A split Air Conditioning System

[Mr 672A]

In the next few months I will be purchasing a Split air conditioning system to cover say one room including a doored Hallway. The Big TV room is 6x8m and the hallway say that a 1m wide by around 12M long. Front Door entry is say 2.5M x2.5M =6.2 Sqm Now if my maths are right that's 48 Sqm for the TV room and 12M for the hallway with a 6.2SM for the double front door entry. Now All I want this Air con for is Cooling as I produce enough hot air, its a case that the Extreme Hot weather is killing me as it sent me to Hospital 3 times last Summer during the day with no OIL Pressure in my old body and I cant die yet to upset some of you guys. I would take a guess that a 8 to 9 Kw unit on Cooling would be Ok but what are your thoughts, I prefer over size than undersize. What are the Pro's and cons. What are things that I should look out for when purchasing a Split Air Con. What do you think a Installer would charge to connect the pipes and gas the unit (electrics ok as I'm Still a Electrician even in fussy old age) The distance from the Evaporator and condenser is only about 4.5M. I will poor a slab of Concreted. An easy Straight install no bends requires except for the two from the brisk wall to the ceiling and the ceiling to the TV room.
Good Brands Daikin? Panasonic? Others? Any Recommendations in Brisbane.
Yes Low Blood pressure is killing me guys and its a lot worse in Summer. The Lowest so far in Summer this year was 68/36 using a Calibrated Omron BP Machine. I was in a cold bath trying not to drown.

[gordon_s1942]

One thing to take into account is how well that area is insulated and is it on the sunny or shaded side of the house plus windows as they bleed thermaly in both Winter and Summer.
Air Flow is important too and I read one time a ceiling fan can often assist with A/C as they keep the air moving and its that movement that cools you down.
Until it died I had a ceiling fan set on reverse spin in Winter and I found with my 10 foot ceilings, with it running it pushed the Hot Air down from the ceiling and upped the temperature by around 3C at head height when seated.

The house my Daughter bought has in inbuilt Reverse cycle unit and we found that even though it has outlets to 3 rooms, opening and closing the internal doors affects the hot/cold flow of air due to the replacement of the Return.

[ol' boy]

Air Flow is important too and I read one time a ceiling fan can often assist with A/C

You better ring up and tell that to the AC manufactures then, as they go to great lengths to allow for natural convection to be taking place in the room where the AC is operating, sensors are set in the unit head to allow for the hight the unit is mounted, and the natural temperature gradients when the unit is in between cycles.
Pushing air around with a sweepfan will call the AC unit to operate or not operate prematurely.

For the OP, once you have sized the unit required, just buy one that looks attractive enough with the longest warranty, cos there is a good chance you'll need it.

If you want to be fussy, then look at the Gases being used by different brands.
A lot has changed since R22 (which was and still is a brilliant refrigerant, that can handle the higher pressures and shift more heat per kg)

As for your idea of "over sized units", it doesn't really work like that.
That kind of little hammer, big hammer thinking is very short sighted in the world of air conditioning.
There is more at play.

You could also wait until the $200 cash back offers are on.
Not sure when, but they seem to do it each year.

[shred]

I read one time a ceiling fan can often assist with A/C as they keep the air moving

I haven't heard this advice given in relation to cooling with an air conditioner, but a ceiling fan can be very useful if you are heating a room with a split system air conditioner. The problem when heating - particularly with high ceilings - is that the air intake is high up on the wall and sucks in the already warm air up near the ceiling before heating it. The result is a layer of cold air near the floor that never gets heated and you have cold feet. A ceiling fan stirs the cold air up and gets it heated.

I suspect that when cooling with an air conditioner, you actually want that layer of hot air to stay near the ceiling, where the air conditioner can suck it in and cool it down.

[gordon_s1942]

From what I understood the reason to use a ceiling fan with an A/C was for circulation only to ensure you dont just get a passage of air (cold) from the unit going down to the floor before rising as it warms up to be drawn back into the A/C unit but possibly not reaching the whole room space.
In Winter with the fan on reverse, it draws the air up the walls to push it down below the fan and obviously the reverse air flow happens when the fan spins normally.
Another thing I was going to bring up is that all A/C dehumidify the air to some degree and for some people who have respiratory problems this may cause problems for them and they may need to have this taken into account when installing an A/C unit.
People who work long periods in A/C areas have been know to complain about dry noses and throats and being subseptable to colds etc.

We perspire when heated and its the evaporation of that which cools us down and we all know to increase the cooling affect is by either fanning ourselves or standing in a breeze as still air does little to cool us.

[ol' boy]

From what I understood

I think nearly every Installation and User's Manual i have read when installing a Split has made a point about the interference a sweepfan will cause to normal operation.

But, each to their own i guess.
If it works for you, brilliant
I'm sure it doesn't make that much difference.

[Mr 672A]

Yep the outside unit will see no sun none whatsoever, the house if fully insulated with a 100mm quality well known (I have forgotton) batts, Over 65% of the roof that the sun hits head on is filled with Solar PV panels bocking the direct hit of the sun.

[bazzle01]

My splits have a setting for auto vent swings so ceiling fans play no part.
I would get an inverter unit as they are more cost effective allowing the compressor to slow down and speedup as required.
My larger unit is an Mitsubishi Electric. Smaller one a Sharp. Both have been going for a few years now.
Also both are heating and cooling. Sometimes you just need some warm air.

[gordon_s1942]

Oceanboy, if the A/C manufactures dont recommend the use of ceiling fans then thats the correct procedure regarding them and it should be followed.

[lsemmens]

Depends upon where you are, have you considered installing an evaporative cooler. Ours works extremely well. I just note that you are in Brisvegas, so am not as certain there, any further north an I'd say, "Forget It". Talk to some of the local installers (not retailers) about swampies, and see how well they perform.

[LeroyPatrol]

I'd move to Tassie......

Leroy

[Mr 672A]

I'd move to Tassie......

Leroy

Suffer from Arthritis and the cold locks my body up. I like the constant 20-30 deg days

[Mr 672A]

Busy week this week as besides our new oven arriving where I will install it as all is ready for it I have also the Aircon people coming in the next few days installing our Fujitsu 8Kw split system. Now normally I always do everything my self but because I forced to get this air-con installed because of the gassing side of it and the sparky comes with them to do the electrical sides of thing (package price) lets see how their quality of Workmanship is compared to mine because I expect nothing but an 100% quality job "eg" If you cut the sarking under the roof tiles you cut it so it can be duct tape back up, The power cables must run under all beams not over, The 80mm duct going up the wall from the external unit gas and liquid pipes must be straight, The outside unit must be put exactly equal on the slab of concrete (i'm supplying the Stainless Steel dyna bolts)that I pored, etc,etc,etc, Yep the owner of the company got pre-warned as to what I expect so lets see guys what happens after the job gets completed.

[gordon_s1942]

Its the gassing side of these systems that had me curious with installing as some of those offered, claimed there was already sufficient gas in the system and it was a simple matter of just 'joining the hoses'.
The nearest experience I have ever had with any form of A/C was when a 3rd party system blew hoses in my XB Falcon requiring new hoses and regassing.
I remember the mechanic 'walking' me through the procedure of having to evacuate the system before it could be regassed which all took a few hours to complete.
This was 30 years ago and they dont use that Gas anymore but I wouldnt have thought the procedure was done very much differently today regarding evacuation etc, etc.

2 years ago I had the compressor/Drier replaced on the AU wagon while I never asked directly , I am sure in the fitting costs was included evacuating the system before regassing.

I agree with you Mr 672A that you want it done properly as your paying for it not them, and you dont want them coming back fixing what should have been done right in the first place.

[weirdo]

Offer the tradies a cuppa or something. (I know that will drag you away from watching them like a hawk lol)
But most people reciprocate good/generous deeds.

[Mr 672A]

(I know that will drag you away from watching them like a hawk lol)

I will try not to do this.

[ol' boy]

The 80mm duct going up the wall

Ducting?!?!?
I thought you said you were fussy?

[Mr 672A]

Ducting?!?!?
I thought you said you were fussy?

I am to a point but the gas and liquid pipes have to go up the wall somehow. I was thinking of sending through the wall into my Workshop Repair room (5th bedroom of the house) and up the ceiling. Option is still on, will talk to the installer when he comes.

[Mr 672A]

Well guess what. Harvey Norman has Fu.ked me again. The Air Con installer has just spoken to us this morning and the aircon is not in the Harvey Norman building.

[weirdo]

Well guess what. Harvey Norman has Fu.ked me again. The Air Con installer has just spoken to us this morning and the aircon is not in the Harvey Norman building.

Maybe they are reading this thread too and figured this is the easiest way