Install Water Piping; Domestic Water Piping - Combi Boiler - Weil-McLain WMB-155C Manual

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16 Install water piping

Domestic Water Piping – Combi Boiler
Hot Water Can Scald!
Consumer Product Safety Commission and some
states recommend domestic hot water tempera-
ture of 130°F or less.
When installing an automatic mixing valve, se-
lection 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 scald and cause injury.
Children, elderly, infirm or physically handi-
capped 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 chil-
dren 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.
If the boiler piping system is connected to heating coils
located in air handling units where there may be exposed
to refrigerated air circulation then it must be equipped
with flow control valves or other automatic means to
prevent gravity circulation of the boiler water during the
cooling cycle.
1. Size piping no smaller than flat plate heat exchanges
inlet and outlet.
2. Additional anti-scald devices may be installed at each
hot water faucet, bath and shower outlet.
3. In hard water areas, soften cold domestic supply water
to heaters to prevent scale build-up.
4. Refer to Figure 42, below for maximum and minimum
domestic water pressure rating for our units, on the
domestic pipes (Combi only).
5. Install (field supplied) domestic water pressure relief
valve with a maximum pressure rating of 130 pounds.
Figure 42
DHW
34
M -
ALL OUNT GAS FIRED WATER BOILER
Minimum Maximum
130
— C
OMBI
Use two wrenches when tightening water piping at
boiler, using one of the wrenches to prevent the boiler
interior piping from turning (wrench on both sides, here
and inside boiler). Failure to support the boiler piping
connections to prevent them from turning could cause
damage to boiler components.
Figure 43
6. Combi Boiler: Domestic water inlet connection showing filter
screen to protect paddle flow switch from sand and other debris.
Pipe in a "union" fitting below this adapter to service
this filter screen.
tic heating water ) must be used to regulate the water temperature
leaving the plate heat exchanger. NOTE: the valve must be set
to supply a domestic water temperature of not more than 120
degrees F. It is the responsibility of the installer to set the valve
and remove the dial.
the entrance of the DHW connection to protect the DHW flow
switch. Failure to install the DHW water filter from dirt and debris
will cause it to malfunction.
Check Valve- A check valve must be field provided
and installed on the outlet of the mixing valve to
prevent expansion devices downstream from back
flowing when the water pressure drops during cold
water draws. Failure to prevent the backflow will
cause water to flow through the flow switch, activat-
ing it, when the cold water draw has ended and the
water pressure increases.
the inlet and outlet of the DHW connections so that the DHW
heat exchanger can be flushed and cleaned from possible build-up
caused by dirty or hard water, which is a maintenance require-
ment.
the plate DHW heat exchanger and other components in the do-
mestic hot water system, water with hardness higher than 50 ppm
Calcium Carbonate must be treated with a "Water Softener" prior
Boiler Manual
Part number 550-100-305/1016
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