4e
Water piping — connect tankless heater
Figure 21 Tankless heater
piping
Table 6
Tankless heater rating table
26
Part Number
550-110-290/0219
CGt
GAS-FIRED WATER BOILER — Series 2 —
Boiler Manual
Boiler
model
number
Heater
number
Intermittent draw
ratings (GPM)
Note 1
Inlet and
outlet tapping
sizes
CGt
590-921-920
2.6
3/4"
Note 1:
Gallons of water per minute heated from 40°F to 140°F
with 200°F boiler water temperature. Tested in accordance
with AHRI Testing and Rating Standard for Indirect
Tankless Water Heaters Tested with Boilers.
NSF/ANSI 372
Tankless water heaters for CGt boilers have
been tested and certified by
CSA Group
(
certificate # 2552127
).
To pipe tankless heater:
1. Size piping no smaller than tankless heater inlet and outlet.
2. The following controls (furnished by others) must be installed:
a.
Automatic mixing valve
see Figure 21. See
DANGER
above.
b. Flow regulating valve. Size according to intermittent draw of
tankless heater. See
Table
6. Follow valve manufacturer’s instruc-
tions to install.
3. Additional anti-scald devices may be installed at each hot water faucet,
bath and shower outlet.
4. In hard water areas, soften cold domestic supply water to heaters to
prevent lime build-up.
To set tankless heater low limit:
1. Adjust setpoint dial to 190°F - 200°F. The boiler high limit should be
set 20°F higher.
Studies have indicated that dangerous bacteria can form
in potable water distribution system if certain minimum
water temperatures are not maintained. Contact local health
department for more information.
These single wall heat exchangers comply with National
Standard Plumbing Code provided that:
•
Boiler water (including additives) is practically non-toxic,
having a toxicity rating or class of 1, as listed in Clinical
Toxicology of Commercial Products.
•
Boiler water pressure is limited to maximum 30 psig by
approved water relief valve.
If boiler is installed in a closet, it is
recommended to insulate the supply
piping of domestic hot water to lower
closet air temperature.
Hot Water Can Scald!
• Consumer Product Safety Commission and some states recommend
domestic hot water temperature of 130°F or less.
• When installing an
automatic mixing valve
, selection and installation must
comply with valve manufacturer’s recommendations and instructions.
• Water heated to a temperature suitable for clothes washing, dish washing
and other sanitizing needs will scaled and cause injury
• Children, elderly, infirm or physically handicapped persons are more
likely to be injured by hot water. Never leave them unattended in or near
a bathtub, shower or sink. Never allow small children to use a hot water
faucet or draw their own bath. If anyone using hot water in the building
fits this description, or if state laws or local codes require certain water
temperatures at hot water faucets, take special precautions:
• Install
automatic mixing valve
set according to those standards.
• Use lowest practical temperature setting.
• Check water temperature immediately after first heating cycle and after
any adjustment.
Protection Must Be Taken Against Excessive Temperature and Pressure!
—
Installation of a Temperature & Pressure (T&P) relief valve is required.
