location of tank sensor for solar DHW
With an external glycol to water heat exchanger, where would be the best location (top, middle bottom) to place the tank sensor so that the controller would turn the system on/off when the differential set points are reached? Don't want it to turn off too soon (top ?) and shorten the cycle but putting it at the bottom might read cold temperatures and start dumping the heat back out to the panels. TIA Mark S
Bottom
If the system is piped correctly, then the coldest water in the tank (at the bottom) is sent to the collector heat exchanger. That's also where the sensor should be.
Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
depends
it depends where the tappings are that send DHW to the external heat exchanger. Usually that is close to the bottom of the tank somewhere. You'd like to measure essentially that water temperature since that is what you'll be heating.
~Fortunat
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