Are These Manufacturer's Instructions Wrong?

[stem]

Every now and again, someone asks a question about the wiring to a Honeywell BDR91 receiver, and I will often reply with a link to, or post a diagram from the installation instructions. When I do so, I notice what I believe to be an error and keep expecting Honeywell to correct it. However it's been there for years.

Maybe it's not been noticed because it is in the final option that relates to using the BDR91 with a cooling system that AFAIK has not been discussed on here. Anyone else spot it? Or is there a logical explanation?

 

[bernardgreen]

I do not think there is an error.

If it was wired as red here

then if the BDR91 was de-powered ( or failed ) the cooling would be switched ON.

I expect in a cooling application the thermostat sends an ON command to the BDR91 when the room temperature is above the set point and an OFF command when the room temperature is below the set point

 

[Dan Robinson]

Would depend on the application selected on the controller.

 

[copea]

The 'HC' option changes whether B becomes live when under or over the set point, so no, it's not wrong.

 

[stem]

The 'HC' option changes whether B becomes live when under or over the set point, so no, it's not wrong.

Perfect. Thanks for the explanation. I suspected that as it's basically a 'relay' the signal could simply reversed so that A & B is just a switch that would be configured for 'on' whether the 'on' be heating or cooling. I guess it's years of working with the old mechanical thermostats that just had a set of changeover contacts one for heating & one for cooling.

 

[Wildcat1961]

I notice what I believe to be an error and keep expecting Honeywell to correct it. However it's been there for years

Although you “suspected the relay could simply be reversed” but expected Honeywell to correct an error that has been in their instruction manual for years?

 

[stem]

Just the thinking process... I thought of a couple of possibilities hence...

Or is there a logical explanation?