[Brumby]

Originally Posted by Lobogris

Thanks for the explanation. Even if the start up load is 36 Amps, it is for a second or two. It will have no impact on power consumption if we have a few shut downs and starts each hour.

There will be no impact, and the start up load is there for mili-seconds only, for small motors it is hardly noticeable. For very large motors ( more than 100 kW or more) and depending on the rating of power supply do we notice of a flicker on lighting when an AC electric motor starts.

It is a bit difficult to explain, it all depends on the power supply rating and available load, higher the difference less noticeable the effect will be. e.g. a power supply of 1000kW with all the load available for starting will not have any noticeable effect when a 100kW motor is started.

Hope I could give a fair idea how it works.

Regards.

[Rudra Sen]

Guys, what should be a right AC (in terms of ton) and which brand to consider for a 750 sq ft room?

Please keep few points in mind while suggesting:

- Only single unit will be used.
- There's only open terrace above the room.
- There are three very large windows.
- Summer temperature (like now) often touches 40 degree.

[mxh]

Originally Posted by Rudra Sen

Guys, what should be a right AC (in terms of ton) and which brand to consider for a 750 sq ft room?

Please keep few points in mind while suggesting:

- Only single unit will be used.
- There's only open terrace above the room.
- There are three very large windows.
- Summer temperature (like now) often touches 40 degree.

It's not possible to cool 750 sq ft with a single commercial AC. You'll either need 3 ACs totalling 6 tons or an industrial solution so plan your room accordingly.

[Rudra Sen]

Originally Posted by mxh

so plan your room accordingly.

Umm, room is already there and before thinking about a second one I need to be absolutely sure.

[mxh]

Originally Posted by Rudra Sen

Umm, room is already there and before thinking about a second one I need to be absolutely sure.

Another option is : Since you have 3x windows, change the design of the windows to fit a window ac in each. I've done this for my hall and fitted 2x window ACs. But you'll definitely need multiple units or a central cooling type of arrangement.

[Aroy]

Originally Posted by Rudra Sen

Guys, what should be a right AC (in terms of ton) and which brand to consider for a 750 sq ft room?

Please keep few points in mind while suggesting:

- Only single unit will be used.
- There's only open terrace above the room.
- There are three very large windows.
- Summer temperature (like now) often touches 40 degree.

The simplest formula that works is

. 1T per 1000 cubic feet ~ 110 sqf for 9 foot ceiling
. 1 T per 5 persons

This works in temperatures like Delhi - 45 degrees peak, with around 25 degrees in the room.

To get the final tonnage you have to consider
1. Whether the sunlight comes through the windows.
2. Is the ceiling insulated.
3. How many persons in the room.

For 1, if true, best bet is to get heat reflecting/blocking film on the glass.
For 2, if not, evaluate the option of either painting the terrace with heat reflecting paint, or get a false ceiling installed.
For 3 estimate the number of persons that will occupy the room during peak summer heat. If there are 20 persons then add at least 4 tons of refrigeration. In case there is a lot of movement in and out of the room, add another ton.

In the end how many tons?
For 25 degrees room temperature with 20 persons in a nine foot room, you need

(750 x 9) /1000 + 20/5 = 10 tons. In case there are fans and the occupants do not mind 28 degrees with fans, you will still need 6 tons+. At this level it is best to go for commercial air conditioning. The options are
1. VRF with ceiling mounted casset units
2. 2 or 3 three ton floor standing units. These can either be independent having one ODU per unit, or have one ODU servicing all the IDU

There is a trade off between capital and running expenditure. Commercial grade units are designed to work flawlessly 24 x 7 for a few decades, hence cost upward of 1L/T and cost much less to operate. Where as domestic units are for light duty, last less than 10 years and are low as 20K/T, though they are more expensive to run.

Ultimately if the room is to be used for commercial purpose - shop, office, gym etc, you will need higher capacity and more efficient units. If it is for recreational use - parties and occasional gathering then you can do with less expensive multiple 2/3 star splits, as the duration of use does not warrant more expensive solutions.

If you opt for commercial grade AC, call up Blue Star/ Voltas, LG and Daikin. They have a separate group for evaluation and designing systems similar to yours. They normally come, evaluate and suggest the optimal solutions free of cost.

[carboy]

Originally Posted by carboy

Well, I have gone for a I am buying a Carrier Midea 1 ton Split AC.. The dealer is someone I know personally & he is the one who told me that 1 ton would be good enough for my needs as long as I don't run it very long. I don't think I will be running it for more than a few hours at a time.

Will be installed this week.

Ok - so it's been a month and a half & this is working well. The room is 170 odd feet, but 1 Ton seems to be more than enough for my usage. Everything seems to be good as of now.

[Rudra Sen]

Originally Posted by Aroy

To get the final tonnage you have to consider
1. Whether the sunlight comes through the windows.
2. Is the ceiling insulated.
3. How many persons in the room.

Thanks Aroy and sorry, I should have been more specific to start with. It's not a commercial place but a living/open kitchen area.

Let me reply to your three points first.

1. Yes, sunlight comes really strong in the afternoon and yes, I've thought about putting 3M CR70 or equivalent.
2. Ceiling is not insulated and not going to be also. Height is around 11.5ft.
3. 2 people and 2 dogs.

For your better understanding I'm attaching a rough drawing here.

[Thad E Ginathom]

Whoa! How to deal with the heat generated by the kitchen? Probably you have chimney, which will help, but not remove all the heat.

[Rudra Sen]

Originally Posted by Thad E Ginathom

Whoa! How to deal with the heat generated by the kitchen? Probably you have chimney, which will help, but not remove all the heat.

There won't be much of cooking and we will have down draft chimney to avoid making a false ceiling.

[Thad E Ginathom]

Originally Posted by Rudra Sen

There won't be much of cooking ...

So no great worry then.

Have sometimes thought of putting AC in our kitchen, although it seems like a very extravagant thing to do. Despite local origins, my wife hates heat and suffers in it more than I do.

[hrman]

Originally Posted by Thad E Ginathom

So no great worry then.

Have sometimes thought of putting AC in our kitchen, although it seems like a very extravagant thing to do. Despite local origins, my wife hates heat and suffers in it more than I do.

I have thought of this too. In Mumbai, the humidity levels go high and the heat generated by cooking make the occupant (my mom) feel even more uncomfortable. The only problem I foresee with an AC in the kitchen may be the frequent AC filter cleaning/ replacement due to the oily kitchen fumes.

In case you decide to go ahead with this, please do post your review. Would be interesting.

[sgiitk]

In Gurugram my son's flat has an AC in the kitchen. So maybe these are not that uncommon now.

[Aroy]

Originally Posted by Rudra Sen

Thanks Aroy and sorry, I should have been more specific to start with. It's not a commercial place but a living/open kitchen area.

Let me reply to your three points first.

1. Yes, sunlight comes really strong in the afternoon and yes, I've thought about putting 3M CR70 or equivalent.
2. Ceiling is not insulated and not going to be also. Height is around 11.5ft.
3. 2 people and 2 dogs.

For your better understanding I'm attaching a rough drawing here.

Attachment 1764451

There are a few options for you, especially if you own the house and can carry out a few modifications. In general there are two ways to approach the problem.
a) Do Nothing - you just increase the air conditioning capacity.
b) Heat management - ensure that there is minimal heat build up, there by reducing the AC load.

Case a)
Your AC requirement will be between 6 and 10 tons

Case b)

1.
Your windows are in Westerly direction, so a film would greatly reduce the heat build up post noon.

2.
A high ceiling will add to the volume. You can reduce the heat load by
. Paint the terrace with heat reflecting paint. This will have to be renewed every two years or so.
. Water proof the terrace. Line it with a heavy duty polythene sheets(s). Put 10 to 15 cm of soil and grow grass. This will cool the terrace tremendously and can reduce a few tons of Air Conditioning.
. Pour "Foam Concrete on the terrace - about 20 cm should do. That will reduce the heat load a lot, though not as much as grass.

For AC

OPTION A)
Two Floor Standing 3 ton units.
. One at the top left corner of the drawing (between two windows facing the skylight)
. If you want the kitchen cooled then place one unit near the "Sealed Glass Window" facing the kitchen. Otherwise it can face to throw air parallel the 6.5' wall.

OPTION B)
0ne 6 to 10 ton ODU

Ceiling mounted cassette inits of 2 to 3 tons spread across the room. Say
. One in kitchen
. One between the skylight and window.
. One between the skylight and wall.
. One between skylight and main door
The placement is as per your requirement. One advantage of such a system is that you can have IDU totaling upto 50% more than the ODU capacity and concentrate cooling where needed and reducing it where not needed.

The advantage of OPTION A) is that you can start with one unit and if required add another at a later date. OPTION B) will be less expensive to run and last a much longer time as such systems are meant for 24x7 use.

In either case you will have to situate the ODU on the terrace above the room and run the piping from the IDU to ODU.

http://www.lg.com/in/highlander-series-ac
http://www.daikinindia.com/products-...floor-standing

[Thad E Ginathom]

Originally Posted by sgiitk

In Gurugram my son's flat has an AC in the kitchen. So maybe these are not that uncommon now.

I can understand it being standard in higher-end property. Those of us who can afford to pay fro comfort, and want it... well, why not!

When we bought our house, the kitchen and living area were more-or-less open-plan. I have never liked this arrangement, so we made the kitchen fully enclosed with a door. The chimney fan limits the heat, and sucks in cooler air from the living room with the door ajar.