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diy solar

Move whole-house AC or get a window AC unit?

I have an existing very efficient 4ton ducted R22 A/C W/propane furnace. I will be replacing it later this fall with a modern 4ton inverter heat pump. There will be at least one rebate to help reduce the cost and the current R22 system is obsolete anyway. The new central system will be less efficient than the existing cooling and heating but I am also adding a decent size PV installation w/40kwh of battery this summer so energy costs will be reduced anyway. That said, I am now installing an EG4 24K hybrid mini-split heat pump that will initially only have PV power, so AC or Heat is daytime only. Later it will also get AC power for night operation. The EG4 24K will cover the core areas of the house directly and the three bedrooms and man cave indirectly. House is fully insulated w/6" walls. I expect the 24K to do fine under normal conditions, but under 20F or over 100F the 4ton may be required. Just received two pallets from Signature Solar today, one was the EG4 24K heat pump, the other all EP Cube, the work starts now.
 
chrisski said:
Sounds like you have a 5 ton unit. Nothing beats central air. If you get minisplits all those rooms in your house that have vents that don’t have a minisplit, will get warm. For me there’s four rooms I want a four head minisplit to cover, but this leaves off a pantry, bathroom, and a laundry room that central air covers. I’m looking at central air with an inverter air conditioner, but only if it will it really uses less energy to do the same cooling, I’m kind of lacking in stats on searches.

I have a 4.5 kw 4 ton AC on a critical loads panel. The installer did not want to go bigger. Basically, the 8 kw inverter actually runs around 6 kw constant, so can’t give more power than that.

Also, if you use this critical loads panel to run off batteries several hours a day, will need to check to see if the 18 k can handle the start up surge. My outback is a beast of a low frequency inverter, but would not handle the start up surge of a 5 ton.

A soft start would limit the start up surge. I have a hard start. I don’t know what happens if I remove the hard start and put a soft start in. I assume it works better. When I tried, there were 4 capacitors in the AC with no documentation of what is what, so I did not install the soft start my self.
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I install inverter heat pumps all the time.
One house i reworked had three gas furnaces with ac feeding thebupstairs rooms, and one gas furnace with ac feeding the main floor.
I replaced that with a single 5 ton inverter system with 3 zones upstairs, all have own thermostat still, and a single 3 ton inverter system tied to a 97% efficient gas furnace downstairs operating with a dual fuel thermostat.
They went fro 1800/ month power bills in summer to 720 a month, and gas bill dropped from 2200/ month to 620 a month.

Heat pumps work, and inverter variable units are extremely efficient, they have zero startup surge, and they have lower operating amps, even in full output mode.
 
Supervstech said:
They went fro 1800/ month power bills in summer to 720 a month, and gas bill dropped from 2200/ month to 620 a month.
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How big a house is that to have a $720 per month electric bill? My entire electric bill for the year was $800 for my 1,300 square foot house before I got solar. I don’t skimp on using electricity, but I don’t waste it either.
 
reader2580 said:
How big a house is that to have a $720 per month electric bill? My entire electric bill for the year was $800 for my 1,300 square foot house before I got solar. I don’t skimp on using electricity, but I don’t waste it either.
Click to expand...

2300 sqft in Phoenix can see nearly $500/month in the hottest months and that's with using time-of-use benefits, or it would be higher. Average across the year is about $230-240/month.
 
reader2580 said:
How big a house is that to have a $720 per month electric bill? My entire electric bill for the year was $800 for my 1,300 square foot house before I got solar. I don’t skimp on using electricity, but I don’t waste it either.
Click to expand...
It is a 200 year old house in the myers park area, approximately 3800 sq ft.
Three apartments on top floor, and a large main floor residence.
 
I run a mini-split off solar in the master bedroom. I started to leave the door open and put a fan in there to share to cold to the other 2500 sq ft. It made a huge difference in my power bill and humidity in S Florida. It runs 24-7. I was considering putting a 2nd one in the TV room. It is my #1 load. I put a soft starter on my 5 ton HVAC but decided not to try to power it right now.
 
inowhavesolar said:
My wife and I are having this debate on which would be better for keeping the house cool, and keeping electricity bill low. There are 2 options:
  1. Purchase a high-efficiency window AC unit (12000+ BTU), and place it in the living room. Solar+battery will keep this running 24/7, blowing cold air into the room, which will slowly make its way throughout the house, lowering the house temp, thereby making the whole-house AC not needing to run. Pros: Powered 100% by solar. Keeps main AC from running. Cons: Visually unappealing window unit in main living space (ie: looks "cheap"). Cold air might not permeate to far edge rooms the house.
  2. Move 50A AC breaker to critical loads panel. Perfectly sunny days should make 5-6K watts from panels, which will offset running the AC. (Sticker on the compressor unit says 35A running load x 240v = 8400W). The battery will supplement the remaining watts, which charges from grid once it drops below 30% SOC. Pros: Whole house AC. No unsightly window unit. Cons: Solar+Battery might only give 1-3 cycles of "solar powered AC" per day. The AC will probably cycle 15-20 times a day during 99F+ summer months.
I've got an EG4 18K + EG4 WallMount Pro (280Ah). Has anyone done this cost comparison? I'm in favor of option 1, while she likes option 2.
Click to expand...

I wonder if better roof and ceillings insulation could help, and also if you have a lot of large windows facing the sun,
I noticed those external windows shades preventing the sun fom heating the windows but still allowing enough light passing through.

Screesns 01s .jpg Screesns 02 s.jpg
 
Another minisplit vote. I'm running them in a 4000 sqft home and they use a very small amount of power most of the time. Average 28,000 btu unit uses 400 to 600 watts cooling and 45 watts for the fan when the compressor is off. They can use 2200 watts but its very rare they go over 600 most of the day. I keep the first floor of the house around 71F degrees with it being 95F outside. The second floor stays around 95F during the day and 87F at night most of the summer. I plan on eventually adding cooling for the upstairs.
 
sunshine_eggo said:
Even so, I'm seriously considering getting the 2 ton PV/AC hybrid minisplit to offset my 5 ton unit.
Click to expand...

FWIW, I am no longer considering this (the EG4 2 ton PV unit). My goal would be to over-panel the unit to get 4-5 hours of max power operation daily. Unfortunately, the array limitations on that unit barely allow for sufficient PV power to run it at peak output.
 
sunshine_eggo said:
Do you turn them off when not in the room? That's one of the banes of off-grid living... While things like ceiling fans can provide comfort at higher temps, they tend to be left on 24/7. We probably gobble 6-7kWh in 3-4 ceiling fans alone.

We have something my wife calls the "grundle fan". It's simply a small carpet dryer on the floor that can be aimed up at a 45 or 90° angle. Hopefully, the location and orientation yields an understanding of its name... I will clarify if needed.

ANYWAY... that little bastard moves a LOT of air, and it burns about 120W even on low... and yeah... it gets left on ALL the time unless I turn it off... and I'm of that age that doesn't like to bend over for anything. We actually have three of them, and I use them to help with air distribution in the rooms that are less comfortable... Works great.
Click to expand...

A typical ceiling fan burns about 15w, that's 360wh per day per fan. I have a fan in all three back rooms and one in the living area. Kind of a joke, just leave them on. We have a few floor fans for the hot-flashy femme-fatale, most claim ~ 20 - 35W on the various labels, and they move some air. I have a Harbor Freight floor fan that is ~150W. It is so loud I can't stand it even on low, but on high it will move a small sailboat. The smaller the blade the less efficient the fan per cfm of air moved, and the louder it will get to move the same amount of air.
 
ksmithaz1 said:
A typical ceiling fan burns about 15w, that's 360wh per day per fan. I have a fan in all three back rooms and one in the living area. Kind of a joke, just leave them on. We have a few floor fans for the hot-flashy femme-fatale, most claim ~ 20 - 35W on the various labels, and they move some air. I have a Harbor Freight floor fan that is ~150W. It is so loud I can't stand it even on low, but on high it will move a small sailboat. The smaller the blade the less efficient the fan per cfm of air moved, and the louder it will get to move the same amount of air.
Click to expand...
Can you send a link to this15W fan? I see wattages consistent with 6-7 kWh a day for three.
 
sunshine_eggo said:
FWIW, I am no longer considering this (the EG4 2 ton PV unit). My goal would be to over-panel the unit to get 4-5 hours of max power operation daily. Unfortunately, the array limitations on that unit barely allow for sufficient PV power to run it at peak output.
Click to expand...

The problem with trying to run things off dedicated PV, is when you don't have PV they don't work, or must run off an alternative source. Further if it doesn't need to run, now you have PV that cannot be used for anything else. I think for overall ROI your best bet is to pump as much PV as you can get into your power plant, where it gets distributed and stored as best works for your loads. The conversion losses are completely swallowed by the ability to maximize utilization of the provided power.
 
chrisski said:
Can you send a link to this15W fan? I see wattages consistent with 6-7 kWh a day for three.
Click to expand...
www.hunterfan.com

Panama ENERGY STAR DC 54 inch with Remote Ceiling Fan

Panama ENERGY STAR DC 54 inch with Remote Ceiling Fan | Casablanca - Rich in history and tradition, the Panama is a true classic. Inspired by evolutions in the automobile industry, this product has been revamped and revitalized while keeping the foundation and integrity that makes it one of our...
www.hunterfan.com www.hunterfan.com
Big momma 22w. But most people don't run them on high all the time. On medium/low most fans run about 15w. Of course Eggo's significant may keep them at maximum squeak/noise. Typically, around 15 watts on low, up to around 30 on high depending on the fan. It will move move air more efficiently at higher speeds, but usually you just want stir.
 
I've been wanting to put in a mini split with two air handlers, but in the meantime.. I've been running a 12K Midea unit (inverter based compressor) and have been pretty pleased.
Just this one window unit does quite well keeping my whole uppermost floor cool (2 bedrooms and a master bathroom), which seems to keep the whole house reasonable. Even this last week as we've had days in the lower/mid 90s, my main floor hasn't gotten above ~74f with just the window unit going upstairs.
A mini split would do the same if not slightly better, and I'd really like a heat pump to be able to heat a bit with excess solar too.

ksmithaz1 said:
www.hunterfan.com

Panama ENERGY STAR DC 54 inch with Remote Ceiling Fan

Panama ENERGY STAR DC 54 inch with Remote Ceiling Fan | Casablanca - Rich in history and tradition, the Panama is a true classic. Inspired by evolutions in the automobile industry, this product has been revamped and revitalized while keeping the foundation and integrity that makes it one of our...
www.hunterfan.com www.hunterfan.com
Big momma 22w. But most people don't run them on high all the time. On medium/low most fans run about 15w. Of course Eggo's significant may keep them at maximum squeak/noise. Typically, around 15 watts on low, up to around 30 on high depending on the fan. It will move move air more efficiently at higher speeds, but usually you just want stir.
Click to expand...
A DC ceiling fan is not a 'typical' fan... fwiw. They exist, but they're more the exception than the norm.
 
I’ve been surprised how little fans cost in terms of incremental use on grid. Basically free.
 
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