Installation / Operation Instruction Manual

Page 34
B RADFORD W HITE
This unit’s e󰀩ciency is higher with lower return
water temperatures. Therefore, to get the most of low
return temperature with multiple boilers, pipe as shown in
Figure 22 through Figure 28
All models and sizes can we ordered with or without a
pump. The only exception is outdoor model NTV 750 &
850.
When the pump is supplied by the manufacturer, the
boiler must be located within 15 feet (4.6m) of the supply
and return header (or the hydraulic separator).
Units MUST be piped in a primary-secondary fashion
(using either piping or a hydraulic separator) such that
the pump that is mounted on the boiler ONLY serves the
boiler. Pumps supplied by the manufacturer are sized for
a maximum of 30 feet (9.1m) of connection size piping
and the headloss of the boiler only. (See Table 12.)
If longer pipe lengths are required, the pump should
be sized for the boiler and for the piping it will serve.
Even with pumps supplied by others, the manufacturer
strongly recommends primary-secondary piping.
6.A.2 Boiler Cold Water Make-Up
1. Connect the cold water supply to the inlet
connection of an automatic ll valve.
2. Install a suitable back ow preventer between the
automatic ll valve and the cold water supply.
3. Install shut o󰀨 valves where required.
The boiler piping system of a hot water heating boiler
connected to heating coils located in air handling
appliances where they may be exposed to refrigerated
air circulation must be equipped with ow control valves
or other automatic means to prevent gravity circulation
of the boiler water during the cooling cycle.
A boiler installed above radiation level, or as required by
the authority having jurisdiction, must be provided with a
low water cuto󰀨 device either as a part of the boiler or at
the time of boiler installation.
6.A.3 Condensate Drain
BOILER PIPE SIZE, HEATER PIPE SIZE,
SIZE INCHES SIZE INCHES
150 1 150 1¼
210 1 199 1¼
285 1¼ 285 2
399 1¼ 399 2
500 1½ 500 2
600 1½ 600 2
750 2 750 2
850 2 850 2
Table 14. Water Connection Pipe Sizes
SECTION 6
WATER CONNECTIONS - Part A
Section 6 is divided into two parts. Section
6A covers Boiler units designed for hydronic
heating. Section 6B covers Heater models,
which are designed exclusively for “volume
water” domestic hot water applications. Refer
to the proper section for instructions on
installing and piping your product. Refer to
Table 9 for the connection pipe sizes required.
6.A Boiler
6.A.1 Boiler Water Piping -
NOTE: This appliance must be installed in a closed
pressure system with a minimum of 12 psi (82.7kPa)
static pressure at the boiler.
Water piping should be supported by suitable hangers or
oor stands. Do not support piping with this appliance.
Due to expansion and contraction of copper pipe,
consideration should be given to the type of hangers
used. Rigid hangers may transmit noise through the
system resulting from the piping sliding in the hangers.
It is recommended that padding be used when rigid
hangers are installed. Maintain 1” (2.5cm) clearance to
combustibles for hot water pipes.
Pipe the discharge of the relief valve (full size) to a drain
or in a manner to prevent injury in the event of pressure
relief. Install an air purger, an air vent, a diaphragm-type
expansion tank, and a hydronic ow check in the system
supply loop. Minimum ll pressure must be 12psig
(82.7kPa). Install shuto󰀨 valves where required by code.