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Call for Space Heating
There are two thermostats controlling every combo system,
the water heater thermostat (controlling the hot water tem-
perature) and the room thermostat (controlling the room air
temperature).
When the room thermostat calls for heat, the circulation
pump is activated. Hot water is then drawn from the top of
the water heater through the air handler, and then returned
to the water heater.
Plumbing
WATER HEATER
DOMESTIC HOT WATER
SUPPLY AIR
BLOWER
CHECK
VALVE
RETURN AIR
COLD WATER INLET
ANTI-SCALD VALVE
(WHEN REQUIRED)
VALVE
(shut off)
VALVE
(shut off)
VALVE
(shut off)
VALVE
(balancing)
COOLING COIL
(OPTIONAL)
DRAIN
VALVE
HEATING COIL
HRV/ERV CORE
Open Loop System
Hot Water Temperature Drop
The water heater thermostat will initiate the water heater as
required as long as there is a 20°F (11°C) temperature drop
between the hot water supplied to the air handler and the
returning water.
A temperature drop less than 20°F (11°C) can cause the
water heater thermostat not to initiate. This will result in a
lower hot water supply temperature or poor space heating
performance with fluctuating domestic water temperatures.
Call for Domestic Hot Water and Space Heating
When both return water from the space heating loop and
new cold water (replacing domestic water being used)
enters the water heater, the mixed entering water is cool
enough to activate the thermostat quickly. In this situation,
the water heater must be capable of satisfying the combined
need for domestic hot water and and space heating at the
same time.
Plumbing components and system
configuration may vary from diagrams
portrayed.
ATTENTION
Chemicals (such as boiler system
additives) cannot be added to a domestic
hot water system.
ATTENTION
Conventional
Cooling
(Not available
through
Nutech)