Looking for creative ways to manipulate heating

Not (real) heating but cooling. And done pre-Hubitat. I have a 2-storey townhouse with poorly designed HVAC. The air-handler is upstairs, the vents closest to the air-handler are upstairs, and the return is upstairs. Thermostat is upstairs.

Master bedroom is downstairs. Sounds like a recipe for uncomfortable nights year around? It was.

Switched the thermostat to an ecobee3 (~5.5 years ago) with sensors and set cooling/heating profiles to use downstairs sensors at night. Helped a little, but electric bills started running real high.

About 4 years ago, I put an in-duct blower in the 12" duct going downstairs and wired it to go on & off when the air-handler blower went on & off (used a current sensor switch and RIB relay). This worked fabulously. I have balanced temperatures throughout the house.

Late last year, as you know, I swapped out the ecobee for a z-wave thermostat and a bunch of temperature sensors. Still continues to work fine. I don't "use" the thermostat's own sensor - just averaging to nudge the thermostat either way.

My average heat pump run-lengths with the ecobee were 16 mins. WIth this setup, I'm around 18 mins (and there are fewer runs).

Here are the current temperatures - the upper 4 are all downstairs and the lower 4 are upstairs.

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It also breathes. Foam doesn't. In the climate (hot humid) I live in, retrofitting foam insulation often makes a mold breeding ground.

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Good point. We don't have the year-round humidity you have, but Summers get pretty sticky here, and I can imagine the cold outside, vs warm inner walls with humidity would be an issue in the Winter for us.

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I used this current sensor:

And passed the neutral for the air-handler blower through the core.

I used a delay on break relay with the idea that I could run the in-duct fan for a few minutes after the blower turned off (to balance temperatures). This is the relay I used:

In the end, it turned out that I didn't need a delay on break relay. Just having the in-duct blower go on and off with the main blower was sufficient. But I had no way to know that going in, and it wasn't that much more expensive.

How hard was it retrofitting the blower in the duct-work? Did you have an HVAC guy do that part or did you do that yourself?

I can dig it out of the pipes but I can not match your details when it comes to showing how and where things go. It will take a bit to get it out again but I will post a pic or two. I built a frame and attached a small servo to a flap. I used @ogiewon hubduino to control it.
As for the blown-in insulation, it won't work since there is already some insulation in the wall.


Don't go to that much trouble. I can visualize what you're describing. I thought you meant you built something like a keen vent, but I now understand that you built and automatic damper. That's slick.

Our ducts are the old rectangular type. Sounds like you have the same. Cool idea. I assume you have some logic that prevents over-pressure in the system?

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I have an in duct blower sitting in my basement for almost a year now waiting to be installed. My neighbour is an hvac guy and got it for me to install. My office is too warm in the summer because of the computers so the blower will get more cold air to it. The rest of the house is perfectly fine.

In winter all is good though. I guess I have a bit of a push to do that project in the spring.

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Myself. It was a PITA. And I did it twice. The first fan I bought (cheap-ass Suncourt) burned out within a few months. The second one I bought (Tjernlund M-10) was expensive, but has lasted since Sept 2015. No issues at all.

This isn't fair. I am a two finger typist and a sloppy mind. It takes me too long to add my two or three sentence reply to things. You guys need to slow down and wait until I am caught up. :wink:

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The dampers don't change how much air is pushed, just which direction it goes.

:grinning: I'm on my laptop at the moment. But it's not a race. However, I_will_go_S_L_O_W_for_you. :wink:

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Well....I'm sure the second time was easier, right?

I'm sorry...I'm really trying hard not to laugh at your pain but this is exactly the type of situation I get myself into way too often.


Yes, I understand. My knowledge of Keen (minimal) is that they have built-in logic that will prevent too many from being closed at once, because doing so could create a back-pressure on the system and cause pre-mature failure of the blower. But I get the difference between dampers redirecting the air and a vent closing it off. So maybe I'll just withdraw that question because it's sounding dumber the more I type :stuck_out_tongue_winking_eye:

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Actually - no. I had used the Suncourt because it was light. The duct runs vertically, and I had no easy way to build a wooden frame to support the in-duct blower. The second time around, I had to work laying upside down in a space that's about 2x2x2 - building a frame to support the heavier blower.

I am 4 years older. If this burns out - I'm hiring someone!


@aaiyar I wish you would post your heating/cooling rules. I think may could benefit from your extensive look at the whole process.
I have taken several ideas from what you have.

Will do. Not today - unfortunately I have to do laundry.


After all the messes I've gotten myself into, I hope I would be smart enough to hire someone the first time at this point. But knowing me, I probably wouldn't. :upside_down_face:

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We are all 4 years older than we were 4 years ago. I don't get the significance? :wink:

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I don't get the significance either. Unfortunately, my back does. :rofl::rofl: