The Homemade Heat Pump Manifesto

[pachai]

Originally Posted by AC_Hacker

S-F,
Pachai, I think you should continue on with your idea, full speed. Don't let anyone slow you down. Take lots of photos.

Full speed ahead!

Thanks....first one. There's a
"Cleaning Supplies Distributer" in my town.
I spoke to him last week, and on Monday
his workers dropped off 4 barrels.
Compromise, I clean out the last gallon
of soap, and I get to keep it....

YMMV / Caveat Emptor / etc.
These are Concentrate, may be dangerous.

(No cost, No shipping charge :-)

[RickHeid]

Thanks Guys, I have a 2 year old 3 ton ac only unit that I was given that I may try my experiments on. I have some of the tools and a federal license to recover the freon so that isn't a problem. I will have to do some practicing on soldering in the plate heat exchanger but it looks like the mig cover gas works okay to keep the inside of the copper clean. I wish I'd have put the copper coil in the well when I put the well in last year. The pulling the pump shouldn't be to bad but the digging the ground back up to put in the pipe won't make the wife happy. The well is 130 or so feet from the house so I might as well put a slinky ground loop over to it. With any luck, presto..... low cost geothermal. Rick

[jroode32]

AC Hacker,

Yes that helped, and thank you much for your time and valuable input.

I ordered a set of gauges and a vacuum pump so hopefully I'll be able to play a bit this weekend the gauges go to 800PSI on the high side gauge and 500PSI on the low side gauge and has a sight glass as well so I should be covered as far as gasses go.

P.S. I did take the cores out of the shrader valves before brazing, thanks to a you tube tutorial.

Thanks again
JRoode32

[AC_Hacker]

Originally Posted by jroode32

...the gauges go to 800PSI on the high side gauge and 500PSI on the low side gauge...

The gauges you ordered will probably be just fine, but just for reference, the rule of thumb with analog gauges is that you want the 'range of interest' to be at half-scale.

I have noticed that when I need tools, I seldom find really great used or on-sale tools. When I don't need the tools or already have them, the great bargains are everywhere... so you might keep your eye peeled for a used R-22 gauge set. I would say $10 is a pretty good price.

BTW, I don't know if you read the whole 'manefesto' thread, but there is a section in there on the need to purge the inside of the copper tubes you are brazing, because tiny black flakes will form in the presence of oxygen. These black flakes can plug a cap tube or TXV orifice. The pros use dry nitrogen for this purpose... CO2 will work too, but it will have moisture in it which has no business inside a HVAC system. Some suicidal experimenters who are bent on their own destruction have used R-290 for a purge gas. Obviously, I would never recommend such a practice.

-AC_Hacker

[AC_Hacker]

Originally Posted by pachai

...his workers dropped off 4 barrels...

Great price!

-AC

[jroode32]

AC,

I understand what you mean by the "range of interest" if you will only be working with R-22 and will never see a reading above 350-PSI and your gauges go to 400-PSI than it will be easier to read as well as a more precise reading. I guess I wanted a "do all" set to start with and once I get comfortable with a particular gas I will buy a set more gas specific, I know R-410A is used a lot and I have seen system pressures over 500-PSI (high side) so that was my logic.

I was wondering about the black flaky stuff that formed when brazing, and I have watched probably every you tube video out there on the subject of HVAC and the "triple evacuation" with pure dry nitrogen seems to be the industry standard. I am going to look into getting a bottle of nitrogen for purging, as it stands right now I haven't received my gauges and pump so I haven't been able to do anything but stare at my first hacked AC project, it does however brew new questions.

I can't thank all of you enough for your help and support...
BR
JRoode

[AC_Hacker]

Originally Posted by jroode32

I guess I wanted a "do all" set to start with and once I get comfortable with a particular gas I will buy a set more gas specific...

Another thing that occurred to me, since I have the HF gauge set too, is that the HF gauge set seems to be intended for someone who is doing home servicing of automotive air conditioning. The standard fitting on the end of the hoses (for automotive AC) is what is known as an "Acme thread". The long time standard in home and commercial HVAC is 1/4" flare fitting, which I usually hear being described as "standard fittings" or "regular fittings". There even seems to be a different fitting for systems that use R-410a... I think they may be 7/16" Acme, but I'm not completely sure of that. I do know it's different.

My local HVAC supply shop has every conceivable fitting adapter imaginable, and they aren't very expensive, so it's no problem adapting "regular fittings" onto Acme thread hose ends.

The manifold body on the HF gauge set has male Acme threads without through-holes so that you can 'park' your hose ends there when you're not using the gauges, and keep crud from getting into your hoses.

It all seemed like too much bother to me, so I replaced the non-through hole Acme thread fittings with regular fittings and ditto the hoses. It ended up being more expensive than a regular R-22 gauge set with regular ends, but that's the way it happened.

Short story: you'll need Acme to 1/4" flare adapters if your Schrader valves have 1/4" fittings.

BTW, I got some of these handy ball valves for my hose ends:

... they're nice but not necessary.

-AC_Hacker

[jroode32]

AC,

I received my gauges and vacuum pump yesterday and when I got them I realized that I had ordered a different set than what I had thought (I must have looked at 50 different sets last Sunday night when I placed the order and somewhere along the line I went into "cyber space unconscious mode" and for some reason thought I went with the "do all gauges) anyway the set I "really" ordered goes to 500-PSI HS and 250-PSI LS so it worked out, they look nice and seem to work well It was a package deal on ebay $60 free shipping for gauges and pump, I'm sure you know what that means, yes it is a HF pneumatic powered venturi style pump. After doing some research on that pump I found a lot of people reported 28" hg and for just a few extra bucks I thought why not, I also thought since im here on the gulf coast and ambient outside temps are mid 90's or higher that the moisture would boil out even it didn't quite get down to 28"hg.

I got home from work around 3:30 so I had plenty of time to "get things started" I had to bring everything down the street to a friends house who has a nice 80 gallon high output compressor as well as a new bottle of refrigerant I had gotten everything set up and ready to pull my first vacuum and within about 2 minutes sure enough the gauge was reading 28"hg so I let it run for the recommended 10 minutes and closed the valve turned of the pump started up my stopwatch app on my phone and let it set for 15 minutes, after 15 minutes the gauge was now reading 27"hg so I turned the vacuum on again and after a few times of doing this I could tell if it was due to a leak or if the gauges were just "settling" I checked all the connection and tightened the connections a bit and still the same results. I decided it was good enough and proceeded with my first charge, the only other test equipment I grabbed was my favorite pistol style infrared temp gauge and my KILL A WATT meter, also were we set it up outside was out of reach of the water hose to simulate the ground loop so I submersed the condensing coil in about a 2 gallon container and monitored the water temp, I followed your charging instruction carefully and within a mater of minutes I had a nice frost forming right at the end of the cap tube and all the way down into the evaporator coil, as I watched the gauges and slowly gave it shots of gas into the LS I finally got it up to 70-PSI but the HS was reading 250-PSI I let it run under these conditions for about 15 minutes and as the water temp rose so did the wattage so i flushed it constantly using a 5 gallon bucket with fresh water and making a mess but it worked.

The bad news is when I brought it back home after it seemed to be working and set it up outside on the back porch to play with it some more (this time with a water hose to simulate the ground source loop) it was working great and ran it for a good 45 minutes, now I had my other 2 temp gauges which I used to monitor out coming air temp (40 degrees F on high fan speed) and water temp. I was too tired at this point to set up the sub-cooling and super-heat testing but just by touch I would say it was about a 20 degree difference. The bad news is this morning after leaving the gauges on it all night, the pressure dropped about 100-PSI and when I turned it on it was still working but the LS stabilized @ 25-PSI and HS 150-PSI, I guess the leak could be in the gauges but I will definitely be do some leak testing today.

I will take pictures of today's work and testing and post sometime tonight, I'm on my way out the door to go play some Paintball its the only sport I play and it keeps me in shape.

Thank You All!
JRoode32

[AC_Hacker]

jroode32,

Congratulations on your first success! Quite a thrill when you see that frost forming, isn't it.

But you do have some tweaking to do to get things really going in the right direction...

Originally Posted by jroode32

...it is a HF pneumatic powered venturi style pump. After doing some research on that pump I found a lot of people reported 28" hg and for just a few extra bucks I thought why not, I also thought since im here on the gulf coast and ambient outside temps are mid 90's or higher that the moisture would boil out even it didn't quite get down to 28"hg.

I have a friend who has that venturi style vacuum pump. It probably does draw down to 28" hg, but to get a good vacuum that will get all the moisture out, you will need to go for a deeper vacuum.

The gauges you are using are good for the purpose that you used them for, monitoring the level of refrigerant in your system.

The problem happens when you try to use the manifold gauges at the low end of the scale. The mechanism they use to cause the needle to deflect is just not sensitive enough to give you a good reading that will tell you if you are achieving the deep vacuum you need for your system to work properly, and to keep working for years to come.

The way the micron gauge works is that it has a tiny heating element and a tiny thermistor mounted near it. When there are molecules of gas present, they will carry heat away from the heater and the thermistor will read a cooler temperature which the display reflects as higher microns (not very deep vacuum)... when you approach a really deep vacuum, the molecules of gas aren't there to carry away the heat, and the thermistor starts reading hotter, which is reflected on the display as lower microns (a deeper vacuum).

I have seen various specifications as to how deep to pull a vacuum, but here is a pretty good description of the procedure.

Your situation is that you are trusting your manifold gauges to tell you what vacuum you are getting. But you are trusting the least accurate part of the gauge's range to give you the most important information you need.

Here is an interesting story from a working HVAC guy:

For years, I didn't know any better and just watched my gauges like I had seen everyone else doing, until I had some extra money in my pocket one day and seen a shiny new micron gauge right there in the display case. I bought it and tried it out the next day. I couldn't get that thing to pull down at all, but yet, my gauge was dead on 30 inches of vacuum. I worked and worked to get my gauges and hoses leak-tight and then realized my pump wasn't working correctly. I sent it in for repairs and things went much better after that, but I often wondered how long I had been hooking it up and doing nothing. That was probably 12 or so years ago and I have used a micron gauge since. Just two weeks ago, I had a system that wouldn't pull below 100,000 on my micron gauge. I kept at it until I found a tiny leak in the unit that I would have never even known was there without the micron gauge.

I had virtually the same experience, with the exception that I was using a friend's vacuum pump which he had bought used off of ebay. He had serviced all of his family's car AC systems with it and was happy with it. He was still using the pump with the original oil it came with... he would let it pull down to 30 inches (no micron gauge), let it run for a couple of minutes, and call it good.

I borrowed it to set up a brand new mini-split I had bought. I did change the oil before I used it, and let it run for three hours before I closed everything up.

Later, I bought a new micron gauge and found that his pump, with new oil would barely pull down to 500 microns.

Two years later, my mini-split is still running just fine, but i really wish I had pulled a proper vacuum, using good working techniques.

After that experience, I bought a new HF two-stage vacuum pump and with fresh oil, it will go down to 60 microns which is great.

By the way, I relayed all this to my friend, and he now has his own micron gauge, and he changes vacuum pump oil every time he pulls a vacuum. He also rebuilt his vacuum pump.

So your situation is that you don't actually know how deep your venturi pump will actually go, and you can't trust a manifold gauge to tell you what you need to know because the low end of the dial is the least accurate part.

If you can find someone with a micron gauge, you would know for sure.

Or if you bought a new vacuum pump you would have a fair level of confidence that it would pull a good vacuum.

Originally Posted by jroode32

The bad news is this morning after leaving the gauges on it all night, the pressure dropped about 100-PSI and when I turned it on it was still working but the LS stabilized @ 25-PSI and HS 150-PSI, I guess the leak could be in the gauges but I will definitely be do some leak testing today.

This is where the soap bubbles come in.

So, I would say to keep working with the equipment you have and save up for a good vacuum pump. The HF two-stage is pretty good bang for the buck.

Regards,

-AC_Hacker

[Geo NR Gee]

After scoring a used Climatemaster High Efficiency 4 ton heat pump and a friend with a Hydra Drill and pump setup, we are going thru the checklist to get the holes in for the closed loop.

The square footage of the lot and footprint of the house made it so that a vertical loop system would be best in our situation.

I eliminated the choice of using a well with an injection field as compared to a closed loop system. I guess the idea of causing a sink hole scares me with the neighbor so close.

First we will bore a test hole to determine how deep we can go. I'm crossing my fingers at 200 feet. The bores will be 15 feet apart minimum.

The HDPE pipe will be onsite and the fusing tool ready for the connections.

Mix-111 grout recipe Information Bridge: DOE Scientific and Technical Information - Sponsored by OSTI will be ready and will be mixed in a cement mixer that we own. One batch makes about 16 gallons. I will check with the manufacturer of the mud pump to see if it will pump the slurry into the bore hole after the HDPE pipe has been installed.

I have hundreds of feet of sprinkler wire and wondered if it would be smart to install some kind of sensor down the bore hole(s) to monitor the temperatures?