5
ONLY USE GENUINE HAYWARD REPLACEMENT PARTS
51300803801 REV B
Model
Gas Input
Natural or Propane
Minimum
Water Flow
Thermal
Efficiency
Heater
Width
Heater
Weight
Btu/hr
GPM
%
in.
lbs.
HDF400
400,000
30
84
21
135
Table 1: SPECIFICATIONS
FEATURES:
120 or 240VAC, 60Hz, Single phase power, 5.5A maximum current
Pre‐mix combus on with silicon nitride hot surface igni on
Cupronickel heat exchanger tubes standard
Integral water bypass to maintain correct water flow through the heat exchanger.
Maximum water flow through
the unit is 125 GPM.
GAS REQUIREMENTS
OPERATING PRESSURES
Natural Gas
Propane Gas
Gas Manifold Pressure* [in. wc]
‐0.1 to ‐0.3
Gas Inlet Pressure, Minimum [in. wc]
4.0
4.0
Gas Inlet Pressure, Maximum [in. wc]
14.0
14.0
Gas/Air Orifice Service SKU
HDXFMXN400
HDXFMXP400
*Nega ve pressure regula on, range shown for allowable hea ng value varia on