36
Mechanical, Hydronic and Process Heating Applications
Piping
NOTE: Hot water heating systems all have unique levels of operating diversity that must be accounted
for in the system design. The system should always include adequate system flow in excess of the
connected water heater flow for proper operation. Where the system flow may drop below the connected
water heater flow a buffer / de-coupler may be needed. Failure to design for adequate flow (i.e.
bypasses, 3 way control valves, flow limiting balance devices, buffer tanks, etc.) will result in water
heater short cycling and may reduce water heater life. Consult Rheem for system design assistance to
avoid these issues.
All high points should be vented. This heater, when used in connection with a refrigeration system, must
be installed so that the chilled medium is piped in parallel with the heater with appropriate valves to pre-
vent the chilled medium from entering the heater.
The piping system of a water heater connected to heating coils located in air handling units where they
may be exposed to circulating refrigerated air, must be equipped with flow control valves or other
automatic means to prevent gravity circulation of the heater water during the cooling cycle. It is highly
recommended that the piping be insulated.
Air-Separation/Expansion Vessel
All heaters should be equipped with a properly
sized expansion vessel and air separator
fitting as shown in
on page 53.
Fig 10: Air-Separation/Expansion Tank
Piping
For these applications, storage tanks are normally not required. Connect the water heaters and
pumps in accordance with the principles shown in the diagram below with the following in mind:
•
Install the water heaters according to “Equa-flow® principles” detailed on page 33.
•
The water heater/s MUST operate on their own primary flow and return circuit, separate to the
system heating circuit. The primary return branch to the water heaters and the primary flow
branch from the water heaters MUST be separated by a distance not exceeding 4 x system pipe
diameters or 300mm, whichever is the smaller. Refer to Fig 11 on page 51
•
A disconnection union must always be provided at the cold water inlet and hot water outlet on the
water heater to allow for disconnection of the water heater.
•
Each high point of the system MUST be fitted with an air bleed valve or automatic air eliminator.
