G Series Outdoor Furnaces
www.heatmasterss.com
DOMESTIC HOT WATER
Flat plate exchanger systems used to pre heat domestic water tanks are generally more
reactive to hot water demands then tube and shell systems. However tube and shell ex-
changers hold up better when hard water is present.
FORCED AIR FURNACE (WATER-TO-AIR EXCHANGER)
The water-to-air heat exchanger must be mounted so that air blows through the fins
(coils). The exchanger should be mounted below the A/C coil if possible. The ex-
changer should be sized to fit existing duct work and should produce about as many
BTU’s as the existing heat source. An exchanger that produces too many BTU’s will
result in uneven heat and the fan stopping too quickly while a heat exchanger that is
undersized will not produced the necessary BTU’s. The heat exchanger can also be
placed into the cold air portion of the duct work but it is not recommended because
some furnaces have an overheat shut off if the fan overheats as a result of blowing hot
instead of cold air.
It is important that the warm-air supply-duct system be constructed of metal in accord-
ance with NFPA 90B-1993, 2-1.1. If the outlet-air temperature of a central furnace ex-
ceeds 250° F (121° C) when it is tested in accordance with the requirements for Simul-
taneous Firing in 56.4.1 and 56.4.2 of the standard. It is also important that the ple-
nums installed to the furnaces be constructed of metal in accordance with NFPA 90B-
1993, 2-1.3.
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