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Hydronic piping
Basic hydronic piping
Depending upon the application, there are many different
piping arrangements that can be applied to the Thermal-Stor
buffer tank. A pressure relief valve must be installed on each
boiler and each buffer tank as regulations require. Installation
and commissioning must always be carried out by a licensed
and experienced contractor. It is the responsibility of the
installer to comply with all building and installation codes in
effect.
Hydronic heating zoned with circulators
FIG. 4-2 on page 14 shows typical space heating piping for a
Thermal-Stor tank. The functions of some of the illustrated
components are as follows:
•
Shut-off valves (recommended) - Used to isolate the
tank for servicing.
•
Backflow Preventer (required by some codes) - Used to
prevent water from backing out into the piping in the
event that inlet water pressure drops.
•
Expansion Tank (required for thermal expansion) - Tank
absorbs the increased volume caused by heating water.
Refer to the expansion tank manufacturer’s instructions for
proper sizing and use.
NOTICE
If a valve is used between an expansion tank
and the tank inlet, the installer must ensure
that the valve is open.
•
Circulation Pump (recommended) - Used to circulate and
maintain hot water within the piping system.
•
Check Valve (required by some codes) - Used to allow
water to flow in only one direction, preventing back-flow.
•
Drain (required) - Used to drain the tank for inspection
or servicing.
•
Mixing valve (required for domestic water) - Used to mix
hot water with cold water to ensure constant, safe outlet
temperatures.
•
Unions (optional) - Used to disconnect the tank in the
unlikely event that this is necessary for service.
NOTICE
Be sure to field-install plugs or caps on any
tank tappings that are not in use.
Thermal-Stor domestic water heating
When paired with an indirect water heater or a heat exchanger
(FIG. 4-3, page 15) the Thermal-Stor buffer tank can be used
to heat domestic water. The hottest water is taken from the
auxiliary heat supply and piped to the indirect heater where it
is used to heat domestic potable water. The water is returned
to the high temperature return tapping so the hottest water
will be available for domestic heating while preserving tank
stratification. Other hydronic heating applications will be piped
into the low temperature or auxiliary returns.
High output piping
When a large amount of hot water is required for hydronic
heating, there are several different piping alternatives. When
hydraulic separation is desired, multiple boilers coupled with
a buffer tank can provide adequate water for both space and
domestic water heating (FIG. 4-4, page 16).
Multiple Thermal-Stor tanks can also be piped together if there
is a continuous demand for heating water. This is typically
done in the reverse-return arrangement. This method uses
more piping than direct-return systems, but the temperature
and boiler flow are more balanced throughout each tank.
To ensure even charging and discharging of each tank, it is
recommended that only tanks of the same size are placed in the
same manifold. It is recommended that each tank be equipped
with its own isolation valves, unions and drains, so that one
tank may be removed from the system if necessary. It is only
necessary to use one backup heat source sensor for control
(FIG. 4-6, page 17).
Installation & Operation Manual
CAUTION
Piping must be balanced. Failure to balance
piping could result in uneven flow and
improper operation.
Domestic hot water priority
Domestic Hot Water (DHW) priority allows a boiler to be
used for both space and domestic water heating by turning
off the boiler output for space heating when there is a call for
domestic hot water. Outdoor reset is required with the use of
DHW priority in order to regulate water temperature and satisfy
heating load. During calls for DHW, the outdoor reset control
will turn off the circulation pump and raise the boiler water
temperature to a minimum of 180°F (FIG. 4-5, page 17).
