Need Help Adjusting Electronic Dampers

[Traderfjp]

Hi,

I have an older Carrier 96 system from 2007 with a fancy thermostat that talks to the other components in the system and has some helpful settings. Anyway, we moved into the house a few months ago so not 100% sure of what is normal for the system. It's a two zone system. One zone is on the 2nd floor and heats/cools our main living area. It works perfectly. Air comes out nicely from vents and even when it's really cold the heat pump can keep up. Although there is a backup propane furnace.

The 2nd zone which has a sensor in our bedroom heats/cools the upstairs bedroom (same floor as main living area), the laundry room still the same floor and an apartment on the 1st floor. If we turn the heat to 73 our bedroom and laundry room quickly get up to temp. Air comes out strong from the vents. The problem is that the apartment stays at 67 while our bedroom, etc. stay at 73. That is a 6 degree diff. I checked the vents in the apartment and while there is air flowing it's not nearly as strong as our bedroom/laundry room. The air trickles our compared to blowing out. I then tried closing all the vents in the bedroom and laundry room and the apartment didn't feel that much of a difference in air flow. Even with the vents closed the temp is held in our bedroom. I tried leaving the vents closed for several days but the air was still not strong coming out of the apartment bents. I even put the air circ. on high but that didn't help.

I think I'm going to call someone but wanted some advice in the mean time. I know that some systems have manual dampers that allow for the restriction of air flow. I was looking at my system to try and adjust the damper but there are wires that go to it. It looks like it's electronically controlled so I didn't want to mess with it. There are two main ducts coming off each side of the main unit with damper controls on each side. There is also a board that has wires that go to the damper. Any advise would be helpful.

 

[Dana]

Assuming the original ducts were designed reasonably, low flow on the zone in question could be either from a restriction, say a filter that has been clogged by a large (and now dessicated) cat, or a zone damper that doesn't fully open, a balancing vane that has been closed way down, or a flex ducts that have been crushed. Flex ducts that have not been fully stretched tight can also impede flow (more than one might think), especially if it's all twisted and flopped around like a ball of mating snakes.

The other cause would be large duct leakage, a flex duct that has been chewed through by rodents, a duct connection coming un-done, etc.

Simply restricting flow on the other zone won't fix either of those types of problems.

So take the time to inspect all ductwork that is accessible and repair any big leaks such as separations. If you find something that looks like it needs repair, take a picture of it.

Dampers with the wires going to them should not be manually adjusted unless they're jammed and not fully opening when needed. The system controls may need to partially open them even when a zone isn't calling for heat in order to maintain the minimum flow rate across the heat pump coil.

 

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[Traderfjp]

Thanks Dana,

The apartment that doesn't get enough flow is way closer to the blower so you would think it would get most of the flow. Not sure what to do.

I just changed all the filters so that eliminates that possibility.
I had an HVAC guy here last year just to check the system and he did a leak test and he said that I was in normal parameters so I can eliminate leaks. The duct work is in the ceiling and we had a leak not that long ago and I saw the duct work and didn't see any kinks of holes. I didn't see every run so that is still a possibility.

Is there anyway that I can test the damper? It would be helpful if I could open up the entire zone going into the apartment and see if that is the problem. Can you advice me on how the damper opens and closes. Is it all based on heat request? I wish I had manual dampers it would be easier. Is there anyway I can test the damper or open it manually? I've been trying to get an HVAC guy over since I posted and no luck. I have American Home Shield. I'm thinking that companies in the area don't want to work with them. On Monday I'm going to find someone without them.

 

[Traderfjp]

Ok. A little more research and it seems there are three electronically controlled dampers. When heat is called for in the bedroom and apt. the dampers open. The set screw is in the middle of both. The other zone was closed. There is a button on the electronic damper that lets you manually move the damper. Can anyone give me advice on how to play with setting to get a good balance of air form upstairs to downstairs?