AC install: room sizing and 2 room considerations

[Hal65]

My space looks like this. I plan to replace the broken AC unit:

 

 

Couple questions:

 

1. Will closing the sliding door (separating the rooms) result in the heat/humidity quickly saturating the bedroom? I prefer to close that door to block the noise and outside light. Maximum length of time it would stay closed is 9 hours. 

 

2. My room has 10 foot ceilings. The online calculators say 10k to 12k BTU should give me the cooling I need, which is -10 to -20 degrees F (About -5 to -10C). The store people say I need 18,000 BTU for my 350 sqf / 33.5 sqm space.

Edited January 6, 2019 by Hal65

[Crossy]

Standard Thai guesstimate for A/C sizing is 5-600 BTU per m^2. Your 33.5m² room would need  16,750 - 20,100, so the store people are using this method.

 

What size is the dead unit, was it adequate when working?

 

With only a small delta-T then 12,000 BTU would possibly be adequate if you don't have outside walls or roof (so a central condo unit below the top floor). Are you sure you only need -5 to -10C?

 

How fast your bedroom heats up once it's been cooled off by having the sliding door open also depends upon your unit's aspect, but a stand fan in the room may be enough to keep it bearable at night.

 

Personally, I'd be looking at a 16-18k BTU inverter aircon.

 

[Hal65]

I'm comfy most of the time with fans, but they can be inconvenient for certain activities. Not sure about the old AC unit, maybe I need to look for a label on it.

 

I have fans in the bedroom already. What I really want to keep at bay is the humidity.

 

 

[johng]

Maybe relocate the aircon to the bedroom....or (better)
get 2 smaller units 1 for bedroom 1 for living room.

[KittenKong]

Putting the new air-con in the bedroom would solve the problems: you would not be pointlessly cooling the living areas at night and you could cool the living areas in the daytime by simply opening the sliding door.

 

It all depends on whether you have a suitable outside wall in the bedroom. If you do then it's easy. If not, you may be able to run the two coolant pipes in plastic ducting from the existing air-con location and just add a very small drain pipe for condensation from the bedroom to outside.

 

As mentioned, two units would also be a suitable solution and that would allow for the most comfort and flexibility. Two small units would be fine, and these are often available very cheaply.

 

Either way, I would always buy inverters.

[Cadbury]

My rule of thumb is always buy unit/s of slightly larger capacity than you think you need.

[bankruatsteve]

My rule of thumb is to buy the size smaller than any calculator says and definitely go with "inverter".

[VocalNeal]

Surely an inverter slows down the compressor to a speed that it needs to maintain the room temperature. If the unit is too big for the room it will slowdown to minimum.

Does it stop like a conventional unit or keep running at minimum?

[bankruatsteve]

10 minutes ago, VocalNeal said:

Surely an inverter slows down the compressor to a speed that it needs to maintain the room temperature. If the unit is too big for the room it will slowdown to minimum.

Does it stop like a conventional unit or keep running at minimum?

Inverters maintain temp much better than conventional.  Mine runs all the time but at much less energy.

[BigT73]

Have you thought about mounting the a/c next to the sliding door on the bedroom side?  as you only close this door when your in the bedroom and can still benifit from it.

[Hal65]

2 hours ago, BigT73 said:

Have you thought about mounting the a/c next to the sliding door on the bedroom side?  as you only close this door when your in the bedroom and can still benifit from it.

 

The bedroom has no exterior walls. I just assumed that swapping the current/broken AC would make the most sense. But you guys are right, the room that really needs cooling is the bedroom. I don't even need cooling in the larger room that has the exterior wall.

 

The sliding door is metal. There are glass panes though. Maybe piping or ducting is the answer

[bankruatsteve]

Maybe make the larger room your bedroom?

[Hal65]

2 minutes ago, bankruatsteve said:

Maybe make the larger room your bedroom?

 

The noise in that room makes it unsuitable. The outside street is Soi Buakao with its orchestra of backfiring motorbike engines, street vendors calling out in Thai, and even girls advertising their services to passing baht busses.

 

 

[BigT73]

1 hour ago, Hal65 said:

Maybe piping or ducting is the answer

This is my external ducting supplied by the a/c guys,  if your not worried about it running along your large room wall to the bedroom from the balcony its a easy fix for them.

 

Edited January 7, 2019 by BigT73

[KittenKong]

2 minutes ago, BigT73 said:

This is my external ducting supplied by the a/c guys,  if your not worried about it running along your large room wall to the bedroom from the balcony its a easy fix for them.

Yes, that will do as long as you can get a slight downwards incline in the ducting from the indoor aircon unit to the outside, for the water drain. The cooling gas pipes will work even if the slope is uphill, but not the water drain as this works entirely by gravity.

 

Other options are to take the water drain pipe outside by some other route, or indeed to connect it to some internal drain. Even a bucket would do at a pinch, though you would have to remember to empty it.

[Lacessit]

16 hours ago, Hal65 said:

 

The noise in that room makes it unsuitable. The outside street is Soi Buakao with its orchestra of backfiring motorbike engines, street vendors calling out in Thai, and even girls advertising their services to passing baht busses.

 

 

Perhaps you need a conventional aircon and not an inverter to create white noise.

[KittenKong]

20 hours ago, VocalNeal said:

Surely an inverter slows down the compressor to a speed that it needs to maintain the room temperature. If the unit is too big for the room it will slowdown to minimum.

Does it stop like a conventional unit or keep running at minimum?

My inverter runs more or less slowly according to the temperature difference, but sometimes it does also stop entirely as I have mine set to 27 degrees which at this time of year may be higher than the outside temperature.
The nice thing about an inverter is that it doesnt "clunk" on and off, but starts and stops smoothly so you are not really aware that it is running at all. Also the indoor temperature is much more consistent, with no big variations as it turns on and off.

[VocalNeal]

"In the trade" called a soft start? I run my bedroom at 27 and also use a fan.

[Hal65]

How do you guys feel about a portable unit in my case? 

 

6,500 THB for 12,000 BTU: https://www.lazada.co.th/products/12000-btu-7-natural-i262675179-s404761093.html?spm=a2o4m.searchlistcategory.list.12.4f1f5660pHZfAG&search=1

 

One way I could use it is to put it in the big room (if very loud) on a chair for water drainage. One tube runs to the bathroom, the other to an exterior facing window or balcony door.

 

Another option: If its loudness is only of the "fan on setting 3" level, then I may just put it in the bedroom also on a chair, run the water tube to a large container, and run 8 to 10 meters of exhaust tubing through to the exterior.

 

 

Less efficiency is not an issue for me. I only need a small drop in room temp and enough humidity removal so that I'm not sweating.

 

Just need the right configuration for acceptable noise level, water removal and heat exhaust

Edited January 8, 2019 by Hal65

[Naam]

46 minutes ago, Hal65 said:

and run 8 to 10 meters of exhaust tubing through to the exterior

forget about it as the condenser fan of the unit won't create enough pressure.

put a cheap conventional 9k btu/h in your bedroom (suction and pressure pipe in a neat channel) and drain the water to the bathroom.

 

[Hal65]

1 hour ago, Naam said:

forget about it as the condenser fan of the unit won't create enough pressure.

put a cheap conventional 9k btu/h in your bedroom (suction and pressure pipe in a neat channel) and drain the water to the bathroom.

 

 

Can't do it directly that way unfortunately.

 

 

But as you said, if there's not enough pressure to push the exhaust air through 8-10 m of tubing, the portable must go in the big room.

 

 

Edited January 8, 2019 by Hal65

[Crossy]

I would really avoid a portable, they do work but on a per-BTU cost they're expensive to buy and run.

 

[Hal65]

33 minutes ago, Crossy said:

I would really avoid a portable, they do work but on a per-BTU cost they're expensive to buy and run.

 

Any idea of kwh consumed for portables and splits?

 

As I can not read Thai I went to Amazon. One portable 12k btu unit advertised 1,200 watts used.

 

On another us website I found a 12k BTU split unit. Its operating voltage was 120v and 8.9A, which computes to 1,068 watts.

 

Does that look in line or are split units way more efficient?

Edited January 8, 2019 by Hal65

[johng]

I would not even contemplate the portable aircon  in my experience they are extremely noisy

and you have to find somewhere to exhaust the hot "exchanged" air and condensed water

split unit ???? 100% better no doubt.

[sometimewoodworker]

On 1/7/2019 at 11:07 AM, Cadbury said:

My rule of thumb is always buy unit/s of slightly larger capacity than you think you need.

If talking about non inverter units that is not a good plan, though it may be OK for an inverter 

Edited January 16, 2019 by sometimewoodworker

[Cadbury]

3 minutes ago, sometimewoodworker said:

If talking about non inverter units that is not a good plan, though it may be OK for an inverter 

I was referring particularly to an inverter. For me anything other than an inverter a/c is old fashioned and part of history.

[Naam]

On 1/8/2019 at 6:25 PM, Hal65 said:

 

Can't do it directly that way unfortunately.

 

 

But as you said, if there's not enough pressure to push the exhaust air through 8-10 m of tubing, the portable must go in the big room.

 

i am not talking about a RUBBISH portable unit but a split unit. the latter does not generate "exhaust air". heat removed from indoors is transported outdoors by the refrigerant circling in the pipes between indoor and outdor unit. these pipes and their insulation fit in a neat "channel" size ~60x30mm. i also repeat that in your case and especially demand the cheapest conventional (9,000 btu/h unit, 850 watt consumption) is more than sufficient.    

[Hal65]

I ended up getting a 12,000 BUT portable A/C off Lazada for 7,500 thb. "Natural" brand (seems to be the most popular).

My reasoning for portable was the 10% extra energy cost was worth being able to take it with me if I move to another apartment. I don't use AC that much unless a guest is over, so the added cost is only about $3 per month and I still get to pay fan room prices.

 

Install:

-- Bought a black plastic board from Home Pro for 850 baht, + 250 for a pickup to get me home.

-- I measured out my window, a side hinged one that would require my custom solution. I cut the board to fit and then cut the exhaust hole with a utility knife.

-- My handiwork is subpar and the board bows inward, creating a small gap for bugs/air at the top (about 5 square inches worth). I can probably fix it later.

 

Performance

-- In the direct line of airflow it feels like a freezer is venting onto you. Feels nice.

-- After 25 minutes the big room on the Buakao side is dry and warm, about 27C or 81F (I set the AC to 26C). The back room / bedroom is still too warm and humid Though. I can literally take one step forward to go from "nice" to "little to warm/humid"

-- I then "aimed" the AC at the opened section of the sliding door to try to improve airflow. Another 25 minutes later and the bedroom was a little better. Quite nice with the fans also on.

 

Conclusion

-- On a range of possible outcomes I give it a 7/10.

-- I spend more time in the bedroom so that was the more important one.

-- The humidity removal is huge, probably more important than reduced temperature.

-- Still have to assess the annoyance factor of manually dumping water. I think it will not be a big deal.

 

 

 

Edited March 2, 2019 by Hal65

[Hal65]

Almost forgot: The AC blew out a Thai power strip in its first 10 minutes. I had to wait 3 weeks for a Chinese 4000w surge protector on Aliexpress to come in the mail, at a cost of $25. The AC draws 1,200w

Edited March 2, 2019 by Hal65