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Old 07-22-14, 09:41 AM   #1
pinballlooking
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Default Mini Split install in a small bedroom 137.5 Sq FT

I am thinking about putting a Mini Split in a small bed room. It is 137.5 sqft.
I am looking at the same Mini Split I put in my bedroom it is a 9,000 btu Gree inverter 27 seer unit.

I have two bed rooms this size so I would install a MS in each of them.

I know 9000 BTU seems big for a small bedroom but reading the specs

Cooling Capacity (Min-Max) 9,000 (3,500-9,600)
Heating Capacity (Min-Max) 9800 (2,200-11,000)

This seems like it would work at the lower sides of it.
https://www.acwholesalers.com/hvac/p...D3DNA1A-sp.pdf

We would have mini splits in all the bed rooms so at night I would adjust the duel zone Mini Split hotter or cooler at night and use the bedroom MS to keep cool or warm. This would allow me to use natural gas heat only on the coldest nights.

The kids rooms do not stay very consistent temps right now that we are using MS in just using the Dual MS and ours we don’t really use our old 4 ton main system any more.

They would be turned off these small SM in the winter in the daytime and just used them at night.

We have a credit of 3,000 kwh hours in reserve so we have extra power to run these units.
I could also really cut my natural gas bill down by doing this.

What do you think about using small inverter Mini Split in small bedroom? Can you see issues with this idea?


Last edited by pinballlooking; 07-22-14 at 09:47 AM..
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Old 07-22-14, 07:23 PM   #2
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Since it can only go down to 2200BTU/h, when the heat load is lower than that, it will cycle on/off repeatedly, which is bad for efficiency and maybe equipment durability over the long run. It isn't ideal, however it will work and is certainly much more energy efficient than using electric space heaters.

Do you leave bedroom doors open? This simple change makes a world of difference for us. We do close them sometimes, of course, but we try to not do it for too long when the weather is extreme, and when everyone finally goes to bed for the night, we make sure all doors are open while we sleep.
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Old 07-22-14, 08:02 PM   #3
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Bedroom doors open is a good idea but we have cats and they would never let the boys sleep if they get in their rooms. If there is ever a fire a closed door could save your life.
In the summer if they play video games it gets pretty hot in the room.
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Old 07-22-14, 08:09 PM   #4
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If it were me, I would rig up a heat pump water heater and run some hydronic space heaters in the small rooms. Each could have its own thermostat to be adjusted for individual comfort levels, drawing tiny fan power when active (50-75 cfm). Or you could install passive baseboard or "radiator" units with honeywell valves (or sophisticated electronic controls) for temp control. The tank heat pump would not short cycle like an air source unit would under low load conditions. Instead of running linesets into each room, evacuating and charging, some easy pex lines would suppliy hot water to the heaters.
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Old 07-22-14, 08:17 PM   #5
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I like this idea we have a tankless hot water heater that could be used for this. But they need cooling to not just heat. Heating is the most important thing and the biggest temp difference from the outside.

I am not sure I would have the skill set to rig up a heat pump. The rooms are on the other side of the house from the garage about 70’

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Old 07-22-14, 09:18 PM   #6
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Quote:
Originally Posted by pinballlooking View Post
...I am not sure I would have the skill set to rig up a heat pump...
There are quite a few posts on EcoRenovator that address the limited skill set that you mentioned.

On the other hand, maybe you should call in a professional to help you make the decision. They are well trained to do this. They make a living doing this kind of thing, and they do it very well, for folks just like you.

-AC
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Old 07-22-14, 09:29 PM   #7
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Quote:
Originally Posted by AC_Hacker View Post
There are quite a few posts on EcoRenovator that address the limited skill set that you mentioned.

On the other hand, maybe you should call in a professional to help you make the decision. They are well trained to do this. They make a living doing this kind of thing, and they do it very well, for folks just like you.

-AC
I installed my two other Mini Splits one duel zone and a single zone. I documented them here.
http://ecorenovator.org/forum/geothe...t-install.html
I have the equipment to install these 2 new Mini splits. In a weekends time I can have them installed.

I don’t have the time to hack a heat pump I think it is very cool and I love to read other peoples projects. Even if I did have the time it still would not provide AC to the rooms.

I have done lots of other projects without hiring it out.

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Old 07-24-14, 10:59 AM   #8
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You could rig a small mini split outdoor unit to a water heater tank. Either a little slinky coil in the tank or a separate r to h2o hx could work. Since the metering device is in the outdoor unit, you wouldn't have to worry about it. If it were reversible, you could pump cold water to the rooms during the summer. The only extra thing you would have to rig up to the indoor units is a drain.

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Old 07-24-14, 04:57 PM   #9
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Why are you so set on a mini-split for a 140 sq. ft. room?

Why not just get a cheap-o window air conditioner for each room?

They're only $100 each for a little one.

Lots of people have grown up with window air conditioners in their bed rooms and they show no outward signs of physical or mental damage.

-AC
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Old 07-24-14, 08:52 PM   #10
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Quote:
Originally Posted by AC_Hacker View Post
Why are you so set on a mini-split for a 140 sq. ft. room?

Why not just get a cheap-o window air conditioner for each room?

They're only $100 each for a little one.

Lots of people have grown up with window air conditioners in their bed rooms and they show no outward signs of physical or mental damage.

-AC
I don't care who you are, that was funny right there.


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