Need assistance with newly installed dehumidifier

[harlock328]

Hi,
Had new installed ultra-aire 120H installed. House sq is ~3800ft (I missed up and forgot to include unfinished basement when I order this. I was thinking only of the finished footage of 2500sqf). Live in NW Wisconsin (about 40miles from twin cities MN). unit installed to existing return duct; not dedicated duct also connect to outside for venting. House has basement (where HVAC is), 1st floor and 2nd floor with dual zone configured. zone 1 1st floor/basement, zone 2 2nd floor. Currently I have system fan to low for both zones (not the fan on 120H) to keep the zone dampers opened when the 120H does kick in. Tech recommended leaving fan to low even if I didn't have a dehum. I've set the ultra to 44r/h but never reaches that. When a/c isn't running R/H hovers around 48. When A/C get's on it will get down to 40 pretty quick and when a/c turns off it will go back up to about 48. ultra is constantly running. Is the 120H too small? WI climate can get very humid but right now it's not bad so surprise the 120H can't keep up. Not sure if the install isn't right, too small dehum; or I'm expecting too much. I want it @ 44 to help protect my wide plank wood floors from moisture fluctuations.

Thanks

[teddy bear]

50%RH will protect floors and eliminate typical moisture problems during times of low/no sensible cooling and high outdoor dew points. I would set the Ultra-Aire 2-3%RH above the level %RH the a/c maintains during long runs. Setting the dehu control below what the a/c provides during high cooling loads assures that the dehu will run alot during high outdoor dew points weather. We have been have very high dew points this summer. Many times the dew point in WI. is as high as FL. Set the dehu to 53%RH and watch the the resulting %RH in the living space.
I understand you are operating the a/c fan in the "on" low mode 24/7??. This will be needed the way the dehu ducts are connected to the a/c.
This requires a little more dehumidification but is premium from the stand point of uniform temp/%RH throughout the home. At the 43%RH setting, a larger dehu would probably run all the time.
Thank you for the opportunity to serve!
Keep us posted.
Regards Teddy Bear

[servicefitter]

Instead of how you have the dehumidifier piped -supply to return. Pipe it return to return because duct pressure would be close to the same and warmer then trying to dehum the cold supply. Wire dehum with a airflow switch to run when fan runs and you can turn RH control down if dehum short cycles. Is the humidifier damper closed and turned off?

[HVAC_Marc]

That's truly horrible. Who hooked that up? Flex like that is very restrictive. You paid for a good unit and it should be as efficient as possible. I'd suggest hard pipe for all connections.

[harlock328]

Thanks for all the replies.
@Teddy Bear - wood supplier recommend 44-48 for their hickory wide planks (6") would be best. I have dual stage furnace a/c. Evolution shows function off, ac off fan on (when I set to low) when A/C is off. Put it to low to keep the zone dampers opened for the dehum when it kicks on. They didn't wire dehum to furnance to tell it to kick on fan when dehum fan turns on. Before hvac fan was set to auto. When it was first installed the fan was still at auto and I could tell it wasn't working at all for dehumidication when dehumidifier turned on. RH was in high 50's; figure it was because dampers were closed so I turned it on to low to open dampers. Had them come out again to go over the install. Different tech came and was surprised the installer didn't turn on fan to open the dampers. Not sure if they put in back draft damper. would system by more efficient if I have them run a dedicated return duct for dehumidifier?
@servicefitter - humidifier damper is closed (honeywell; latch set to summer) confirm also humidifier is off in evolution system. My existing ERV is off after installing the dehumidifier since it also does venting. Though I probably turn it back on for winter; not sure about that if erv should be on or leave utlra-aire on for venting (turn off the dehumidifer part)
@hvac-marc - Ultra-aire provided the HVAC contact which is same HVAC that installed the HVAC system when my house was built. There was no other HVAC installer available in my area for ultra-aire. Unfortunately this installer has never installed dehumidifier; this was their first one. Why I posted here wonder if install was right.

[kdean1]

Is there a damper on the pipe for the bypass humidifier? It should be closed to prevent the air from the dehumidifier from circulating back through it.

[teddy bear]

Thanks for all the replies.
@Teddy Bear - wood supplier recommend 44-48 for their hickory wide planks (6") would be best. I have dual stage furnace a/c. Evolution shows function off, ac off fan on (when I set to low) when A/C is off. Put it to low to keep the zone dampers opened for the dehum when it kicks on. They didn't wire dehum to furnance to tell it to kick on fan when dehum fan turns on.

Before hvac fan was set to auto. When it was first installed the fan was still at auto and I could tell it wasn't working at all for dehumidication when dehumidifier turned on. RH was in high 50's; figure it was because dampers were closed so I turned it on to low to open dampers. Had them come out again to go over the install. Different tech came and was surprised the installer didn't turn on fan to open the dampers. Not sure if they put in back draft damper. would system by more efficient if I have them run a dedicated return duct for dehumidifier?
Back flow through the dehu is not critical in this case.

@servicefitter - humidifier damper is closed (honeywell; latch set to summer) confirm also humidifier is off in evolution system. My existing ERV is off after installing the dehumidifier since it also does venting. Though I probably turn it back on for winter; not sure about that if erv should be on or leave utlra-aire on for venting (turn off the dehumidifer part)
@hvac-marc - Ultra-aire provided the HVAC contact which is same HVAC that installed the HVAC system when my house was built. There was no other HVAC installer available in my area for ultra-aire. Unfortunately this installer has never installed dehumidifier; this was their first one. Why I posted here wonder if install was right.

Did you raise the dehu setting to 50%RH? does it shut off?
Ideally to minimize the dehu run time raise the %RH control setting above the %RH that the a/c reaches during long runs. Again 50%RH is should prevent any adverse affect on the wood in your home. The Ultra-Aire dehu is designed to run 24/7.
The picture is not clear on one point. Is the dehu supply connected to the a/c supply? It must be to get the full benefit of the dehu. I assume that you are able to maintain the low %RH but are running the dehu most of the time.
As the outdoor dew points go below 50^F, the dehu will stop running. Idealling, you should figure out how the use the ERV for fresh air ventilation year around instead of the Ultra-Aire. Mainly because you have it and it will reduce the moisture load in the fresh air.
Thanks again for helping us bring your a/c contractor up to speed on installation of dehumidifiers in quality homes.
Keep us posted.
Regards Teddy Bear

[harlock328]

Is there a damper on the pipe for the bypass humidifier? It should be closed to prevent the air from the dehumidifier from circulating back through it.

At the humidifier there's manual damper which I confirmed is closed.