VOLTMAX ELECTRIC BOILER Installation and Operation Manual
(
Revised June 2017)
, Page
12.
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.
3.4.1.5 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.
3.4.1.6 Air bleeder
The air contained in the heated water must be
removed from the system to prevent corrosion
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.
3.4.1.7 Circulating pump
The pump can be located either just upstream or
just downstream from the boiler. On installation
where the operating pressure is high, the
preferred location of the circulator pump is
upstream of the boiler in such a way as to lower
the pressure on the boiler when the pump will be
in operation.
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 supply 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
For example, an 180kW electric boiler has a
power of 614,160 BTU/h. The system is designed
for a drop-in temperature (Delta T) of 20°F.
Flow required = 614,160
¸
20
¸
500 = 61.4 GPM
The following table lists the required pump flow
rate in relation to the boiler capacity and Delta T.