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What’s your ASHP delta T?

Air Source Heat Pumps (ASHPs)

Last Post by Gary 2 years ago

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TheBinMan

(@thebinman)

Eminent Member Member

Joined: 2 years ago

Posts: 18

Topic starter 13/12/2024 12:06 am [#1940]

Just wondering what delta T folk use with their ASHP?

Did increasing it or decreasing it solve any issues or is it all about efficiency?

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AllyFish

(@allyfish)

Prominent Member Contributor

Joined: 4 years ago

Posts: 520

13/12/2024 8:58 am

Around 5.5degK at design output. Narrows to about 2.4degK on WC low load. Constant flow system so variable deltaT.

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cathodeRay

(@cathoderay)

Famed Member Moderator

Joined: 4 years ago

Posts: 2950

13/12/2024 2:04 pm

This is of particular interest to me at the moment, as I am trying to work out how my Midea heat pump controls (modulates) its output in response to changing OATs, not whether it uses weather compeensation (it does), but how it implements it in running parameters including the LWT/RWT delta t. The actual LWT/RWT delta t is complicated by the fact that my heat pump almost always (slow) cycles, making the delta t change all the time. However, as it happens, I calculated the mean delta t earlier today for two periods when the OAT was relatively stable over 24 hours, the first mean OAT at 11.40 degrees, the second mean OAT at 6.37 degrees, and the mean delta t values for the two periods were 2.24 and 3.52 degrees.

Neither I nor others who have looked have managed to find a setting in the Midea controller that allows the delta t to be set externally. It appears to come from the heat pumps internal control systems.

Midea 14kW (for now...) ASHP heating both building and DHW

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