39
110331-03 - 1/22
PHTM II
Combi Installation, Operating & Service Instructions
11
Domestic Water Piping
NOTICE:
DHW feature on this boiler is designed
to only heat potable water (i.e. water from a well
or water utility that is suitable for drinking) having
following characteristics:
•
Hardness less than 12 grains/gallons
•
pH between 6 and 8
•
Chlorides less than 80 PPM
Use of water not having these characteristics
could result in premature failure of DHW handling
components in this boiler and is not covered
under warranty. If there is reason to believe water
is contaminated in any way, discontinue use
of domestic hot water and contact a qualified,
licensed water treatment professional.
DANGER
Scald Hazard.
• Under certain conditions this boiler
can deliver domestic hot water (DHW) at
temperatures in excess of DHW set point on
boiler control. A field supplied ASSE 1017 or
ASSE 1070 certified tempering valve is therefore
REQUIRED
as part of this boiler's installation.
• Select and install tempering valve in
accordance with valve manufacturer's
instructions and applicable local codes. In
absence of such codes follow Uniform Plumbing
Code (IAPMO/UPC-1). Also note additional
tempering valves may be required at fixtures
themselves.
!
Combi connections are G1/2". Adapters to 3/4" sweat
connection are provided in parts carton (Figure 11-1).
DHW components in this system and their functions are
as follows:
1. ASSE 1070 or ASSE 1017 listed tempering
valve (required)
Low draw rates and transitions from heating to DHW
are two examples of conditions that can cause
temperature of water leaving boiler to significantly
exceed DHW set point. A tempering valve is
required to minimize spikes in DHW temperature.
Select and install in accordance with valve
manufacturer's instructions and applicable codes.
2. Flow limiter
If DHW draw rate is in excess of rating in Table
3-1, temperature of hot water may be too low for
comfortable use. Internal, 6 GPM (23 L/min), flow
limiter is factory installed, but an additional flow
limiter may be required. Select one having a flow
rating approximately equal to that shown in Table 3-1
at desired temperature rise.
3. DHW pressure relief valve
Limits pressure in DHW piping. Use a valve
designed for DHW service such as Watts #3L
or #53L. Select a valve with a pressure setting
less than or equal to 145 psig (1,000 kPa). Pipe
discharge to safe location using same size as
discharge connection to valve.
4. Drain valve
Permits plate heat exchanger to be periodically
back flushed to remove sediment.
5. Globe or ball valves
Used to isolate DHW piping during back flushing
and other servicing. In addition, valve may be used
to limit DHW flow if necessary.
6. Expansion tank
If back flow preventer or check valve is installed
upstream of cold connection, thermal expansion
tank will prevent build-up of pressure in DHW piping.
Use an expansion tank designed for potable water
service.
7. Water filter (highly recommended)
Install Aqua Pure AP430SS or equivalent on potable
cold water supply to prevent scale.
8. Buffer tank (Optional)
When recirculation line is installed as shown in Figure
11-3, a small (2-6 gal) potable water storage tank
may be installed as shown. Reduces burner cycling
during very small DHW demands and also helps
minimize temperature fluctuations. An unpowered
storage electric water heater is ideal for this
application.
Gasket
Gasket
DHW Connector
(Fits 3/4" Female Socket Elbow)
Figure 11-1: DHW Connections
CAUTION
Component Damage.
•
Internal components near Hot and Cold
connections can be damaged by excessive
heat during soldering. Use precautions to limit
heat exposure.
• Failure to do so could cause internal leaks
resulting in damage to boiler.
!
NOTICE:
Elbows pointed toward back of boiler
are recommended to start DHW piping.
