1.5ton or 1.0ton capicity in my room size

[siraj_7]

Hi Guys,

Firstly I'd like to thank all Pakwheelers for all the great advices i've had over the years (speically for the Suzuki Khyber threads in this site from which I have taken a great deal of help in maintaining my khyber over the years)

I am facing a delimma to buy 1 ton or 1.5 ton. Brand already decided; to choose from Mitsubishi Heavy Industries (MHI) or Mr.Slim

My room is recently shifted to upper story, the room faces constant sun light from roof and the Kitchen is below this room. The room was pleasent in winters but since summers its unbearable and no human can dare sleep in it since the bed, the chairs, the sofa and everything emmitts heat and you would wakeup exhausted in the middle of the night breathless and dehydrated! The room temprature is 30-35 even at night.

The background of the story is that I had bought a 1 ton/12K BTU GREE a/c and it sucked big time now I have read a lot every where and I have a hunch to buy 1 ton but I am really afraid and don’t want to waste my money if I later find out that the a/c is below capacity. I want an a/c that can take room temprature down from 35 to 19 in my current room. However experts say if A/C is bigger than required capacity it will quickly cool but not dehumidify and the room will be damp (my room's humidity measured with a meter is 80)

· Capability: Temprature down from 29(starting temp) to 26 in the span of 7 hours of sleep

· Room size: 12ftx13ft and 9.5ft high, Covered by all 4 sides and on the ground floor

· Outer installed in a duct (10x5 feet and 20 feet high), placed 1.5 feet away from adjucent wall
· Power cable = 7/36 Pakistan Cable from panel to socket and 7/52 from pole to meter and meter to panel
· Voltage = 210-230v (Volt meter in panel and in main hall so I notice all the time)
· Ampereage meter shows full amperes they should be.
· The A/C sent twice to GREE Company, gas refills and other minor repair but no use and I gave up on this piece of machienery

Also I would like to know the inverter based model of Mr.Slim and MHI and their prices in both 1 and 1.5 ton capacity.

Also I need to know where to get that vaccum pump thing for installation and what are the benefits compared to normal desi installation.

Also is the 3.5K original kit worth it or any 1.5 K kit would do?

Also would a 3 kVA stabilizer suffice since the rating is 2.25 kVA or should I get a 4kVA stabalizer (I have already pre-decided to go for a servo motor and preferebly stabmatic or any foreign brand)

I Apologize for making you read 469 words J

[siraj_7]

Since this room is on upper story I will put the outer on the roof top to eliminate any possiblity of improper cooling due to outer put in a duct

[Xulfiqar]

firstly you need to shield the roof from direct sunlight, make a tarp umbrella or something, second you need to get the measure the temperature of the A/C evaporator output, and before switching on the A/C exhaust the room of hot air, ideally this is done by running the A/C with its blower pointed to the ceiling fan running full speed and keeping a door open for about 10 minutes, if you have an old house with "roshandaan" above the doors - they are there for this purpose..

calculating heat sq ft area, methodology says that you will have a heat load of 10,000 BTU/hr in this room, so a 12000 BTU A/C can remove the heat from it to normal level (25*C) - this is dependant on A/C evap placement and thermal efficiency of the outer unit. (ensure the line set is fully insulated) and it should be vacuumed for before opening the block valves of a brand new A/C, if it has been pumped down with dirty gas, you need to replace it.

Your heat load is the sun, if you have a large window, tint it and put some reflective foil on it to reflect heat, try to insulate the roof as much as you can, you need to contain the cold air, it is being heated up by the walls and roof.

[siraj_7]

Hi Xulfiqar thanks for the reply :)

I need some further clarification but before that I thought i should clarify that the story i wrote about gree was in a seperate room that was not facing sunlight. The new room has dimensions 12x13x10.5(height) and has 35-30celcius and 80% humidity at the moment and I need the temp down from 35-30 to 20 atleast as I like it chilled and I am planning to buy a new a/c mr.slim or MHI and the outer will be placed on roof top rather than the duct as the temp outside (on the roof) is much lower that whats inside the house (the duct) so the efficiency of the outer will be better

1.

Firstly you need to shield the roof from direct sunlight, make a tarp umbrella or something
You mean that I should get the whole roof insulated or heat proof (which I am already considering) or do you mean I should make this tarp umberella to cover the outer that I will now keep on roof top.

1a.
second you need to get the measure the temperature of the A/C evaporator output
Sorry I don’t understand this at all, please explain what shoud I need to do regarding this and whats the evaporator outpu

2.
second you need to get the measure the temperature of the A/C evaporator output, and before switching on the A/C exhaust the room of hot air, ideally this is done by running the A/C with its blower pointed to the ceiling fan running full speed and keeping a door open for about 10 minutes, if you have an old house with "roshandaan" above the doors - they are there for this purpose..
I am considering putting a power ful exhaust in the room which will exhasut the hot air as there is no window that faces the road as this room is covered on all four sides and has sunlight direct on its roof (there is one window but it opens in the duct which is arleady warm with kitchen exhaust - bad architecture)

3.
calculating heat sq ft area, methodology says that you will have a heat load of 10,000 BTU/hr in this room, so a 12000 BTU A/C can remove the heat from it to normal level (25*C) -
by 25 you mean that this 12K BTU a/c will only be able to take the temp down to max 25 and not further below as I would prefer something like 18-20?

4.
this is dependant on A/C evap placement and thermal efficiency of the outer unit
What is ac evap and what should be its proper placement and how to ensure proper/standard/recommended thermal efficiency of the outer unit

6. (ensure the line set is fully insulated) and it should be vacuumed for before opening the block valves of a brand new A/C, if it has been pumped down with dirty gas, you need to replace it.

I assume line set means the two pipes that carry gas between outer and inner) By insuring line set is fully insulated
Do you also mean that both lines lower and higher pressure lines should be individually insulated in foam pipe and not insulated in 1 pipe?
I am assuming you are refering to the better/expensive installation kit (there are installation kit for foreign brands which are worth from 800 to 3000 rupees since only local brands come with company kits) which would contain proper insulation or can you refer me to a brand of insulation foam pipes which will ensure proper insulation of my line set also you mean that I should get the a/c installation done with vaccum pump, Also if the pipes / line set are new can I assume they would not have been pumped by dirty gas and are good to for usage and how in the first place can I find out if they have been pumped with dirty gas

(I am sorry I may sound dumb but I am confused a bit – Is vaccum pump a device that will make a vaccum in the pipes that carry gas from inner to outer and clear any debris or dirty gas after the pipes / line set is connected to block valves and before the block valves on the compresser are opened to let the gas circulate freely)

Thanks!

regards,
Siraj

[Xulfiqar]

evaporator = inner unit
line set = lines between inner and outer unit - both should be perfectly insulated, some A/C units have expansion device on the evaporator so in that case the return pipe only needs insulation.

condenser = outer unit
block valves = valves used to pump down and trap gas in the condenser before removal (new A/C come with gas in the condensing unit)

dirty gas means gas that has mixed with air not vacuumed from the lineset, Such gas will not work and only increase your "bijli ka bill" The lineset should be vacuumed with a vacuum pump for at least 1 hour to ensure all air and moisture from the lineset is gone, Only then should the block valves opened up. 100% of A/C installations in Pakistan skip this step. They just let the gas loose in a dirty system which then causes high head pressure and loss of cooling - they do it to ensure you remain a customer for life.

The umbrella tarp is something to cover the roof of the room from outside, its done to create a shaded barrier between the sun and the roof concrete, so it wont heat up and channel heat into the room. You can get creative and make such an umbrella with a used panaflex skin, or even with a layer of thermal insulation bonded to the roof (expensive)

For getting to 18*C in the room get a 1.5 ton unit and follow all the above as I said, Install an exhaust fan in the room in a way that it is at the very top, you need to get hot air out of the room and hot air is at the top of the room. Your A/C is only efficient if you somehow move air in the room - The top of the evaporator is the suction for the blower, ensure it has at least 3ft of space above it for proper air intake volume and the unit should be placed such that its output strikes the centre of the room, get a fan to aid it.