you could do that as well but then it would put the maximum stress possible on the compressor. With that bing said I think scroll compressors can take a bit of abuse and would still probably last a while, however by using the programable t-state would allow you to take some of the load off by setting a temp a bit above the lowest achievable temp. your idea would be great to do in order to find the lowest achievable temp of what ever brand freeezer you have and if you find out that it won’t go below -20F maybe say its not worth it, but if you have one like mine that can hit -40F and can get there somewhat easily, it makes a lot of sense to set the temp to -15 to -20 for regular use storing frozen materials and bump it even lower when chilling packed columns the day before running like I do. I have found it to work great like this and have had mine running for almost two years without problems so far. That includes a period where my probe did fall out of the freezer causing it to stay on for an entire week straight, and she is still running strong.
Love this stuff. Ive got an inkbird sitting around from a different project i should re-purpose.
Ive got new freezer that has C-Pentane. Should work pretty well.
I think that’s the same refrigerant that the one i modified uses and it works great! let us know how it goes!
Thanks for posting this up. It might be a while till i get around to it but i will put up some pics when i get to it.
Thinking about moving the holding tank in the freezer, in an alcohol bath for thermal mass.
So at my work we have a walk in oven that turns out will never be used. We did however need a deep freezer… Since being an oven it was already insulated I decided to convert it to a freezer… So far it’s sustained -10 and recovers well but I must say it is a spectacular thing seeing people with a positive attitude towards those that just has to get crazy and have a little fun. Every time I checked out forums with HVAC techs, they are filled with ego maniac premodonna that have no constructive advice. Just go out and spend 15k as if it were easy money. It’s refreshing seeing people with at the very least, entertaining criticism.
Welcome to the forum… We do have a pretty good group here! Im on a few other forums and this one is my favorite
I built a diy glycol chiller. And of the few good hvac forums I found, one straight up didn’t welcome diy people or people trying to learn anything. And another was equally shitty towards someone trying to learn. What a weird crowd them hvac’ers are
So any size freezer as long as it’s a scroll pump and cyclopentane? Would this hold up better than a Chinese cryo from like Alibaba? I’m wanting to push for -60 to-80c if possible.
Awesome idea! Especially these modified and pretty much any freezer or fridge should be 12 wire on a dedicated 20amp circuit. The electrician in me had to throw that out there.
Any temp freezer hiting -40C or less is a so callef cascade system
Meaning two independent systems
Of wich one is cooling the system that is coolinjh the freezer to supress it s
Vapor pressure for the coolant gas neccesary to get this cold create high pressure and beeing cooled this suppresses theiir vapor pressure reliefing the compressor to compress
Must be all the time spent on hot roofs… or being called the “AC guy” too much
i bet an hvac guru could swap out a freezer compressor, resize the expansion valve and add another few inches of insulation, run propane refrigerant and get into -50c range.
i think those things will probably max out around -40, i believe getting colder requires cascade refrigeration, which is just essentially a second compressor with a different refridgeeratiopn setup, applied science has a great video on it. Ultra low-temperature cascade refrigeration system repair - YouTube
anyone ever heard of using a stand pipe, vessel, or “reverse accumulator” on the compressor discharge to help add volume to a refrigeration loop? maybe this would help combat high pressures in a refrigeration system designed for r12 or 134a running r290?
How did the freezer project go?[quote=“Roguelab, post:32, topic:20037”]
h
[/quote]
Thank you for the tip. Works great. I used a combination of both of your methods @Rowan @organicace and simply backed the temp probe out of the housing a few inches. Seems to work in a similar way to the original tip (still regulates temp somewhat) without the work or wiring.