Tankless Heaters; Hot Water Precautions; Piping Tankless Heaters - Weil-McLain 4 Series Manual

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Tankless Heaters

1

Hot Water Precautions

DANGER
!
Hot water can scald! Water heated to a temperature
suitable for clothes washing, dish washing, and
other sanitizing needs will scald and cause injury
2
(Figure 21). If anyone using hot water in the
building are children, elderly, infirm or physically
handicapped persons, or if state laws or local codes
require certain water temperatures at hot water
faucets, take special precautions as listed below.
3
The 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
4
Special precautions:
• Install an automatic mixing valve set according to
the standards above
• Use the lowest practical temperature setting
• Check the water temperature immediately
after the first heating cycle, and again after any
5
adjustment is made

Piping Tankless Heaters

1 Size piping no smaller than heater inlet and outlet
2 Automatic mixing valve must be installed See
6
Figure 18 Follow the manufacturer's instructions
3 Install and size flow regulating valves according
to continuous draw of the heater See Table 12
Follow manufacturer's instructions to install
4 Operating control with small adjustable differential
scale is recommended; install in the temperature
control tapping in the heater plate
7
5 Multiple tankless heaters (see Figure 22):
a Use a cold water supply header with individual
risers to each heater
b Use a hot water outlet header with individual
risers to each heater
c Size headers by increasing one pipe size for
8
each additional heater
d Do not pipe multiple heaters in series
6 In hard water areas, soften cold domestic water
supply to heaters to prevent lime build-up
28
sTeam series
94
Figure 17 Hot water danger
220220
Figure 18 Tankless heater piping
T o a u
Table 8 Tankless heater ratings
Intermittent
Heater
Number
(GPM)
590-921-910
*Based on continuous draw with no recovery period
**GPM is based on 40-140°F DHW with boiler water at 200°F
NSF/ANSI 372
boiler manual
4
D A N G E R
HOT
BURN
g
d p i p i n
l v e a n
i n g v a
i c m i x
t o m a t
c o l d
F r o m
s u p p l y a t e
A l t e r n
w a t e r
Continuous
Draw* Draw*
(GPM)**
9 11
Tankless water heaters for the 94 boilers
have been tested and certified by
CSA Group (certificate # 2552127).
550-100-157/0523
a t e
A l t e r n
230053
Inlet and
Outlet
Tappings
3/4"