Home A/C advice needed.

[Rugskipper]

Last week, we noticed that our old A/C was not keeping up with the heat. It chugs all day, and inside temp creeps up to about 80 before the sun goes down, and temp goes down to about 75. Repair guys have been out twice, and despite an R22 charge with fresh o-rings, and a leak check, are unable to find a real problem, other than old age. (I trust the HVAC company- our best friend is their office manager, and they have always shot straight.) We've owned the house for 10 years, and the central air unit was old when we moved in. Now it just runs all day long and never shuts off. Time was, we could get it cold enough to hang meat if we wanted to.

I've looked for central A/C reviews and recommendations online without much success. Are there any pros here that can tell me what brands to look for, and which to avoid?
How high a SEER rating should I look for without encountering diminishing returns?

Also, we have a master bedroom with three exterior walls which is the farthest distance from the blower, and it's always too hot in the summer and too cold in the winter in relation to the rest of the house despite two vents and a return. How can we address this?

Thanks.

 

[Maddog 521]

Have you cleaned the unit outside? Shut the unit off and wash the coils out with the garden hose. Spray it good with the highest pressure you can. Those coils get full of dust and prevent the unit from running right. Try it, it should help.

 

[zercool]

We don't have central air, so I can't really answer the technical questions, but as to brands and such, I think you answered your own question:

"I trust the HVAC company- our best friend is their office manager, and they have always shot straight."

Ask them to gin up a quote for replacement, and then get a competing quote from another shop.

 

[NE450No2]

If you do decide to replace the unit I would recommend you get one with a fair amount more of cooling capacity.

The last place I lived had a loft type room upstairs.

It was always hot. I put a window unit in it and it not only kept in cool in the hot part of the day, but cut down my electric bill a bunch.

Where I now live, my "Man Cave" is on the west side of the house.
The people we bought it from had put a window unit in it as well.

Many times I just run the window unit as I spend a lot of time in there.

Cuts way down on the electric bill.

 

[Rugskipper]

Have you cleaned the unit outside? Shut the unit off and wash the coils out with the garden hose. Spray it good with the highest pressure you can. Those coils get full of dust and prevent the unit from running right. Try it, it should help.

Coils are clean. We have a lot of cottonwood trees around here, so I pressure wash the coils twice per season whether they need it or not.

 

[oldRoger]

I would recommend a talk with your HVAC guys. Where better than to start with someone you trust? Tell them your problems with the hot/cold room booster fans in the vents sometimes can fix this if it is a long run. They will have seen the problem before and have several fixes in mind. I added a vent in my cave and it cost about $100.
You didn't mention heat pump so I assume different heat source.
Regardless 10-12 years is about it for compressors.
Your HVAC guys should be able to show you the trade off between SEER and added cost, and then help figure your payback at your power costs. I would assume an 8-10 year life, increasing power costs (green energy) and would want my money back in say four years from higher SEER units.
After getting their advice I suggest getting at least one other quote (Trust but verify) ask around, someone you know has had AC problems lately.
Too big is generally not a great idea, short cycling and humidity issues might surface. If your current unit used to do the job its prob. the right size.
For your info, many of the compressors are made by the same co, Copeland.

 

[dg101win]

Just a quick 2nd question about this. Would using a pressure washer on the outside unit be safe?

 

[Rugskipper]

Just a quick 2nd question about this. Would using a pressure washer on the outside unit be safe?

Its OK if you dial it back a bit, and don't hit the fins from the side. You have to hit them straight on or they will bend and cut off airflow.

 

[Rule3]

Bottom line: It's past it's time and old and inefficient. The time has come for a newer High efficiency unit. Yes they are expensive but will pay for itself over time.

We run AC probably 9-10 months of the year.

You good AC company will due a heat load calculation and determine the correct size there is also a calculator for efficiency.

Here in Florida Trane are one of the best. When we had our 12 year old unit replaced the air handler in the attic literally crumbled into pieces of rust and it was still working (sort of).

http://www.gartnerhvac.com/airconditiongcalculator.html

 

[Gordo1]

I just replaced a 9 year old 10 SEER unit. My electric bills were just getting out of hand. I had previous experience with AC units in Florida where I live and figure anything past 8 or 9 years I was on borrowed time.
I had a 15 SEER Heat Pump / AC unit installed two weeks ago. I have not seen an electric bill yet but this unit is about 75% quieter, in fact the only way you know it is on is when the thermostat switch clicks. Also the air distribution is more uniform. It was not cheap but my AC guy figures I will save between $70 and $80 per month in the hot season and I should recognize similar savings in the winter months. I also opted for a 10 year parts and labor contract which was quite reasonable.

 

[Dennis The B]

Last week, we replaced...

...our ten-year old compressor/condenser. We had an R22 unit made by Carrier, and it gave up the ghost. We replaced it with a new unit with R410A (Puron). The new unit required new tubing and a new evaporation coil, since Puron runs at much higher pressure (300+ lbs/sq in). We have a 1.5 story bungalow, built in 1926. It had central heating installed some years before we moved in in 1982. We replaced the furnace, and had central air added in 1998. However, the original condenser croaked in 2000, and the original dealer had gone out of business, and the factory wanted too much of a pro rated amount for a replacement. We then had the Carrier installed.

The HVAC folks (like you, we know and trust them), advised us that we needed about 1 ton per 600 sq. ft. Our house has about 1200 sq. ft. on two floors, plus the basement. We had a two-ton Carrier installled, guaranteed for ten years, and two years on labor. Price was just under $2,500.

There's a marginal increase in efficiency, if you put a slightly larger evaporation coil on the furnace. We had a 2.5-ton coil with a 2-ton condenser. Seemed like it worked fine. However, now our evaporator coil and condenser are matched.

Whatever you do, don't use a pressure washer on the condenser fins. It's not necessary, and it will damage them, even on low settings. Use a regular garden hose, and set the nozzle to a firm spray, and keep it parallel to the fins. However, I believe that you're beating a dead horse.

Good luck.

 

[bricker]

You also have an evaporator coil inside in the air handler. It should be cleaned also, since that is where your heat is removed.

 

[MK]

You also have an evaporator coil inside in the air handler. It should be cleaned also, since that is where your heat is removed.

Yep, that was what I was fixing to mention.. How dirty is the evap
coil? If clogged, it can really reduce the cooling. Also the blower
wheel itself should be checked for dirt in the blades.
A dirty blower wheel doesn't move near as much as air as a clean one.
The evap coil and blower would be the first things I'd be looking at
on a system that seems basically OK, and used to cool OK, but
doesn't anymore.
Beyond that, maybe double check the metering to make sure the
evap coil is not starving for refrigerant. Expansion valves can get
flaky, and a flow rater valve can be crippled just by a spec of dirt
clogging the hole in the piston.
Also check for return air leaks.. You don't want to be sucking in hot
attic or wall air. The usual temp differential between the return grille,
and the registers will usually be in the 15-20 degree range.
So say if the air going in is 80 degrees, the air coming out will be
appx 60-65 degrees. As the return air drops in temp, the outlet temp
will drop in proportion. IE: if it's 72 going in, it will be appx 52-57 or
so coming out.
But say if a leak pops up in the return air duct, and all of a sudden
the return air is 95 degrees going to the coil.. Bad news.. 75 to 80
degrees will be the best you will likely get coming out of the registers.
I'd make sure those issues are addressed before totally condemning
the present system.
If you do buy a new unit, it will have to be 410a, and you will need
a new condensing unit and a new evaporator coil. And like one said,
maybe even new copper if it's iffy looking.. At the least, the present
copper would have to be flushed out.. You are looking at a good amount
of work and $$$ to install a new system due to the change to 410a.
You can't buy new R-22 units any more unless they are old stock from
last year. And most of that has been sold by now.
So that could be an incentive to make double sure there are no problems
with the present system that might have been overlooked.
A new system, while being more efficient, is going to cost you the
price of several nice guns to have it installed..

 

[nun]

Without reading threw everyones post and not knowing state your in I will say this : in Missouri Max design temp is 95*f.  So when temp gets above 95*f the it will run constantly not shutting off very long when it does. Like some mentioned clean outcoil make sure filter is clean.  If you believe it's time for new have the companys give you estimites.  Make sure they do a heatload calculation (sizes AC by window type, size of house, material of house, and other things). Then look at warrenty on unit. Don't just go with a larger unit if wrong you will have humidity problems.  And finally is far as seer goes, go with the highest seer your budget can afford. Sorry I'm a little groggy it's late and I'm at the hospital just had hernia surgery this afternoon.

 

[ohiobuckeye]

Cleaning the coils in both the indoor and the outdoor units is good advice, and make sure the air filters are clean and not restricting airflow.
Assuming the unit is working properly and is just undersized for your home, you might try this...Cover your windows with the reflective solar film available from most home supply stores. My heat pump A/C was big enough to cool my home, but rooms that faced the afternoon sun would have some mild "hot spots". My system would overcome those "hot spots" , but the rooms on the shaded side would have icicles hanging from the ceiling... Closing off the windows with heavy shades helped, but still created a small solar oven under the curtains. My windows are all high quality Andersen Thermopane, but were installed before the newer windows with the built in solar heat blocking became available. Applying the solar film to the glass made a huge difference. It blocks the radiant heat from the sun very well, and we don't have to keep the rooms dark as a dungeon to stay cool. The A/C runs less and probably saved the cost of the film the first summer. Do your homework on the films...there are different types and i don't recall the exact details of why I selected the one I used. It will definitely help relieve the load on your A/C if not totally solve your problem.

 

[Rule3]

The unit is 10 + however many years old. It's tired. Trying to fix, finagle, repair, nurse, clean whatever is probably just throwing money away. It is probably costing money in excess electric bills.

 

[duckloads]

make sure the ductwork is OK. If your not getting enough airflow to the farthest point, you might have leaks

 

[pistolite]

Without reading threw everyones post and not knowing state your in I will say this : in Missouri Max design temp is 95*f.  So when temp gets above 95*f the it will run constantly not shutting off very long when it does. Like some mentioned clean outcoil make sure filter is clean.  If you believe it's time for new have the companys give you estimites.  Make sure they do a heatload calculation (sizes AC by window type, size of house, material of house, and other things). Then look at warrenty on unit. Don't just go with a larger unit if wrong you will have humidity problems.  And finally is far as seer goes, go with the highest seer your budget can afford. Sorry I'm a little groggy it's late and I'm at the hospital just had hernia surgery this afternoon.

I am curious as to how too large a unit causes humidity problems. If it's from being too cold and causing condensation couldn't you just turn the thermostat up a little?

 

[gbrady]

I worked in a heating/cooling company for 13 years as a leak detector on the cooling side. If your unit is holding a charge of freon, look inside the house for blockage of your coil/blower unit or in your duct. Now would be a good time to replace your unit as all of the major brands are looking to move their products. For your part of the country, a heat pump would be your best bet.

 

[dodgeit]

I am curious as to how too large a unit causes humidity problems. If it's from being too cold and causing condensation couldn't you just turn the thermostat up a little?

An A/C unit removes condensation from the air (Humidity). That is part of the cool air experiance. Now if the unit is too big it doesn't run long enough to remove condensation before it gets to the proscribed temp set in the thermostat. So it feels muggy in the house and you get mold and mildew.