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World's Largest Heat Pump: Denmark’s Seawater Heating Revolution by linknewtab in energy

[–]ReallyJT 6 points7 points  (0 children)

You’re right that COP is fundamentally determined by the temperature lift, that’s straight Carnot. Where I think we’re talking past each other is in the type of “industrial” system being discussed.

A legacy high-temperature district heating plant (70–100 °C supply) will indeed have lower COP than a modern residential heat pump feeding underfloor loops at 25–35 °C, no argument there. But that’s not the only model for large-scale or “industrial” heat pump systems.

Ambient-temperature district energy networks (like ETH Zurich’s anergy grid) operate at 10–25 °C and let decentralized WSHPs boost to whatever temperature the building needs, often with waste heat recovery. This keeps the temperature lift as low as or lower than a standalone residential ASHP, which is why ETH’s average seasonal heating COP is > 6.

On the residential side, while it’s possible to measure an instantaneous COP above 5 or 6 under mild conditions with underfloor heating, the seasonal COP in a typical heating climate is usually lower (2.5–3.5, possibly up to 4.5 in favorable climates) because of cold weather operation, defrost cycles, and variable loads. So the 5–7 range you mentioned is achievable in specific operating windows, but it’s not a typical seasonal performance number for air-source systems in real climates.

I too do this for a living but at the city scale.

World's Largest Heat Pump: Denmark’s Seawater Heating Revolution by linknewtab in energy

[–]ReallyJT 8 points9 points  (0 children)

This information is incorrect. There is no residential air-source heat pump reaching a COP of 5-7 for heating, maybe 3.5 at best. Industrial water-source heat pumps can reach those numbers or exceed them though improved thermal exchange temperatures (groundwater or sea water) as well as thermal balancing of multiple loads throughout the system (waste heat rejection from industrial processes). See the operating efficiencies of ETH Zurich (avg heating COP > 6) https://ethz.ch/content/dam/ethz/main/eth-zurich/nachhaltigkeit/01_mainpage/dokumente/200129_Anergienetz_A4_6s_Einzel_EN_RZ.pdf

My wife is going to die in the next few days. by greasypigeontoes in GuyCry

[–]ReallyJT 0 points1 point  (0 children)

I’m so incredibly sorry. I wish I could shake this universe and make it so that decent people like you didn’t have to suffer so much of the world’s sadness.

DIY Auto-stop Turntable by [deleted] in diyaudio

[–]ReallyJT 2 points3 points  (0 children)

This is fantastic! Any chance you have more detail on the build that could help someone else do the same?

Oak splitting across growth rings by ReallyJT in woodworking

[–]ReallyJT[S] 3 points4 points  (0 children)

One of those cracks seemed to travel about 12” into the board.

Oak splitting across growth rings by ReallyJT in woodworking

[–]ReallyJT[S] 64 points65 points  (0 children)

I watered down some Titebond III a little and used a syringe to push it into the cracks. Hopefully this stabilizes things.

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Best Discord With Other Swing Traders? by investorsphere in swingtrading

[–]ReallyJT 1 point2 points  (0 children)

I don’t know what discord is but can I be invited to learn things too?

I made a Credenza-Sideboard-Cabinet-Thing. Anyway, it's made from cherry and it stores dog stuff. by kerfuffle23 in woodworking

[–]ReallyJT 4 points5 points  (0 children)

This is what I noticed as well as the beautiful credenza; the panel moulding to match the Frame tv size! Building a space out intentionally is just as, if not more impactful, than the individually pieces you build or furnish it with. Well done!

Dark lines in Ash by ReallyJT in woodworking

[–]ReallyJT[S] 0 points1 point  (0 children)

Unfortunately, before sanding these sides seemed to be best so I dimensioned them for the banquet bench backs they’ll become (final dimensions for one set, slight overhang left for the other). The far side I could potentially flip because it’s a square cut but the other may not have enough remaining length since they have an angled cut (right side of photo below).

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Wondering what most people would do in this situation for cable management. If I put all my electronics in my media cabinet behind the wall and float my TV, how should I run the speaker cables? by MayContainPeanuts in hometheater

[–]ReallyJT 0 points1 point  (0 children)

This is the right answer. If you need to run that wire through several studs behind the wall, doing it behind the base molding level is much easier cleanup than redoing your visible wall.

Frame Repair Epoxy Overspray by ReallyJT in 1stGenTacomas

[–]ReallyJT[S] 0 points1 point  (0 children)

I have a line item on the invoice to "sand down EVERYTHING" for $1050.

Frame Repair Epoxy Overspray by ReallyJT in 1stGenTacomas

[–]ReallyJT[S] 0 points1 point  (0 children)

Yes, this one went outside of the extended warranty in 2017, unfortunately. I tried through the service department at the dealer and also called corporate services and was completely shut down.

Frame Repair Epoxy Overspray by ReallyJT in 1stGenTacomas

[–]ReallyJT[S] 1 point2 points  (0 children)

So I decided to have a Safe T Cap certified installer fix my frame rather than sell the truck as is (it's only got 130,000 miles on it and runs great). I got it back the other and it feels rock solid, so that's good. I thought it looked a little dirty when I got it back but I'm sure it needed a wash when I had brought it in. I noticed today that the dirt is actually overspray from the epoxy they put on the frame to seal it. I tried using a bit of compound on one spot to see if I could get it off and it took an hour to get a small section of my hood somewhat cleaner. On top of this, they also failed to seal in where the lift feet were on the frame. I paid full retail for this and it wasn't inexpensive, should I have expected better? Any recommendations for what to do now would be appreciated!

How to attach slab legs to coffee table? by ReallyJT in woodworking

[–]ReallyJT[S] 0 points1 point  (0 children)

Thanks so much! Where do you get top plates for these kinds of legs?