Overview Of Condensing Gas Water Heater - andrews Fastflo WHC56 Service Manual

Overview of Condensing Gas Water Heater

This water heater is a high efficiency, fully condensing appliance. Unlike a traditional water heater, a condensing
type captures heat from the exhaust gas and uses it to preheat the incoming cold water as it passes through the
secondary heat exchanger as illustrated below.
Conventional
type
About 200°C
Primary heat exchanger
The condensing gas water heater
discharges condensate.
When heat from the exhaust gas is collected
within the secondary heat exchanger,
condensation occurs from moisture in the
exhaust gas and the resulting water is
discharged from the drain pipe (approx. 100cc/
min maximum). It is not a water leak. Do not
plug or block the drain line as it must always be
allowed to freely flow.
The condensing gas water heater
tends to show white steam.
After the exhaust gas passes through the
secondary heat exchanger, it becomes low in
temperature and moisture rich which tends to
produce steam at the vent discharge terminal.
This is a normal occurrence.
Exhaust
Combustion gas
About 200°C
Condensing
Exhaust
Gas Water
About 50°C
Heater
Secondary heat exchanger
Combustion gas
About 200°C
Primary heat exchanger
Drain pipe
(Installation example)
Condensate
comes out from
here.
– 2 –
Water is heated
using the exhaust
gas which is about
200°C.
During combustion, white
steam may often be seen.
This is normal.