Hello folks, This story can get long and drawn out but I'll try to shorten this starting comment so you get the Idea. My house is a vintage 1965 with NO central air conditioning. I have been researching A/C only mini splits and so far I believe I need a 24,000 BTU unit. I need to cool about 1000 sqft. I can only use a single wall unit inside area because of wall space. I also only have a 150 amp panel which I'm gonna run a 240 volt line to it and remove one of my baseboard electric heaters to give me room in the box. So far I've looked at Daikin, Mitsubishi, Della and a couple others. I'm going to install this myself and have some very good help to assist me. What I'm asking is your input on experiences, service, parts, and over all qualities of various units. I am fully open and all ears on suggestions. I'm running 2 window units now and my electric bill for June was $487.00 and July's was $595.00. And I know why, the A/C window units are draining the 120 Volt power hard. One is 12,000 BTU and the other is 8000. This is killing us. Now, we are in New Jersey. Any advise/guidance please from you HVAC folks would be really appreciated! Thanks, Dave.
I'm not an HVAC guy, so pardon my butting in, but I put in a Mitsubishi mini-split system a few years ago, mainly for AC and humidity control. I installed everything and my son-in-law, who IS an HVAC guy, connected it up and charged it for me. Prior to that all we had used for climate control for 35+ years was a woodstove, with a single propane heater for backup for the last 15 years as we began to travel once the kids had moved out. This has been one of the better investments I've made, being trouble-free so far. It sure is nice to come inside from some of these hot humid days we've had lately, and cool and dry off.
I’ve heard about the ‘mini splits’ not sure what’s involved, many seem happy. I have a 2 story house, central A/C, 1996 vintage. The issue is the one zone, so the 2nd floor rooms get warm. I did some research & ended up with a fairly powerful free standing A/C unit, vented to a window. Mind you, these upstairs rooms, 1 or 2 only have to be cooled periodically, son home from military, visitor, whoever. So far I am pleased with the setup. With the door open it cools more than the one room, quiet. I’m not home now, bought on Amazon. There’s a co in WI that makes 1/4” plexiglass type inserts that fit where the screen goes for venting. This works best with crank out windows. Just throwing it out there as a lower cost, DIY solution, for some.
I wonder also if a newer window unit would use less electricity? Now Summer temps are half over, is your window unit older?
Just to be clear here, if you are considering doing this to cut your AC electric bill "in half", going to 240V will not do that. The same amount of work being done requires the same amount of electrons flowing. Now, it's possible that the mini split system MAY be slightly more efficient than the window units, but I'm not sure it'd be enough to be worth it. Back in 2012 when I took out our old (original 1940) coal converted to oil furnace to be replaced with the wood/oil combo furnace (since been replaced too) I had our whole central HVAC system ripped out and our AC was done via a single (older) 12k BTU window unit upstairs. Our house is a cape cod style, so we were cooling the whole upstairs and ground floor...about 1800 sq ft total. It worked surprisingly well, and I don't recall our electric bills being especially spicy either. Do you feel like your insulation and air sealing is pretty decent on the house? I know people that have "free" wood for heat often ignore insulation and air sealing shortcomings. Just curious what your electric bills are normally...and what your kWh usage is?
I understand the factors of the bill situation. A 240 unit will not have to work as hard and pull the amps that the window A/C unit is trying to do. Also, the window unit never shut off, even in the evenings. I also added a full layer of R-13 Insolation on top of what we had originally in the attics, it was the old school blown in crap, and it settled bad over the years. Also, I'll mention we had a severe Voltage issue in this grid and sometimes the power would get down to as low as 95 Volts to the outlets. YES, I complained and complained... They said it was from the load on the grid. Along with that, the AC unit would also trip the circuit breaker, 15 amp because it was pulling so many amps. The AC say's on the side at normal run it's pulling 9.3 amps. It shouldn't be tripping a breaker and it was. Now that the heat wave is over, our voltage and tripping issues have gone away.
The amps will be lower (per leg), but the total watts will be the same (if you are comparing the exact same unit on 120 vs 240) and that's what you are billed on, total watts used. Now if you need to do this to balance out the 2 legs of the breaker panel, then going 240 would help with that. That's terrible! 120V +/- 10% is about the limit that many things will tolerate (5% is considered "acceptable") but you are double that! I'm really surprised you (and everybody) haven't had issues with things burning up!
I am very good friends with our local USCG base, "High voltage" electrician. He said the exact same thing you said. I don't ever claim to be an electrician, but I understand it well and have done all my own wiring on my addition and 2 out buildings. I did take a 10 week course on "electrical home wiring", but again I'm NOT an electrician.
This is also exactly what he said as well, this is why I'm going the 240 route. The window air conditioner was just working way too hard to keep up. Also keep in mind, we had 6 days at one point over 100º's outside and in the mid to high 80's all night. I even had to get up in the middle of the night and shower off.
Dave, have you done an energy audit on your house? This generally includes a blower door test and identifies air sealing and insulation issues usually less than $400 dollars and a lot of electric companies subsidize it.. I have been a General Contractor (not an HVAC specialist) it is my opinion that insulation and weather sealing is a far greater cost benefit solution than putting in more BTUs with that being said the coefficient of mini splits are generally 4 times regular traditional units. Mitsubishi have best rep according to my guy but currently the Daikin has 10 year warranty.. Mitsubishi know this and prices accordingly bogieb has a thread on them and seems very pleased it, adding mini splits, is on my construction plans for this summer as my beautiful bride, who loves her Dave lights BTW, believes the proper inside air temperature should be 60° or less in summer! Window shaker AC are too loud
Any idea how well the A and the B leg in your existing panel is balanced, for the way you are using it currently (lil electrical pun there ) So when you went through this hot spell, do you have any idea the results if you had put a clamp-on ammeter on the incoming legs? (A & B) Would they be relatively the same load? If yes, then changing to a 240V unit will do very little for you (like I said before, other than the potential for an efficiency gain in old skool AC vs the mini split) If not balanced, then simply shuffling a few breakers around in the panel (between A & B leg) can balance the loads, for the way you are loading the wiring/panel in your house, currently Most people don't realize that every other breaker going down the rows in the panel are on the opposite leg. So breaker 1,3,5,7,9 etc are on leg A, then 2,4,6,8 are on leg B, or some variation thereof. I was just about to say the same thing...and it made me wonder about it when Dave said the AC never shut off, and he still had to shower in the middle of the night to cool down. Normally, even if the AC doesn't have the power to cool the house to XX temp, it does still dehumidify the house, which makes a huge difference in comfort, despite the temp. This assumes that the AC is working correctly (do we know the outlet temp of the AC units?) so it made me think: insulation/air sealing issues? One thing that makes a HUGE difference in how well it all works, and how long the AC runs is using the ceiling fans running in summer mode (pushing down) Our central AC was running for several hours at a time (unusual) during that last hot spell, and it finally caught my attention that someone (probably the kids) had shut a couple of the ceiling fans off...I turned them back on and it wasn't 3-5 minutes after that, the AC turned off. Normal, for us, is that the AC will run for an hour or a lil more, then off for say 2 (during extreme heat) or during more "normal" summer weather it'll run 1-2 times for the whole day...usually in the evening, when the brick starts to radiate through the walls a little. I'm probably not saying anything that Dave isn't aware of already with this stuff, but hey, I'm on my lunch break and sitting here typing prolongs my time in the office (AC )
Im just came in from outside, it was a beautiful day.. I'll write the book tomorrow and give you all some basic Idea of things. Simply put, I've lived in this house since 1965, from my childhood until I purchased this from my father in 1985. I have made MANY Improvements to this home, new windows, extra Insulation, etc... Things have gone wacky in the last few years and I'm thinking there is MUCH more to this story and it could go political.... Just do some research on what the (Left) politicians have done in this state with the Electric companies. I really didn't want to go there but please, (RESEARCH) it... You'll find it.
A min-split will absolutely use less electricity than general window and/or portable AC's. I had a 2019 6k BTU window unit in my office (needed for WFH as it gets very hot from all the electronics running). I would close the doors to that room so it didn't try to condition the kitchen also. I also had a 12k BTU portable AC in the living room (also 2019 model). I would close off the doors to the bedrooms, and sometimes the bathroom too and on hot days the units would struggle to keep a decent temp (I mean 76-78*) during the afternoon when the western sun beats on the house. Keep in mind, this is a 960 sq/ft house and is only 2x4 construction so cannot hold much insulation. I replaced the window/portable units with a 24k BTU outside condenser (Fujitsu) in 2021. I have a 16k head in the living room and a 12k head in the office. nd the Electrical usage and cost went down (and the noise went down too). The house temp stays more even, and the bedrooms stay within about 2* of the main parts of the house. All of that was prior to having solar installed. Now for heating, they do suck a bit of juice.
Hmmm...I dunno that it's efficiency really, but most power in a smaller package is more like it. (For a given HP) And the wiring/switchgear can be smaller than a lower voltage/single phase too. The wiring to feed a 20 HP 120v motor would be huge, but for a 3 phase/480v, it's just 3 #10 wires n a ground. It's kinda like comparing a single cylinder engine to a twin, or 4 cylinder...or maybe a V8.
