In the HVAC zone

[rockfan4]

I have a zoned HVAC system, pretty simple, one zone for the main floor and another for the basement. During this recent cold snap I noticed the basement was warm, much warmer than the thermostat is set and in fact warmer than the main floor. So I looked and the damper motor isn't moving, none of them are. This stupid house is only 6 years old, I can't believe they're dead already. So I bought one new damper motor to replace the basement damper, and I figured I'd replace the two for the main floor later. I got it Friday and installed it today, and it works as designed. But it turns out the design is stupid. Not only is it energized when the upper floor is calling for heat, it's energized when everything is off. Yup, energized basically 24/7. They only draw 8 watts, but that's still dumb.

I looked at the manual for the zone controller, and it will run a 3 wire damper motor, power open and power close. I lose the fail safe of the dampers all opening when they lose power, but on the other hand if they only run several times a day rather than being powered constantly, they're going to last a lot longer, hopefully longer than 6 years. I guess I should have mentioned they're Honeywell dampers, and there's a company that makes a kit to use Belimo motors on the Honeywell dampers. By kit, I mean they have a shaft extension that makes the shaft longer so the Belimo motor can grab it. They charge an extra $25 for that adapter, seems to me there has to be a less expensive source.

What I'm looking for is a 1/2 or 5/8 diameter rod, with a 5/16 hole in the end, and a set screw or something similar to clamp the damper shaft, about 1 1/2 or 2 inches long. Google has failed me so far.

And check your dampers!

[john walker's workshop]

Make one?

[Nickshu]

I just had our basement finished and the HVAC sub put in a ZoneBoss pneumatic system. Same dampers but run off a small pneumatic pump in the control box. HVAC guy recommended for the exact reasons of it draws very little power and there are no electric motors to fail. If you are at your wits end w/ your system maybe look at one of these.

[dad911]

Look at shaft couplers on Amazon or mcmaster

You could also used reinforced hose, id 5/16" and hose clamps for such a low load.

[rockfan4]

Originally Posted by john walker's workshop

Make one?

If I had a lathe, or even a drill press, I probably could.
I found a guy on eBay who would do custom work, he'll make shaft adapters out of 6061 aluminum for $6.00 each, plus shipping.

The couplers on Amazon and McMaster Carr are all only 3/4 or 1" long, and I think that would interfere with the clamp on the motor.

[biosurfer1]

I have no clue if this is a possibility in your system, but the commercial controls I used to work on had a simple drop-down that let you select if it was reverse acting or not. You could set the dampers to open or close based on energization(?) and select of they failed open or closed.

I have a feeling residential systems may be more limited. I have a zoned system at my house that works "meh" at best but I haven't had time to install a new system yet. Cobblers kids have no shoes kind of thing.😒

[rockfan4]

Just a followup.
I ordered shaft adapters from a guy on eBay, I ordered them on a Sunday afternoon and he made them and shipped them on that Monday, I had them by Thursday. I installed them yesterday, and other than wrenching my back trying to get to the damper that was between the furnace and the wall, I had no issues.

If you want to do this yourself I'll give you the dimensions for the adapters:
They're 5/8" diameter, 2" long, with a "P" sized hole in one end, 7/8" deep. "P" is .323 inches, if you don't have a P drill bit you could get by with a 21/64". On the sides of the hole he drilled and tapped two holes for 10-32 set screws, 90 degrees apart. The center of the holes are 3/8" from the end of the shaft.

None of this requires much torque, but the motors will put out 45 in-lbs, so make sure everything is tight.

Hopefully this is the last time I have to do this job.