So I have read here. Sounds like that is the way to do things huh? Thanks for the education today you guys.
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Drawing a vacuum on a mini split?
- Thread starter the_extremist
- Start date
RipVanWeed
Member
I installed my own 24k btu minisplit from Friedrich last year.
After investigating the pumps and manifold situation, I opted to bring in an HVAC guy to suck the lines down.
I told them on the phone that I self installed an A/C and needed the lines vaccumed. They agreed to do it with no responsibility on their part for the system in the future.
I have a couple of Aussie dogs that go off when the perimeter is breached. I put them in the family room and let them bark for awhile when he got here. Pulling a vaccum on system start is all done at the compressor except operating the controls indoor. Thats your job, just make sure you understand the startup instructions completely.
Be sure to have an extension cord all setup for him. I had my own tools ready to open the valves to charge the system, but he did it for me. Complimented me on my neat install and was on his way. $100, none the wiser.
We were standing next to it, he was packing up his gear and pointed out that it was still running. I couldn't tell! That inverter technology and the way the whole thing works is so quiet I really have to check close to hear it run.
This is the one I got,
$1500 add lineset and shipping, about $1800/1850.
http://www.kingersons.com/Friedrichsplitairconditioner24k.html
Whatever kind you get make sure the compressor will run in outdoor temps down to your minimum. Most minisplit compressor systems will not operate below 50f. That Friedrich runs down to 0f.
Check the flares on your line set, one of mine was uneven and would not have held pressure. By the way, the lineset came direct from Graingers.
Hope this helps, Good Luck,
After investigating the pumps and manifold situation, I opted to bring in an HVAC guy to suck the lines down.
I told them on the phone that I self installed an A/C and needed the lines vaccumed. They agreed to do it with no responsibility on their part for the system in the future.
I have a couple of Aussie dogs that go off when the perimeter is breached. I put them in the family room and let them bark for awhile when he got here. Pulling a vaccum on system start is all done at the compressor except operating the controls indoor. Thats your job, just make sure you understand the startup instructions completely.
Be sure to have an extension cord all setup for him. I had my own tools ready to open the valves to charge the system, but he did it for me. Complimented me on my neat install and was on his way. $100, none the wiser.
We were standing next to it, he was packing up his gear and pointed out that it was still running. I couldn't tell! That inverter technology and the way the whole thing works is so quiet I really have to check close to hear it run.
This is the one I got,
$1500 add lineset and shipping, about $1800/1850.
http://www.kingersons.com/Friedrichsplitairconditioner24k.html
Whatever kind you get make sure the compressor will run in outdoor temps down to your minimum. Most minisplit compressor systems will not operate below 50f. That Friedrich runs down to 0f.
Check the flares on your line set, one of mine was uneven and would not have held pressure. By the way, the lineset came direct from Graingers.
Hope this helps, Good Luck,
R
RedRain
get a heatpump mini split, they will allower colder cooling operational temps, but last time i checked the AC mini splits with inverter will work to 14f, a heat pump AC will allow cooling to 0f. These numbers will change with larger BTU systems. the larger the BTU, or TONS,the colder you can run You can run a normal house AC down to -50.
also I wouldnt worry about leaks if you are using a flared lineset. if you are not brazing, cutting, joining copper lineset then you wont have a leak unless you are a complete tool and you dont tighten your connections. use 2 wrenches and do not use any pipe gunk on the threads as any contamination inside the lines can and will cause system failure.
i would also pull vaccuum for a few hours to ensure a low micron level. you really should have a micron guage when dealing with r410a, but you can just leave the pump on for an extended period of time. make sure to use fresh oil as well, once the vacuum pump oil becomes milky it has absorbed too much moisture. good HVAC mechanics will use fresh oil on every vacuum. the moisture is absorbed into the oil so use fresh oil!!! r410 is so picky and sensitive compared to r22.
R
RedRain
well nitrogen is a dry gas and will assist in drawing moisture from inside the lineset. a vaccuum guage will do this as well.
if you are only pulling vacuum to -20 then you still have a ton of moisture in your lines. you should be pulling to -30 and it should hold there until you open the valves. you can test for leaks by just pulling vacuum but this will also show you how much moisture is present in the lines. if you are pulling vacuum and your guage is at -30, but when you close your guage it starts creeping back up, but you have pressure tested with nitrogen and know there are no leaks preset there is moisture in the lines. sometimes it can take hours for a pump to rid a system of moisture. i have 1/2" hoses to pull vacuum and a pump that is ported, polished and balanced and has 1/2" instead of the standard 1/4" inlet ports. my pump pulls vac like no bodys business. yellow jacket / ritchie ad JB make good stuff. pressure testing with nitrogen is used when brazing, cutting or joining pipe to ensure your welds are holding. but nitrogen will assist in ridding moisture from a line. without a micron guage, you wont really know what is going on.
there is alot of things that can go wrong if you dont know/ dont check / dont have the proper stuff. Just take your mini split to an HVAC shop and have them braze threaded quick connects into your mini split. this way you can disconnect, move and reinstall and service without calling a pro into service, recover your system. you cant handle the refrigerant or get holding tanks without a license. you can spend all the money on tools, but wihtout the proper knowledge of how a system works or the principles of refrigeration you are better off taking it to a pro. you make your system totally DIY and you know its done right!!!
mini splits are so expensive and picky and hard to get parts, why do people use them? a normal full sized condenser gives you unlimited repair part access, -50 cold weather working, power efficiency. You can just as easy have brass quick connect taps installed on a house ac and air handler. you also get more air flow and the ability to use a programmable thermostat with a real ac.
the_extremist
Member
Okay, I just said "fuck it" and went all out. 5.5cfm two stage pump and a digital micron gauge are on their way. I have another one of these Mr Slims to install in a few months and maybe another after that so I might as well have good tools.
What I'm wondering now is, what kind of hose do I need to connect the condenser unit with the gauge and pump? 1/4"? What kind of fittings? I really would like to get a longer hose so I could run it through my line set penetrations before I seal them up with foam and have the pump down in the basement went I draw the vacuum test. I don't need the neighbors wondering what in the hell is making all that noise, ya dig? Is this possible?
What I'm wondering now is, what kind of hose do I need to connect the condenser unit with the gauge and pump? 1/4"? What kind of fittings? I really would like to get a longer hose so I could run it through my line set penetrations before I seal them up with foam and have the pump down in the basement went I draw the vacuum test. I don't need the neighbors wondering what in the hell is making all that noise, ya dig? Is this possible?
D
driftersmokinjo
Yup a gamble it always is even when doing everything by the book you still run into troubles some times. You are also right about some hvac guys skipping this part. I have been behind some rea hack's with a HVAC license and all the tools to do it right but leave them in the truck. It don't take a lot of smarts to do hvac or I would be out of work lol. Sounds like you did just fine. You got a good vacuum and that is the most important part. Good vacuum= no leaks
R.R. My reference to -20 was just a starting point . If it wont hold that there is no need to continue till you find the leak. If you continue to pull a vacuum and have a small leak you will pull moisture into the system.
D
driftersmokinjo
Better go with RedRain's idea if that is your plan. Doesn't sound like a normal install. Tell the hvac guys you talk to that you want to make it portable for your hunting/fishing cabin so the thieves won't get it while your gone. When you ad or take away length to your line set you also need to add or recover freon acording to line set length..also I would bet with all the members on here there is 1 that dose hvac in your area. how to contact them idk.
dunkydunk
Member
The manifold gauge will come with hoses, so long as you bought a gauge set appropriate for r410a (I know you did). vacuum pumps don't make a great deal of noise, just a loud purrrrr..... for the 20-30 minutes you need to run them. I forget what the fittings are called, but they are identical to inner tube fittings in function, they attach only to the outside unit. The gauge set should come with hoses.
The Mr. Slim, on the other hand, makes no noise whatsoever, they're awesome.
the_extremist
Member
I just want a long hose for the vacuum so I can use the pump inside. No changing the length of the line set here.
And I only ordered a digital gauge that reads in microns because I'm only doing the vacuum test, not pressure or anything else. Do I still need a standard gauge set if I have the micron gauge? I'm only drawing a vacuum because the unit comes pre-charged with refrigerant, correct?
D
driftersmokinjo
I would get the standard manifold gauge set. That way if you ever have a problem you will have the gauges to help diagnose problems in the future. For longer hoses (6 foot is most common) you can get them at any Hvac supply house and adapters to make longer hoses. with out a license.
Excellent info in this thread. CA certified journeyman electrician here and I was planning an install very soon. Thanks to the HVAC guys for chiming in! Funny seeing people on this board that I could potentially know from some jobsite somewhere in the past...
I had a couple question for some of you with experience with these units. I have two 10x10x8 rooms with an interior wall between them. Both rooms sealed, 4kw each. I want to run a single zone in the room nearest the exterior wall and run fans between the rooms for air exchange. If I have a high volume of air exchange between the rooms and a large enough unit for both rooms, will this work? Will there be a significant temperature difference between the two rooms (both rooms will be perpetual flower)? I'd imagine the key would be, of course, proper airflow between rooms. I was thinking the single zone Mr Slim 24k btu unit. Would I just be better off getting a dual zone? Will that be enough for cooling a total of 8kw with CO2 gen and dehums.?
Also, what do you guys think about the Viot vacuum pumps? The Yellow Jackets look sweet and all but the price on the Viot pumps would be a little easier to swallow. Even if they only do the job once or twice decently before crappin out, that would be fine by me. I know I wouldn't be able to just buy one of these pumps and guage sets and call myself an AC guy but the whole procedure seems easy enough...
Any insight is totally appreciated. Thanks in advance...
I had a couple question for some of you with experience with these units. I have two 10x10x8 rooms with an interior wall between them. Both rooms sealed, 4kw each. I want to run a single zone in the room nearest the exterior wall and run fans between the rooms for air exchange. If I have a high volume of air exchange between the rooms and a large enough unit for both rooms, will this work? Will there be a significant temperature difference between the two rooms (both rooms will be perpetual flower)? I'd imagine the key would be, of course, proper airflow between rooms. I was thinking the single zone Mr Slim 24k btu unit. Would I just be better off getting a dual zone? Will that be enough for cooling a total of 8kw with CO2 gen and dehums.?
Also, what do you guys think about the Viot vacuum pumps? The Yellow Jackets look sweet and all but the price on the Viot pumps would be a little easier to swallow. Even if they only do the job once or twice decently before crappin out, that would be fine by me. I know I wouldn't be able to just buy one of these pumps and guage sets and call myself an AC guy but the whole procedure seems easy enough...
Any insight is totally appreciated. Thanks in advance...
R
RedRain
rule of thumb is 3000w per 12,000btu (12K BTU = 1 ton)
i'd go with a 3 ton. if you are running burners and dehums. Dual zone is nice and would be what i would get in your situation.
on the pumps, you get what you pay for. i stick with yellow jacket/ritchie. i want reliability and accuracy. vacuum pumps draw moisture from lines and evacuate the lines of the environment. I am in the trade, so I don't mind spending a lil more for something that is tried, tested and true.
Thanks guys! I think I'll look into the 3 ton units. I'd definitely rather be safe than sorry.
As far as the pumps go, I completely understand what you are saying Rain, about getting what you pay for. In my situation though, if it works once and I have to throw it away (probably won't be the case) then that's fine by me. I just really want to avoid having a tech come out to my location.
DunkyDunk, can I ask what size pump you went with off the Viot site? They have a lot of pumps and from the pictures they don't look like bad units.
I'm still up in the air about how I want to handle this, but I do have a few more weeks probably before I have to decide.
Thanks again guys...
As far as the pumps go, I completely understand what you are saying Rain, about getting what you pay for. In my situation though, if it works once and I have to throw it away (probably won't be the case) then that's fine by me. I just really want to avoid having a tech come out to my location.
DunkyDunk, can I ask what size pump you went with off the Viot site? They have a lot of pumps and from the pictures they don't look like bad units.
I'm still up in the air about how I want to handle this, but I do have a few more weeks probably before I have to decide.
Thanks again guys...
the_extremist
Member
Okay, I have everything I need except for hoses to hook up the Micron gauge and the vacuum pump. What do I ask for at the HVAC supply house? 1/4" SAE? Can I get them 10+ feet long?
dunkydunk
Member
I don't remember off hand, it's a two stage unit and it cost a little over a $100. It's solidly built, and a cute little bugger all yellow and blue. With a mini split, you are only pulling vacuum on 25 feet of line. The Viot (1.58 cfm, 2 stage, there was no model #, I just went and looked) drew down the lines in seconds. You can see the water vapor boil through the vacuum pump oil on a little Jules Verne window on the pump. After 45 seconds, the window went clear. I think you pull 90% of vacuum pretty quickly, after all, how many cubic feet of volume is in 25' of skinny copper pipe? I let the pump run for at least 30 minutes, they recommend 20, and all was good.
I love my little Viot pump, purrs like a kitten, sucks like a mother...
I wish I could use it more often.
G
Guest 18340
It's worth mentioning again; Make sure the flares on the line set are perfect! Especially the smaller diameter tube.
In the install instructions that come with the Mr.Slim theirs a diagram of what the flare should look like.
I installed my Mr.Slim exactly the way dunkydunk installed his mini split and it has worked flawlessly. Pay attention to detail and installing one is a breeze.
In the install instructions that come with the Mr.Slim theirs a diagram of what the flare should look like.
I installed my Mr.Slim exactly the way dunkydunk installed his mini split and it has worked flawlessly. Pay attention to detail and installing one is a breeze.
the_extremist
Member
