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GAS-FIRED BOILER Boiler Manual
PART 5: BOILER PIPING (CONTINUED)
B. GENERAL PIPING INFORMATION
C. SEPARATE LOW WATER CUTOFF
A low water cutoff may be required by state
local code or some insurance companies. Check
code requirements before installation of the
Munchkin Boiler. It is also required that a low
water cutoff be used if the boiler is installed
above the piping level.
If required:
• Use a low water cutoff designed for
hydronic installations that is an electrode
probe type
• Install in a tee on the supply piping above
the boiler
• Follow low water cutoff manufacturer’s
instructions
D. BACKFLOW PREVENTER
Use a backflow preventer specifically designed
for hydronic boiler installations. This valve
should be installed on the cold water fill supply
line per local codes. (See piping details at the
end of this section.)
E. SYSTEM WATER PIPING METHODS
Expansion tank and make-up water
1. Ensure expansion tank size will handle boiler
and system water volume and temperature.
Allow 3 gallons for boiler and its piping and
4 gallons for the 399.
2. Expansion tank must be located as shown in
Boiler Piping Part 5, or following recognized
design methods. See tank manufacturer’s
instructions for details.
3. Connect the expansion tank to the air
separator only if the separator is on the
suction side of the circulator. Always install
the system fill connection at the same point
as the expansion tank connection to the
system.
4. Most chilled water systems are piped using a
closed type expansion tank.
Diaphragm (or bladder) expansion tank
1. Always install an automatic air vent on top of
the air separator to remove residual air from
the system.
F. CIRCULATORS
Sizing space heat system piping
1. See Piping Details in this manual Part 5. In all
CAUTION
DO NOT install automatic air vents on closed-
type expansion tank systems. Air must remain
in the system and return to the tank to provide
its air cushion. An automatic air vent would
cause air to leave system, resulting in water-
logging the expansion tank.
CAUTION
DO NOT use the boiler circulator in any location
other than the ones shown in this manual. The
boiler circulator is selected to ensure adequate
flow through the Munchkin Boiler. Failure to
comply could result in unreliable performance
and nuisance shut downs from insufficient flow.
CAUTION
All piping methods shown in this manual use
primary/secondary connection to the boiler loop.
This is to avoid the possibility of noise or actuator
problems in zone valves because of the high-head
boiler circulator. For other piping methods, consult
your local Heat Transfer Products representative
or refer to separate Munchkin Boiler piping details
in this manual (Part 5).
CAUTION
Undersized expansion tanks cause system
water to be lost from relief valve and makeup
water to be added through fill valve. Eventual
boiler failure can result due to excessive make-
up water addition.
NOTICE
The Munchkin Boiler control module uses
temperature sensors to provide both high limit
protection and modulating temperature control.
The control module also provides low water
protection by sensing the water pressure of the
heat exchanger. Some codes/jurisdictions may
require additional external controls for high
limit and/or low water cutoff protection.