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Dual-purpose hot water heating (Domestic and Space Heating):
Priority Control Devices
such as a flow switch, an Aquastat or other electronic controller can be used to
prioritize the domestic water system over the heating system.
Warning:
Follow all local codes, or in the absence of local codes, follow the most recent edition of the
National Standard Code, ANSI Z21. 10.3.
Warning:
This illustration is a concept design only. The reference to the 1/8
th
hole in check is only for
the State of Massachusetts. There are a wide variety of variations to the application of controls and
equipment presented. Designers must add all necessary safety and auxiliary equipment to conform to
code requirements and design practice. For more details, contact the Takagi Technical Department at
(888) 882-5244
* Size the pump to provide at about 2 GPM through the system at 15 Ft of Head plus applications
and piping head losses. 2 GPM will allow the system to operate at its optimal performance.
* If the application requires a higher re-circulating flow rate, make sure that the re-circulating flow
rate is no greater than 4
GPM. If the flow rate is too high, the system could be damaged by
erosion.
Takagi
P
T
An approved Pressure Only
Relief Valve, Tie to Location
approved by Local Codes and
Must Meet BTU Rating of Takagi
Model Used
Unions
4" Gas Exhaust Vent (Discharge
Must Comply with Local and
State Codes). Can Not Be
Common Vented with Other
Appliances
Atmospheric
Vacuum Breaker
Pump (Must Be Sized Properly
With Each Application). Pump
Shall Run 60 Seconds Every 6
Hours
Pressure
Gauge
Apply Correct
Thermal
Expansion
Tank-Size Per
Application
Tempered
Water To
House
Cold Inlet
Shut-Off
Valve
Check Valve Will
Have 1/8" Hole in
Check, As Per
Mass. Code
Thermometer
Thermostatic Mixing Valve
Shut-Off
Valves
Check Valve
Hot
Water
Outlet
Cold
Water
Inlet
T-Handle Gas
Shut-Off Valve
**Maximum allowable distance of
50-Ft. from water heater and
heating panel
Heating Coil
(used with air-handler)
Diagramatic Layout of Radiant Heating and
Domestic Water Heater Per Mass. Code
Thermometer
Check
Valves
Gas
Inlet
Drain
Plug
Water
Filter
120 VAC Switch or Outlet
