https://en.wikipedia.org/wiki/Enthalpy_of_fusion heat of fusion water-ice 333.55 J/g https://en.wikipedia.org/wiki/Table_of_specific_heat_capacities heat capacity Water at 25 °C liquid 4.181 J/g°C (apolgies for potential unicode gore on degree symbol) https://en.wikipedia.org/wiki/Enthalpy_of_vaporization heat of vaporization water-steam 2257 J/g not sure how much longer this will be around but here goes ;) https://www.eia.gov/consumption/residential/reports/2009/state_briefs/pdf/va.pdf https://www.eia.gov/consumption/residential/ perhaps it's better just to look at recommended specs given my space https://www.hydrosolution.com/en/articles-and-tips/guide-and-tips/what-is-the-right-btu-size-for-my-heat-pump/ "You can find out the right BTU size by measuring the surface area in square feet. Calculate the surface area of the space that you need to heat or cool (length times width), multiply it by 10 and round up to the number of BTUs." ...i come up with something between 6,000 and 12,000 btu - it's a loft so i'm not quite sure how to count the high ceiling and open truss leading up to the small upstairs area. i forget what my little window ac unit is but it isn't quite up to the task to say it nicely. it's a GE, and currently lowes is selling one that looks almost exactly the same that lists 5,000 btu. lowes site says it is suitible for a 150 sqft room however - that's about a 12.25'x12.25' room. my downstairs is about 600 sqft by compirson. that is 4x as much, so by lowes' metric i should need a 20,000 btu unit, and maybe double that to include upstairs? lowes' website really sucks by the way! ACCESS DENIED!!!!! https://www.betterhomesbc.ca/products/heat-pumps-btu-to-tons/ BTU Number of Tons 12,000 1 Ton 18,000 1.5 Ton 24,000 2 Ton 30,000 2.5 Ton 36,000 3 Ton 48,000 4 Ton 60,000 5 Ton so i have roughly less than half a ton from my window unit right now. I think the old system was 1.5 tons before it broke, and that fed a mini-split in the big garage area in addition, so i was probably had less than a ton to begin with. I suspect hydrosloutions must be sizing their units for canadians. according to their rubric i should already be good with my little window unit(which i am not here in virginia). there is still a little ice in my little diy space cooler, and condensate still dripping from the coils down into my sink. I'm not sure how much it is helping with temperature, but i think it's definitely taking the edge off: humidity is in the 30s. Just guestimating the amount of ice i put in the cooler, based rough equivalence of the salad tubs i used as forms to 2 Liters, I think i put about 8 kg(maybe 10kg) ice in the cooler. i also had significant amount of cold tap water. so based on my water heat of fusion numbers(333.55 J/g) x10kg = 3335.5 kJoules of heat absorbed. google tells me 1 btu = 1055.06 Joules so that converts to about 3161.43 btu if idid my arithmetic right? i'm still not sure how that compares to a btu rating for a heat pump? google AI tells me BTU in the context of Heat pumps really stands for BTU/hour, and so by comparison, i ran my little diy ice-cold coils on a box-fan for about 5 hours this evening, averaging about 632 btu/hour. this isn't really surprising me, since i didn't notice a big change on my indoor thermometers, though i think the humidity is definitely a few percent lower than it is usually. it's not a huge effect, and maybe there is some error in my cheap hygrometer i am using- perhaps it is only 2% lower. However i think there is definetly room for improvement, and i think the ice would melted faster if i switched to a bigger pump - right now i am just using the most basic 100GPH submersible fountain pump. I also think there is probably enough room for me to double the number of coils over the surface of the box fan(from 20 ft to 40 ft). I would ofcourse need to make more ice if i want to see a noticeable change. lets say i want to take the edge off a very hot afternoon coming up by running my contraption for about 6 hours starting in the afternoon, with the plan of depleating the ice around dusk, and letting the window unit run solo for the remainder of the evening. assuming(unrealistically) i can match the output of my little 5k btu window unit, that means i need 30k btu worth of ice. 30,000 btu =~ 31652 kJ 31652 kJ / 333.55 kJ/kg =~ 95 kg ...so basically 10x what i did today. i think i might actually have freezer space for this, but it would completely fill both my little chest freezers, and take multiple days freeze all the blocks. Also, the cooler i am using to house the pump in the ice-water bath is not big enough. I guess heat pumps really are a miracle. i like to take my time coming to conclusions, and prefer to be sure i am making good decisions, but perhaps this project is not realistic given my time frame. it was supposed to be a simple idea to try and lessen the heat somehow quickly and with low budget to allow me to continue working in the hot barn until i have time and am able to install the heat pump. at the price listed it is very tempting to install another window unit, however that is sort of the opposite of what i am trying to do long term. the ice is just about melted now at this point though the water is still chilly, and there is still condensate on the coils. perhaps there is some value in the rig as-is, maybe the best option is to just use it with minimum addition work put into it. there are some problems to solve with my insulation i have discoverd, and perhapse fixing those should take priority followed by trying to clear space and installing the heat pump. space is a problem though. i have got valuable materials sitting out on decks, exposed to weather. i need to build some little spaced to house some of these different things. that costs money, which i wish i had more of. i will have to work some magic. so now i'm a magician! XD p.s. there is some good info on this site: https://www.carrier.com/residential/en/us/products/heat-pumps/heat-pump-efficiency/