Simple AC tips to help keep your cool this summer
 

*

I don't have an air conditioner, but I will apply these same principles to my room fans. Thanks!

Oh yeah, that reminds me. Another simple tip is to move to a cooler, drier climate.

Or buy 7 window units like Saylors mom did.
I cant even imagine,what it must cost to try & cool that old house.

LMAO

I wouldn't think that shutting of the supply vents to unused rooms would cause any issues. I would think that the volume of air that the fan pushes is what it is, and that closing off supply vents would simply allow that air to be pushed to the vents that are open.

Am I wrong?

It'll get to the high 90s here in Denver today, but yeah, it's at 10% humidity.

That's what I always thought as well, but I was told by several people who are a hell of a lot smarter than me that it's not the case.

great thread and thank you for the tips!

That's surprising.

What if you have 2 a/c units, one for upstairs and one for downstairs? I've heard all kinds of different advice on running one or both. Some say set both to same temp always; some say run only upstairs and let the cooler air drop to downstairs; and some say run the downstairs unit when you're downstairs and upstairs unit when you're upstairs.

Yes, it is. The way it was explained to me is your fan can only move x amount of air through whatever size your duct is, and the only way to move more air is with a more powerful fan, or a larger duct.

Interesting question, and one that we haven't discussed. I would never shut either of them completely down, that's for sure. IMO you should set them both at whatever temp you desire, and let 'em go. Obviously the upstairs one is always going to run more.

me ac is clean and working good .. had to replace a capasitor this year .. we clean our outside unit at least twice a year mainly because we live right on a country road and lots of farmer traffic rolls in the dust ....

I don't see why that would be the case, though.

It saves on the ac unit but it doesn't save on the bill.

So, you pick. More of a push on the AC to save a few bucks on the bill (shortening the life of the unit) or lengthening the life and overall production of your unit while paying a bit more.

Don't know for sure but when we have shut the upstairs unit off the downstairs unit has a harder time keeping the first floor cool.

You never want to shut off an AC unit in the summer. Even if we get one of those rare 82 degree days, if you decide to shut it down and open your windows for only one day, the moisture you will let in will permeate your walls, carpet, furniture etc, and can take 3-5 days to get back out of your house once you turn your AC back on.

At my first house the AC unit was located on the west side. Totally unshaded and during the afternoon/evening the unit was blistering hot because of the sun.

I built a large three sided well ventilated wooden cover to shade it and it made a difference in how quickly it could cool down the house.

When I built this house I designed it so the unit would sit on the east side out of sun during the peak cooling times of the day.

Soak those lows in, soak 'em in:

<table class="city-details" border="0" cellpadding="0" cellspacing="0"><thead><tr><th>Current Conditions
</th> <th class="day med-small">Today</th> <th class="day med-small">Tomorrow</th> <th class="day med-small">Monday</th> </tr> </thead> <tbody> <tr class="hero"> <td class="location small"> Albuquerque, NM </td><td>Partly Cloudy
</td><td class="day small" align="center">94° / 70°</td><td class="day small" align="center">94° / 69°</td><td class="day small" align="center">91° / 70°</td></tr></tbody></table>
Aaaaaww yeah!

Yes this is very wrong. The air moves through a piece of duct work. The duct work will only flow a certain amount of air. If you shut of vents you are putting external pressure on your blower motor which will make it work harder to try and attain the RPM's that it is suppose to turn. Which will make the motor get hot and over a period of time will make it burn out earlier than it should.
Another thing it can do is not move enough air across the indoor coil, the evaperator coil, which will make your system not cool properly and can send liquid back to the compressor in your outdoor unit causing it to slug and burn it out prematurely as well.

So, if I turn the breaker off right by the outdoor A/C unit and remove the grate from the top I can blast the coil with water from the inside? Do I need to protect/avoid anything from the water as I do this?

Bugeater, You are fixing to find out that you are going to be a very popular man. Especially in the worst of conditions since that is generally when a capacitor or a compressor or something else fails.
Your friends and family will be calling you and expecting it done for nothing or for a favor later or calling in a favor.

What type of epa card did you get? I have been doing this stuff for 7 years. Been to a lot of classes. And to a lot of seminars by various equipment manufacture.

[QUOTE=Bugeater;7765718]Hey CP peeps, I'm willing to bet some of you have noticed it's freaking hot outside. And since I've spent the last year going to school for HVAC, I thought I'd share some things I've learned about air conditioning systems. If you don't think yours is operating properly, here are some simple things you can check out on your own.

First off, check your outside unit. On it you will find two copper tubes coming from the house and into the unit. Touch them both.

QUOTE]

Way too hot to go outside. Next.

On most units the electrical components (contactor, capacitor) are in an isolated area and aren't an issue. You definitely want to avoid hitting those. The compressor and condenser fan motor are both sealed and can withstand some water on them.

Blast might be a strong word here. And be careful going across the "grain" or the coil. You don't want to fold over the fins. The fins are what allow the air to take the temperature off of the refrigerant.

I've been looking at some for free simply because I want the experience. But that will change next year. And I don't have the equipment yet to make major repairs.

I have a universal license. What's funny is you really don't need to know a whole lot to get it, you just need to be able to memorize a bunch of stuff. I've already run into several people who have them and really have no clue how to properly charge a unit.

That is very true. A lot of people don't know how to use sub-cool, and super heat to charge units.
I have found a lot of people that want to use the "flash" technique to charge R-22 systems. I just have to laugh at them knowing they don't know what they are doing and charging someone for them to feel the suction line.

That's pretty much what most of the other maintenance guys I work with do. The only thing that trips me up is trying to determine if a unit has a TXV or not. Sometimes you can't tell unless you open them up, and that isn't always an easy thing to do.

It is always best to look. But if you can get model and serial you can also call your distrubitor and tech support of the manufacture and they can tell you. If you are doing maintenance in and or on a specific building it won't take long to find out.
This much I can tell you if it is 410 it will have an expansion valve or an R-22 that is a 13 SEER or higher it will have one as well. Most of the older units don't have them but if someone has changed a condensor and left the old coil then they should of added a TXV.
Here is something that I had to learn the hard way. That a load of people don't know. If you are working on an American Standard or a Trane and you have to change a compressor out. There are 2 line driers that look like mufflers on the side of the condensor where the lines come out of the coil and go back to the compressor.
I didnt know about those so I put a new line drier at the evaperator coil and it basicly made a restriction.
Are you working on anything other than residential split systems yet?

That's interesting that you say that, I had my condenser changed out a couple years ago and I don't believe they changed the evap, and it doesn't have a TXV. I know the pistons are model-specific as well, and I have no idea if they put the proper one in either. That's another reason I went to school for this, it drove me nuts not knowing how the heck any of this stuff worked, and you have no idea who you can trust in the business.

I haven't taken any classes on commercial systems yet, and I have PTACs at one of my properties and all I've learned from them is that they are a complete pain in the ass.

Don't trust anyone else in this business! There are to many people that think they know what they are doing simply because they have been doing it for 20 years.
If you know the series of operations and the flow of refrigerant you should be alright. Things just get bigger. Meaning 2 speed equipment, bigger tonage attained by multiple compressors and so on. Be sure to learn your 3 phase power stuff for the commercial work.
Now you will find some equipment that uses amonia as its refrigerant in larger buildings. Be very careful with those units. Amonia is a lot more explosive than other refrigerants.
PTACS do suck but they are basicly glorified heat pump window units. Cheaply made and not meant to be repaired much.

Heh, we have a commercial rooftop unit that cools the hallways in one apartment building, and I noticed the two huge compressors in it. That thing intimidates me...lol. Haven't had any trouble with it other than it inexplicably froze up after we had a power outage, but I just shut it down for a day to let it thaw and it's been fine ever since then.

Good stuff Bug....thanks for the info. :thumb:

Well they are wrong or they are taking a simplistic view in a very small house. Assuming you have plenty of ducts shutting off a room or two that are not being used will not hurt your system. Too little airflow can cause the coil to not get warm enough from the passing air which can be a problem.

This is from yesterday.

http://i.imgur.com/Xm9Li.jpg

Those 2 compressors do not pump refrigerant through the same lines. They have seperate refrigerant lines that run through the same coils. I was taught to think of them as 2 systems working in series to make it a 15 ton or whatever tonage the unit is. So if you have a problem with the charge you will have to check the charge the same number of places as you have compressors in a unit. I have worked on some that you have to crawl up in the rooftops to service all 6 compressors.

No, it won't necessarily "hurt" the system, my point is that it's not going to make the remaining rooms much cooler, if at all. And you're not really going to save much money by shutting those rooms off.

If you shut off more than 10% of the airflow it will void your warranty. And it will take life off your system. The average a customer gets charged when I have to change out a blower motor is $400.
If you have a 3 ton system. That equates to 1200 cfm's of air. The average bedroom will have a 6 or 7 inch piece of duct that feeds the register that you see in your floor. A duct calculator figured at .10 static pressure will tell you that a piece of 6" duct will flow about 100 cfm. A piece of 7" duct about 150 cfm.
So you can only safely shut off 1 register in your home if you have a 3 ton system.
Now there are exceptions. A variable speed blower will ramp up to make the difference up. If you have a zoned system the extra air will be put into the "dump" zone.

Just to clarify, here's an example from my own house. I've never been satisfied with how well my system cools, so I always used to keep the main bath vent closed. My thinking was that since it was a small room, and we were rarely in it for very long, that there was no sense in pumping a bunch of cold air into it. Plus I figured it meant that more cold air would go to the other rooms.

Well it turns out I was wrong on both counts, it's not sending any more air anywhere else, it's not making my system work any less harder, so I may as well have it open. And regardless of where it's coming from, the more cool air you have moving through your house, the better off you are.

Not true. If you think of it in simplistic terms imagine a 5 ton AC unit that has to cool 3000 sq ft. Now imagine all ducts are closed off but one 500 sq foot room (with the thermostat there). It will cool that room much quicker and cycle off much faster (other considerations of wear and tear aside for the moment).

Now is it safe and is it worth the savings is an entirely different argument but all things being equal smaller sq footage = energy savings.

Well that goes against everything I've been taught, which is a fan with x amount of power can move y amount of air through a z size duct, and anything else would require breaking the laws of physics.

That will get to temp quick, but won't remove humidity. Removing humidity is the main point of an A/C system.

Either way, do what works best for your home and makes you comfortable. I'm just throwing things out that have worked for me.

I have had an argument with my co workers for some time, but I think its a bad idea to keep flipping the damn temp controll up and down all day long. Maybe flipping it up and down a few times a day is OK, but all day long, up, down, up, down in my opinion will break the damn thing. Its not my $$ so I probably should take the IDGF mode, but still.

AC units normally only move a fraction of the air through a pipe it is capable of. Of course my scenario might part your hair as you walked by the duct but the amount of air flowing through a duct is nowhere near what its capable of.

I recently found out that planting big trees around your house for shade can make a huge difference. Had no idea.

What? A/C units move no air.

You're right that it's not the size of the duct that limits the amount of air moving through it. The speed of the fan is what does that.

Well yeah, the problem with that is you can't plant big trees. You have to plant small ones and wait for the damn things to grow.

Been having some AC issues. Excuse my explanation I don't know much about this stuff. Last summer our AC worked fine. Now this summer has been a mess. When I originally turned it on for the summer the fan wasn't working... so I got someone to come over and they got the fan running and the ac worked fine for awhile. I left town for a week so I shut it off and when I got back home and turned it on again it blew warm air...so I had someone come over again and they got it running fine again. And when I say fine I mean the AC blew constantly and never shut off but the house was cool atleast. Well eventually it started to blow warm/very weak again and I noticed the lines were freezing inside and outside the house. So I shut off the ac, ran the fan to let them thaw out and changed the filter. The pipes still froze up after I turned the ac on again. So I said screw it and got a totally new AC unit. However the vents upstairs work very poorly and one of them that previously worked good just totally quit blowing. So the thermostat is set on 74 and it stays about 75 degrees upstairs and runs constantly and it feels like it's 65 or so in the basement. Going to be a nice energy bill.

Probably low on freon. Sometimes it doesnt get the inside cool enough and ends up freezing up. Call Bug he'll get you going or if you are here in KC I've got a guy thats good and pretty cheap.

No this will not work like you are thinking at all.
Blower are sized by the size of the system that they are put into.
If you have a 5 ton Air Handler it has a motor and a blower wheel sized to move 2000 cfm's of air. If you restrict or block off half of the registers in your home it will make the blower slow down because it can't move that air. Then that air becomes a restriction. When the blower slows down it won't even be able to pull half of the normal amount of air. Also when you do this and it can't move enough air across the coil and that will cause the coil to freeze up. Along with all of this you are making that motor work hard pulling more amps, costing your more energy, as well as the motor uses that air to keep itself cool.

Well there again if the duct work is sized properly for the system by the installer then there won't be much of a fraction left over. If someone oversizes duct you will not get much air flow into your home. And your effenciency is no good.
And it won't "part your hair" if you close off that extreme amount because the blower will not be able to move that much anymore.

This is not true. Duct is like a water line you are only going to get so much air through it.
Meaning you can't hook a piece of 10" duct right off the plenum box of a 5 ton unit and think it will blow just fine. 10" duct will not move that much air. The speed of the blower motor is ony in rpm's that the motor will turn. The speed will only affect the fps that the air will travel. Not the volume of air.

Sounds like on the first part of your story your evaperator, indoor coil, might of been dirty and or low of refrigerant.
If you have duct that is lined, insulated on the inside, you may have a piece of insulation that has come off or lose and it blocking the air from getting to the piece of duct that feeds that register.
Did you have a split system or a package unit?
Also you have to watch a lot of these companies. I know some that will sell you what they have in stock rather than get you the same sized unit as what they replaced.
If you had a 3 ton system. Did they replace it with a 2 ton unit? You will lose a lot of air that way.

Ah, we're starting to get into things that are covered in the installation class, and I haven't taken that yet. But a higher speed fan would screw up your temp drop over the coil so it wouldn't necessarily cool any faster anyway.

I'm in Omaha, eight hours round trip travel time would make that service call pretty expensive.

This is true. :thumb:

Stick with HVAC advice. You can transplant any size of tree if you've the money, space, and water.
Posted via Mobile Device

Duly noted.

I live in an apt and the crawlspace that houses my AC scares me. It doesn't work worth shit. Bug, you can take a look the next tme you are in town.

Oh yeah got to love them crawl spaces. Better than an attic this time of year where it is 200+

Crawl space? :spock:

Most apartments either have the units outside or on the roof. Either way though, you should have a maintenance guy that can look at it for you. No guarantees he knows what the hell he is doing though.

Interesting. In November my wife and I bought a house way bigger than what we need because we both hate moving and don't want to have to move when we decide to have kids.

I've had half the house shut down all summer; I was thinking exactly like Dave Lane is thinking. I guess that was a mistake.

Man I thought the same thing forever as well. It's hard to wrap your mind around the physics behind it.

I'm a bit surprised that's the only thing anyone took any exception to. I thought for sure someone would take me to task on recommending the cheap crappy air filters.

Well if it hasn't froze up by now you must have quite a bit of duct leakage or the refrigerant levels will not be quite right when you start using the whole house. Try opening all the vents and see what difference it makes. See if the house cools better. I know it will cool more evenly. But see if the system will stay off a little longer between cycles. See if you have a little better airflow not just out of the registers but see if your return grills where your filters are at catch more dust. At the return you can use a piece of paper to see how strongly it is pulling the paper towards or on to the grills. If you have a couple of thermometers put one on or as close to the returns as possible. Put another at one of the registers. This time of year you should have somewhere around a Delta T of 15. That is the temperature difference between the two. 14 to 17 this time of year. Anything out of that range will show that the system is not opperating properly.

Why that is one of the best pieces of info that you gave!
A person should change thier filters every month. But for the sake of your customers to recommend a pleeted high capture filter you HAVE to know how the system was installed. Because if the return duct is not sized properly or if the surface area of the return grill is not large enough a pleeted filter with a small amount of dust can be a huge restriction to the airflow.
Not to mention they are 5 times more expensive.

I do use the cheapest pleated ones over the winter since I run woodstove to heat my house and the dust from it is terrible. My furnace doesn't even run all that much and those things are filthy after just a few weeks.

Well that is good that you check and are aware. And that you are a heat and air guy you can fix your own stuff. If you tell someone or do something for someone else that costs them any money or break down you are the bad guy.
In this business you will either be a hero or a zero.

This is not true I have a 6" duct I move 1000 cfm through. It has an inline fan but you can move huge amounts of air through ducts if you want.

Are registers and vents synonymous?

I have 4 filters (2 for each a/c unit) in the ceiling in the hallway upstairs. Are these the only filters, or are there more in the ducting or near the units? The only ones I've ever changed are those ones in the ceiling.

I opened all of the vents today. It seems so counterintuitive to cool more of the house.

Those "large tree" transplants always fascinate me.

Feel free to share some stories. Is there a size that hits the sweet spot in terms of money and "worth it"-ness?

Dude you can think what you want but until you have been to school and educated yourself you will not understand. You can believe what you want but there is a huge difference between cfm and fps. You are moving are at 1000 fps but you CANNOT move 1000 cfm of air through a 6" round piece of duct.

fps = feet per second
cfm = cubic foot minute

When you mess up your system and it costs you 10k to replace it and they tell you that your duct is all blown apart and needs to be replaced for an addition 2500 to 3000. Maybe then you will understand.

Yes registers and vents are the same thing.
The filters depend on the installer but no there shouldn't be another filter at the air handler.

What have you noticed so far about the change that you have done?

Gotta kind of laugh that a guys name on here is talking about trees.

So here's a question for you HVAC gurus:

My house has a main floor, an upper floor, and a finished basement. The furnace and everything is located in the basement. As is probably a pretty common problem, it's a giant pain in the ass to cool the upper floor; the main floor is fine; and the basement turns into a walk-in freezer if I leave the vents open.

The big issue aside from the whole "heat rises" thing is that the amount of air coming out of the vents in the basement is MUCH higher in the basement than the main floor and much higher on the main floor than the upper floor.

So I guess my question is just whether there are "best practices" to make the most of this. My guess is that the underlying issue isn't an easy fix. But I've been shutting the vents all the way off in the basement since it stays cool on its own. Is that a bad thing based on what you guys have been saying?

That's the same issue as differences from room-to-room which I touched on in the last paragraph. Open the vents, and leave the thermostat on the "Fan On" setting for a couple days and see if it makes a difference.

Tried all of this, my bill is still going to be 450 this month. 2000 square foot house. 75% insulated windows. What the f***