making an A/C unit more efficient

[bobdole369]

OK so back to my original question - since we now know that I have an undersized, poorly designed cooling system - what can I do to increase the cooling effect, especially during the lava hot summer?

Shading it was brought up a few times - anything else? I was thinking of going through the ductwork and resealing anything, possibly putting insulation on the outside of the ducts since I'm fairly sure they are just bare.

 

[Chryso]

If both you and your neighbor are using that much power it sounds like you don't have any insulation.

 

[Deviant Grasshopper]

Originally posted by: bobdole369
OK so back to my original question - since we now know that I have an undersized, poorly designed cooling system - what can I do to increase the cooling effect, especially during the lava hot summer?

Shading it was brought up a few times - anything else? I was thinking of going through the ductwork and resealing anything, possibly putting insulation on the outside of the ducts since I'm fairly sure they are just bare.

Tape a piece of tissue to a long stick and use that to look for air leaks around your ductwork. Places where 3-4 ducts merge into 1 seem to be the worst for leaks.

 

[Capt Caveman]

If the house doesn't already have them, ceiling fans will help.

 

[AlienCraft]

Originally posted by: bobdole369
To clear one thing up - it's $500 for the month of July, $485 for August, $503 for September. Neighbors bill is the same for the same house. Thats why I didn't question in. We also have 9 PC's, a fridge, a dryer, electric stove, iguanas, fish, 4 TV's (roomie has an HD CRT that weighs like 300 lbs - I bet that thing alone uses a kilowatt).

Once it hits may or so it just stays on continuously until mid-october.

TO clear another thing up - its central air and all spaces are cooled. The hot air return is a huge louvered hole in the living room. No returned air from the upstairs, it all gets sucked in through this one vent in the LR - vents are in 3 BR's and bathrooms upstairs, one in the kitchen and LR downstairs. This is 1980's sprawl-building ghetto townhouses that were built when SFL was experiencing tremendous growth - so no real thought was given to how the AC unit actually works, or its efficiency. Without tearing up walls I see no easy way to resolve the return air problem. It's just stuck that way.

On hot days I go out several times in the afternoon - run the hose until the water gets cool and spray off the condensor for about 3 minutes. It noticeably cools the air coming through the condensor unit and the air inside gets noticeably cooler for a bit.


No mice, but boy do we get a lot of lizards in there. Believe it or not, despite the oppressive supervillianish heat ray laser sun that we get in the summer, those little lizards are always looking for heat, and since theres nearly always some water via the hose, thats where they hang out.
I used to work at a place that did heat pumps for your pool so I kinda get the HVAC cycle. One thing that we ARE missing that I think would make a difference is to shade the condensor. It's untouchable in the summer. I could easily cook an egg on that thing.


So I AM regularly cleaning the coils, all the fins are straight, the pressure is right with no leaks, the filter is regularly changed out, I even recently cleaned the evap coils inside the air handler with a degreaser/bleach mix to retard any nasty growths. Got a good deal of slime outta there. I also flushed the drain and made sure the automatic drain overflow turn off mechanism was working and not being activated.

OK so in short the basics are covered. I don't see any suggestions that make me go "OOOOOH I didn't think about that".

I don't own the house, my roommates family does. I live with a girl and her brother and my fiancee any myself - its owned by their dad who is loath to upgrade something that is "working". I don't blame him, he makes no money on us. The unit is likely undersized. If it were mine I'd have already gone 2 steps up on the condensor unit and compressor.

I was considering building a timed water spray mechanism, seeing as how hitting it with the hose cools it down a bit. (sorta like the intercooler water spray deals you see on turbo cars). Anyone ever do something like that?

The heat load from the 9 PCs and other stuff make it impossible for the AC unit to keep up. No doubt that those loads were never calculated in. Second best idea would be to put a portable AC unit in the room with the PC's in it, try to mitigate the total load somewhat.
Also any ceiling fans? Need to keep the air off the ceiling.

 

[GasX]

I'll bet you haven't changed the filter. Check the grill on the air return. It should pull off. Find out what size filter is behind it and go to homedepot and buy some replacements.

Pull down the blinds on the sunny side of the house.

Those two simple things could make a big difference

 

[tasmanian]

Originally posted by: richardycc

Originally posted by: tasmanian
Turn it down to 69*. The ac uses 75% less power at that temperature.

this is AC, not heat, I think you got it the other way around.

I wasnt being serious.

 

[Iron Woode]

the fact is you need a new, high efficiency AC unit sized properly for the house.

no amount of tweaking is going to improve your situation.

some ceiling fans can help circulate the air.

 

[torpid]

What temperature do you set?

 

[bobdole369]

I'm shocked that noone but myself mentioned using water - a much better conductor of heat - to supplement the fan on the condensor unit! What gives?! I thought for sure there were some HVAC gods in here that know that trick. No mention of swamp coolers (granted I think I did say that I live in S. FL - where swamp coolers do not work but still). No "Sun-blocker" a la Mr. Burns. No peltiers in some bizarre way overengineered and unnecessarily complicated and expensive creations? No ice buckets with radiators and motors and fans? No leaving the fridge open? No setting the oven to cold? No tenting the fridge?

To answer torpid - 74 most days, but once it hits June it doesn't matter as the coolest it can get is about 13 degrees less than outside (i.e. if the blazing hot sun makes it 98 out - then inside it shall be 85). And the air runs non-stop - that motor on the compressor doesn't turn off for nigh on 5 months - well maybe it does as part of its cycle, but the air doesn't turn off.

Oh and I do have ceiling fans, every single room - all on most of the day. And the filter is clean (for the xth time) - I do it monthly. Its never very bad. Running without a filter doesn't make it any cooler.

 

[torpid]

I have the same can't-cool-enough issue and just ended up setting my thermostat at about 78+ (we don't get 100+ days often in Madison so this might not solve your always-on problem) and it saved a LOT of money. Since your unit can't do an adequate job actually cooling, you should mainly rely on it for a bit of cooling but mostly humidity reduction. Turn it off when you aren't home and buy some good floor fans. We did that and went from $300+ bills to $150-200.

I would be curious to see if you actually CAN solve the problem of inadequate cooling without a new unit, though. I'm just aiming for "won't die and won't go broke" myself.

 

[imported_Lothar]

Originally posted by: Brainonska511
Make sure there are no mice inside.

Best advice in this thread.

 

[TastesLikeChicken]

When is the last time the AC unit was serviced because your bill seems way out of line? I have a 4/3 in Orlando with 2500sf under air. Even with the crappy old 3 ton air handler and compressor it still cooled my house to 75 and would cycle even on the warmest of days. The highest electric bill I've ever had is $475. We replaced our air handler to a 5 ton 2 years ago and just had a new, higher-efficiency compressor put in (and switched over to R410a refrigerant since R22 is being phased out). The electric bills should be quite a bit cheaper this year.

You may want to have your refrigerant checked and your system fully serviced. It usually runs @ $125 or so, depending on if they have to charge your system, and how much refrigerant they use. You'll want them to test for leaks. They should also clean your condenser coils, check the duct pressures, and test the temperature output of your air handler. It's money well spent that can easily be made up for by lower electric bills.

 

[Vette73]

Have you checked the evaporator coils? Mine in my new to me house were clogged up. my air handler did nto have a access point to clean them so i had to cut it open and make one. Once in I cleaned them very well I got a tool to straightn out the parts that were not 100 level and straight.

here is a Pic with some that are really clogged.


Air filters stop a lot of dirt/dust but not all. A lot of it will stick to the Evap. Coils and clog over time.

 

[bobdole369]

Ahhhh, I did not check the underside of the evap coils. I couldn't really get to the bottom side from the side panel, just the top of them., but based on the filters that get replaced monthly - its not out of the question that its full of gunk.

 

[Rubycon]

You cannot make a unit more efficient than designed. However if the coils are dirty, compressor has leaking valves (on aged units) or the charge is incorrect it will not have the original cooling capacity. For hot areas you may need to add additional "spot" cooling such as a portable unit or a window shaker. Increasing the the capacity of a CAC by replacing the A coil and condenser unit can cause short cycling and reduce beneficial dehumidification resulting in a clammy or close feeling environment.

 

[YOyoYOhowsDAjello]

Originally posted by: Lothar

Originally posted by: Brainonska511
Make sure there are no mice inside.

Best advice in this thread.

Indeed

http://atot.spreadshirt.com/us...ir-Conditioner-3874780

 

[IGBT]

..if your roof is a solar mass (black/dark) yo can apply a roofing material that is bright white/silver and stop absorbing visible/UV light. I did this on a flat tar/gravel roof and the results were amazing. The house no longer heats up on bright sunny days. The addition of double pane windows also enhanced the effect. If you have a solar mass over your head your in a giant crock pot.

 

[NoShangriLa]

Originally posted by: bobdole369
To clear one thing up - it's $500 for the month of July, $485 for August, $503 for September. Neighbors bill is the same for the same house. Thats why I didn't question in. We also have 9 PC's, a fridge, a dryer, electric stove, iguanas, fish, 4 TV's (roomie has an HD CRT that weighs like 300 lbs - I bet that thing alone uses a kilowatt).

Once it hits may or so it just stays on continuously until mid-october.

TO clear another thing up - its central air and all spaces are cooled. The hot air return is a huge louvered hole in the living room. No returned air from the upstairs, it all gets sucked in through this one vent in the LR - vents are in 3 BR's and bathrooms upstairs, one in the kitchen and LR downstairs. This is 1980's sprawl-building ghetto townhouses that were built when SFL was experiencing tremendous growth - so no real thought was given to how the AC unit actually works, or its efficiency. Without tearing up walls I see no easy way to resolve the return air problem. It's just stuck that way.

On hot days I go out several times in the afternoon - run the hose until the water gets cool and spray off the condensor for about 3 minutes. It noticeably cools the air coming through the condensor unit and the air inside gets noticeably cooler for a bit.


No mice, but boy do we get a lot of lizards in there. Believe it or not, despite the oppressive supervillianish heat ray laser sun that we get in the summer, those little lizards are always looking for heat, and since theres nearly always some water via the hose, thats where they hang out.
I used to work at a place that did heat pumps for your pool so I kinda get the HVAC cycle. One thing that we ARE missing that I think would make a difference is to shade the condensor. It's untouchable in the summer. I could easily cook an egg on that thing.


So I AM regularly cleaning the coils, all the fins are straight, the pressure is right with no leaks, the filter is regularly changed out, I even recently cleaned the evap coils inside the air handler with a degreaser/bleach mix to retard any nasty growths. Got a good deal of slime outta there. I also flushed the drain and made sure the automatic drain overflow turn off mechanism was working and not being activated.

OK so in short the basics are covered. I don't see any suggestions that make me go "OOOOOH I didn't think about that".

I don't own the house, my roommates family does. I live with a girl and her brother and my fiancee any myself - its owned by their dad who is loath to upgrade something that is "working". I don't blame him, he makes no money on us. The unit is likely undersized. If it were mine I'd have already gone 2 steps up on the condensor unit and compressor.

I was considering building a timed water spray mechanism, seeing as how hitting it with the hose cools it down a bit. (sorta like the intercooler water spray deals you see on turbo cars). Anyone ever do something like that?

Get heavy drapes to block out the sun heat during the day. Turn off all applances/lights in the house when not in use and that include idling computer/s. Make sure ductings are not block, and absolutely sure that the return air resgister is not block or hampered in anyway.

 

[NoShangriLa]

Originally posted by: SarcasticDwarf

Originally posted by: AlienCraft

Originally posted by: Brainonska511
Make sure there are no mice inside.

Clean the filter and try to vacuum any dust on the inside that you can get at. Keep it at a constant setting? My parents claim (from the central air people) that keeping it cooled is easier, because after the home is cooled down, it's fairly easy to keep it at that temperature. Thus, if that's true, make sure you have decent insulation and put curtains/shades on sun-facing windows to help cool the house during the day.

But overall, if it's having a hard time cooling the area, you probably need a bigger air conditioner for the room.

Without going through the check list such as Tinting the windows, planting shading shrubbery, checking the wall insulation, etc. the single most effective thing you can do is to get rid of your outdated technology and step up to a slightly larger, more efficient unit.

Also, on your old unit, make sure the fins are cleaned and straight on the heat exchanger. You want to get that foaming cleaner that HVAC guys use. It's nasty shit, so be careful with it. Also, old ducting is probably sealed with duct tape, and that stuff fails over time, so you may be wasting AC in non livable space. New insulated ducting is far more effecient as well.
Also, if the hot air return is not located properly, the system will never cool as well as it could.

Yeah, it sounds more like his system is designed improperly and has undersized equipment than anything else.

Or, could it be that cooling 9 PC heaters weren't calculated in the cooling load.

 

[NoShangriLa]

Originally posted by: bobdole369
OK so back to my original question - since we now know that I have an undersized, poorly designed cooling system - what can I do to increase the cooling effect, especially during the lava hot summer?

Shading it was brought up a few times - anything else? I was thinking of going through the ductwork and resealing anything, possibly putting insulation on the outside of the ducts since I'm fairly sure they are just bare.

Bare ductwork is fine as long as they are in heated/cooled space (ie, not in the attic, or in the exterior wall).

 

[Regs]

My PC in an hour of 3D gaming becomes a space heater. I'm not even exaggerating.

 

[IronWing]

Paint house white if it isn't white already. Paint roof white or install white shingles. As mentioned, plant trees or or other tallish plants on east, south, and west sides. Build one of those Florida screened yards on south side of house using heavy material to cut light. Go naked.

 

[NoShangriLa]

Originally posted by: TastesLikeChicken
When is the last time the AC unit was serviced because your bill seems way out of line? I have a 4/3 in Orlando with 2500sf under air. Even with the crappy old 3 ton air handler and compressor it still cooled my house to 75 and would cycle even on the warmest of days. The highest electric bill I've ever had is $475. We replaced our air handler to a 5 ton 2 years ago and just had a new, higher-efficiency compressor put in (and switched over to R410a refrigerant since R22 is being phased out). The electric bills should be quite a bit cheaper this year.

You may want to have your refrigerant checked and your system fully serviced. It usually runs @ $125 or so, depending on if they have to charge your system, and how much refrigerant they use. You'll want them to test for leaks. They should also clean your condenser coils, check the duct pressures, and test the temperature output of your air handler. It's money well spent that can easily be made up for by lower electric bills.

It could be that it is an old heatpump running on R-22 refrigerant with wide tollerant level therefore it is at 10 or less SEERs. Today high efficency heatpump run at 18-19 SEERs (twice as efficent as the older models) with tigher tollerant of R-410A refrigerant.

 

[NoShangriLa]

Originally posted by: bobdole369
I'm shocked that noone but myself mentioned using water - a much better conductor of heat - to supplement the fan on the condensor unit! What gives?! I thought for sure there were some HVAC gods in here that know that trick. No mention of swamp coolers (granted I think I did say that I live in S. FL - where swamp coolers do not work but still). No "Sun-blocker" a la Mr. Burns. No peltiers in some bizarre way overengineered and unnecessarily complicated and expensive creations? No ice buckets with radiators and motors and fans? No leaving the fridge open? No setting the oven to cold? No tenting the fridge?

To answer torpid - 74 most days, but once it hits June it doesn't matter as the coolest it can get is about 13 degrees less than outside (i.e. if the blazing hot sun makes it 98 out - then inside it shall be 85). And the air runs non-stop - that motor on the compressor doesn't turn off for nigh on 5 months - well maybe it does as part of its cycle, but the air doesn't turn off.

Oh and I do have ceiling fans, every single room - all on most of the day. And the filter is clean (for the xth time) - I do it monthly. Its never very bad. Running without a filter doesn't make it any cooler.

I mentioned geothermal as a way of cooling, but that cost a substantial amount money. Another method of using water is water cool heat exchanger, but the cost of waste water is much higher than electricity on air source heat pump. You can also use cooling towel method to employ water as a coolant, but the cost of filtration, bacterial, and toxic material control only worth while for large building/industrial plants.

I you don't mind living with mold and distroy the house in the long run, then it is perfectly fine to fill the basement with water to employ evaporation as a cooling method.