IV. Domestic Hot Water Performance and Piping
A. Domestic hot water ratings for the Minuteman® II are based two 5 minute draws with 10 minute recovery period at 100°F average temperature rise. Refer to Table 1 for ratings.
Table 1: Domestic Hot Water Ratings
BOILER | WATER DRAW | PRESSURE DROP |
MODEL | (GPM) | (PSI) |
|
|
|
2.9 | 14 | |
|
|
|
3.1 | 16 | |
|
|
|
3.1 | 16 | |
|
|
|
3.3 | 18 | |
|
|
|
B. Drain domestic water system.
1.Shut off cold water supply at main shutoff valve.
2.Open 1 or more system faucets to relieve pressure. Open system drain valve, leaving faucets open to relieve vacuum.
3.Disconnect exiting domestic hot water heating system ( if applicable).
C. Connect hot water piping to ½" NPT outlet of heater. See Figure 7.
WARNING
Install an automatic mixing valve (tempering valve) at the tankless heater outlet to avoid risk of burns or scalding due to excessively hot water at fixtures. Adjust and maintain the mixing valve in accordance with the manufacturer's instructions.
D. Connect cold water piping to ½" NPT inlet of heater. See Figure 7.
Figure 7: Domestic Hot Water Piping
NOTICE
Domestic water temperature has the potential to exceed the desired temperature during a space heating cycle.
E. Fill domestic hot water system.
1.Open all faucets to allow air to purge from heater and piping.
2.Open domestic hot water shutoff valve (if used).
3.Open cold water inlet shutoff valve.
4.Purge air from domestic water system. Close faucets.
5.Check system for leaks. Repair as necessary.
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