Hello,
When my central A/C unit starts up, the blower starts at the same time, so for the first couple minutes or so it's blowing hot air, until it has had a chance to cool itself off. Now if it's working properly it should delay starting the blower until a couple minutes after the A/C starts. Any idea how to fix this?
Thanks,
John
This is Turtle.
You need to give the Model number of the furnavce or air handler and the brand too. Then someone can try to answer your question. All you can get now is a guess with no model number and brand.
TURTLE
It may not be "cold" but it should be room temperature, not "hot". If it is, you've got bigger problems.
Are you certain? Every standard central air unit I've seen starts the blower and compressor at the same time. The delay only occurs on the heat side of things.
There may be nothing to fix. If there is, it will be a thermostat (that controls the blower) that has failed.
Maybe not. In many homes the A/C is ducted through the attic where, even with great insulation, the air in the duct is going to get hot if the A/C has not cycled recently.
I was thinking the same thing, but frankly I am not sure how my current system works. I have checked, it never bothered me.
I suspect there is no problem. While John does not want the hot air to come into his rooms, it has to go somewhere if it is in the ducts and the distribution fan starting sooner is not going to distribute more warm air. It will just do it sooner.
Turtle has asked for the model information, so I am guessing he knows and some do have a delay built in.
My units start start together in AC and in heat function the blower waits till its fired a minute or so. My Lennox is 3 yrs old, it`s probably normal.
To be able to get a higher SEER rating, there has to be a time delay in the blower. The idea is the same as the heating cycle.
It shouldn't be 'a couple on minutes,' maybe 30 to 45 seconds, IMHO.
This is a new one. All the central air conditioners I've had work with the blower and the compressor both starting at the same time. There may be some units that delay the blower start, but I fail to see the problem. All that will happen is it will get the room temp air moving and in a minute or so, it will be cool air.
Without a model or serial number, no one can tell you... But..
On higher SEER Goodmans, they use a shitty stack sequencer for the blower, and the blower will be delayed up to 30 seconds after the outdoor unit starts.... On better equipment, depending on the SEER, you should get a delay on blower OFF, when the thermostats been satisfied, and a slight delay on the blower when the unit starts, and on some, it will come on at the same time..
Btw...it does NOT cool it self off...it removes heat...there is no such thing as cold.
"CBHVAC" <
You never met my mother in law
As we say in alt.hvac.....
Man...Dats KOLD!
>
This is Turtle.
Everysince the 10 SEER became the norm they started delaying the blower 15 to 20 sec. on start of cooling and run the fan 45 to 60 seconds after the condenser shut off to get the 10 SEER rating. Most everything will delay made in the last
10 years or less. The Delay is decided in the furnace or the air handler and just replacing the condenser will not get you the delay or the 10 SEER rating.We need a Model number and Serial of the furnace or Air handler if possible to know if it is suppose to delay or not. Most everything with inshot burners will be delayed. Till we know this. Your guess is good as mine.
TURTLE
You almost made me spit up tea all over my monitor and keyboard.....
Sorry to leave that out. It is a Carrier "high efficiency" hvac unit. That's all the info I have right now. I'm sure it's at least 10 years old, maybe even 20 years or more. So I guess this is normal operation? However I live in hot sunny Calif, where the temps pass 100 degrees routinely in the summer, and in the attic it's even hotter. So the air coming out of the vents during the first minute or so is hotter than room temp. Is there any after-market device that can be added on to solve this problem? Come to think of it, maybe all I need is one of those solar attic fans....
John
Turtle wrote:
Sorry no.
Your first step is to make sure you have proper static air ventilation. Even with that it will get quite hot. Adding fans can lower the air temperature in the attic some, but not enough to really make a difference.
While the A/C is not on, the air in the ducts is going to get hot no matter what you do. However that is not really all that much air and it is very shortly overcome by the cool air that follows.
You could leave the fan on so air would be flowing all the time, but that would increase your cooling bill. You would not get a hot flash when it first turned on, but you would acturally get more heat, over a longer period, from the slightly warmed air while the A/C was not on and only the fan was on.
BYW a delay allowing the A/C to run a couple of seconds before the distribution fan comes on, is not going to help much. The air in the ducts is still going to be hot and that air has to move before the new cooled air can reach your rooms.
This is Turtle.
The problem is two things.
Sounds like your attic area is just getting too hot for being normal because of not being vented properly. Solar fans are junk. You can get these thing install to cut down on the temperature to about atleast 10 ºF above the ambiant temperature outside. There is a lot of thoughts on what is best and least costly but here is mine. Get a electric power rooftop vent-o-later from Home Cheap-0 for about $59.00 and install it on the roof. Secondly install a couple of wind powered roof turbines to pull the heat out. Thirdly Get a Ridge roof cap installed. Now with all this make sure you have plenty of eve vent to let the air in. Now you only have to do one of the three listed. Vent the attic area more.
Now the warm air coming out the first time it turns on after a couple of hours or so of being off is hard to stop. Now the stopping the warm air from coming out after a 15 minute or so cycle can be stopped by the cooling the attic area down to a cooler temperature. There is 3 types of flex duct and Sheet metal insulation used and are rated in R-4 , R-6 , and R-9 . People with R-4 insulation are mostly the only ones that see the warm air coming out during cycles. The people with R-6 and R-9 usely never notice a problem. People with R-4 when the cool off the attic area will not see the warm air coming out after they cool the attic area off to a normal temperature [ 10ºF above the ambiant temperature ].
If you want to discuss it. E-mail me and discuss it.
TURTLE
From a former Palm Springs AC guy...
First, a 20 year old unit in that climate is junk. Time to trash it and get a new one....thats problem #1. You need to be looking at 14SEER or higher there.
As far as normal, ICP_Carrier operation is normal on the old units like that. Since most homes are on slabs there, attic or overhead crawlspace is the only way to run ducts, and designed properly, you will get a bit of warm air out of them on startup, and it would not matter if the coil was minus 40 when the fan came on, you WILL get a bit of warm air on startup. Also, it takes up to 15 minutes of run time on some of the older units to start to really work well. Your air will blow warm until the unit is condensing refrigerant well enough to get liquid to the metering device, and until that happens, you will get whats called flash gas, and it will indeed take a bitof run time to stop this.
BTW, it hit over 100 here, and it was about 135F in an attic I was in...just be glad you didnt have the 98% humidity to go with it.
Attic fans will not do much...however, depending on your location, a good evap with Upducts will work wonders.
Also, 20 year old duct will not be insulated to todays standards, so your heat gain in the duct will be a bit more..but it will not matter if you have R100 on the duct, its GOING to be warmer after some off time as the ducts will be higher than the ceiling, and your warm air will collect there first. If you want to eliminate this, set your fan to run 24-7. No..there are no "aftermarket" devices to stop this...unless of course you want to put a delay on make timer on the fan relay, and run the risk of slugging the compressor..
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