Overview of Condensing Tankless Gas Water Heater
This water heater is a high efficiency, fully condensing appliance. Unlike a traditional tankless 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
The condensing tankless 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.
2 gallons/hour (7.5 liters/hour) maximum). It is not a
water leak. Do not plug or block the drain line as it
must always be allowed to freely flow.
Note : The condensate discharged is acidic with a
pH level of approximately 2-3.
A condensate neutralizer may be required by
local code prior to disposal.
The condensing tankless 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.
8
Exhaust
About
400˚F (200˚C)
Combustion gas
About
400˚F (200˚C)
Primary heat exchanger
Condensing
Exhaust
Tankless Gas
About
Water Heater
120˚F (49˚C)
Secondary heat exchanger
Combustion gas
About
400˚F (200˚C)
Primary heat exchanger
Drain pipe
(Installation example)
Condensate
comes out
from here.
Water is heated
using the exhaust
gas which is about
400˚F (200˚C).
(Ex. EN18WI30LS)
During combustion, white
steam may often be seen.
This is normal.