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View Full Version : Delay-off for furnace main blower when using A/C


tanuki64050
Jul 14, 2007, 02:56 PM
Re Lennox G23Q2/3-75-2 with HS25-311-1P A/C:

The built-in delay-off for the blower works well with the furnace, but there seems no easy way to set up a delay-off for the blower when using the A/C.

Right now I've connected the low blower wire to the CF terminal on the BCC2 blower control. This at least lets the blower run on low to circulate that expensive amount of cold in the evaporator. Otherwise, the blower shuts down as soon as the A/C compressor is shutdown by the thermostat. Wonder why Lennox didn't build in a delay-off for the A/C. Very energy inefficient!

What is a good way to install a blower delay-off when using the A/C?
Adding a delay-off relay to the BCC2 Y terminal?

Any suggestions?

Thanks

acetc
Jul 14, 2007, 04:00 PM
Could be done as simply as installing a time delay relay in the circuit to the fan relay, the green wire from the thermostat goes to the fan relay in the furnace. Wire time delay to fan relay , wiring diagram will come with time delay, this relay should delay on break.
Most furnaces made today do have this capability.

tanuki64050
Jul 18, 2007, 02:50 PM
Could be done as simply as installing a time delay relay in the circuit to the fan relay, the green wire from the thermostat goes to the fan relay in the furnace. Wire time delay to fan relay , wiring diagram will come with time delay, this relay should delay on break.
Most furnaces made today do have this capability.

Thanks for your reply.
That's about I had decided to do, but had hoped there might be any easy to jumper something I'd not thought of.
Thank you again.
Week

hvacservicetech_07
Jul 18, 2007, 07:45 PM
I think you are wasting your time, your not going to gain much. The reason you have a delay in heating is to cool the heat exchanger.

tanuki64050
Jul 20, 2007, 03:38 PM
I think you are wasting your time, your not going to gain much. The reason you have a delay in heating is to cool the heat exchanger.

True. Your experience is much greater than mine, so I'll just leave it as is. (low blower on continuously during summer with A/C on) General comfort is good and the cool basement air is circulated upstairs. There's no way to prevent cool air settling down the open staircase, which makes the basement too cool. Now it is fairly well equalized.

Thanks for your answer!
Week

hvacservicetech_07
Jul 20, 2007, 06:19 PM
Running the blower continuous is probably the best idea for your situation. I usually advise this to people with larger homes because it keeps the tempature more even throughout the house, and it really doesn't cost you much more, I doubt you will see much diffrence on your utility bill. Good luck!

tanuki64050
Jul 25, 2007, 03:36 PM
Running the blower continuous is probably the best idea for your situation. I usually advise this to people with larger homes because it keeps the tempature more even throughout the house, and it really doesn't cost you much more, I doubt you will see much diffrence on your utility bill. Good luck!

A bit of calculating tells me that leaving the low blower on continuously will cost me about $3/month at current rates. A clampon ammeter gave me 0.25A. Didn't bother trying to calculate duty cyle, as it is too variable.
Thank you for your reply.

Bridgerman
Jan 20, 2011, 06:11 PM
Check out www.mygreenfan.com

There is product called GreenFan that will do exactly what you are looking for. It attaches to your thermostat and can be installed in less than 5 minutes. It monitors how long your compressor was on and adds a delay after the compressor stops. The basic version costs less than $35. It comes with a money back guarantee.

dhahahh
May 17, 2012, 12:48 PM
Where can you purchase the product called greenfan

Bridgerman
May 21, 2012, 10:27 AM
You can call the number on the web site's buy now page. The pricing may have changed since my last post. GeenFan has also been upgraded to work in heating mode as well. I think they were reporting a 7-20% decrease in fuel usage.

The new product is about the size of a dime and mounts behind the thermostat.

I believe that there has been a third party report prepared for the California utilities that documents the savings and the report may have supported a price increase. I have seen a copy of the report and it is very detailed, but I can supply it to anyone interested.

dhahahh
May 21, 2012, 11:43 AM
What is the website where I can purchase greenfan. I googled it and couldn't find anything. Can you send me a link or the exact website. I prefer a website link if you can.thanks for your time

dhahahh
May 21, 2012, 11:51 AM
What is the website where I can purchase greenfan. I googled it and couldn't find anything. Can you send me a link or the exact website. I prefer a website link if you can.thanks for your time

Bridgerman
May 21, 2012, 12:32 PM
what is the website where i can purchase greenfan. i googled it and couldnt find anything. can you send me a link or the exact website. i prefer a website link if you can.thanks for your time

My Green Fan - Save Energy and Help the Planet! (http://www.mygreenfan.com/)