Ever built a steam engine?

[Astro]

I have often times kicked around the idea.
Came across this video awhile back and it stirred my interest in it again.
ttps://youtu.be/Sp8FMqgc5Io
I can not post links so you will have to add an h to the front of it.

[hiker]

Blast from the past,,Dan b the guy that started this site ,,built a variety of gens,,  https://otherpower.com/steamengine.html

[Astro]

Blast from the past,,Dan b the guy that started this site ,,built a variety of gens,,  https://otherpower.com/steamengine.html

COOL!!!
I have never come across a steam engine, so I would have to build one. YIKES that sounds like a ton of work in just planning. Plus I would need a better class of friends with a little higher end machine shops.
But that does not mean I do not have thoughts about it all.
I like the idea of heating my shop for basically nothing and making electricity at the same time.
Which also makes me wonder why people are heating water for heat, with dump loads, when oil heats up more easy then water.
If I heat water with a dump load, I am going to do it in a small water heater that is in line before my house water heater. That reduces the load on my water heater. I have a gas water heater, but still. It takes 8.33 btu to heat a gallon of water 1 degree. So if I can raise the water temp going into my water heater by 3 degrees even, that is 24 btu I saved. My water heater is in the basement and while it is not a livable space, being dug into the ground it is almost always 60-65 degrees down there. So in theory and since I do not care if it 50 degrees down there if I first brought my water into a vessel of say copper or another heat conducting metal and just let it sit in the 60 degrees, it would warm up slightly anyway. Yes it would cool the room slightly, but again, idc, I do not go down there much anyway, except to service things down there once in awhile.
 Anyway sorry for my rambling. But yes I would love to heat my shop in the winter while making electricity. That is the point to my thoughts on a steam engine.

[JW]

my site has been hacked flashsteam.com but I can give access to it.
Heres a video

ACB R&D misc 2004 5
https://www.youtube.com/watch?v=A5O7zYJE-GQ

ACB R&D 2005 PSTG3 (b50).mp4
https://www.youtube.com/watch?v=W9H5NXdSM5g

ACB R&D 2004
https://www.youtube.com/watch?v=jZasy9XNbYU

[Astro]

my site has been hacked flashsteam.com but I can give access to it.
Heres a video

ACB R&D misc 2004 5
https://www.youtube.com/watch?v=A5O7zYJE-GQ

ACB R&D 2005 PSTG3 (b50).mp4
https://www.youtube.com/watch?v=W9H5NXdSM5g

ACB R&D 2004
https://www.youtube.com/watch?v=jZasy9XNbYU

Awesome!!! That is cool.
 I have a few things rolling around in my head. Well, I should say things that are 80% figured out.
One of them is this, if it takes 8 btu to heat a gallon of water, and I have a 3,000 plus gallon rain water cistern outside my back door. Why couldn't I take 1600 ft or so of irrigation pipe that comes in a roll. throw it down there. (weighted down if I need to or actually secured to the walls nice and neatly   ) Have the ends come into a big camping cooler I have. Hook up a 12v pump off a lawn sprayer. Fill the cooler with antifreeze/water. Run the return end of the pipe (after it comes up out of the cistern) through a car radiator from the junk yard with it's electric 12v fan. Put a speed controller (I already have most of this stuff) on the fan.
Ta da air conditioning in my shop. It would take 24,000 btu to raise 3000 gallons by 1 degree. However the cistern is 8 ft into the ground and is 8 ft in diameter. The ground temp is going to cool the water back down, so I think I would have far more then a 24.000 btu air conditioner for little of nothing in cost or bills.
Part of the reason I bought this house was because of that cistern, because I like to grow a garden anyway, but if I can use it to cool my shop a little, that is cool. literally.
As for heat, I have a few ideas. As you might have noticed I like to make things work for me in multiple ways, ( I like efficiency) so my heat ideas are no different and will take care of more then just heat.
 My biggest problem with heat is that insurance companies can get a little blah blah blah about "home made" things that heat. But if I need to I will build a cinder block little tiny structure in my back yard and put it in there. It complicates getting the heat inside the shop or house, but not by much.

[Astro]

See what happened is they pissed me off. Long story, but in the end they did. Yeah I want to save the planet and all that. But they pissed off the wrong smart person and now I am going to share ideas and get as many people off the grid as I can. Because I figured out the best way to fight back is to take as many dollars out of their pockets as I can. They have kept me broke so long, it does not matter anymore if those dollars go into my pocket, only that they get less in theirs.

[Astro]

Oh and for anyone thinking about a steam engine, or ..... whatever,  100lb propane tanks can be had for pretty much free when they are old. Most propane tanks are 1/4in thick metal, but some are more. You can tell by the weight of an empty tank.
Just make sure if you are going to put heat of any kind to it, you wash it out really well and let it sit for a long time with no valve in it. Then wash it out some more. Maybe throw dry ice in it and wash it out again.
You can also take them in and have them recertified (pressure checked) for around $50, before you do anything. Which gives you 100 to 200 pounds pressure tank.
Or you can be brave and just hook your air compressor up to it and let it buck. Most newer air compressors have thinner wall tanks then the propane tank and run up to and past 100 pounds. My old compressor runs up to 140 psi. and then some. But it weighs a metric ton and is not very big either, so it is stout.
Who knows what uses one could have for a 100 plus pound pressure tank in the quest for off grid living.

[Mary B]

Co-op never checks the dates on my tanks when I refill them LOL I am sure they are way out of date being 20 years old. But they lived indoors out of the rain and snow so zero rust. And they actually put 20 pounds of propane in a 20 pound tank, those tank exchange places often are 16 pounds or less! And you get back whatever crappy looking rusty tank joe blow swapped in the hopes of getting a new tank...

I have some old tanks with the old valve that I have made into portable air tanks. One has a cheater for getting tires on the bead(was handy when I had a 4wd van and 33 inch mud tires... they would never seat the normal way), other is just a plain air tank with a cheesy coil hose off a cheap compressor I use for air brushing, comes in handy if the mower gets a flat out in the yard... I can dump enough air in to get back to the garage and take the tire off to fix it.

[hiker]

Mary,,those brass bleed off screws on propane tanks,,Dang workers that refill the tanks alway manage over time to round  out the screw head slots ,,,ive always had to throw out a hint,,Hey careful now don’t round off that screw head Slot,,35-40 bucks for a new valve,, Why they can’t just change out the air bleed screw I asked ,,we don’t do that Here,,💕🙏🇺🇸

[Astro]

Co-op never checks the dates on my tanks when I refill them LOL I am sure they are way out of date being 20 years old. But they lived indoors out of the rain and snow so zero rust. And they actually put 20 pounds of propane in a 20 pound tank, those tank exchange places often are 16 pounds or less! And you get back whatever crappy looking rusty tank joe blow swapped in the hopes of getting a new tank...

I have some old tanks with the old valve that I have made into portable air tanks. One has a cheater for getting tires on the bead(was handy when I had a 4wd van and 33 inch mud tires... they would never seat the normal way), other is just a plain air tank with a cheesy coil hose off a cheap compressor I use for air brushing, comes in handy if the mower gets a flat out in the yard... I can dump enough air in to get back to the garage and take the tire off to fix it.

I have one for air storage/capacity as well. I was thinking about cutting one up and making and outdoor oil burner out of it. I have a diesel truck, so when I change the oil, it is 3 gallons at a time. Plus I know where I can get used oil. Just from family and friends I would have more then I needed.
My plan was....... if you read my ta da air conditioning post, I figured I could wrap the old propane tank turned into an oil burner with copper tubing and in the winter instead of piping my glycol water mix down through the cold cistern water to cool it, I could pipe it thru the copper coils for heat. Being outside my shop would not stink like an oil burner either. I am pretty good with figuring out how to automate and control things, so that I am not worried about. Might have to mix a little diesel in with the used oil to thin it out, but that is no big deal.
BUT idk, then I keep thinking and that project turns into an idea for a bigger better project and so on. LOL.
I finally arrived at what I want to build, but it is not cheap. Not cheap at all.
Told my wife there is nothing worse then a painter without paint or brushes and there is nothing worse then a inventor with out funds. Just think if Michelangelo did not have paint or brushes the Sistine chapel would not look like it does.

[SparWeb]

Hiker, Mary,
The same thing happens to the acetylene tanks for my torch.  Who ever came up with that tiny little valve stem?  Every time I swap a tank I just pray the valve can be turned.

... I should bring that tiny wrench to test it before I leave the store!

[Astro]

I just find it funny how in the summer we take cold water from the city or well which is usually about 55 degrees, then we send that 55 degree water into a heating vessel and pay to heat the water so we can have a hot shower, bath, do dishes, ect. Meanwhile we pay to run an energy hogging air conditioner because it is 85 plus degrees outside and we want to cool it down inside of our house.
Doesn't that sound whacked??
Why not take the 55 degree water, put it first into a tank, cycle it through a heat exchanger (basically a radiator) and use it to cool the house then to the water heater and cold water taps?
Even if it only worked a little, you would save 8.33 btu for every degree you raised 1 gallon of water 1 degree and you would get at least a tiny bit of cost reduction on your air conditioning bill.
Just saying it would be more efficient and if a guy did it all himself it would not cost much.
 I had a whole note book at one time of these kind of thoughts and projects, because I swore someday I was going to be able to afford to move to the mountains and go off grid. I moved on from a relationship and never seen the notebook again and most of my dreams have kind of died over the years, but all that stuff is still rolling around in my head.

[joestue]

so i live in the pnw and share a geodesic dome which is split into 4 appartments. very long story but the landlord (who built about 30 of them about 40 years ago) is quite impressed that i've been able to do both major structural and cosmetic repairs to the building in a fraction of the time anyone else he has hired has ever been able to get anything done. which affords me a lot of pretty interesting opportunities.

so when i told him i'd buy a heat pump and install it myself he is like.. ok great i'll pay you for it. but how are you going to distribute the heat across three floors. so i told him that's easy.

apparently no one else thought it was. you can read my reddit thread here.
https://www.reddit.com/r/HVAC/comments/n1fcsy/what_would_you_use_to_control_this_system/

I later came up with a simplified diagram here:
https://imgur.com/a/vGxHuTJ


anyhow the reason i haven't built it yet.. is because of white water mold, which i have caught growing in my cat's water bowl.

you simply can't have a hot water preheat tank for a number of liabilities.

when i get around to it, i'm going to cut the condenser output line and add a heat exchanger in the basement. the heat pump won't notice where the heat went.

[Astro]

so i live in the pnw and share a geodesic dome which is split into 4 appartments. very long story but the landlord (who built about 30 of them about 40 years ago) is quite impressed that i've been able to do both major structural and cosmetic repairs to the building in a fraction of the time anyone else he has hired has ever been able to get anything done. which affords me a lot of pretty interesting opportunities.

so when i told him i'd buy a heat pump and install it myself he is like.. ok great i'll pay you for it. but how are you going to distribute the heat across three floors. so i told him that's easy.

apparently no one else thought it was. you can read my reddit thread here.
https://www.reddit.com/r/HVAC/comments/n1fcsy/what_would_you_use_to_control_this_system/

I later came up with a simplified diagram here:
https://imgur.com/a/vGxHuTJ


anyhow the reason i haven't built it yet.. is because of white water mold, which i have caught growing in my cat's water bowl.

you simply can't have a hot water preheat tank for a number of liabilities.

when i get around to it, i'm going to cut the condenser output line and add a heat exchanger in the basement. the heat pump won't notice where the heat went.

 Unless you want to add a pump, My thought was to let it use the pressure it already has from being pumped into the house. So it would not have any air and would still be pressurized the same as the rest of the plumbing.

But I digress, I woe up this morning with the thought that, really the most efficient way would be to cool the gas coolant running through the central air unit with said incoming cool water. Then you do not need a condensor unit like the ac unit has currently. It would not need to work very hard at all.
Even if you were worried about this whole pre tank thing, (which I think if you kept the air out, you would be ok), all you would have to do is instead of a tank, run it through a plate exchanger. Have it cool a glycol mix and use the glycol mix to run through a radiator style exchanger.
I just woke up and am not thinking yet, give me a couple hours and I am sure I can solve your worry about a tank.
But before I go make a coffee with my filtered water that I buy in clear plastic 5 gallon jugs that sit around for weeks from the time they get filled to the time a customer uses them, do you really think water that is is a tank for 30 hours or so is going to be that big of a problem???

[Astro]

So you take the incoming water and you tun it through a copper coil placed inside an tank of glycol/water. Heat transfer takes place, because you are using the glycol/water to run through a radiator style heat exchanger for the cooling effect and as such the glycol water mix is getting warmer. Every time you use water in your house it cools the glycol mix down and warms the water up.

 But, I still think if we could cool the coolant gas from the ac condenser, we would be talking some major cost savings.
Give me a day or two as that is a totally new idea to me.
Probably basically the same thing except the coils would have the ac coolant and the tank would be just like a water heater tank in line before the actual water heater. You might have to take some extreme cation here because you would not want ac coolant bubbling in your soon to be hot water. But it could be done for sure, just need to think about it a little longer.

[Astro]

I just read where the avg family uses 300 gallons of water a day!!! Wow. So we could calculate all this out if we desired. But I feel like any savings is better then doing the way we do now. Like I said before, we are not talking rocket science so the investment should be low and should fall within my 5 year pay back rule.
We use about 1500 gallons a month. But we do not drink, make coffee with or cook with tap water. (Really I should just use my cistern like it was intended, but water is reasonably priced here)
Long story short I was living in the mountains. It is all rocks and when it rains the water just runs until it finds a crack to go down, So little filtering effect. We all had wells and septic systems. Then while enjoying the beauty of the mountains and having my coffee one morning it dawned on me that I did not live at the top of the hill and everyone knows $#|+ runs down hill. I have not drank tap water since.

[Mary B]

My water comes via 100 miles of pipeline form the other end of the county and some deep fens and aquifers. Town well is 2,000 feet deep now and they never hit good water, just rusty nasty iron laden crap that came out of the tap orange the first 20 years I lived here.

So now instead of iron I have sulfate off the charts. If you are not used to the water it will park you in the bathroom for a couple days because sulfate acts as a laxative! I RO filter my drinking water now... reminds me, time to order new filter cartridges...

[Astro]

My water comes via 100 miles of pipeline form the other end of the county and some deep fens and aquifers. Town well is 2,000 feet deep now and they never hit good water, just rusty nasty iron laden crap that came out of the tap orange the first 20 years I lived here.

So now instead of iron I have sulfate off the charts. If you are not used to the water it will park you in the bathroom for a couple days because sulfate acts as a laxative! I RO filter my drinking water now... reminds me, time to order new filter cartridges...

That is what we buy, RO water. I should just get a RO unit, but I have so many things on the want list it is way down there. I need to pit a new water softner in, the one here when we moved in had not been working for a number of years. It finally started to leak about 8 months after we moved in and I by passed it. But the plumbing is a mess down there from cistern, no cistern, water softner, no water softner, so I need to redo a bunch of it as well, when I finally put in a water softner. It never ends.

[joestue]

i could definitely run a hot water preheat tank on the input of the washing machine hot water inlet. that way it doesn't matter if something starts growing in the water.

anyhow, almost everyone that needs air conditioning is going to be running a condensing temperature of 120F or higher simply due to the crappy heat transfer coefficients of standard window shaker AC units. so there really is no excuse why that heat can't be dumped into the hot water. but there are folks where legionela is a concern and they have to run an even hotter water tank.

i have a heat exchanger on my parents shower drain and we were getting a 7F temp increase on the cold water inlet to the heater. it doesn't cost a lot but such a system would never pay for itself due to the labor of cleaning the heat exchanger.

[Astro]

i could definitely run a hot water preheat tank on the input of the washing machine hot water inlet. that way it doesn't matter if something starts growing in the water.

anyhow, almost everyone that needs air conditioning is going to be running a condensing temperature of 120F or higher simply due to the crappy heat transfer coefficients of standard window shaker AC units. so there really is no excuse why that heat can't be dumped into the hot water. but there are folks where legionela is a concern and they have to run an even hotter water tank.

i have a heat exchanger on my parents shower drain and we were getting a 7F temp increase on the cold water inlet to the heater. it doesn't cost a lot but such a system would never pay for itself due to the labor of cleaning the heat exchanger.

See right there you bring up a good point and a good idea. To eliminate the heat exchanger, all one would have to do is wrap copper tubing around the drain and insulate the whole thing. It will not perform as well, but cost to do and upkeep would be very very low. It would be better if the drain was out of a metal that had good heat transference. Then the drain water stays in the drain pipe and the water in the water pipe. Even better would be a copper drain pipe inside of the cold water inlet pipe, but that brings up what happens if there is a leak and you do not notice, your incoming water could be contaminated. You would need to monitor water going in and water coming out of such a set up very closely to make sure that it is not gaining any extra or losing any. Maybe have someone build a board or controller to hook those inputs into and alert you or shut it down if there is a problem.
Yeah cleaning heat exchangers sucks. But everything needs upkeep. That is part of the reason we live in a throw away world. Part because things are not made as well as they used to be and part because nobody takes care of anything. I have yet to see any of my neighbors clean out their ac units and I have lived here 3 years. Kind of dumb when you think about it, your house is almost always your largest investment.

[DamonHD]

FYI: https://showersave.com/

Rgds

Damon

[Astro]

Ok, so back to my being mad about the cost to run my central air. (people that know me know I do not anger easy, but when I do finally get mad, look out).
So, since I am paying 18 million dollars a year to run my ac, why not just build a shroud above it (my fan blows up and out the top) take the water pipe before it goes into the water heater and run it out side and into a coil of copper above the ac unit?? Put a couple of valves in so I can shut that loop off and drain it in the winter and then in the winter just let the water run like it is piped now. I could even install a couple solenoid valves and a temp probe with a hose down to my sump pump pit and the whole thing would just take care of itself depending on the outside temp.  Hell, I might even make a solar heater box to pre heat it before it goes into the coil above the ac condenser.
Granted I would not save anymore during the winter, but that is because I am not spending 18 million dollars to run the ac either.
Ideally, one would and could come up with a much more efficient idea, but it would cost a fair bit more too.

[Astro]

FYI: https://showersave.com/

Rgds

Damon

That is exactly what I am talking about. But I see the biggest source of wasted heat being the ac unit.
Just imagine if the ac unit. your freezer and refrigerators condenser units were all cooled by the water you use going into your water heater.
It would not only be a savings on heating your water, it would make those condensers last longer as they are not going to need to work nearly as hard. If they are not working as hard, they use less energy.
 We have the technology to do this with the snap of fingers, but......... there is no profit in it. There might be idk, but anytime you start talking about not paying as much in utilities, it tends to piss of the people who make electricity, pipe and haul gas or dig coal or whatever fuel they provide.
Well again, you should have let me have a few bucks in my pocket.

[Astro]

Now one might wonder what all this crazy rambling is leading up to. Well, I will be as surprised as you.
I do know one thing, I have spent thousands upon thousands of hours with all kinds of engineers designing things.
For instance a chemical deburring line we designed. The process of that taught me a lot. Very fascinating indeed.  Now as I get older, the question is what can I do with everything I have learned?
Btw, I am not bad. You should meet chemical engineers, they are some crazy mo fo's.
Right now I just have "theories" lol.
 

[Astro]

So check this out. The last month has been beautiful. No ac during the day and no heat at night. We have propane heat, but still have the furnace fan obviously. Everything else pretty much the same. still use electric oven as normal and still wash and dry the same amount of clothes.
Our electric bill was 1741 kwh the month before (it was hot outside) down to 750 this last bill.
So you can see why I am wanting to get my ac off my bill or otherwise make up the cost for it over the year. WHy I am trying to maximize it and even the heat it is throwing off.
House is old, but all new windows (cheaper ones, but new double pane) insulated pretty well (we added a foot on top of what was in the attic when we moved in, it needed it) no real drafts to speak of. I am getting a fair bit of heat/cool loss in my duct work, as there is no vents in the basement and it stays pretty warm/cool down there for having no vents.)
The AC unit it sized about a 1/2 ton to small, I THINK, because the house did not have much for vents upstairs and so I do not think they counted that sq ft when calculating. Finally the AC unit is fairly old, not like 40 years old, but probably more then 15 years old. We kept our ac set at 74 all this summer.
I can deal with the heat (propane) cost, we have a great co-op and we go through about 1100 to 1300 gallons a year for heat and for our large water heater. I have the water heater turned up, because we have a huge jet bathtub we installed. That makes it tough to justify putting in a pellet stove or anything like that because our propane is reasonable and the pay back would be probably more years then I care for. (remember I have a 5 year payback rule and shoot for 3 or under)
So it is the electric bill I am at war with. More specific, the AC.

[Astro]

Ok so, my ac unit is a 2.5 ton and should be a 3 ton. It was made in 2002. I get that it needs updating.
But to go from a 12 seer 2.5 ton to a 3 ton 18 seer, is going to cost around a minimum of $3000.
Sticking to my 5 year payback rule I would need to save $200 a month in the summer months. Ac runs about 3 months and 6 weeks at it's hardest. 5 years 3 months a year, 15 months. $3000 divided by 15 months. So $200 a month.
So the question is (and this is where I like engineers and people that like math) do the calculations warrant the upgrade?
Running some simple numbers, if a new 18 seer 3 ton cut my ac bill in half (idk if it would do that, I doubt it,  again I am not going to do the math) I would save $125 a month (given what price I pay on avg for kwh), during those 3 months. SO $375 a year savings on a $3000 investment. OR an 8 year payback. SO that does not fit into my 5 year rule.
I know that going up in seer helps, but the cost also goes up.
At that rate I would be better of spend the $3000 on a stand alone ac unit that hooks directly up to solar panels. One set up would not be enough to cool the house, but the pay back is 100% of everything it puts out.
Same with building a turbine.

[Mary B]

A central AC unit is going to last 10+ years... you need to calculate use cost over lifespan to make a decision...New one is going to use a lot less electricity too so calculate that in.

[Astro]

A central AC unit is going to last 10+ years... you need to calculate use cost over lifespan to make a decision...New one is going to use a lot less electricity too so calculate that in.

 They are not guaranteed to last that long. They usually do though. I worked in an industry that by the time we ramped up to production from concept to protype, it was already outdated. We already had working prototypes for the next generation before we had ramped up production on the previous version.
They say "if your ac unit is 10 years old or older it should be updated" due to energy advancements.
I did calculate the pay back time and depending on how hot the summers are it is going to take 8 years if they are the way they were this year. (it was a pretty warm summer). But it could take 10-11 years and it could take 7 years. Any less then 7 and the heat is going to be the last thing to worry about, because everything would begin to collapse if the summer was that hot.
So figure 8-9 years. That payback sucks and is not good enough. There are better ways.

[joestue]

Take your 2.5 ton system and figure out if its running properly. My guess is it isn't. Maybe the txv needs adjustment, maybe it needs a new one, maybe it needs more or less air flow through the coil to deliver the cooling capacity and dehumidification you need.

anyhow, if that's not good enough, find yourself a 5hp vfd and run the compressor off the vfd. run it up to 75Hz if you like. or down to about 45hz. no need to install a bigger system just to pull more water out of the air, or get a shorter run time because it can't quite keep up.

if you're in the usa i can help you out with the transformer selection needed to transform 3 phase from the vfd into the proper 2 phase voltage that a standard capacitor run compressor motor needs. its not a particularly high kva requirement.

a 5 ton 240v system will need a 240v to 120v transformer rated for 6 amps, and you will need a 240v to 16/32v transformer to "add" 16 or 32 volts to the second phase to make more current flow through the "start" winding.
the compressor will self start even with head pressure, if you program the vfd properly. if not, you will need to preserve the standard 5 minute delay between restarts which is standard for most all hvac heat pumps.

getting the hvac system to control the vfd is very easy. just use the contactor that previously provided 240v to the compressor, to instead close the circuit to turn the vfd on.

to get a higher seer rating, keep the 2.5 ton compressor and plumb in a bigger condenser. 20 pound propane bottles can safely be used to hold r-410 provided you hydrotest the tank to 400 pounds and you keep it cool while recovering the refridgerant.

a compressor from a refridgerator can be used to suck it all out of your system.

you can flow propane instead of nitrogen through your system while brazing the tubes together. (no need for a regulator and propane or argon bottle). and.. to be honest, there is a 8% silver solder that melts at like 500F that is just fine for R-410 systems. it has a high enough fatigue limit it wont fail. (r-22 could be used with regular soft solder)

old fans are horribly inefficient. a 1/3rd hp induction motor sucking up 200 to 300 watts will move as much air with a stamped sheet metal fan blade, as a 60 watt inverter fan motor with its aerodynamically designed plastic injection molded fan blade.

i have not had good success driving pmdc motors with 60-80$ chinease 2hp vfds, due to unreliable startup.
but you can buy a legit vfd from automation direct or elsewhere and they now have the capacity to drive synchronous motors properly. the 250$ spent is.. actually less than the pmdc inverter fan motors that are now installed in 18 seer hvac systems. go to the dumpster behind an hvac shop and find a junked motor. change the bearings, epoxy the magnets back on, it will work again.

question being, is your time worth it.

[Astro]

Take your 2.5 ton system and figure out if its running properly. My guess is it isn't. Maybe the txv needs adjustment, maybe it needs a new one, maybe it needs more or less air flow through the coil to deliver the cooling capacity and dehumidification you need.

anyhow, if that's not good enough, find yourself a 5hp vfd and run the compressor off the vfd. run it up to 75Hz if you like. or down to about 45hz. no need to install a bigger system just to pull more water out of the air, or get a shorter run time because it can't quite keep up.

if you're in the usa i can help you out with the transformer selection needed to transform 3 phase from the vfd into the proper 2 phase voltage that a standard capacitor run compressor motor needs. its not a particularly high kva requirement.

a 5 ton 240v system will need a 240v to 120v transformer rated for 6 amps, and you will need a 240v to 16/32v transformer to "add" 16 or 32 volts to the second phase to make more current flow through the "start" winding.
the compressor will self start even with head pressure, if you program the vfd properly. if not, you will need to preserve the standard 5 minute delay between restarts which is standard for most all hvac heat pumps.

getting the hvac system to control the vfd is very easy. just use the contactor that previously provided 240v to the compressor, to instead close the circuit to turn the vfd on.

to get a higher seer rating, keep the 2.5 ton compressor and plumb in a bigger condenser. 20 pound propane bottles can safely be used to hold r-410 provided you hydrotest the tank to 400 pounds and you keep it cool while recovering the refridgerant.

a compressor from a refridgerator can be used to suck it all out of your system.

you can flow propane instead of nitrogen through your system while brazing the tubes together. (no need for a regulator and propane or argon bottle). and.. to be honest, there is a 8% silver solder that melts at like 500F that is just fine for R-410 systems. it has a high enough fatigue limit it wont fail. (r-22 could be used with regular soft solder)

old fans are horribly inefficient. a 1/3rd hp induction motor sucking up 200 to 300 watts will move as much air with a stamped sheet metal fan blade, as a 60 watt inverter fan motor with its aerodynamically designed plastic injection molded fan blade.

i have not had good success driving pmdc motors with 60-80$ chinease 2hp vfds, due to unreliable startup.
but you can buy a legit vfd from automation direct or elsewhere and they now have the capacity to drive synchronous motors properly. the 250$ spent is.. actually less than the pmdc inverter fan motors that are now installed in 18 seer hvac systems. go to the dumpster behind an hvac shop and find a junked motor. change the bearings, epoxy the magnets back on, it will work again.

question being, is your time worth it.

I like the way you think.
I am pretty familiar with vfd's. Never thought of that idea. Also it never dawned on me to swap the fan for a more efficient one.
I know it will eventually need replaced. Maybe in the next 5 years or so, so I do not want to spend a ton on it.
I am gradually getting the place fixed up and while we do have an "emergency" fund for big ticket items, I am not the type to waste money getting a new one, when this one works and the pay back on a new one does not come close to what I think it should.