Domestic HOT Water Priority

1.Circulators – With space heating zones using circulators, the Single-wall Indirect should be added as an additional zone with a circulator.

2.Zone Valves – Select a valve with a low-pressure drop to assure adequate flow through the water heater.

3.Hybrid – The space heating zone can be zoned using zone valves and the Single-wall Indirect zoned with a circulator.

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.

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 the ratio of domestic hot water load to space heating load.