A little hack to hopefully lower my AC bill

[TheSiege]

The porta cool comes on with the AC via a dry contact connect to smartthings. The dry contact is attached to a 24VAC relay connected to the start signal of the blower motor inside the furnace. So it does run for few min after the ac is off but the blower is still running clearing the ducts and coil of the cool air in their still. I attached to the blower and not the AC start because I will use it in the winter too for ceiling fans and/or fireplace commands, the relay also turns on a 800cfm 8'' round booster fan to supply my addition better. I could get another relay and attach them to the AC call to start and the heater call to start instead of the blower. I also set my ecobee to have a minimum off time to not short cycle the compressor. I was going to use a misting system hooked up to a sprinkler valve and connect to the 24v inside the condenser but this way should negate any mineral build up on the coils or adding anymore to the brick and can still be used in the winter.

My condenser is located on the west side of my house. I might move it to the north when I upgrade so it should get more shade. God knows this SEER 11 AC needs to be replaced anyway. I think its a 3 ton unit with a 3.5ton coil for a 3400sqft house. 1700 on top and on bottom.

The picture is at a bad angle, but the porta cool is facing the corner of the AC and it oscillates to hopefully get a decent amount of air on the two sides.

 

[local]

What you are doing is not really going to help and the minuscule savings, if any, you get on the AC side will be eaten by running the porta cool. You would be better off just doing a deep chemical clean of the condenser and evap coil if it has not been done this year.

 

[TheSiege]

What you are doing is not really going to help and the minuscule savings, if any, you get on the AC side will be eaten by running the porta cool. You would be better off just doing a deep chemical clean of the condenser and evap coil if it has not been done this year.

The load pulled by the porta cool is super small. You dont think the 10-15 degree air temp drop will make much of a difference? I could add a condition based on outside air temp to only run above 90 degrees. You are probably right about the evap coil though.

 

[local]

The load pulled by the porta cool is super small. You dont think the 10-15 degree air temp drop will make much of a difference? I could add a condition based on outside air temp to only run above 90 degrees. You are probably right about the evap coil though.

Probably not. AC systems are designed to perform a certain amount of work. The refrigerant flow will be regulated to only do that much work. You can test it yourself though by measuring your discharge air temp. Without a lower discharge air temp the unit has to run just as long. If you do have a lower discharge air temp then you actually have a problem with your system as it was not able to perform to spec before.

 

[brianmanahan]

what do you have the thermostat set at?

i used to do 72 but eventually went up to 80 to save money

 

[rcpratt]

what do you have the thermostat set at?

i used to do 72 but eventually went up to 80 to save money

Pretty sure I’d offset all those savings from having to wash my sheets every day after drenching them in sweat each night.

 

[TheSiege]

72 during the day, 76 when away or sleep. That being said, I ignore the kids room sensor since my wife covers the vent to keep it warmer for the baby. I ignore the basement sensors during the day, but I also use a whole house fan so they are enabled during the sleep. There is no sensor in the Master bedroom since I have a mini split in there. And my older sons room doesnt have a sensor since he just wants it cold in there as much as possible. The whole house fan setup is in one of the two basement doors that isn't used. It pulls out air at 3500CFM a piece, supposedly so about 10000CFM. And the logic is setup to turn off the fans if the temp within the house hit 61 degrees or 1 hour after sunrise since thats when outside temps start to increase. The white sensors show which ones are active currently. Nothing changes with the occupy or unoccupied since those aren't 100% reliable and not really needed. The grandroom is the biggest pain to keep cool/warm. It was an addition with 4 vents, three in the room below. But no additional returns, and the HVAC was still sized for the original house which was 2400sqft vs 3400. Also, the grandroom gets south and west sun. Has 2 sets of french doors, 2 2x4 old plastic type skylights and the two 3x4 windows are still aluminum. Thats why there is a booster fan to supply the addition.