VOLTMAX ELECTRIC BOILER Installation and Operation Manual
(
Revised August 2017)
, Page
12.
valves, valves or valves shall be installed on the
pipe. The installation of the safety valves is
governed by the local code.
3.4.4 SYSTEM PRESSURE CONTROL
AND EXPANSION TANK
Pressure control devices within the system
ensure that each component operates within
minimum and maximum allowable pressures and
maintain minimum pressure for all normal
operating temperatures. They also allow air
bleeding, prevent cavitation at the pump inlet and
prevent water from boiling within the system; all
this is accomplished with minimal addition of new
water.
The increase in boiler water volume resulting
from higher temperature is stored in the
expansion tank during periods of high operating
temperature and is returned to the system when
the temperature decreases.
The expansion tank must be able to store the
required volume of boiler water during maximum
design operating temperature without exceeding
the maximum allowable operating pressure, and
to maintain the required minimum pressure when
the system is cold. Contact your installing
contractor, plumbing supply house, or local
plumbing inspector for assistance. The point
where the expansion tank is connected should be
carefully selected to avoid the possibility that
normal operation of automatic check or manual
valves will isolate the tank from a hot boiler or
any part of the system.
The expansion tank should preferably be located
on the suction or intake side of the pump.
3.4.5 WATER PRESSURE MAKEUP
REGULATOR
Make-up systems must be employed as required
by codes. An automatic fill valve (automatic
pressure regulator) must be used with a backflow
preventer as required, to maintain minimum
system pressure by supplying water to make up
for leakage.
A minimum pressure of 5psi (34kPa) must be
maintained at all times.
A backflow prevention device that complies with
local standards must be installed upstream of the
pressure regulator.
3.4.6 AIR BLEEDER
The air contained in the heated water must be
removed from the system to allow the proper
functioning of the heating system and the boiler.
Installation of manual or automatic air vents is
required to eliminate all air from the boiler and the
heating distribution system.
The main air eliminator must be installed near the
outlet of the boiler on the highest point of the
main supply piping. It is imperative to ensure that
all air possibly located in the boiler be eliminated
at all time.
Regularly purge air from the pipes and beware
that the heated water does not cause injury or
damage.
If the boiler is located at a location higher than
the heat distribution system such as a heated
floor, an automatic air eliminator should be
installed close to the boiler outlet.
3.4.7 CIRCULATING PUMP
The pump capacity required is determined in
relation to the capacity of the boiler installed and
the type of heating distribution system on which it
will be connected.
They are generally designed for an operation at a
differential of temperature (Delta T0) of 10 to 20F
between the supplies and return temperature to
the boiler.
Use the following equation to determine the
required water flow.
Pump flow rate = Boiler power ÷ Delta T ÷ 500
Pump flow rate is expressed in US gallons
per minute or GPM.
The Boiler output (in net BTU per hour) is the
maximum amount of heat to be transferred
through the heating loop to meet the heating
load.
Delta T: The boiler water temperature drop
For example, an electric boiler rated at 180KW
has an output capacity of 614 160 BTU per hour.
The system is designed for a temperature drop of
20°F.
Required pump flow rate = 614,160
20
500 =
61,4 GPM