PVI Industries Air Conditioner PV500 34 User Manual

INSTALLATION & MAINTENANCE MANUAL FOR  
QuickDrawâ  
SEMI-INSTANTANEOUS  
ENERGY: STEAM TO WATER  
U-TUBE SINGLE-WALL & DOUBLE-WALL HEAT EXCHANGERS  
FLOOR  
DRAIN  
FLOOR  
DRAIN  
Typical Construction  
Figure 34-1  
1.  
2.  
3.  
4.  
5.  
6.  
7.  
8.  
9.  
U-tube Heat Exchanger  
Steam Inlet **  
10.  
11.  
12.  
13.  
14.  
15.  
16.  
Potable Water Inlet  
Check Valve **  
Shutoff Valve **  
Intratank Circulator *  
Potable Water Outlet  
Tank Drain Valve  
Relief Valve  
Y-Strainer *  
Steam Pressure Gauge *  
Steam Valve  
Condensate Drain **  
Main Steam Trap *  
Thermostatic Trap  
Control Enclosure  
* Optional  
** Not supplied by PVI  
(shown with dashed lines)  
CAUTION: TEMPERATURES HIGHER THAN 125°F. INCREASE THE RISK OF SCALD INJURY!  
IMPORTANT: Clearances for servicing and inspection are 18" at top, sides and rear and a  
minimum of one tank diameter in front.  
PVI Industries, LLC · P.O. Box 7124 · Fort Worth, TX 76111  
(800) 433-5654 · www.pvi.com  
PV500-34 05/03  
1
Section 34  
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QuickDrawâ  
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.  
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.  
WARNING!  
Make sure the safety relief valve is piped to  
a proper drain per instructions. Scalding  
STEAM & CONDENSATE CONNECTIONS  
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).  
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.  
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.  
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.  
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.)  
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  
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.  
PV500-34 05/03  
Section 34  
3
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QuickDrawâ  
STEAM WITH SINGLE-WALL / DOUBLE-WALL (con't)  
STEAM VALVES  
CAUTION  
Most valve problems are caused by dirt or  
trash in the steam line. This is most likely to  
occur during installation. Teflon pipe tape,  
pipe joint compounds, metal particles and dirt  
will clog up strainers and orifices and prevent  
valve seats from closing. Clean all pipe line  
strainers at start-up and check the valves  
1. One or more two-position, on-off, electric  
valves are used to control the flow of steam.  
The valves will return to the closed position  
when power is off. This feature will prevent an  
excessive temperature buildup in the event of  
a power failure. The valve manufacturer’s  
operation and maintenance instructions are  
shipped with the unit. Refer to these  
instructions during start-up and file for future  
referencing on maintenance.  
again after  
a
few days operation as  
recommended by the valve manufacturer.  
Inspection of strainers and blowdown piping  
should be part of the normal maintenance  
routine on this equipment.  
OPTIONAL SAFETY SYSTEMS  
1. This heater may be supplied with a pressure  
changer. The system requires a manual  
reset to begin operation again. Note that  
the system does not necessarily detect a  
leak, but it prevents steam from entering the  
potable water if there is a leak.  
gradient  
monitoring  
(PGM)  
system,  
consisting of a differential pressure switch, a  
delay timer and a steam purge valve. It  
serves as a safety system to prevent the  
contamination of potable water with steam.  
The pressure switch monitors both steam  
and potable water system pressure. If the  
potable water pressure falls to a point  
slightly above the steam pressure and stays  
there for a short period of time, then the  
heater shuts down, closes the steam valve  
and opens a steam purge valve to quickly  
reduce the steam pressure in the heat ex-  
2. Another safety option is the tank purge  
system (sometimes called a double solenoid  
safety system). The tank temperature is  
monitored and if it exceeds an adjustable  
limit, the heater is shut down and a valve  
opens to dump the overheated water. This  
allows cold make-up water to enter the tank  
and quickly reduce the tank temperature.  
START-UP OPERATION  
Should an electrical power failure occur,  
steam valves will close and stop steam flow to  
the unit.  
1. After all the steam, condensate and water  
lines are installed and inspected, the steam  
supply source and the condensate receiver  
should be checked for correct operation.  
Steam supply pressure to the heater must be  
equal to or less than the supply pressure on  
the heater decal. A pressure reducing valve  
can be installed in the supply line to meet this  
requirement.  
WARNING!  
Excessive steam pressure can cause the  
steam valve(s) and condensate trap to  
malfunction and can cause the heat transfer  
rate to exceed the relief valve capacity which  
can result in an explosion causing damage,  
injury or death.  
2. Steam is directed to the heat exchanger  
through a header and steam control valves.  
The steam control valves are normally closed,  
on-off, electric valves and solenoid-operated.  
PV500-34 05/03  
Section 34  
4
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QuickDrawâ  
STEAM WITH SINGLE-WALL / DOUBLE-WALL (con't)  
START-UP PROCEDURE  
1. Fill tank with water; open relief valve to  
purge air from top of tank. Check for  
plumbing leaks.  
main steam supply valve. This will allow  
condensate that has collected in the supply  
line to drain through the trap installed in  
front of the steam valve. When the steam  
supply line is free of condensate, push  
operating switch to “on”, opening the electric  
on-off steam valves allowing steam to flow  
through the heat exchanger.  
2. Push control switch, located on the control  
box, to activate the steam valve and  
thermostats. Check steam valve for  
operation; the valve solenoid should “click”  
to open valves when operating switch is  
pushed “on”. The tank circulating pump, if  
present, should also operate. Check  
thermostat settings. The temperature  
limiting device is set at 200°F. Temperature  
setting: The operating thermostat is set at  
the factory at approximately 130°F and the  
upper operating thermostat is set at  
approximately 125°F. Adjustment may be  
made by turning the operating thermostat  
dial to the desired temperature.  
4. Open nearby hot water tap to maintain a  
flow of water through tank when starting up  
units. Observe condensate flow at the  
receiver or other collection site to verify  
satisfactory flow. Regulate flow of water  
through tank to allow steam valve to cycle  
off and on, and check operation of unit.  
3. Push the operating switch, located on the  
control box, to “off” before opening manual  
MAINTENANCE  
CAUTION  
The relief valve is a primary safety device.  
1. A preventive maintenance program should  
be established to assure a long, trouble-free  
life for the water heater.  
3. It is required for safe practice to operate the  
temperature and pressure relief valve once  
a year by lifting the lever briefly. If the valve  
does not open and close properly when  
testing, it must be replaced.  
2. Scale will normally form in the tank during  
operation and will accumulate on the bottom  
of the tank. The scale is formed from the  
natural chemicals in the water that  
precipitate out during the heating cycles.  
Some water supplies contain more of these  
chemicals than others, and the scale  
buildup will occur more rapidly. Other  
factors affecting the scale buildup are the  
amount of hot water used and the  
temperature of the water. The more hot  
water used, the more fresh water containing  
the scale-forming chemicals is brought into  
the tank. As the temperature of the water  
increases, the rate of scale deposited will be  
increased. The unit should be inspected and  
cleaned as required by local water  
conditions.  
4. The temperature limiting device and  
thermostat temperature sensors that extend  
into the water in the tank may become  
coated with scale, depending on the type of  
water in your area. This coating will affect  
accuracy of sensors and can allow water  
temperature to exceed the desired limits.  
These controls should be removed from  
tank and inspected at necessary intervals.  
Remove scale if present.  
WARNING!  
To reduce the risk of electrical shock injury  
or death, on control systems using 120 volt  
external power, be certain switch is off and  
power disconnected before work is  
performed on this heater.  
PV500-34 04/03  
5
Section 34  
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QuickDrawâ  
STEAM WITH SINGLE-WALL / DOUBLE-WALL (con't)  
TROUBLESHOOTING NOTES  
Problem:  
1. No hot water at even low flow  
a. Cause: Steam valve(s) not opening  
Solution: Check that electrical coils are energized. If not, trace wiring problem. If so, the valve  
may be faulty, the steam pressure inadequate to open the valve (< 5 psi depending on the  
valve), or the linkage (if applicable) is out of adjustment.  
b. Cause: Condensate flow is blocked  
Solution: Float-type traps will not open if the inlet steam pressure exceeds the trap rating.  
Check steam pressure against the rating stamped on the trap. Check that there are no valves or  
clogged strainers between the heat exchanger and the condensate receiver.  
c. Cause: PGM system tripped  
Solution: The pressure gradient monitoring option prevents the steam valve from opening if the  
water pressure in the tank is within 10 psi of the steam pressure. Correct water pressure  
problem.  
Problem:  
2. Heater recovery is slow or outlet temperature is below setpoint:  
a. Cause: Steam supply insufficient  
Solution: Loss of steam delivery pressure, see below.  
b. Cause: Condensate not draining  
Solution: Check that there is not excessive condensate lift. For low pressure steam, any lift at  
all may affect performance. Check the sizing of the trap. Check that the condensate receiver is  
not pressurized. Check that there is no blockage in the condensate line from the trap to the  
receiver. Unclog any strainers in the system.  
c. Cause: Condensate trap not operating  
Solution: If the condensate temperature near the heat exchanger is considerably less than the  
steam temperature, then condensate is being backed up into the heat exchanger. Check that  
the supply steam pressure does not exceed the trap pressure rating. Check the trap for  
blockage or mechanical failure. Check that the trap is sized sufficiently for the load.  
d. Cause: Heat exchanger is breached  
Solution: If excessive condensate is draining, the heat exchanger may have a leak and be  
filling with water.  
e. Cause: Heat exchanger is fouled  
Solution: Inspect the heat exchanger for excessive scaling or fouling on the water side.  
f. Cause: Abnormal operating conditions  
Solution: The water temperature has a significant effect on the efficiency of the heat  
exchanger. Check if the setpoint is higher than specified. Confirm the measured flow rate with  
meters or by volume and rate. Check that there are no other loads on the heater.  
Problem:  
3. Steam delivery pressure to heat exchanger is low or drops off:  
a. Cause: Low supply steam pressure.  
Solution: Unclog strainer. Check for blockage or restrictions in the line between the boiler and  
the water heater. Check for low boiler output or upstream blockage and make necessary  
corrections.  
PV500-34 05/03  
6
Section 34  
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STEAM WITH SINGLE-WALL / DOUBLE-WALL (con't)  
b. Cause: Steam valve(s) not fully opening  
Solution: Check steam pressure before and after steam valve. The pressure drop should not  
be more than half of the inlet pressure. Check valve for blockage. Check linkage for adjustment.  
Check modulating signal (if applicable). Check the supplied voltage to the valve coil.  
c. Cause: Piping flow restricted.  
Solution: Calculate the flow velocity and expected friction loss. If excessive, larger inlet and  
outlet piping are necessary.  
d. Cause: Main valve malfunction.  
Solution: Refer to the valve manual for instructions on main valve repair.  
e. Cause: Main valve undersized.  
Solution: Check steam pressure before and after steam valve. Check valve capacity against  
the load. If insufficient, increase trim or valve size.  
Problem:  
4. Outlet water temperature not constant.  
a. Cause: Insufficient recovery  
Solution: If the thermostat or controller is always open, then the outlet temperature will vary  
with load. See above for causes of insufficient recovery.  
b. Cause: Malfunctioning thermostat  
Solution: Measure the tank temperature near the thermostat and compare to setpoint. The  
thermostat should turn on and off within 5°F of setpoint.  
Problem:  
5. Unusual noises coming from heater.  
a. Cause: Flashing condensate  
Solution: Pinging, rattling or banging noises are usually the result of condensate flashing to  
steam. Condensate not draining properly. Check that there is not excessive condensate lift.  
Check the sizing of the trap. Check that the condensate receiver is not pressurized. Check that  
there is no blockage in the condensate line from the trap to the receiver. Unclog any strainers in  
the system.  
Problem:  
6. Heat exchanger visibly leaking.  
a. Cause: Plumbing connection loose  
Solution: Check and tighten plumbing connection.  
b. Cause: Double-wall heat exchanger tube leak  
Solution: If one of the tube walls is breached, a double-wall heat exchanger will leak at the  
joint between the tubesheets. Isolate the heater and replace the heat exchanger.  
Since PVI cannot control the use of the water heater, water conditions, or maintenance, the  
warranty on the water heater does not cover poor performance, structural failure,  
or leaking due to an excessive accumulation of scale.  
PV500-34 05/03  
7
Section 34  
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