Element: Heat Interface Units

00:05
This is the Heat Interface Unit. Across the top, you have the isolation valve for the secondary flow, secondary return, primary flow, primary return, domestic hot water, domestic cold water inlet, and domestic cold water outlet. Following down the secondary return, there is the

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strainer, vessel connection, and pump. This leads down to the plate heat exchanger heating secondary inlet, and here you’ll see the plate heat exchanger heating secondary outlet, a temperature sensor probe, and the pressure relief valve. Here is the secondary return pipe with a port

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for the filling loop. Returning to the top of the unit and following the primary flow inlet down, there is the primary strainer, trickle bypass, the connection for the differential pressure control valve, the occupancy solenoid, and following the pipe down you’ll then come

01:20
to the tee off to the heating zone valve, into the plate heat exchanger heating primary inlet, and the other way tees off to the hot water primary Inlet. At the top of the plate heat exchanger you have the heating primary outlet, and the thermostatic valve teeing off to the

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return. To the other side at the top of the hot-water plate heat exchanger, you have the outlet, through the proportional valve to the primary return. This feeds up through the differential pressure control valve, the connection for where the heat exchanger sits and the trickle

02:06
bypass connection to return to the system. Here you have the cold water inlet, the strainer to protect the system, and the water meter. Coming down to the tee and back out, then to the domestic cold water outlet. This is the bypass for your filling loop, and the connection through the back down to the

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proportional valve and up to the hot water plate heat exchanger cold water inlet. Moving down the hot water plate heat exchanger at the bottom is the secondary hot water outlet, going up to the thermostatic mixer, and then up to the hot water supply, and here is a flow

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switch to prioritise hot water. This is the pressure vessel and the vessel connection.