Multiple Single Zones..or..Single Multi Zone?

sixthwheel · 04-20-14, 08:01 PM

This is my first post, here. I love all the DIY projects you guys/gals have documented so well.

What would be more efficient for the 2 rooms I want to heat or cool? A dual zone LG unit with 9k and 12k wall mounts at 21 SEER when both units are running. Or 2 single zone LG units. The 9k at 28 SEER and a 12k at 26 SEER.

We cool both zones 24/7 during the summer months. Heating would be minimal in the bedroom during the winter months. The milder seasons, we just keep the room we're using at the time comfortable. So probably 50/50 for half the year.

I gather that the dual zone systems are most efficient when both indoor units are running. But I don't know how much less efficient they are with only one indoor unit running. And I need to figure in the extra power required to run 2 outdoor units if I go with two single zone systems.

Thanks

jeff5may · 04-21-14, 07:13 PM

Something to consider: with the small single units, the outdoor unit is usually the same physically. When rigged to a certain indoor unit, the ODU adjusts its capacity to match. That's why the 3/4 ton combo is rated for a higher seer than the 1 ton combo. Since it's loaded down less, it operates more efficiently.

Question: are you trying to replace your existing system with mini-split units, or trying to supplement what you have already with a higher-efficiency source? Your response makes a big difference.

sixthwheel · 04-22-14, 12:52 AM

This will replace the roof A/C and also the propane furnace in my 36' fifth wheel RV. I'm looking for 9k in the bedroom and 12k in the kitchen/living room. My wife and I travel the U.S. and this is our home.

Thanks

ecomodded · 04-22-14, 03:31 AM

The outdoor unit weighs 120lbs and is 3 feet tall

Your 36ft trailer will not require 20,000 BTu's to keep cool , or warm.

my 2000 sqft home would, to help put things in perspective for you.

If the trailer does not travel I would look for 2 5000btu (someone must sell them) indoor units and 1 9000BTu outdoor unit.

jeff5may · 04-22-14, 06:17 PM

How mobile or portable do you need it to be? As ecomodded stated, the ODU's tend to weigh a lot, and are cumbersome to handle. Also, the refrigerant lines are rigid. To be very flexible, you would need to replace the refrigerant lines with fridgie flex hose ($$$).

If you do go with a mini-split unit, I would get a cassette indoor unit with some kind of split outlet. I would pipe the supply air to both zones, and use louvers or something to direct the flow. Then, you can use the remote control in whatever room has priority. The thermostat is built into the remote control on most mini-splits; a wired, stationary thermostat may or may not even connect to the unit.

NiHaoMike · 04-22-14, 06:19 PM

Just go with a window heat pump or two.

sixthwheel · 04-22-14, 11:20 PM

ecomodded:

Thanks for the advice. I'm looking at the Mitsubishi 6k's and the Daikin 7k's. It would be nice to have the narrower width indoor units. This rig has 5 slides, so I gain quite a bit of space once she's opened up. If I had to go with fewer BTUs, I think I'd rather stick with LG and use two 9k's. The Mitsubishi, Daikin, Fujitsu and others with 7k units would provide fewer BTU's, a lower SEER/HSPF rating and cost $500 to $1000 more for the system. I read that an oversized system would cool the space down too quickly and not properly dehumidify. Don't they pretty much run constantly? Can you not start at a higher temp and gradually bring it down? Are there any other downsides?

jeff5may:

The roof A/C on my rig weighs 100+ lbs, so I'll only add a bit more weight than I'm removing. As far as mobility, I have 2 choices for mounting the outdoor unit. I can have a support welded to the tail end and use rubber shock mounts. I could have a full frame or cage welded around it so I could attach it at 4 points. It would be a lot stronger than what you see holding them on the sides of buildings.

What I would prefer is to mount it on heavy duty slides in the basement storage area. It's a huge space and has 34" of height. The LG is 32" tall, so I'm sure I can make it work. The propane furnace that I plan to remove is down there. I'll just need to reroute some plumbing pipes and install a door. I've looked into the flexible refrigerant lines enough to know that they exist. I've never seen a price, but I'm sure they are pricey. I believe that with a wide enough loop of regular copper lineset, I can slide the tray out without kinking it.

NiHaoMike

We used 2 window units in our old rig when the roof unit died. Some parks we stay in don't allow them. The wife says it looks "too ghetto" and she ain't havin it with this newer, nicer rig. We used a 5k window unit in the bedroom, and it was great most of the time. It would struggle a bit on very humid nights. We had a 9k for the rest of the rig and it made it tolerable, but never what I'd call "comfortable" during the day. I know the mini splits are way more efficient so you can't really compare them to window A/C's.

You've also got to keep in mind, this is an RV, not a house. The walls are about 2" thick with aluminum studs. I think they use some kind of polystyrene foam board sandwiched between the inner and outer walls. Lots of windows, all single pane. Nothing I can do to make it better. I wish the ceiling was done that way. I'd like to fill it with expanding foam. That said, I can tell it's insulated better than our old rig by just how quiet it is inside. For now, I'll have to live with the losses.

Does anyone have any thoughts about my original question? Singles or Multi?

Thanks

ecomodded · 04-23-14, 12:42 AM

Quote:

Originally Posted by sixthwheel

ecomodded:

Thanks for the advice. I'm looking at the Mitsubishi 6k's and the Daikin 7k's. It would be nice to have the narrower width indoor units. This rig has 5 slides, so I gain quite a bit of space once she's opened up. If I had to go with fewer BTUs, I think I'd rather stick with LG and use two 9k's. The Mitsubishi, Daikin, Fujitsu and others with 7k units would provide fewer BTU's, a lower SEER/HSPF rating and cost $500 to $1000 more for the system. I read that an oversized system would cool the space down too quickly and not properly dehumidify. Don't they pretty much run constantly? Can you not start at a higher temp and gradually bring it down? Are there any other downsides?

Thanks

the narrower width indoor units would be worth the lost Btu's in your case, as space is at a premium. Paying more for less goes against my nature but sometimes you have to do what is best more then what is cheapest. I Work part time in Sales, Kidding.. But I do have expensive taste! true

As to them running constantly , in your trailer it will cycle more frequently and for shorter duration then for others as your heating and cooling about 200sqft the unit will be finished heating or cooling fast.

I believe the moisture removal rate is directly rated to the units size, although a small unit will remove less moisture in a given amount of time it will run for slightly longer to maintain the temperature and may well remove similar amounts of water in the same 24hrs.

Some others on the site are much more knowledgeable about mini splits then me , but I have been study up on this stuff , I am pricing my own 2 units now.

jeff5may · 04-23-14, 07:46 PM

If you have room, it sounds like the best rig for you is a 9k unit and a 12k unit. Make sure and get inverter (variable speed/capacity) units. That way, if the load is heavy, they can put out the btu's. When the load is light, they can slow down, saving power and money. The price tag is bigger, but they are definitely worth it. Rather than slamming on and off like a window shaker, the inverter units start up slow and quiet. If you crank the remote to max, they're still not loud indoors.

I've heard mixed opinions about the LG units. Some people love them, but most who have used certain other brands tend to like the other one better after awhile for one reason or another. (Mitsi is not one of those brands. people either adore or loathe Mitsi units...) Some brands to look into are Gree, Midea, and Shinco. These three mfr's make at least 50 other companies' units, branded as whatever (GE, Whirlpool, Daikin, Haier, Soleus, etc.). Samsung is another, but I haven't heard much about their units (except that they cost $$$ like Mitsi, Fuji, Daiken).

To be able to mount the ODU's on a slide rack would be awesome! If you go that way, I would definitely get some short flex hose to go between the ODU's and the stationary part of the system. That way, you can run all the wires and hoses in a loom tube or umbilical bundle and not have to worry about leaks. Once you get into the body of the vehicle, you can run copper lines to the indoor units. just make sure to secure them solidly to prevent vibration and physical contact with other hard objects. Most people run armaflex between and around the wires and pipes leading to each IDU as cheap insurance against mayhem.

pinballlooking · 04-23-14, 08:26 PM

If you like the LG check out Gree Terra series.

Terra Series - Ductless Wall Mount Heating and Cooling | Gree Comfort

https://www.acwholesalers.com/Gree/G...inCat=&subCat=

We have LG duel Zone and a Gree we like the Gree better. 27 Seer is pretty sweet.
My LG is LMU187HV the one you have the PDF link to.

http://ecorenovator.org/forum/geothe...nstall-12.html
post 115 I compare both units.

04-21-14, 07:13 PM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Something to consider: with the small single units, the outdoor unit is usually the same physically. When rigged to a certain indoor unit, the ODU adjusts its capacity to match. That's why the 3/4 ton combo is rated for a higher seer than the 1 ton combo. Since it's loaded down less, it operates more efficiently. Question: are you trying to replace your existing system with mini-split units, or trying to supplement what you have already with a higher-efficiency source? Your response makes a big difference. Last edited by jeff5may; 04-21-14 at 07:14 PM.. Reason: words

04-22-14, 03:31 AM	#4
ecomodded Supreme EcoRenovator Join Date: Sep 2012 Location: Vancouver Island,Canada. Posts: 1,037 Thanks: 116 Thanked 100 Times in 87 Posts	The outdoor unit weighs 120lbs and is 3 feet tall Your 36ft trailer will not require 20,000 BTu's to keep cool , or warm. my 2000 sqft home would, to help put things in perspective for you. If the trailer does not travel I would look for 2 5000btu (someone must sell them) indoor units and 1 9000BTu outdoor unit. Last edited by ecomodded; 04-22-14 at 03:35 AM..

04-22-14, 06:19 PM	#6
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	Just go with a window heat pump or two. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

04-22-14, 11:20 PM	#7
sixthwheel Lurking Renovator Join Date: Aug 2013 Location: texas Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	ecomodded: Thanks for the advice. I'm looking at the Mitsubishi 6k's and the Daikin 7k's. It would be nice to have the narrower width indoor units. This rig has 5 slides, so I gain quite a bit of space once she's opened up. If I had to go with fewer BTUs, I think I'd rather stick with LG and use two 9k's. The Mitsubishi, Daikin, Fujitsu and others with 7k units would provide fewer BTU's, a lower SEER/HSPF rating and cost $500 to $1000 more for the system. I read that an oversized system would cool the space down too quickly and not properly dehumidify. Don't they pretty much run constantly? Can you not start at a higher temp and gradually bring it down? Are there any other downsides? jeff5may: The roof A/C on my rig weighs 100+ lbs, so I'll only add a bit more weight than I'm removing. As far as mobility, I have 2 choices for mounting the outdoor unit. I can have a support welded to the tail end and use rubber shock mounts. I could have a full frame or cage welded around it so I could attach it at 4 points. It would be a lot stronger than what you see holding them on the sides of buildings. What I would prefer is to mount it on heavy duty slides in the basement storage area. It's a huge space and has 34" of height. The LG is 32" tall, so I'm sure I can make it work. The propane furnace that I plan to remove is down there. I'll just need to reroute some plumbing pipes and install a door. I've looked into the flexible refrigerant lines enough to know that they exist. I've never seen a price, but I'm sure they are pricey. I believe that with a wide enough loop of regular copper lineset, I can slide the tray out without kinking it. NiHaoMike We used 2 window units in our old rig when the roof unit died. Some parks we stay in don't allow them. The wife says it looks "too ghetto" and she ain't havin it with this newer, nicer rig. We used a 5k window unit in the bedroom, and it was great most of the time. It would struggle a bit on very humid nights. We had a 9k for the rest of the rig and it made it tolerable, but never what I'd call "comfortable" during the day. I know the mini splits are way more efficient so you can't really compare them to window A/C's. You've also got to keep in mind, this is an RV, not a house. The walls are about 2" thick with aluminum studs. I think they use some kind of polystyrene foam board sandwiched between the inner and outer walls. Lots of windows, all single pane. Nothing I can do to make it better. I wish the ceiling was done that way. I'd like to fill it with expanding foam. That said, I can tell it's insulated better than our old rig by just how quiet it is inside. For now, I'll have to live with the losses. Does anyone have any thoughts about my original question? Singles or Multi? Thanks Attached Thumbnails

04-23-14, 07:46 PM	#9
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	If you have room, it sounds like the best rig for you is a 9k unit and a 12k unit. Make sure and get inverter (variable speed/capacity) units. That way, if the load is heavy, they can put out the btu's. When the load is light, they can slow down, saving power and money. The price tag is bigger, but they are definitely worth it. Rather than slamming on and off like a window shaker, the inverter units start up slow and quiet. If you crank the remote to max, they're still not loud indoors. I've heard mixed opinions about the LG units. Some people love them, but most who have used certain other brands tend to like the other one better after awhile for one reason or another. (Mitsi is not one of those brands. people either adore or loathe Mitsi units...) Some brands to look into are Gree, Midea, and Shinco. These three mfr's make at least 50 other companies' units, branded as whatever (GE, Whirlpool, Daikin, Haier, Soleus, etc.). Samsung is another, but I haven't heard much about their units (except that they cost $$$ like Mitsi, Fuji, Daiken). To be able to mount the ODU's on a slide rack would be awesome! If you go that way, I would definitely get some short flex hose to go between the ODU's and the stationary part of the system. That way, you can run all the wires and hoses in a loom tube or umbilical bundle and not have to worry about leaks. Once you get into the body of the vehicle, you can run copper lines to the indoor units. just make sure to secure them solidly to prevent vibration and physical contact with other hard objects. Most people run armaflex between and around the wires and pipes leading to each IDU as cheap insurance against mayhem. Last edited by jeff5may; 04-23-14 at 07:53 PM.. Reason: words

04-22-14, 12:52 AM	#3
sixthwheel Lurking Renovator Join Date: Aug 2013 Location: texas Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	This will replace the roof A/C and also the propane furnace in my 36' fifth wheel RV. I'm looking for 9k in the bedroom and 12k in the kitchen/living room. My wife and I travel the U.S. and this is our home. Thanks

04-22-14, 06:17 PM	#5
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	How mobile or portable do you need it to be? As ecomodded stated, the ODU's tend to weigh a lot, and are cumbersome to handle. Also, the refrigerant lines are rigid. To be very flexible, you would need to replace the refrigerant lines with fridgie flex hose ($$$). If you do go with a mini-split unit, I would get a cassette indoor unit with some kind of split outlet. I would pipe the supply air to both zones, and use louvers or something to direct the flow. Then, you can use the remote control in whatever room has priority. The thermostat is built into the remote control on most mini-splits; a wired, stationary thermostat may or may not even connect to the unit.

04-23-14, 08:26 PM	#10
pinballlooking Super Moderator Join Date: Jun 2013 Location: SC Posts: 2,923 Thanks: 172 Thanked 564 Times in 463 Posts	If you like the LG check out Gree Terra series. Terra Series - Ductless Wall Mount Heating and Cooling \| Gree Comfort https://www.acwholesalers.com/Gree/G...inCat=&subCat= We have LG duel Zone and a Gree we like the Gree better. 27 Seer is pretty sweet. My LG is LMU187HV the one you have the PDF link to. http://ecorenovator.org/forum/geothe...nstall-12.html post 115 I compare both units. Last edited by pinballlooking; 04-23-14 at 09:37 PM..