Bryant Plus 90i no high speed fan

Problems related to residential installations.

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Joined: Fri Mar 09, 2012 8:06 am

Bryant Plus 90i no high speed fan

Post by Brian_Skipper » Fri Mar 09, 2012 8:38 am

I have a new Bryant Evolution systems furnace, AC and Thermostat installed. It seems we have the brand new thermostat SYSTXBBUID01-D.

Our home was steam but 22 years ago converted to forced air. Old 2 stage worked well but new system can not get enough heat to second floor. I have cronologued the heat conditions and find the unit needs to go to High Speed to force air to second floor. Static pressure is well below 1" by Bryant build in system monitor. My installer can not figure out what is needed.

Generally the unit stays on low speed too long. We generally have two -
1. Raising form Night Set Back - it takes 2 hours with fan on low speed to raise temp from 19 to 23 deg C. Unit never goes to High speed with degree by degree rise from 19-23.
2. Normal cycle of heating allows low speed fan to try and satisfy set point. Tech has adjusted time between low speed to High speed (was 10 minutes, now 5 minutes) but this made no difference. Like ther thermostat did not adjust. So sometimes the thermostat does get satisfied and no air is pushed up stairs.

I would like the system to go to HS just like the old furnace did. I recongnize this may compromise energy efficiency but we need heat in our bed rooms.

Can you help with this issue? Thanks

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- Bryant Plus 90i no high speed fan

Post by heatseeker » Fri Mar 09, 2012 10:41 am

sounds like you need your ductwork balanced correctly. Obviouslyair flow is the issue that is the place to start as opposed to adjusting furnace settings.

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