PVI Industries U-TUBE SINGLE-WALL PV500-34 - Manual (Page 3)

QuickDraw 
PV500-34 05/03 Section 34 3
STEAM WITH SINGLE-WALL / DOUBLE-WALL (con't)
RELIEF VALVE PIPING
The water heater is supplied with a pressure
and temperature relief valve, sized in
accordance with ASME requirements. Each
relief valve should be piped to a suitable floor
drain. No reducing coupling or other restriction
can be installed in the discharge line. It is
strongly recommended that this valve should be
manually operated at least once a year.
WARNING!
Make sure the safety relief valve is piped to
a proper drain per instructions. Scalding
injury and/or water damage can occur from
either the manual lifting of the lever or the
normal operation of the valve if it is not
piped to a proper drain. Insure that the
safety relief valve piping is of the proper
material and rating for the temperature and
pressure of the system and that it is secured
to prevent possible injury. If valve fails to
flow water or reseat, consult the factory. The
relief valve is a primary safety device.
STEAM & CONDENSATE CONNECTIONS
1. The condensate trap controls the discharge of
condensate based on the load on the heat
exchanger, thus preventing the discharge of
live steam through the unit. Appropriately
sized traps are available from your PVI
representative. The steam trap must have a
pressure rating equal or more than the
maximum steam pressure supplied to the
water heater. The trap must also be sized
according to the steam flow shown on the
heater decal.
2. Connect the steam supply to the steam inlet
fitting on the unit as shown in Figure 34-1. A
Y-strainer (100 mesh recommended) must be
installed ahead of and near the unit to prevent
particles of scale and other solids from
damaging the seats of the steam valve. It is
good practice to install a blowdown valve on
the Y-strainer piped to a suitable location that
can be opened at intervals to clean the
strainer screen. A condensate trap may be
located upstream of the steam valve. This trap
will drain the condensate that collects in the
piping and must be plumbed to a suitable
drain or the condensate receiver plumbing.
3. Connect condensate trap inlet at or below the
outlet of the heat exchanger. The ability to lift
condensate via steam pressure cannot be
assured on Quickdraw products due to the
possible use of a modulating steam valve or
multiple solenoid steam control system. The
recommended methods of condensate
distribution are:
a. Plumb to a condensate receiver and
pump or vacuum return to the
condensate return header.
b. Plumb to a pneumatic/electric actuated
condensate pump trap for return to the
condensate return header.
c. Drain to atmosphere – (would require
constant make-up of boiler water).
Inadequate drainage of condensate can
adversely affect heat transfer and limit the
performance of the water heater. Please
note, damage to the water heater attributed
to poor condensate drainage is not covered
in the product warranty.
4. On the Quickdraw semi-instantaneous steam
heater, the 3/4" thermostatic trap must be
plumbed in parallel with the main steam trap
for optimal operation of the heater. It speeds
the removal of air from the heat exchanger
when the steam valve opens. It also serves
the second purpose of a vacuum breaker to
protect the heat exchanger and allow proper
drainage of condensate. (See Figure 34-1.)
5. Locate the thermostatic trap in a tee six
inches above the main condensate line
between the heat exchanger and the main
trap. Plumb its outlet to a point downstream of
the main trap.