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General guidelines are shown below for component
selection and design/installation criteria for the piping
system. Local codes supersede any recommendations in
this manual.
Shut off/flow regulation valves:
Use full port ball valves or
gate valves for component isolation. If valves are going to
be used frequently, ball valves are recommended. Globe
valves are designed for flow regulation. Always install globe
valves in the correct direction (fluid should enter through
the lower body chamber).
Check valves:
Swing check valves must be installed in the
horizontal position with the bonnet of the valve upright.
Spring check valves can be mounted in any position. A flow
check valve is required to prevent thermo-siphoning (or
gravity flow) when the circulator pump is off or when there
are two circulators on the same system.
Storage (Buffer) tank:
A buffer tank is required for all
hydronic heating systems using heat pumps. The tank
should be sized to provide 2 gallons of storage capacity for
every one thousand btuh’s of nominal heat pump capacity.
Pressure relief valve:
Most codes require the use of a
pressure relief valve if a closed loop heat source can be
isolated by valves. Even if local code does not require this
device, the manufacturer recommends its installation. If
the pressure relief valve in the buffer tank is not already
rated at 30 psi (207 kPa) maximum pressure, one must be
installed. The pressure relief valve should be tested at start
up for operation. This valve can also be used during initial
filling of the system to purge air. Note that the waste pipe
must be at least the same diameter as the valve outlet
(never reduce), and valves may not be added to this pipe.
The bottom of the pipe must terminate at least 6” (15 cm)
above the floor. If the piping is connected to a drain, there
must be an air gap.
Backflow prevention check valves:
Most codes require
backflow prevention check valves. Note that a single
check valve is not equal to a backflow prevention check
valve. Even if local code does not require this device,
the manufacturer recommends its installation. This is
particularly important if the system will use antifreeze.
Pressure reducing valves or feed water valves:
This valve
lowers the pressure from the make-up water line to the
system. Most are adjustable and directional. A “fast fill”
valve is required for initial filling of the system. Some have
screens, which must be cleaned after the initial filling. If
Hydronic Section
there is a restriction in the screen, the system could go to
0 psi (0 kPa), potentially causing pumps(s) failure. A valve
should be installed on each side of the pressure reducing
valve for servicing. Both valves should have tags reading
“Do not shut this valve under normal operation – service
valve only”.
Expansion tanks:
Expansion tanks are required on hydronic
systems to help absorb the pressure swings as the
temperature in the system fluctuates.
Elbows/tees:
Long radius elbows or two 45° elbows
will lower pressure drop. Standard tees have a greater
restriction on the “T” portion than tees designed with
angled outlet ports.
Antifreeze:
Antifreeze is required if any of the piping
system is located in areas subject to freezing.
Dielectric unions:
Dielectric unions are recommended
whenever connecting two dissimilar metals to one and
other to prevent electro-galvanic corrosion.
When using the various types of hydronic heat distribution
systems, the temperature limits of the geothermal system
must be a major consideration. In new construction,
the distribution system can easily be designed with the
temperature limits in mind. In retrofits, care must be
taken to address the operating temperature limits of the
existing distribution system. The maximum storage tank
temperature for the unit is 130°F (54.4°C). Typical in floor
radiant systems require much lower temperatures, typically
100°-115°F, which is ideal for the unit.
The unit uses an external temperature sensor such as the
lower thermostat in a water heater storage tank to control
the tank temperature. The thermostat should be wired to
the P5 connector wires, P5-11 and P5-4 tan wires. When the
tank temperature drops below the thermostat setting the
contacts in the thermostat will close and initiate a signal to
the unit to heat water.
A storage tank must be used to store the heated water
supplied by the unit. It is not recommended to send heated
water from the unit directly to the hydronic zones since the
unit also has the ability to condition the space with forced
air. There must be adequate storage capacity in the storage
tank to accommodate the hydronic load while the unit is
operating in forced air mode. The hydronic storage tank
should be sized to provide 2 gallons of storage capacity for
every one thousand Btuh’s of nominal heat pump capacity.
AFFINITY COMBINATION INSTALLATION MANUAL
Summary of Contents for YACT038-072
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