# How would this incorrectly wired t-stat affect boiler operation?



## spamispeople (Feb 21, 2009)

I was replacing an older honeywell programmable thermostat at a customer's house and noticed the wires were hooked up to the B & W terminals... 

I guess the B terminal is used for a heat pump setup, but I was wondering how it would affect an oil fired water boiler's operation?


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## Mississippiplum (Sep 30, 2011)

W would be the back up strips in a handler and b would be for the reversing valve in the condenser on a heat pump system I believe.

Sent from my iPhone 10.5


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## spamispeople (Feb 21, 2009)

Mississippiplum said:


> W would be the back up strips in a handler and b would be for the reversing valve in the condenser on a heat pump system I believe.
> 
> Sent from my iPhone 10.5


Thanks. The boiler is the only t-stat operated system in the house. So I was wondering how it would affect the boiler's operation with the t-stat wired to B & W instead of the normal R & W. 

I know very little about electricity, including low voltage.


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## Gettinit (May 9, 2012)

W and B on thermostats are usually for heat. As long as you are just making and breaking then it is fine.


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## plumb1bob (Dec 14, 2012)

If the thermostat is newer it will not anticipate heating cycles, most newer t-stats have programing and types of heat parameters. Some will preset timing to bring up to temp by program time. not being on R and W would mess all this up. BUT did the original installer do this for a reason


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## spamispeople (Feb 21, 2009)

plumb1bob said:


> If the thermostat is newer it will not anticipate heating cycles, most newer t-stats have programing and types of heat parameters. Some will preset timing to bring up to temp by program time. not being on R and W would mess all this up. BUT did the original installer do this for a reason


I assume it was wired that way because the 2 wires coming out of the wall were black & white, and that the homeowner installed it without reading directions.


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