NO. SUGGESTED ITEMS FOR INSTALLATION
Short pipe nipple and pair of boiler loop tees in piping
1between system supply and return. One set per each group of boilers.
2Boiler pipe loop. See piping sizing data.
3Boiler circulator. See pump sizing data.
4Thermometer.
5Theraltimeter.
6Plug cock to control flow rate.
7Safety flow switches. For interlock with other systems or instead of low water cutoff.
8Relief valve.
With one
With a group of
9boiler, the sensing element as above. For additional boilers, install a 2nd limit control if required by local codes. With any
required by local code.
BOILER INLET - OUTLET SIZES
10
10
MINIMUM BRANCH SIZES TO BOILERS
11 | per pump) 2" | |
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| |
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11 | per pump) 2" |
Flow control valve. Required only if flow rate of system
12primary is excessive for size of boiler branch tees or if chilled water main is above boilers.
13System supply temperature thermometer.
14Boiler headers for three (3) boilers can be larger than pipe loop, if desired, to aid in balancing.
The system flow rate is selected to give the desired system temperature drop - depending on the design criteria.
The boiler generator flow rates, on the other hand, should be selected to give the temperature rise through the generator that is both economical and offers the best generator efficiency.
The boiler temperature rise is normally between 100C and 200C (200F and 400F). The system temperature that will be introduced to the boiler (inlet temperature) plus the selected boiler temperature rise selected from PUMP AND PIPE SIZING DATA should not exceed the high limit control setting of 1150C (2400F).
There should be a relation of the minimum system load to the size boiler selected as the first firing or base boiler. This will stabilize operation during minimum load periods.
B.Commercial Boiler Replacements
Application of
Figure 12 shows a line drawing of how the system headers should be connected to the pipe loop installed with the replacement boiler(s).
SCHEMATIC OF THE LINEAR-TEMP® SYSTEM
FIGURE 12.
Supply and return headers of the old system should be connected to the boiler loop with a pair of tees set close together. The boiler loop pump and the boiler(s) should be wired to operate only when any of the system pumps are in operation. The number of zone pumps that may be in operation at any particular time will take their required flow rate out from the first tee in the boiler piping. This water will be circulated through the proper branches from the supply header to the zones calling for heat. The water will be brought back to the return header and then into the second tee in the boiler pipe loop. There will be no conflict between the boiler pump and the zone pumps when the two tees in the boiler loop are placed close together.
Normal use of flow control valves is required to prevent cross circulation of zones as with any multiple pump system. Flow control is not required on boiler circuit.
Attention should be given to balancing gas inputs and water flow rates. Large systems with multiple boilers should include main water temperature control (with or without outdoor reset) to stage the boilers on and off in relation to the load on the system.
3. WATER SUPPLY LINE
These boilers can be used ONLY in a forced circulation hot water heating system. Since most forced circulation systems will be of the closed type, install the water supply line as shown on piping diagrams, Figure 7 to 11 on pages 14 and 18.
Fast filling of large pipe, old radiator installations and pressure purging of series loop systems (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.
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.
4. EXPANSION TANK
CAUTION
A closed system will exist if a check valve (without bypass), pressure reducing valve (without bypass), or a water meter (without bypass) is installed in the cold water line between the water heater and street main (or well).
Excessive pressure may develop causing premature tank failure or intermittent relief valve operation. This is not a warranty failure. An expansion tank or a similar device may be required in the inlet supply line between the appliance and the meter or valve to compensate for the thermal expansion of water under supply pressure, see Figure 7 on page 14.
An air separator as shown in the piping diagrams is recommended especially for modern commercial hydronic systems.
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