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Story of a dirty air conditioner


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Posted

Thought it might be of interest for some to see the dynamics of an air conditioner before and after cleaning.

A couple of weeks ago when the temperature started going up my a/c at work was not up to it. Mornings just ok, afternoon uncomfortable. To show the a/c tech at the lab I slapped together a breadboard with a microcontroller, digital temperature/humidity sensor and a USB interface to my computer and put together some software to graph its history. This is in case he came early in the morning and says everything looks fine. smile.png

When he opened the case the fan and fins were basically caked in grime with the fan not able to handle the load on it.

This is the photo of my data monitoring system.

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This is the temperature plot over 2 days. The peak temperatures were around 2-3PM and the low points on the graph very early morning. The outside unit was running continuously but very little help in cooling.

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After cleaning showing temperature (top graph) humidity (bottom graph). The rise in temperature at the beginning of the graph is after shutting the a/c off and him opening the window for the pressure hose. After cleaning, closing window and turning on you can see the quick drop in both temperature and humidity. It was cool again. After it stabilized you can see the rise and fall of the temperature as the a/c cycles on and off (hysteresis) and the corresponding increase/decrease of the humidity reflecting the coils cooling and condensing the moisture.

BTW, if using an inverter a/c, both those lines would be nearly flat as it maintains temperature and as such humidity in a linear fashion.

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The a/c unit is a Mitsubishi Heavy. Not sure if it is 9k or 12k, I lean toward it being 12k as the room is 20sqm and the moderately short cycle times of 16 minutes.

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Posted

Very informative thank you. I just call the air conditioner cleaning guy. If the water in the bucket is dark after the first rinse I ask for a second rinse. He seems to understand that ok and does it.

Posted

Very informative thank you. I just call the air conditioner cleaning guy. If the water in the bucket is dark after the first rinse I ask for a second rinse. He seems to understand that ok and does it.

In my case the water was pretty much pitch black on the first round. The same thing happened less than a year ago with the same amount of gunk. Because I have two servers in that room on all the time I need to have the a/c on 24/7.

Posted

Sorry I was just having a bit of fun with you. No hard feelings. I keep my bedroom ac on 24/7 as well and 2-3 others on about 12 hours a day. I also have them cleaned every 4 months or so and it seems to keep the electric bill down after cleaning.

Posted (edited)

good post, informative. I'm far from technically sophisticated smile.png so I have them cleaned twice/year. Will be watching the water in the bucket next time.

Edited by likewise
Posted

good post, informative. I'm far from technically sophisticated smile.png so I have them cleaned twice/year. Will be watching the water in the bucket next time.

Makes a good noodle soup and might be more hygienically than some others.

Posted

How much is an air conditioner cleaning usually?

In Chiang Mai it averages around 500 Baht for a full inside and outside unit cleaning.

Posted

I clean them myself.Not sure about the rest of you but it seems that about 80% of the hotels I stay at the. Filters are dirty.I quit

Notifying the hotel,I just clean it myself.You would figure the owners/managers of the hotel would have them cleaned on A regular

Basis.

Posted

Sorry I was just having a bit of fun with you. No hard feelings. I keep my bedroom ac on 24/7 as well and 2-3 others on about 12 hours a day. I also have them cleaned every 4 months or so and it seems to keep the electric bill down after cleaning.

Does that send your electricity bill through the roof, or is it more efficient?

Past few Summers, we've had a Bedroom AC on all night. One in the Computer Room several hours a day/night and the same in the lounge.

Average Electricity has been between 5K Baht and 6K Baht PER MONTH.

Posted

In the hotel, the maintenance guys have a little temperature gun that they aim at the AC. 14° or above - needs cleaning. Below 14° - still OK.

Posted

Sorry I was just having a bit of fun with you. No hard feelings. I keep my bedroom ac on 24/7 as well and 2-3 others on about 12 hours a day. I also have them cleaned every 4 months or so and it seems to keep the electric bill down after cleaning.

Does that send your electricity bill through the roof, or is it more efficient?

Past few Summers, we've had a Bedroom AC on all night. One in the Computer Room several hours a day/night and the same in the lounge.

Average Electricity has been between 5K Baht and 6K Baht PER MONTH.

Not to bad, I'm paying between 3-4K a month. May creep up to 5K during the hot hot season. I pay my bill directly to the power company so no apartment mark up per unit.

Posted

I have a pretty decent air con guy and according to him air con should be cleaned every 3 months if in regular use and 6 months if occasional use.

It should also be cleaned every 3 months if there are pets on the premises as pet hair blocks up the pipes.

If air con is NOT in use on regular basis, it should be turned on for an hour every week to make sure gas does not dry up.

In case of animals, it is wise to use high pressure gun to clean out all the pipes, as pet hair does create blockage which leads to overheating and leaks

Posted

Sorry I was just having a bit of fun with you. No hard feelings. I keep my bedroom ac on 24/7 as well and 2-3 others on about 12 hours a day. I also have them cleaned every 4 months or so and it seems to keep the electric bill down after cleaning.

Does that send your electricity bill through the roof, or is it more efficient?

Past few Summers, we've had a Bedroom AC on all night. One in the Computer Room several hours a day/night and the same in the lounge.

Average Electricity has been between 5K Baht and 6K Baht PER MONTH.

Thats about the figure i get here also....so it may be the normal....If I use the welder a lot, it usually hangs either side of 6K...But i run a pool as well in that bill.

Hope this helps.

Posted

I have a pretty decent air con guy and according to him air con should be cleaned every 3 months if in regular use and 6 months if occasional use.

It should also be cleaned every 3 months if there are pets on the premises as pet hair blocks up the pipes.

If air con is NOT in use on regular basis, it should be turned on for an hour every week to make sure gas does not dry up.

In case of animals, it is wise to use high pressure gun to clean out all the pipes, as pet hair does create blockage which leads to overheating and leaks

to make sure gas does not dry up

...which leads to overheating and leaks

cheesy.gif

Posted

I am more interested in the breadboard and usb interface. Could you post a schematic please?

Actually I just slapped it together without a schematic. I'll put together something for you. Because serial comm ports on PCs are becoming more scarce I designed a USB-Serial converter, the module you see at the bottom, and all new designs I do use this now. I sent the board out to a commercial PCB facility and had a bunch made. Then have a tech who populates it here.

The parts for the breadboard:

1. PIC16F688 (any PIC or microcontroller will do)

2. A HopeRF HHT02D (SHT11 equiv) digital (2 wire) temperature/humidity sensor. This is an expensive item, $30USD at Futurlec but they had a similar version for $10 and I bought several of them. If only monitoring temperature a very simple solution is the LM35 sensor for about 72 baht at Elements.

3. 1 resistor

Power for the system comes from the USB bus so no external supply needed.

The USB-Serial converter uses one IC, FT232RL (about 100 baht IC)

There are sensors shown on this Thai website - http://www.thaieasyelec.com/products/sensors/humidity-temperature.html

And here - http://www.arduino.in.th/product/78/dht11-digital-temperature-and-humidity-sensor

I bought several of those DHT11 sensors as they are cheap but haven't written the software for it yet.

Posted

I am more interested in the breadboard and usb interface. Could you post a schematic please?

Actually I just slapped it together without a schematic. I'll put together something for you. Because serial comm ports on PCs are becoming more scarce I designed a USB-Serial converter, the module you see at the bottom, and all new designs I do use this now. I sent the board out to a commercial PCB facility and had a bunch made. Then have a tech who populates it here.

The parts for the breadboard:

1. PIC16F688 (any PIC or microcontroller will do)

2. A HopeRF HHT02D (SHT11 equiv) digital (2 wire) temperature/humidity sensor. This is an expensive item, $30USD at Futurlec but they had a similar version for $10 and I bought several of them. If only monitoring temperature a very simple solution is the LM35 sensor for about 72 baht at Elements.

3. 1 resistor

Power for the system comes from the USB bus so no external supply needed.

The USB-Serial converter uses one IC, FT232RL (about 100 baht IC)

There are sensors shown on this Thai website - http://www.thaieasyelec.com/products/sensors/humidity-temperature.html

And here - http://www.arduino.in.th/product/78/dht11-digital-temperature-and-humidity-sensor

I bought several of those DHT11 sensors as they are cheap but haven't written the software for it yet.

Thanks very much.

Currently in Oz but will check it out.

Posted

I clean them myself.Not sure about the rest of you but it seems that about 80% of the hotels I stay at the. Filters are dirty.I quit

Notifying the hotel,I just clean it myself.You would figure the owners/managers of the hotel would have them cleaned on A regular

Basis.

There is a bit more involved in cleaning an aircon than cleaning the filters.

Posted
TheCruncher, on 30 Mar 2016 - 11:42, said:
thrilled, on 29 Mar 2016 - 00:53, said:

I clean them myself.Not sure about the rest of you but it seems that about 80% of the hotels I stay at the. Filters are dirty.I quit

Notifying the hotel,I just clean it myself.You would figure the owners/managers of the hotel would have them cleaned on A regular

Basis.

There is a bit more involved in cleaning an aircon than cleaning the filters.

such as?

Posted
TheCruncher, on 30 Mar 2016 - 11:42, said:
thrilled, on 29 Mar 2016 - 00:53, said:

I clean them myself.Not sure about the rest of you but it seems that about 80% of the hotels I stay at the. Filters are dirty.I quit

Notifying the hotel,I just clean it myself.You would figure the owners/managers of the hotel would have them cleaned on A regular

Basis.

There is a bit more involved in cleaning an aircon than cleaning the filters.

such as?

Cleaning the fan and fins on the indoor unit, similar on the outdoor, unblocking the drain tube.

The "pro's" have a pressure washer with a short lance to get in the indoor unit and a water catching arrangement to keep the carpet dry (ish).

Posted
TheCruncher, on 30 Mar 2016 - 11:42, said:
thrilled, on 29 Mar 2016 - 00:53, said:

I clean them myself.Not sure about the rest of you but it seems that about 80% of the hotels I stay at the. Filters are dirty.I quit

Notifying the hotel,I just clean it myself.You would figure the owners/managers of the hotel would have them cleaned on A regular

Basis.

There is a bit more involved in cleaning an aircon than cleaning the filters.

such as?

Here's a service manual form Saijo Denki that shows what's involved:

http://saijo-denki.co.th/download/technic/16clean.pdf

Posted

I am more interested in the breadboard and usb interface. Could you post a schematic please?

This is the bread board for the DHT11/DHT22 version. The schematics below that. As I mentioned, the hardware design is very trivial, it's the microcontroller code that is a pain. You could actually use an Arduino or Rasberry Pi to control the sensor if you have those. First schematic is for a SHT11 sensor the second for a DHT11/DHT22 sensor. The sensors are much cheaper on Amazon or ebay.

post-566-0-84482600-1459485592_thumb.jpg

post-566-0-17656000-1459485600_thumb.jpg

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Posted

Some excellent replies and info thanks to all. Cleaning should certainly help reduce running costs.

For me the important thing is getting rid of the mold and fungi. Anyone who has ridden in a mini-bus and looked at the blackened ceiling..........

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