The Reznor’s Model HRPD Series Rooftop Outdoor, Power-Vented, Dual Duct Furnaces
Reznor® Model HRPD Series Rooftop Dual Duct Furnaces are designed to be used in series as the heating component in a heating, heating/cooling, or makeup air system. Each of the dual furnaces is certified for 80% thermal efficiency for use with either natural or propane gas, as specified. Eight sizes are available from 250,000 through 800,000 BTUH input. Each furnace includes an integral power vent system which provides metered combustion air, dilutes flue products, and eliminates the need for vent caps. The weatherized, aluminized steel cabinets are mounted on 12 gauge zinc grip rails designed for setting directly on a roof or slab surface. A separate blower system, such as Reznor Model RBL, is required for air delivery.
Each furnace has a Thermocore® aluminized steel heat exchanger with venturi-design tubes. The die-formed burners are of aluminized steel and include flared ports with a stainless steel insert.
Standard features for each furnace include a spark-ignited intermittent pilot and a single stage, 24-volt gas valve. Each furnace has all the required limit and safety controls including a venter pressure switch which verifies power venter flow prior to allowing operation of the gas valve.
STANDARD FEATURES:
● Orifices for natural gas
● Aluminized steel heat exchangers (When inlet air temperature is below 40°F or temperature rise is less than 40°F, optional stainless steel heat exchanger is recommended.)
● Aluminized steel burners with stainless steel insert
● 120-volt supply voltage
● 24-volt control voltage transformers
● Redundant, single-stage combination gas valves
● Spark-ignited intermittent safety pilots with electronic flame supervision
● High limit safety cutouts
● Power venters
● Differential air pressure switches to verify vent flow
● Terminal block wiring
● Left side access for burners and controls (slide out burner drawers)
● Fan control
● Weatherized cabinet with interlocking joints (U.S. Patent No. 5,373,653) and mounting rails
NOTES:
1. Burner and control access shown left hand side (standard). Specify right hand side for opposite access and connections.
2. Standard airflow as shown. Direction of airflow may be reversed by field relocation of airflow baffles in the heat exchangers. These furnaces must be disassembled to change air flow direction as well as the baffle change.
3. One-inch fiberglass insulation full length and width of top.
4. Approved for installation downstream of an air-conditioning coil (optional stainless steel heat exchangers, stainless steel burners, and stainless steel bottom sections are recommended).
5. Not approved for residential use.
OPTIONAL FEATURES – FACTORY INSTALLED:
● Orifices for propane gas
● Elevations to 9,000 ft
● 409 stainless steel heat exchangers
● 409 stainless steel burners
● 409 stainless steel bottom pans
● Burner Controls for Recirculated Heating
◊ Two-stage gas valve on each furnace (operate in tandem from 2-stage room thermostat)
◊ Electronic modulation, 50-100% tandem operation from room thermostat
● Gas Controls for Makeup Air
◊ Two-stage operation with 1-stage gas valve and 2-stage ductstat (50 or 100%)
◊ Four-stage operation with 2-stage gas valves controlled from 2-stage ductstats with either unit-mounted controls or remote electronic controls with or without display module
◊ 4:1 Turndown Electronic modulation (25% of full output) with duct probe (55-90°F) with unit setpoint, with remote adjustment, or with signal conditioner for customer-provided computer control
◊ 8:1 Turndown Electronic modulation (12% of full fire output) 20-100% firing rate on first furnace controlled from ductstat with remote adjustment and 2-stage with outside air stat on second furnace or same turndown capability with signal conditioner for customer-provided computer control — 8:1 turndown electronic modulation requires stainless steel heat exchangers, burners, and bottom pans (8:1 turndown not available on Size 700)
● Voltage supply, 208, 230, or 460 single phase
● Intermittent spark pilots with timed lockout
● Right side controls (right when facing airstream)
● High and low gas pressure switches
● Airflow proving switch
● Curb cap base