discharge 140 ⁰F, Max temperature rise 100 ⁰F.
– 4,501 - 15,000 CFM
• Able to handle 3” of external static pressure
– 800 – 1,600 MBH
• Initial offering
– 4,501 to 10,000 CFM
– 800 & 1,200 MBH
Questions