COP of 5 when running in perfect conditions (load, EWT temps, variable stage compressor, infinite heat sink/source). You might want to research how realistic constant COP of 5 really is.
Ground source heat pump owner here in the US. The original system was installed in 2007, and the loop field was designed to "best knowledge at the time". Well in the 20 years since then, NREL changed guidance on how far apart and how deep loops need to be installed. Rightly so, because our circa-2007 is "short looped", it's not sufficient for the house loads, but there is nothing we do about it other than putting on more expensive pumps, more expensive antifreeze and live with heat pump compressors dying pre-maturely because they are working at their design limits. All this makes it as expensive as traditional system (and if we tried to go net-zero with solar, the amount of solar required (because it runs so inefficiently) is larger than our roof area.
So I'm looking at a backup gas boiler to take load of the heatpump/ground loop (house has radiant heat).
And they are not quiet. 5-Ton water to water compressors are not quiet.
And the control system (HDX) and amount of expertise required to keep the thing running is a major barrier to getting low cost maintenance.
Maybe a 2026-designed system will work better and actually live up to the hype you talk about, but there are decades of poorly designed and discarded ground loop heat pumps that have "poisoned the well" if you will.
Does the ground source heat up (or cool down) over time, making it less effective? The deep ground is very well insulated, which is why after a century of operation the London Underground is 10 degrees warmer. I wonder whether GSHP users need to balance their load by (say) consuming more heating than they actually need in winter so that summer cooling remains effective.
I think there are two types of this, only have experience with 1 so far. Within a single season, absolutely. In deep winter entering water temp (EWT) is around 30degF (this is a pretty accurate measure of bulk ground temp). Typical for where I live is 50degF.
Other type is permanent change that persists year over year. Haven't lived here long enough to measure this. But if you pull more heat from the ground in the winter than you put back into it into summer (we use a water to air compressor for AC in summer), then yes, it can happen and does happen. Don't know if we are in this bucket yet.
I wonder if you could cost effectively store heat during the summer, running a system strictly to do that vs doing it as a side effect of conditioning.
Out of curiosity, has the demand stayed the same? I'm asking because you see the same with electricity grids, designed in a different time with much lower demand.
Sorry to hear this, it seems like a great system to me but you have to have the capacity right. I'm planning on getting one in the next year but the drilling will be more than we need and we opt for no glycol (yet) as that also gives us headroom
I don't think system ever met demand when commissioned (we are 3rd owners). 1st owner largely neglected the system (which I interpret as reaction to it not working well), 2nd owner had local company known for "fixing geothermal" do a lot of retrofits (new higher flow pumps, increasing diameter on plumbing within the utility room to decrease "lift/work" required of the compressors, more feedback sensors / logic boards, added backup electric water tank heating for the radiant system, switch to methanol). These fixes have seamed to limit failure modes to a smaller set of things: mainly compressors dying early.
Currently system is running 20% methanol to combat the 29degF EWT (entering water temp) in deep winter. House is in Zone 6a.
One thing I learned in researching all of this is that use of ground source over many years can move the bulk ground temp permanently. (House also has water-to-air water furnace for AC). If heat pulled from ground in winter is not sufficiently replaced by heat added during summer, can move bulk ground temp over time. (If densely packed residential ground loops ever became a thing, I think this is a real risk.). But I am not sure if we have this issue at our place, still in first year, not enough data points.
When very precision molds are made, what Noctua talks about in "multiple tuning iterations are required until the geometry, cooling, gating, and moulding parameters are perfectly stabilised" is the standard process for this type of stuff. (Gears, bottle caps, or any molds than make 8, 16, 32, 64, or 128x of the same part in one shot, require that you start with "steel safe" geometry, meaning you mold the first test parts, measure them, and then modify the mold (by cutting material AWAY, it's very hard, usually bad idea, to add steel back to a mold)).
You can do your best to determine what geometry is "steel safe", and all of this is baked upon having very good engineering understanding of what material you are molding (and using very expensive software like MoldFlow to simulate this).
Legos are made from ABS, there are decades of research and data on how ABS behaves in mold, it's relatively safe to use results from Moldflow and be pretty confident in it. Noctua is using LCP. LCP is very niche, and it sounds like they themselves are doing the research on moldability/warp/process effects. And while also being a company that produces things on timelines, the friction/side effect is that sometimes best guesses will fail and they have to start over with new molds (that's a 2 month hit usually) and months of testing. That is what they were trying so say.
I design glass-filled nylon and polycarbonate parts/assemblies with tolerances 1-5x higher than theirs. The 6-month delay they described is something I've lived through many times when we had to "cut new molds" because we couldn't salvage the first mold. (Advanced molds like these are $50k - $200k+). As a company/designer gets more experience with new materials and colorants (like their stuff with LCP), they will probably be able to hit end-goals on first try more often as they collect learnings from their failures.
Noob here. If you dont mind ive got some questions for you!
Ive recently started messing with the idea of making my own model car kits as a hobby. I understand a lot of the basics, but have never done anything like this before.
Im obviously not going to make kits in mass, but, i plan on doing injection molding using polystyrene. I do not currently have a cnc, but have been eyeing a SainSmart, though they say "can do metal under certain circumstances", but doesnt cover any of those circumstances. I also was looking at various injection machines and the price for entry is insane to me - $1000 for something that would probably burn your house down.
Anyway, to my questions..
1. Suggestions for a hobby cnc that can work aluminum? Id be willing to go as far as $2kUSD, unless theres something more that you think would serve me significantly better
2. Suggestions for a hobby injection machine that can do ~60-100g shots, that wont try to burn my house down, and doesnt cost a ton?
3. Any tips or thoughts for someone diving in to this?
4. Things i should purchase for QoL with cnc or injection molding?
5. Where does one buy materials (in hobby quantity) like aluminum block stock and polystyrene pellets?
Those are all things I've spend some time in, I'm not sure what to say. Learning curves for each one of those things are pretty dang steep. With AI you can probably speed up learning curves, but I think you will still go on many dead ends.
On the small CNC that will work with aluminum... There is a whole tradespace around how small of a feature you are trying to mill vs spindle speed vs machine stiffness & spindle runout. If you were to get something like a HASS you can sorta do it all, but when you get into the hobby stuff, you need to be very certain about what smaller set of machining limitations you will be dealing with and if they will still get you where you need to go. You need to work backwards from what actual tolerances you need to hold for the downstream thing to be able to work. (For instance, if you are making an aluminum mold, when you machine it, you will most likely be repositioning the work piece... if your machine isn't square enough so that when you flip the part on it's side or upside down, then do your next op, the part may not have been square to begin with, so now you have something that won't match the other thing you are trying to mate to.)
I build a 2'x5' 3 axis with ATC, starting from a CNCdepot concept and did my own control. I probably spend as much money on precision straight edges, levels, 90deg blocks, lapping tools, etc that were required to build a machine that could hold tolerances to 0.001", which is probably where you need to be landing to have molds that work.
I guess I am just trying to say it's a very big and ugly can of worms you are opening up.
Before buying anything, you might just want to try using firstcut/protolabs. They will machine the aluminum molds and mold the parts for you. Price per part is not going to be pretty, but it's going to be way less than spending thousands on machines that will never get you to where you want to go.
As for "desktop" molding, there is some startup now pushing their kludged together machine, maybe that is the one you are referencing. I'd stay far away from that thing. I think they were charging a couple $k for it, I feel like you need to be at 5x-10x that for anything reasonable. But at that point, the amount of power and infrastructure you need is well outside anything you'd want to put in your house or even garage. Don't really have a good answer for you here.
One thing to look at, if you are doing those model kits where like 20 parts are all in one flat sheet and you twist them to remove them, people are starting to make these on FDM 3D printers, which might be worth looking at. Now you can prototype and do production on the same machine, which at your stage, is the right place to be.
Thanks for the expert point of view. It was between "difficult polymer" and "marketing blurb". Glad it's the first and I hope anyone from Noctua reads HN and adds this small clarification.
I knew the technology itself can have tight enough tolerances that are not a concern from an engineering perspective when talking about a 0.5-0.7mm clearance, but no details about the challenges of this LCP.
Good eye! Almost like an inverted golf ball. If I remember correctly from undergrad aero, purpose of dimples on golf ball is to detach/disrupt more of any laminar flow earlier as air passes around the ball, which decreases drag. Golf balls travel way faster than a runner, but possibly still has some minor effect?
Agreed. Same or greater injection molding challenges for bottle caps, small plastic containers, things that also are in the hundreds of millions of parts annually. More challenging as they are often using polypropylene which is harder to mold due to its high anisotropy (shrinks in different rates depending on if it's flow or cross-flow direction).
I'm using Widex Allure. I only need to use one ear for now, and the low latency from the Widex was what won it, tried a couple Oticons that had a disorienting amount of lag. Also the Widex has really great high frequency transient filtering, much better than the Oticons in my experience. With a house full of screaming kids, this was also critical.
How's that different to all the time and effort spent on making television shows so that they can direct your attention to the next beer commercial, which also took lots of time and effort to make?
Printable PC/Nylon/ABS are not the same as the injection molded equivalents, you may want to research this more if that is an issue. I've printed every material under the sun trying to chase various material properties, and I usually just come back to printing in PLA due to it's excellent mechanical properties (up to a certain temp), excellent layer adhesion, and near 100% success rate. When you stray from from PLA, you will start running into warping, shrink, layer adhesion, and other issues. If you need parts in PC/Nylon/ABS, get the design dialed in in PLA (I as almost all others recommend bambulab), and then send the part to FirstCut/Protolabs to have it machined out of whatever you want.
I've found ChatGPT and Claude to be extremely helpful as guides for this sort of stuff. As long as the software has decent/good documentation for the features you are trying to create, the AI does a great job telling you how to do things. There's definitely deep end stuff that the AI doest have enough reference material for, but I find it much quicker than blinding clicking through stuff or speeding watching YouTube videos.
You can also ask it to build a study guide for you to help build foundational knowledge.
But as always, expect some hallucinations, so ask it to provide links/references.
Yes! And when you need advice on an electronic circuit you can export it in netlist format from KiCAD. This is a textbased representation of the schematic which is very understandable by LLMs
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