24 replies to this topic

[HydroHarold]

I put in a new hot air/central AC unit back in '05 to replace the old hydronic/hot air boiler...  A/C is going full blast now with the heat wave and I decided to see if there were any special A/C operating instructions with the unit's instructions.  "Home Owner's/User Guide" contains no operating instructions at all, only installation specs.

 

1.   Supposedly this unit has a 4 speed fan system.  I have only experienced 2 speeds, the lower one when heating and a higher speed with the A/C.  What contols which speed the blower uses?

 

2.  There is a small black rocker switch on the control box on the front of the furnace unit.  This activates the blower constantly on a slower speed than when heating.  Should this be "ON" for A/C and better air circulation?

 

3.  What's the best thermo "differential" setting for central A/C?  Right now it's set for 1º above for "OFF" and 1º below "ON".  Unit is running 20 minutes plus per cycle.

 

What I figured at the time was the better company to install/maintain (and not by price) has gone bye-bye and I'm trying to save a little $ on the operations running more efficiently.

Edited by HydroHarold, July 18, 2013 - 12:04 PM.

[olcowhand]

Best thing to boost efficiency is to hook up a fine mist water spray on your outside unit.  Our milk cooling units are nothing more than an AC unit with more capacity.  Once it gets 90+, they run constantly to just keep up.  I put out a fine mist nozzle on the end of a water hose & restrict the flow to just a real fine mist, and it cuts their run time by I'd say 40%.  Right now I'm turning the water on manually, but intended to hook it to a dishwasher solenoid valve wired to one leg of the compressor's magnetic switch so it would start the spray automatically.  Just never have gotten around to it yet.

[HydroHarold]

I've seen those commercially sold units with the "spider tubes" and regulators.  I never thought I'd need one, but I'm going to see how my plant "fog nozzle" does with the compressor.  That's a good idea and if it works I may invest in the "real one".

[larryd]

The mist spray sounds like a good idea

larryd

[hamman]

Check your filter to make sure it is clean. If not replace it. Your thermostat should take care of the differental on its own. Running time will be determined by the house and how the ductwork is laid out. Just make sure that the air filter is clean. You can loose efficiency having a dirty filter. I replace our every 6 months. A lot of people run their circulating blowers constantly. It is actually more efficent that way. Less power used when not stopping and starting. We ran our blower 24/7 365 days a year where I used to work. Made the place cooler or warmer, depending on season. Make sure drapes and shades are closed to help cool the house and keep it cool. Hope this helps. JM2CW. Roger. 

[HDWildBill]

All the above are good suggestions.  You should clean both of your coils at least once a year and make sure the moisture drain runs free.  It is also a good idea to check your freon level at the beginning of the season.  Make sure your outside unit does not have any restrictions for air flow around it.  When I did HVAC in the early 90's I was amazed at what people would do to hide the condenser unit and then wonder why it the system wasn't cooling.

 

Make sure your windows and doors a draft free and of course the more insulation the better.  When you change or check your filter check the squirrel cage fan as well to make sure it is clean and make sure

[bja105]

If it means anything to you, I have been an HVAC service tech for 13 years, and I am very good at it.

Skip the misting or spraying.  I have seen some coils destroyed by the minerals and increased corrosion.  Your outdoor unit is designed and capacity rated at 95 degrees, it will be fine in this weather.  The outdoor coil may need a cleaning, but I am hesitant to recommend a homeowner do that.  Lots of ways to damage the coil or fan, get wires into the fan, or loose fingers.  If it has not been cleaned in a few years, have a pro come out and do a 'clean and check.'  Somebody good, not a scammer, will charge $100 or so.  I can promise that the $39 gut will try to sell you something, need it or not.

 

"Fan On" has pros and cons.  It won't hurt the blower, they last longer running constantly, rather than starting and stopping.  It does use electricity, 600 to 1000 watts (like 6-10 100 watt light bulbs), unless you have a fancy variable speed blower, they use 60-200 watts, depending on load.  Running the blower constantly can reduce the temperature differential upstairs to downstairs in two story homes.  That mostly matters at night.  When the sun goes down, less load on the house, the ac shuts off.  Cold air falls to the first floor, keeping the thermostat satisfied, while the hot air rises upstairs, where you are trying to sleep.  In the day, especially today, the ac will be running most of the time, so the constant fan benefit is reduced.

Cons of constant fan, noise, higher power use, and higher humidity.  At the end of a cooling cycle, the constant fan re-evaporates the condensation on the indoor coil.

 

 

As far as fan speeds, leave them.  They should have been set up by the installer.  There is not much difference between the 4 speeds, anyway.

 

It is hot out.  Your ac is going to run all day.  Where I live, out outdoor design temperature is 87 degrees.  97% of our cooling hours are 87 degrees or cooler.  At 87, a properly sized system should run 100% of the time, and loose ground when it gets hotter than 87.  Design temp in your area may be lower. 

[coldone]

I am not HVAC, I am refrigeration. I dont care if you are comfortable, I just want to freeze you solid. That being said, can you get the make and model of the ac unit? With the newer ones, they all have different operating characteristics. WIthout knowing exactly what you have most everyone will be guessing.

 

The fine mist spray can be of benefit but the chemicals and minerals in the water can destroy your unit fast.Obstructions to airflow around the condensor (outside coil unit) can drasticly reduce your efficiency. Once the outside temp hits the 90s your AC is struggling and will remain on constantly.

 

I advise against the homeowner checking the freon levels. Most of the newer units use R410A and Joe homeowner dosent know this. They use regular gauges that are made for R22. R410A runs at much higher pressures and can blow the R22 gauges up along with the hoses.

[Jack]

WoW A lot of good info there.

[olcowhand]

Of course I am no HVAC guy, but I do all my own HVAC repairs.  I am on well water, and my coils have NO corrosion whatsoever on them.  So I am likely just a lucky one not to have high mineral content.  I just do what works, and it works for me.  That said, I don't use mist on my home unit, as it is of a size it will kick on & off on all but the hottest of days.  Also, cooling milk is much different than cooling a home.  My milk cooling units are also more heavy duty than home units, but work the same way.  With my water, I would not hesitate if needed to spray my house coil, but with different mineral/chemical content, it could be hazardous to the unit I'm sure.

[coldone]

I havent seen a milk cooling unit but I am sure that its alot more industrial than a home unit. I bet there is alot more BTUs to be pulled out of warm milk than in the air of a house.

 

I wanted to try the misting on my home unit but the water is full of minerals.

 

 

I have always wanted to do a homemade ground source heat pump but I just cant bring myself to spend the money on a SWAG.

[John@Reliable]

HH, I own a hvac company, and both coldone and bja105 are spot on.

As far as checking freon, sorry WildBill, but that's old school The only really important part is >>> proper airflow and system design, you can't have one with out each other, but we can work with what we have "most" of the time. I have "internet friends"   all over the place, so if needed I may be able to get you someone local if needed.

[HydroHarold]

Wow, thanks everyone, both "professional" AND "Joe Homeowner dabblers"! :D  Lots of good info there for us all.  I have most of the suggestions under control already, shady open space for the compressor, clean the filter 2X per mo. (did it again this afternoon, allergies!), etc.

 

I think I'll try the Lo Fan for a while, with the way my electric bill is going to be this period a few more "mega amp hours" won't even be noticed!   I will NOT be misting though, yup I've got hard water and my "soft water" isn't all that mineral free either.  The misting system I found on the net...http://www.mistcooli...ing-system.html seems OK, but I'll just let the unit do what it's originally designed to do.

 

I do use several types of  fans (quiet 20" box type and ceiling) to keep the air from stratifying in the house (single floor L-shaped 1320sq.ft., 1950's "insulated" ranch).  The air outlets are 50's baseboard looking things and not the rectangular vent types, bed for A/C, OK for heat.  The layout and ductwork to the rooms require extra air movement as the kitchen + den area are only open to the rest of the house by a single doorway.  I just replaced the bedroom ceiling fan with one that's bigger and much quieter (20 years newer! ) and the house is totally comfortable.

 

I know that insulating the entire attic floor would go a long way towards savings... I'd need 3 roll-offs for Wifey's side of the attic!   There's not much between the sidewall sheetrock and the world except 1/2" Celotex and some aluminum siding...  A new vinyl job is in the works...

 

Thanks ALL again!!!!

Edited by HydroHarold, July 19, 2013 - 12:15 AM.

[olcowhand]

The best thing you can do is increase insulation HH.  I pulled my old vinyl off about 2 to 3 years ago, then pulled enough storm boxing (88yr old home) so I could place insulation in.  Dramatically reduced heating/cooling costs for darned sure.  Added 16" insulation in my attic as well.  Before insulating, the area of the roof above the attic space would never have snow clinging to the roof from the escaping heat.  Now when it snows, the entire roof is a blanket of white stuff.

[olcowhand]

For the HVAC pro's (coldone, John & bja105), this better explains my more unique reason for using water mist.  READ HERE