LP-719 Rev. 000 Rel. 000 Date 6.25.20
19
Part 4 - Water Piping
WARNING
!
Failure to follow the instructions in this section WILL VOID the
warranty and may result in property damage, severe personal
injury, or death.
CAUTION
Dielectric unions or galvanized steel fittings must not be used in a
system with this boiler. Doing so WILL VOID the warranty. Use only
copper, brass, black iron, or stainless steel fittings.
The National Standard Plumbing Code, the National Plumbing
Code of Canada, and the Uniform Plumbing Code limit heat
transfer fluid pressure to less than the minimum working pressure
of the potable water system up to 30 PSI maximum. In addition, the
heat transfer fluid must be water or another non-toxic fluid having
a toxicity of Class 1, as listed in Clinical Toxicology of Commercial
Products, 5th Edition. Failure to follow this warning could result in
property damage, severe personal injury, or death.
A. General Plumbing Information
CAUTION
Use two wrenches when tightening water piping at boiler. Use one
wrench to prevent the boiler return or supply line from turning.
Failure to prevent piping connections from turning could cause
damage to boiler components.
The building piping system must meet or exceed the the piping
requirements in this manual.
The water connections must be installed in accordance with all local
and national plumbing codes, or any applicable standard which
prevails.
• Pipe material must be suitable to meet local codes and industry
standards.
• The pipe must be cleaned and without blemish before any
connections are made.
• The size of the DHW pipes should be 3/4” diameter, and the CH
pipes should be 1” diameter.
• Isolation (shut-off valves) should be used on both the CH and
DHW loops to ease future servicing.
• All piping should be insulated.
• If the Combi Boiler is installed with a backflow preventer in
the DHW cold water supply line, means shall be provided to
control thermal expansion. Contact the water supplier or a local
plumbing inspector on how to control this situation.
It is recommended to install a sweat shut-off valve and a union in
the return and supply piping to ease future servicing. If there is a
backflow preventer or any type of a no return valve in the system,
install an additional tee here suitable for an expansion tank.
Plumbing of this product should only be done by a qualified, licensed
plumber in accordance with all local plumbing codes. The boiler
may be connected to an indirect water heater to supply domestic
hot water. HTP offers indirect water heaters in a wide range of gallon
sizes in either stainless steel or glass-lined construction.
The boiler control module uses temperature sensors to provide
both high limit protection and modulating temperature control.
The control module may also provide low water protection by
sensing the water level in the heat exchanger. Some codes/
jurisdictions may require additional external controls.
Do not apply a torch within 12” of the boiler. If sweat connections
are used, sweat tubing to the adapter before fitting adapter to
the water connections on the boiler. Damages due to improper
installation practices ARE NOT covered by warranty.
B. 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.
C. Expansion Tank
Expansion Tank and Make-Up Water
1. Ensure that the expansion tank is designed and sized to correctly
handle boiler and system water volume and temperature.
CAUTION
Undersized expansion tanks cause system water to be lost from the
relief valve, causing make-up water to be added. Eventual boiler
failure can result due to excessive make-up water addition.
SUCH
FAILURE IS NOT COVERED BY WARRANTY.
2. The expansion tank must be located as shown in Applications, this
manual, or following recognized design methods. See expansion tank
manufacturer’s instructions for details.
3. Connect the expansion tank to the air separator only if the air
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
Always install an automatic air vent on top of the air separator to
remove residual air from the system.
Expansion tanks must be sized according to total system volume. This
includes all length of pipe, all fixtures, boilers, etc. Failure to properly
size for system expansion could result in wasted time, money, possible
property damage, serious personal injury, or death.
WARNING
!
Model
Heat Exchanger Volume (Gallons)
150
2.0
199 / 199C
2.7
Table 9 - Heat Exchanger Water Volume (To Aid in Expansion Tank Sizing)
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 an air cushion. An automatic air vent would cause air to leave
the system, resulting in improper operation of the expansion tank.
D. Piping the Boiler
NOTE:
Observe the minimum 1” clearance around all uninsulated hot
water pipes when openings around pipes are not protected by non-
combustible materials.
Connect the 3/4” DHW inlet and outlet pipes. A shut-off valve between
the city water supply and DHW inlet is recommended for ease of
service. HTP offers threaded 3/4” DHW tankless isolation valves with
a DHW pressure relief valve for ease of installation and future service.
Connect the 1 1/4” CH return and supply pipes. Isolation valves are
recommended for ease of service.
CAUTION
Boiler Models should not be operated as a direct potable hot water
heater. Only Combi Models should be used to directly heat hot water.
Use at least the MINIMUM pipe size for all appliance loop piping. This
is to avoid the possibility of inadequate flow through the appliance.
Using less than the required minimum pipe size and piping could
result in system problems, property damage, and premature
appliance failure. Such problems ARE NOT covered by product
warranty.
NOTE:
The addition of a high temperature limiting device is important
if the boiler is to be connected to a domestic hot water system.
