Aircon Question

[SubicSteve]

I have a split unit A/C in my apartment.  It is set up in the living room and cools off the living room pretty good and then cools down my bedroom if I leave the door open.  It doesn't get as cool as I would like in the bedroom so I want a thru the wall unit in there to get the room cooler and hopefully use less electricity since I use the aircon everynight.

 

Here is what I have now:

 

Carrier
A. SINGLE SPLIT
NOMINAL RATING HP 2
INDOOR UNIT MODEL  42LUC018308
OUTDOOR UNIT MODEL  38LUC018308
POWER SUPPLY V / Ph / Hz 208-230/ 1 / 60 208-230/ 1
COOLING CAPACITY kJ/Hr  18,150
SYSTEM POWER INPUT Watts  1900
SYSTEM CURRENT A 8.49
ENERGY EFFICIENCY RATIO (EkJE/RW)-Hr  9.6

 

The bedroom is 12ft x 14ft x 10ftH and I have a wall opening of 24x17 inches

 

Should I get a 2HP unit for the wall with the highest EER I can find and use that unit to cool down the whole apartment or should I get a small unit just for the bedroom?  Do they make inverter thru the wall units yet?

 

Looking for any advice anyone can give.

[P.S.]

maybe only for calculation that will help:

 

http://www.northernac.com/newcalc.htm

[Bruce]

Several things here. You do NOT have a 2hp unit if the BTU rating is 18,150. 1 HP = 1 ton cooling = 12,000 BTUs 

2 HP = 24,000 BTUs yours is a 1.5HP / 1.5 ton. HP and TONs are equal.

 

The higher the SEER (more important than EER) means less operating costs, HOWEVER may also cost a lot more to buy and parts are more expensive.

 

In the US they are called Mini Split Systems. You can get 1 outside housing (condensing unit) and 1-2-3 inside air handler units to meet your needs.

 

Because we are in the Philippines... buy BIGGER than you need unless you will run 24/7. An AC unit is designed to KEEP a space cool more than to GET a space cool. So if you are the typical owner and turn off when not home, it takes much longer to get the place cool when you return is you do not have a size at least 1/2 HP / 6,000 BTUs rating more then the space actually needs.

 

Add in unknowns of wall color outside, windows, lack of insulation and color of roof and it is safer to go 6,000 to 12,000 bigger than some book says. Based on gthe room size you wrote, I would get a full 24,000 BTU unit and not something with conflicting ratings between 2hp (24,000 BTU) and then somewhere else it says 18,000 BTU.  

 

As for hole space..... buy the size you need and then retrofit the hole. ALSO***************** a TRUE thru-the-wall AC is made for the thickness of the blocks. A simple window unit installed through a wall is not as deep front to back and does not work as well in heat exchange due to the block wall restricing some of the air flow.

 

The term inverter is for the electrical change for the motors which are 32-36 VDC. Runs quiet!

[Dave Hounddriver]

HP and TONs are equal.

 

 

From Wiki:

 

 A 1 Ton A/C provides 12,000 BTuh. 33,472 BTuh = 1 hp therefore 1.5ton Air Conditioning = 0.53776 hp.

[Mel-Low]

I lived in a 40 sqm (about 400 sqf) room that had a 2-hp air con.

 

Sometimes, the electrical circuit breaker would go off.

 

Later, I found out from the building management that the electrical circuit was designed for a maximum of 1.5-hp air con.

 

So, the air con caused the electrical outages.

 

What really helped was to position two floor fans to blow on me continously from different sides, while I slept.  They also helped keep mosquitoes from biting me.

 

Otherwise, during the day, I put the fans on to rotate and circulate the air and I wore very little clothes inside my room.

 

In Manila, running a single 1.5-hp air con day and night would cost probably US $200 per month.

[Bruce]

HP and TONs are equal.

 

 

From Wiki:

 

 A 1 Ton A/C provides 12,000 BTuh. 33,472 BTuh = 1 hp therefore 1.5ton Air Conditioning = 0.53776 hp.

 

 

Nope! Nice try Dave but still wrong. Close but wrong. And Wiki is not a 'supervised and vetted' authority. I can long onto that site and change thigs to say that 1 ton is 300,000 BTU if I wanted and it would be up to another user to correct it, IF he wanted to.

 

Here is where you and that Wiki poster went off track. BTU ratings and TONS and HP all change in different temp ranges. The COLDER you want get, the larger the equipment needs to be. 1 TON in High Temp (acual term) is for AC because the average ac evap temp is 38-41 degrees and is meant for air conditioning a room. 1 TON / 1 HP = 12,000 BTUs. For AC ONLY.

 

Medium Temp is for beer coolers, sandwitch boxes and such and the evap temp is right above 32F +- and some times does cause freezing issues. Then Low Temp is for average freezers and requires a defrost system as the evaporator will get frozen / condensated water vapor in your AC unit runs off and into a tray and then a pipe outside. But for Low Temp that same water vapor freezes on the coil and defrosting is needed.

 

Here is where the wiki poster got confused. 1 Ton of AC is 12,000 BTUs but 1 ton of Low Temp is (from memory here) 4500 BTUs.

 

Cooling is rated to take into consideration the constant warm air moving across the evap in the air handler unit. There is a MAX of heat that the evap can absorb and no more. This is why we have sizes. A 1 TON can NOT handle the heat load of a (too big of a )room beyond the heat load entering that room from all 6 sides. So a larger unit is needed when the max load is too great. Remember that the AC needs to cool the evap to say 38 - 41F degrees while the warm air is trying to heat the coil.

 

But to drop that coil temp about 10 degrees (medium temp) or 30 - 40 lower (low temp) takes a LOT more energy now rated as tons..... or HP...... 

 

In the US, the HP rating for AC units has not been used in 30 years or more. We use TONS and since 1 TON =12,000 BTUs = 1 HP for AC, as all the same, it is easy to figure out.

 

The bottom line here is 'someone' is mixing 'green grannies with Macintosh' Both are apples ..... but different. If you want to convert BTU's and HP ratings... you MUST use the correct table!  

 

Anything that says REFRIGERATION..... is not what you want. Air Conditioning is High Temp and as it always has been 12,000 BTU = 1 TON = 1 HP! 

 

........... In addition to be an annoying person, I also have owned a AC / Refrigeration company since 1977. www.freonfix.com   

[earthdome]

One thing I found when purchasing an air conditioner is that the sales staff had no clue what size I needed and was trying to get my to buy a 2.5HP AC unit for a small 25sqm studio apt.

 

I found an online app to calculate the BTU required for my size apt and conditions. In the Philippines most AC units have their capacity listed in kj/hr not BTU/hr. For purposes of estimation 1 kj/hr ~= 1 BTU/hr. 

 

In my case I didn't need a 2.5HP unit, a 1HP unit had enough capacity for my apt.

 

Ohh... I will be moving to Baguio next month and will be selling my AC unit since it isn't needed there. New 16,820PHP. I am located in La Union (Luzon)

[Dave Hounddriver]

Nope! Nice try Dave but still wrong. Close but wrong

 

I belong to 'another forum' where the majority of armchair experts say that the info I provided is correct.  Hard to know who is blowing smoke on the Internet.

[Call me bubba]

here is some info that i have had saved from my 1st time( oh yes i recall that 1st time, it was )...oh i was talking about air con,,

 

TOTAL FLOOR AREA BASIC COOLING CAPACITY
M2 SQ. FT.   BTU/H*
9   14   100    150 5000                                                       

                                                                                                  
14  23 150    250 6000                                     
23  28 250  300 6500
28 33 300   350 7250
33 38 350   400 8000
38 41 400   450 8750
41 46 450   500 9650
46 51 500   550 10 500
51 65 550   700 12 500
65 93 700   1000 15 000

 

the figures above are from the link listed below.(could not paste well)

 

http://www.green3dhome.com/YourHouse/Bedroom/RoomAirConditioner.aspx

 here is a site that you can measure what unit you may need

http://www.fairair.com.au/Calculator.Size.aspx
 

[Bruce]

Nope! Nice try Dave but still wrong. Close but wrong

 

I belong to 'another forum' where the majority of armchair experts say that the info I provided is correct.  Hard to know who is blowing smoke on the Internet.

 

Well Dave, i do not know about the other forum members, but in 'the real world' where I have been doing AC installs and servicing for over 30 years, 1 ton = 12,000 btu = 1hp in HIGH TEMP situations.

 

This seems to be the stumbling block for those other guys. Compressor manufacturers can provide a table to look at showing the BTU capacity of their products at different evap temp ranges. The same compressor's ratings (all do) drop as the colder you want to keep the (space). Be it a walk in freezer or a room to cool.  

 

I googled the question of hp to btu conversion and saw this conversion below. It is INCORRECT as stated because the writer DID NOT say at what temp range the evaporator is designed to run at. From memory for the below statement to be correct, it appears it is a REFRIGERATION question assuming a low temp box. Not Air Conditioning. See below. 

 

1 HP = 2545 BTU / Hr  

 

Now we all know that Google CAN'T be wrong....... :hystery: But that information posted is simply incomplete. 

 

If you and I agree that 1 ton = 12,000 BTU (high temp ac cooling)...... Then using the conversion above, it would take a (rounded off) 4.5 HP to make 1 ton / 12,000 BTU unit!  

 

A small window ac unit starts at 5,000 btu, 6,000 1/2 ton, 9,000 3/4 ton and 12,000 btu as 1 ton. Do we agree on that? So that little / small / compact window ac unit you bought back in Canada / US to cool that bed room..... well, using that conversion I got off Google... do you really think that little unit has a 4.5 HP compressor in it? Any idea how much electricity it takes to run a 4.5 hp motor?

 

So I am asking you to go back to the other forum and ask them to explain how HP / TONS change as the evap temp range lowers.

Then to answer the following.... 1 ton = ??? at high temp, 1 ton = ??? at medium temp and 1 ton = ??? at low temp. Once you start asking them about temp ranges and box temps and how it factors into sizing and ratings... they should see their error and then try to back pedal and 'qualify' their prior statement. OH! Sorry Dave, I thought you meant a refrigeration box and not a room ac unit.... :bash:

 

When it comes to high temp air conditioning.... 1 hp = 1 ton = 12000 btu. Period.  

 

It is possible that the members of the other forum are over educated engineers..... no joke. They design CRAP and I, the local installer have to make it work.... If they had of served a few years as an in the field working ac tech.... their building designs

would show it. What most people do not realize is that all building and zoning departments have a plan inspection phase and those inspectors catch most design errors.