Re:How a Heat Pump Works
by kenmacd on Friday February 10, 2023 @12:59PM
(#34743178)
I like his videos, but I don't trust his numbers in this one. He shows a COP of ~1 when it's 10 degrees out. These are the easiest possible conditions for the HP, and where all the specs show the highest COP. His graph showing the HP is running equal to a baseboard heater seems very suspect.
[ Parent
| on HN ]
Are you thinking 10 degrees Celsius? I think all his numbers are Fahrenheit.
He's located in NB, so I assumed it was Celsius. To check I just compared them to the Environment Canada data it seems to match pretty close for NB in Celsius.
Ah, yeah. I thought I saw some "60s" and so forth on one of the graphs, but I may have read it wrong in the moment.
Re:How a Heat Pump Works
by jeffalyanak on Friday February 10, 2023 @04:08PM
(#34745859)
Edit: nevermind, thought this was still about Technology Connections.
The issue with the COP graph (9:05) is that it's comparing the mini-split system to the prior system. The mini-split doesn't have radiators in the same place as the prior system, so he runs it 1-2˚ hotter (7:50) to get the rest of the house to the same temperature. Also, the system isn't using much electricity on warm days (8:48), so the inefficient placement of the minisplit is more dramatic.
The more interesting graph is the total kWh saved per day (8:07). The colder it gets, the more energy he saves. That's because more heat needs to be pumped into the house, so a worse COP multiplied by more total heat equals more electricity savings (at least for the temperatures he's measured).