Water heater provides space heating - open direct

Heating · Pulse Combustion · printed page 159 (PDF page 160)

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Open Direct Provides Space Heating

Text in the illustration

- open (water changes regularly)
- direct (potable water in heating loop) system
- not allowed in some areas
- system operates at house plumbing pressure
1. call for heat
domestic cold water
domestic hot water
mixing valve
check valve
pump on
radiant heating
water heater
2. call for domestic hot water
pump off
simplified for clarity

Generated explanation

Two schematics depict an open-direct system in which a storage water heater supplies both domestic hot water and radiant space heating using potable water at house plumbing pressure. During a call for heat, the circulating pump is on, and arrows show heated water passing through the radiant heating loop and returning to the water heater. During a call for domestic hot water, the pump is off, and cold-water arrows show incoming water flowing through the heating loop toward the tank while hot water exits toward the domestic supply. Both diagrams identify a mixing valve and a check valve at the piping connections above the heater. The annotations state that water changes regularly and that this arrangement is not allowed in some areas.

Components

storage water heater circulating pump mixing valve check valve radiant heating loop domestic cold-water piping domestic hot-water piping water heater vent

Related illustrations

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Water heater provides space heating - closed indirect

· p. 160

The schematic shows a storage water heater providing domestic hot water and space heating through a flat plate heat exchanger. A dashed line separates the closed space-heating circuit from the open domestic-water side, w