Honeywell T775

zepfan

Does anyone have experience using the Honeywell T7752016 for supply air control? If so what are the best settings in term of Integral, and throttling range, when used for supply air control? We have one installed on a make up air unit that is suppose to supply 70 degree air year around by modulating a three way valve in stalled on a coil. So far it is doing ok, but the response time is slow, and the supply air temperature tends to creep up. Currently the integral is set at 200 seconds, and the TR at 10 degrees. Thanks to all

ratio

The Application Guide suggests an integral of 12-200 seconds for discharge air control. I'd probably ratchet it down & see how it responds. Where are you sensing temp at? I've two jobs with stratification issues, one is a DOAS unit, so not unlike MUA.

AFAIK there isn't one 'best' setting, just dialing it in until performance is acceptable.

zepfan

Thanks for the response. The supply air sensor is in the supply plenum of the unit. That may be part of the issue, it may need to be located further from the unit.

ratio

Maybe an averaging sensor or an array of sensors across the plenum? That should give you a better idea of the air temp & also slow down response a little I think.

I just had a job where the duct would stratify pretty significantly (80° across the sensor, 40° thought most of the duct). The unit has a 70/30 split manifold w/ modulating gas valves. The only place to get a sensor in was apparently right under the li'l burner. The unit would slowly modulate itself down until the 70% burner was off, & then it was stuck. We gave it a more aggressive reset curve & it seems to have fixed it—for now. I'm honestly expecting it come back once we get back into milder temps.