SYSTEM INSTALLATION
GENERAL
If the system is to be filled with water for testing or other purposes during cold weather and before actual operation, care must be taken to prevent a down draft entering the boiler or freezing air from contacting the system. Failure to do so may cause the water in the system to freeze with resulting damage to the system. Damage due to freezing is not covered by the warranty.
Good practice requires that all piping, etc., be properly supported.
The boilers described in this manual may be used for space (hydronic) heating or for the heating of potable water. If the heater is to be used for hydronic space heating, follow the instructions on pages
HYDRONIC INSTALLATION
The following is a brief description of the equipment required for installations noted in this manual. All installations must comply with local codes (see figure 10).
Table 12: INSTALLATION ITEMS
NO. | SUGGESTED ITEMS FOR INSTALLATION | |
1. | PAIR OF SHORT PIPE NIPPLES, PAIR OF BOILER | |
| LOOP TEES AND BALL VALVE BETWEEN SYSTEM | |
| SUPPLY AND RETURN - ONE SET PER EACH BOILER | |
2. | BOILER PIPE LOOP (See Sizing Data Table 4.) | |
3. | BOILER CIRCULATING PUMP (See Sizing Data Table 4.) | |
4. | THERMOMETER | |
5. | PRESSURE GAUGE | |
6. | LOW WATER CUTOFF (If Required By Local Code.) | |
7. | SAFETY FLOW SWITCH | |
8. | RELIEF VALVE | |
9. | BOILER INLET - OUTLET | |
10. | SYSTEM SUPPLY TEMPERATURE THERMOMETER | |
11. | DRAIN or |
|
WATER SUPPLY LINE
These boilers can be used ONLY in a forced circulation hot water heating system. The pump must be interlocked with the boiler to prevent boiler operation without water circulation. See maximum and minimum flow rate information. Since most forced circulation systems will be of the closed type, install the water supply line as shown on piping diagram, figure 10. Severe damage will occur if the boiler is operated without proper water flow circulation.
Fast filling of large pipe, old radiator installations (where high pressures are not available) requires bypassing of the pressure reducing valve. Generally, pressure purging is not possible with a well pump system. High point air venting is essential. For details, refer to OPERATION section of this manual on page 22.
If the system is of the open type, a pressure reducing valve will not be required as the water supply to the system will be controlled by a manually operated valve. An overhead surge tank is required. A MINIMUM PRESSURE OF 15 PSI (100 kPa) MUST BE MAINTAINED ON THE BOILER AT ALL TIMES to avoid potential damage to the boiler that may not be covered by the warranty.
CONVENTIONAL SPACE HEATING INSTALLATION
Modern fin type boilers are exceptionally fast heating units. The low water volumes in relation to firing rates require special attention to water flow rates for smooth, efficient operation. These considerations for the A. O. Smith copper heat exchanger boilers are covered below.
Refer to table 4 showing flow rate vs. pressure drop and temperature rise.
Figure 10 shows a typical installation of the boiler.
A system with several flow controlled zones, or with a 3-way mixing valve system could present a flow rate to the boiler of less than required for a maximum of 50°F (28°C) temperature rise. Design system with compensating bypasses to the boiler.
A system bypass should be installed as shown in figure 10 to prevent boiler circulation starvation when the system zones call for reduced flow.
This bypass may also be used with multiple boilers manifolded for reverse-return flow. The system bypass would be installed from boiler outlet to suction side of pump.
The boiler piping system of a hot water heating boiler connected to heating coils located in air handling units where they may be exposed to circulating refrigerated air, must be equipped with flow control valves or other automatic means to prevent gravity circulation of the boiler water during the cooling cycle. It is highly recommended that the piping be insulated.
INSTALLATION AS BOILER REPLACEMENT
Installation as boiler replacement on an old system with large water volume may result in condensation within the boiler on cold starts. This condensing of water vapor in the combustion area can be prevented if a portion of the system water flow is diverted past the boiler to cause an increase in boiler temperature rise.
BYPASS BALANCING
With systems where water temperature can be expected to drop appreciably due to long standby periods, or heavy draw down, a bypass pipe of at least 1" size with a balancing cock should be installed between the boiler inlet and outlet (see figure 10). When the system first starts, the valve should be slowly opened until the condensing ceases. This adjustment remains at a permanent setting to establish required temperature rise across the boiler.
AIR SEPARATOR
An air separator as shown in the piping diagram is reccommended especially for modern commercial hydronic systems.
VENT VALVES
It is recommended that automatic, loose key or screwdriver type vent valves be installed at each convector or radiator.
SYSTEM HEADERS
Split systems with individual supply and return lines from the boiler room should normally have this piping connected to supply and return manifold headers near the boiler. To achieve good water distribution with minimum pressure drop for several circuits, manifolds should be larger than system loops.
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