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To determine the approximate reduction in output from the tank use the following formula: For example, what would the first hour rating be if a model AL53A were installed with a boiler having a DOE heating capacity of 120,000 BTU/h? Increasing the boiler DOE heating capacity above the values listed in Table 3 will not increase the rating of the water heater. 3. Circulator Sizing - Refer to Table 3 for the minimum flow rate through the water heater coil and the corresponding pressure drop through the coil. Calculate the pressure drop of all straight pipe and fittings on the supply and return of the water heater at the minimum flow rate. Add the piping/ fitting pressure drop to the pressure drop through the water heater coil. 5 Select a circulator which will provide at least the minimum flow rate at combined pressure drop. B. System Zone Control The AllianceTM water heater must be installed as a zone separate from the space heating system. The domestic hot water zone's piping and circulator must be sized for a minimum flow rate with all zones in use and a maximum flow rate with only the water heater in use. For this reason, the preferred method of zone control is with circulators. 1. Circulators - With space heating zones using circulators, the Alliance™ should be added as an additional zone with a circulator. 2. Zone Valves -Select a valve with low pressure drop to assure adequate flow through the water heater. 3. Hybrid -The space heating zone can be zoned using zone valves and Alliance™ zoned with a circulator. Refer to Figures 3 and 5. C. Domestic Hot Water Priority Two options are available, Priority and Non-Priority. 1. Priority Demand for space heating is interrupted or postponed until the domestic hot water demand is satisfied. This option provides maximum delivery of domestic hot water. Priority is recommended when: a. Boiler net output is 100,000 Btu per hour or less, or b. When boiler output required to satisfy domestic hot water demand is at least 50% of the boiler output required to satisfy space heating demand, or c. When an interruption in space heating can be tolerated during a long domestic hot water draw. The delay in space heating may not be noticed due to the fast recovery time of the AllianceTM water heater. Certain water heater system malfunctions (such as domestic hot water zone circulator failure) could delay space heating indefinitely. When zoning with zone valves, priority can be provided with a three-way valve. Carefully size the valve for proper flow to all zones. 2. Non-Priority Boiler output is divided between space heating and domestic hot water heating. Delivery of domestic hot water can be reduced during simultaneous space and domestic hot water heating operations, depending on such factors as boiler output, boiler over sizing, number of space heating zones calling for heat and ratio of domestic hot water load to space heating load. D. Component Location 1. Alliance™ Location When such a location cannot be avoided, a suitable drain pan must be installed under the water heater. The drain pan must be connected to a drain. Adequate clearance from combustible materials and for service must be provided. The AllianceTM is design certified for installation on combustible flooring. The Alliance™ may be installed in a closet or alcove. 2. Boiler Location - Locate the boiler as close to the Alliance™ as practical. 3. Fixture Locations -For fastest delivery of hot water, place AllianceTM close to points of use. E. Additional Recommended Components 1. Shut-off Valves - Allows isolation of water heater from domestic water system and/or boiler system during service. 2. Unions - Allows water heater movement during service if adequate clearance cannot be provided. 3. Vacuum Breaker -Protects water heater's tank from possible collapse if a hot tank is allowed to 6 cool to room temperature, or if tank is drained without opening a hot water faucet. A Watts® Model No. N36 is an appropriate vacuum relief valve. 4. Thermal Expansion Tank If water heater is installed in a closed water supply system, such as one having a back-flow preventer in the cold water line, provide thermal expansion control. Contact the water supplier or local plumbing inspector for additional information. An Amtrol Model ST-12 is an appropriate diaphragm style thermal expansion tank for most installations. F. Removal of Existing Domestic Water Heating System 1. External Tankless Heater - Disconnect from boiler piping and domestic water system. 2. Tankless and Storage Heaters - Disconnect from domestic water system. Heater does not need to be removed from boiler. If left in place, do not plug inlet and outlet tappings. G. Water Quality Improper water quality will reduce the expected life of the Alliance™ water heater. Hard water, sediment, high or low water Ph, and high levels of chlorides in the domestic water should be avoided. Sediment and hard water will coat the water heater coil surfaces and reduce the rating of the wate...

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