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• 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.
• Follow all local codes, or in the absence of local codes, follow the most recent
editionoftheNationalStandardCode,ANSIZ21.10.3.
• 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
manufacturer.
NOTICE
120VAC
switch or
outlet
Hot water outlet
Unions
T-handlegasshutovalve
Check valve
Electronically controlled
pumpmer.Acvates
every6hoursfor60
seconds. Wire to
product approved pump
Heang Coil
(used with air-handler)
Cold water supply
3-inch gas exhaust
vent (Discharge must
comply with local and
state codes.) Cannot
be common vented
with other appliances
An approved temperature and pressure
reliefvalve.Tietolocaonapprovedby
localcodesandmustmeetBTUrangof
water heater model used
Check valve will have
1/8-inchholedrilling
inclapperoponal
Atmospheric
vacuum
breaker
Shuto
valve
Pressure
gauge
Apply correct thermal
expansion tank-size
perapplicaon
Shutovalves
Shutovalves
Check valves
Cold water inlet
Gas inlet
Water
lter
Drain
plug
Thermostacmixingvalve
Hot water
supply and
return to
heangcoil
System installed with reverse
acngaquastattoshutofan.
Suggested but not required by
248CMR
50’-0”maximumdistancefrom
water heater to fan coil.
(Developed length) Not including
coilinheangunit
NSF-61product
approved pump
Automactemperingdevice
must be installed below
the top of the water heater
as per manufacturer’s
recommendaons
Piping loop
between water
heater and fan
coil shall be in
compliance with
248CMR
Tempered water to
plumbingxtures.Must
meet temperature
requirementsof248CMR
All water piping should be insulated
inaccordancewith780CMR
(Massachusesenergycode)
-Dual-purpose hot water heang-
(Domestic and Space Heating):
Diagrammatic layout of radiant heating and domestic water heater per Mass. code.
The recirculation pump is to provide no less than 2 GPM (7.5 L/min) and no more than 4 GPM (15 L/min)
through each activated unit in the system
Installaon
Installaon Manual
Ball
Valve
Isolation
Valve