Aircon Choice

[trogers]

I have decided to install aircon in two rooms: one bedroom of about 47cu m and one room, initially a bedroom but destined to be an office, of 40cu m. For reasons of economy, we use air at night as little as possible - probably a maximum of 35 nights a year and set to 22 degrees or so

-a 22ºC setting when the outside temperature is 28º or higher rules out any inverter

-the same applies for "35 nights a year" usage.

although when the smaller room becomes an office the heat of the mainframe (kidding, but I do have a lot of hard drives) it will be needed for much of the hot season to make the room comfortable.

-"making the room comfortable" does not mean anything. some people feel comfortable at 30º, others sweat at 22º. so what temperature do you want to achieve? 25º or below during the hot season = forget about an inverter unit because it's wasted money.

I read about multi units...

Sounds like inverters are not for us! BTW, I thought my post was very clear - we have two rooms to cool at night for the mid term and then one during the day and one at night and for what it's worth I usually set a daytime temp of 25 and a night time one of 22 and regard them as my comfortable setting.

From what you say, if a setting of 25 degrees during the hot season rules out the use of an inverter it seems to me that they'd be pretty much useless in Thailand for most people at the time they need them most. I don't know anyone who sets their thermostat much higher than that. You have to wonder why they sell them.

Inverter units should not be undersized, ie. 40 sqm room using 10,000 BTU because they cannot run at partial load conditions, which are their main efficient mode. I have been using both Daikin and Panasonic inverter units, and electricity bills through March and April have been lower by 25% compared with my previous Mitsubishi units.

Your limited hours of usage will probably not justify the extra capital outlay of inverters.

[Naam]

I have a Daikin Inverter and use it at night set to 26c and works very efficiently and quietly.

My bills have been reduced to half of what they were before with a conventional A/C unit.

Well worth paying a few thousand baht more due to the long term savings off the electric bill.

you didn't change your conventional idea for fun but most probably because it was an outdated and inefficient old rattler, i.e. your claim has no basis.

The basis of my claim is simple Naam as i now save half of my previous electric costs per month.

Therefore it proved to me that the inverter system is well worth paying extra for the longterm savings.

The old rattler as you put it was actually 7 years old and i sold it on as a second hand sale.

i'd accept the basis of your claim without hesitation if you talked about a period of at least two years.

[Naam]

Inverter units should not be undersized, ie. 40 sqm room using 10,000 BTU because they cannot run at partial load conditions, which are their main efficient mode. I have been using both Daikin and Panasonic inverter units, and electricity bills through March and April have been lower by 25% compared with my previous Mitsubishi units.

Your limited hours of usage will probably not justify the extra capital outlay of inverters.

i basically agree with what you said... except "bills mar/apr are lower".

reason: compared to last year (2010) we had a rather "cool" march and april, partially with clouds and rain. my electricity bill was down too ~10% (no inverters) but as the share of my airconditioning is only 50% of the total electricity bill it is safe to say that the different weather conditions gave me a saving of 20% on aircon energy use.

there's also a flaw in the claim that inverters are most efficient at partial load. that applies to gasoline and diesel engines which are more energy efficient at lower load/rotations (peak torque) but not to electric motors which -with only small variations- draw a certain amount of input energy to achieve a matching output capacity over the whole range of demand.

the big advantage of inverters vs. conventional units is the stepless adjustment of output according to varying demands, be it the difference of number of persons in the room, ambient outside temperature, varying inside heat sources, etc.

but -as you mentioned correctly- inverters can only save energy if their peak capacity matches peak demand AND if that demand varies. should these two main factors not exist, each and every Satang additional cost is pure waste.

[trisailer]

This might be a little off topic, but....

I have read through past posts regarding AC's because I'm evaluating my electric bill which had been averaging 3500/mo and took a jump last month to 6,000baht for one month!

I can't explain the huge jump in my electric bill. The AC in the living room which gets used throughout the day and is set on 27 is 5 years old and the brand is "Infinity" I can't find any energy numbers for this unit, but measured the usage myself using my outside electric meter (counting the revolutions) the problem is that I don't have any history to compare to. When the compressor is running the usage is 3.33kw/hr (calculated load 13.8 amps @240 volts rated for 50 amps)this is a 35,000BTU unit. with just the fan the usage is .34kw/hr (actually this includes a floor fan the refrigerator and 2 small lights) I've also measured all the electrical appliances in the house and everything appears with in normal values.

A couple of things that may be responsible (that I can think of) 1. I started smoking a month ago and am in and out to go smoke outside 20 times a day. 2. I have been turning the AC off and on manually most of the month thinking that I will save on the fan electric.3. I got some new music video's and have been playing the music pretty loud during the day. I suspect the AC, it is a cheap Chinese thing and it may be going bad, although I don't see or hear anything.

I cleaned the filters on both units that get used and they were about 25%

My first suspicion was that the meter was off. One neighbor reported that his bill had also doubled but two others say their's is normal.

The usage has come down since the last bill but it is still projected out to be 4548 baht/mo at the current usage rate since the last meter reading.

I'm open to ideas.

[juehoe]

[...]

Adelaide

Alice Springs

Bendigo

Brisbane

Cairns

Canberra

Darwin

Hobart

Melbourne

Perth

Sydney

Anybody know which one would be the best analogy for Bangkok's climate?

I would assume Darwin. The northern part of Australia has a similar tropical climate (hot-humid) as Thailand.

[Naam]

When the compressor is running the usage is 3.33kw/hr (calculated load 13.8 amps @240 volts rated for 50 amps)this is a 35,000BTU unit.

nothing wrong with that, even on the low side. but that could be the error margin of your [not exactly] sophisticated measuring method. one of my units is a 3-year old 36k btu and its rated consumption (including indoor fan) is 3.63kWh.

[Darrel]

I can't explain the huge jump in my electric bill.

You have cleaned your filters but have you ever had the coolant level checked on your 5-year-old compressors? It can leak away over time, and if the pressure is low the compressor will churn endlessly but provide little cooling.

[Greenside]

Here's what I have decided to do: 12000 Btu Samsung or possibly LG unit in the main bedroom and a 9,000 Btu inverter unit of the same brand in the small bedroom on the basis that when I start to use it as an office not only will the cost of power have undoubtedly gone up but my all day usage pattern in the hot season at least is most likely to make the extra 5k baht or so worthwhile.

Compared with the nightmare of trying to find the right boiler (see other thread) this decision has been pretty straightforward thanks to your input.

[trisailer]

When the compressor is running the usage is 3.33kw/hr (calculated load 13.8 amps @240 volts rated for 50 amps)this is a 35,000BTU unit.

nothing wrong with that, even on the low side. but that could be the error margin of your [not exactly] sophisticated measuring method. one of my units is a 3-year old 36k btu and its rated consumption (including indoor fan) is 3.63kWh.

Thanks Naam and Darrel. Actually I was going to get my AC guy here with a amp meter to do these measurements, but decided on using the meter instead because the meater turns 400 revolutions for each kw making it pretty easy to capture a accurate reading of useage with a stop watch. I took 3 readings of the AC compressor load counting 40 revolutions each time and then averaging them to generate the number.

Checking the charge of the coolent is a very good idea. Do you guys agree that if the charge were low than the load (amps) would be on the low side since the compressor would not be working as hard to compress less gas? At the same time the compressor would have to run longer to achieve the same cooling. I'll get it checked. I did have all of them cleaned and checked 6 months ago, but worth it to check again.

Thanks again.

[Naam]

Do you guys agree that if the charge were low than the load (amps) would be on the low side since the compressor would not be working as hard to compress less gas?

a logical conclusion, however the actual reason is not the reduced amount of refrigerant to compress but the lower amps are caused that the compressor works against an overall lower system pressure.

[Naam]

Here's what I have decided to do: 12000 Btu Samsung or possibly LG unit in the main bedroom and a 9,000 Btu inverter unit of the same brand in the small bedroom on the basis that when I start to use it as an office not only will the cost of power have undoubtedly gone up but my all day usage pattern in the hot season at least is most likely to make the extra 5k baht or so worthwhile.

Compared with the nightmare of trying to find the right boiler (see other thread) this decision has been pretty straightforward thanks to your input.

check the price difference between 9 and 12,000 btu! it might be worthwhile to buy the inverter unit with a higher rated capacity. you'd have enough 'power' should you need it plus the advantage that the output is adjusted to demand, i.e. no energy waste, only higher initial capital cost.

[trisailer]

Do you guys agree that if the charge were low than the load (amps) would be on the low side since the compressor would not be working as hard to compress less gas?

a logical conclusion, however the actual reason is not the reduced amount of refrigerant to compress but the lower amps are caused that the compressor works against an overall lower system pressure.

Good point. Actually wear within the compressor could account for longer run time to achieve the same cooling. I don't know what kind of pump is used to compress the gas, but lower tolerances could lower efficency. Is there a way to check the efficency of the pump?

[Naam]

Good point.

1. Actually wear within the compressor could account for longer run time to achieve the same cooling.

2. I don't know what kind of pump is used to compress the gas,

3. but lower tolerances could lower efficency.

4. Is there a way to check the efficency of the pump?

1. in theory yes, in practice most probably negligible.

2. in olden times piston compressors with valves (similar to an automotive engine, up/down/up/down), nowadays exclusively rotary systems.

3. "eggsburts" like me see it the other way round. tolerances increase caused by wear and tear and reduce efficiency.

4. not really, except for "is evaporator temperature = 12ºC or lower? if yes... don't worry, be happy".

[klikster]

One of OP's points that I didn't see addressed anywhere in the thread is interesting.

I read about multi units where one outside compressor runs several indoor fan units and as I understand that inverters are more effective when run for long periods of time it sounds like it makes sense to run one to feed two. Anyone researched or bought one?

This would seem to offer installation and footprint advantages. Anyone have experiences or expert opinions?

[Naam]

One of OP's points that I didn't see addressed anywhere in the thread is interesting.

I read about multi units where one outside compressor runs several indoor fan units and as I understand that inverters are more effective when run for long periods of time it sounds like it makes sense to run one to feed two. Anyone researched or bought one?

This would seem to offer installation and footprint advantages. Anyone have experiences or expert opinions?

multi units exist(ed) in a variety of versions.

-a single fixed rotation compressor which served several indoor units which had to run simultaneously,

-individual compressors serving specific indoor units but having a common condenser coil and condenser fan,

-small companies "handicrafted" single compressor units which enabled switching indoor units independently by adding a rather complicated array of bypass valves,

-single variable speed compressors which enabled running indoor units independently by adjusting compressor rotations through frequency conversion,

-single variable speed DC driven compressors, rotations adjusted by an inverter regulating voltage.

advantage: one compact outside unit

disadvantage when single compressor: compressor or starting capacitor failure = none of the indoor units work.

[Greenside]

Well my plan failed as soon as we walked into the supplier we had chosen to work with, The guy we had originally consulted wasn't there and the lady sitting at his desk insisted on starting from scratch as she couldn't lay hands on his notes. We told her what we wanted and she proceeded to rubbish both Samsung and LG on the basis that their service experience was that the fans lost power after about three years and needed replacement. Her suggestion: Panasonic. Price: Higher. Price for inverter model: eye watering..... Oh, there are two types...one that saves electricity and one that saves even more electricity. Prices? I'll have to call you on those. Head spinning I gave up, but will have to get back to it soon I suppose.

Daikin have (they say) been making multi units for 40 years - here's the link. Their set-ups are too big for me but if I wanted more rooms conditioned on a fairly continuous basis a multi unit inverter sounds like it might make sense.

BTW, the salesman at Siam TV in Chiang Mai made much of the different filters featured in the Samsung range - he showed me a selection of meshes labelled 60, 80, 100 which are fitted into increasingly pricey fan units. Given the rubbish air quality here in the burning season I thought this would be worth paying for but of course other manufacturers rate their filters in different ways so comparison is hard. Incidentally, I also liked the fibreglass case on the compressor unit that the Samsungs have (but not, for some reason, the inverter models) - it looks easy to keep clean and of course rust free although I guess the sun will be an issue.

Edited June 14, 2011 by Greenside

[trogers]

Watch out about multi systems. They do not usually mean one compressor feeding two fcu at the same time, but rather, feeding only one of either two at any one time.

[sotsira]

Most A/C engineers that i've spoken when i was looking to buy my A/C

always said that Samsung and LG units are the most troublesome,

they all recommended either Daikin, Mitsubishi and Panasonic to me.

[br12stol]

Cant praise the Daikin units enough, just installed new one in bedroom its very quiet and everyone I spoke to says they are best

[Beardog]

Well my plan failed as soon as we walked into the supplier we had chosen to work with, The guy we had originally consulted wasn't there and the lady sitting at his desk insisted on starting from scratch as she couldn't lay hands on his notes. We told her what we wanted and she proceeded to rubbish both Samsung and LG on the basis that their service experience was that the fans lost power after about three years and needed replacement. Her suggestion: Panasonic. Price: Higher. Price for inverter model: eye watering..... Oh, there are two types...one that saves electricity and one that saves even more electricity. Prices? I'll have to call you on those. Head spinning I gave up, but will have to get back to it soon I suppose.

Daikin have (they say) been making multi units for 40 years - here's the link. Their set-ups are too big for me but if I wanted more rooms conditioned on a fairly continuous basis a multi unit inverter sounds like it might make sense.

BTW, the salesman at Siam TV in Chiang Mai made much of the different filters featured in the Samsung range - he showed me a selection of meshes labelled 60, 80, 100 which are fitted into increasingly pricey fan units. Given the rubbish air quality here in the burning season I thought this would be worth paying for but of course other manufacturers rate their filters in different ways so comparison is hard. Incidentally, I also liked the fibreglass case on the compressor unit that the Samsungs have (but not, for some reason, the inverter models) - it looks easy to keep clean and of course rust free although I guess the sun will be an issue.

boy that really sucks & is so typical of Thailand. I did see that LG wasn't that favored on TV for reliability & the US Cnet reports were pointing toward them being the worst.

Our Toshiba which is a Carrier product came with a 5 year warranty opposed to a 1-3 year most of the other brands offer. But you can be sure if something goes south on the unit we will still have to pay for the servicing fee just like Mitsubishi water pumps & Compass fans. So far the Mitsubishi company totally rebuilt our pump that was immersed in water for 500 baht well worth it.Make sure to get the company to explain how they work the warranty. Sony & Black & Decker like you to pay for the shipping & send them the product. AC's they usually come out for but water heaters they might try to get you to pony up & ship to them + repairs under warranty. Ludicrous but it happens only here in Thailand.

[trisailer]

Cant praise the Daikin units enough, just installed new one in bedroom its very quiet and everyone I spoke to says they are best

Agreed, we installed a new one in our bedroom and it is very quiet. It also has a high EER rating.

I agree with Naam. Run the numbers before you buy and be sure you have a reasonable payback for the extra cost.

[wpcoe]

BTW, the salesman at Siam TV in Chiang Mai made much of the different filters featured in the Samsung range - he showed me a selection of meshes labelled 60, 80, 100 which are fitted into increasingly pricey fan units. Given the rubbish air quality here in the burning season I thought this would be worth paying for but of course other manufacturers rate their filters in different ways so comparison is hard.

Although probably not as cost-effective, and definitely more labor intensive, if you purchase a unit with a less effective filter screen is to use 3M Filtrete electrostatic material -- available at Tesco Lotus, Home Pro, etc.

If all other features of an air con unit were similar, yes, I'd go with the one with better a better filter, but if you find one system that has better features -- except for the filter -- you can use the Filtrete material to compensate for that shortcoming.

And, yes, the effectiveness of various filters can be significant. Many years ago my parents moved to the desert in Southern California -- in case you didn't know, deserts can be very dusty! -- and my mother's eyes watered and bothered her the first few years she lived there. Then, my dad tried a more expensive filter (this is on a central furnace/air con system) without telling her. Her eyes were back to normal within a week.

[SantiSuk]

......... I don't know anyone who sets their thermostat much higher than that (25 degrees). You have to wonder why they sell them.

Odd - I was just thinking you are the only person I've heard of who would set an aircon at 25 degrees or less. 27/28 is just fine for me when I'm around the house during the day and it helps to train the body not to feel too uncomfortable when outside or when the power goes. But we do also use a fan directed at the bed on a low setting in conjunction with the aircon at 28 (on a two hour timer) during hot summer nights.

I spent two years in Houston in my early career. The outside temp was typically 90/90 (degrees F/humidity). Office/shop/restaurant aircons were typically set at 19 degrees F. Ridiculous (that's a full-stop - not "<deleted> ridiculous") - you had to wear a jumper!

I don't think the US has changed much if my more recent trips to NY were anything to go by - US still thinks that squandering energy is a public right.

I digress - sorry - and I do love America and many things American BTW

[luudee]

......... I don't know anyone who sets their thermostat much higher than that (25 degrees). You have to wonder why they sell them.

Odd - I was just thinking you are the only person I've heard of who would set an aircon at 25 degrees or less. 27/28 is just fine for me when I'm around the house during the day and it helps to train the body not to feel too uncomfortable when outside or when the power goes. But we do also use a fan directed at the bed on a low setting in conjunction with the aircon at 28 (on a two hour timer) during hot summer nights.

I spent two years in Houston in my early career. The outside temp was typically 90/90 (degrees F/humidity). Office/shop/restaurant aircons were typically set at 19 degrees F. Ridiculous (that's a full-stop - not "<deleted> ridiculous") - you had to wear a jumper!

...

Guys, it all depends on how long you have lived here (or in TX for that matter ).

Here is luudee's theory :

The longer you live in a high temperature/high humidity climate, the lower

your A/C will be set.

So if you have been here like me more than 15 years, your A/C is probably

somewhere between 22-24C. If you just got here, your A/C is at 28C. And

everybody else is somewhere in between !

I spent some time in Galveston TX btw ... but was "native" to CA (SFO) ...

Cheers,

luudee

[klikster]

Luudee, maybe I am the "semi-long-termer" who doesn't fit your theory. Full time since '96 and I'm a 27/28 degree type.

Um, maybe next year I have to crank the setting down to 22/24

Summers in Houston are cool compared to where I grew up .. and humidity often touched 90%.

Edited June 19, 2011 by klikster

[Greenside]

And the final decision: Panasonic non-inverter. One 9,000 and one 12,000 BTU for a total of 30,500 Baht including full installation and 2 years cleaning. A premium of about 3,000 over the Samsungs but everyone swears they are much better so in the scheme of things it doesn't hurt too much.

[Schooner]

This is a little astray of the topic, but I am looking for ways to reduce my electric bill and one of the things I've noticed is that the tops of the recessed lighting in my house is open to the roof space.

I got to thinking about this when a gecko I was chasing ran up through the light fixture and escaped. I went to Home Pro thinking I would look for a cap of some sort to keep the air in and the animals out and it turns out that some of these recessed light fixtures have a glass cover below the light which would be perfect. Unfortunately they are 600 baht each and I need 33.

I'm thinking of a way to retro fit mine, maybe buy the glass circles and find a way to attach them, velcro or even cut notches in the fixture to accommodate the glass covers.

Anyone have experience with this?

[Greenside]

You'll do a whole lot better starting a new thread - this one has pretty much run its course.