Air handler

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Old 12-12-20, 02:34 PM
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Air handler

I have a TWE040E13FB2 American Standard Variable Speed Air handler. I have a 2.5 ton AC condenser (single stage) and Hot water coil at the air handler (single stage). This is zoned into 2 zones with a Honeywell HZ311 Zone Control which was just installed. The HZ311 has a BK available which says that when both zones call for heat or AC it gives 24v out of BK so that the Variable speed air handler will speed up the fan. I tested it and when both zones call for heat or AC I get 24V out of it. When one zone is turned off 0 volts, so I know it is working.

I took the factory jumper off at the air handler from "R" to "BK'. That made no difference in fan speed on heat or cool. I left the jumper off and connected BK from the HZ311 to the BK on the hair handler. Doesn't seem to to adjust the fan speed at all.

The only other connections are to G for fan, W1 for heat for heat, Y2 for AC, R and B.There are no wires on W2,W3, O, T or Y1.

Why didn'tt anything change when I cut the jumper from R to BK. Why doesn't anything happen when the HZ311 energizes and de-energizes BK on the air handler. It would be nice for the fan to blow less when only one zone calls for heat or cooling.

Thanks in advance
 
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Old 12-12-20, 07:56 PM
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Welcome to the forums.

I was looking over a manual from a variable speed air handler and saw this.
It doesn't say remove...... it says cut. Is there a jumper on the board ?
My forum partner is the Trane/American Standard pro. He'd know.

Cut the BK jumper on the AFC when using the BK functionality from the thermostat.
 
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Old 12-12-20, 08:07 PM
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yes. it is cut. From the factory there is a metal jumper from R to BK. So the connection between the 2 is broken. When the jumper is cut there is no difference in fan speed whether I am in Cool or Heat mode. I would suspect that fan speed be reduced when cut because BK is no longer getting 24v.
 
 

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