honeywell t87k and t87n non mercury thermostat

allenleo

do yourself a favor; stop using the t87k and t87n. if you are using these thermostats, there is somethings you have to know about them first. the t87k is a heat only thermostat and cannot be used with cooling applications. the t87n is a heat/cool thermostat and cannot be used on heat only applications. neither of these thermostats work with a typical cad cell relay set up. in order to use it with a cad cell relay you would have to add a 24volt transformer and an r8222 power to power isolation relay or you will end up burning out the new transformer. its not worth it. the cost for the additional transformer and relay is too much. the other thing that i have noticed about these thermostats is that they are very inaccurate, even when set up to a switching relay that will power them with 24 volts from the tt contacts. my company has stopped using these thermostats because they have become cost ineffective and the source of many callbacks. we are using the honeywell focus pro 5000 thermostat now. it is a digital non-programmable thermostat that can be used for many different heating and cooling applications and they cost only about six dollars more than the honeywell t87k and are cheaper than the t87n. with what you save on the transformer, relay, and possible callbacks, it is well worth converting to. the honeywell focus pro thermostat is battery operated, so that means no need for a separate transformer, but can still be used with relays that have contacts powered by 24volts.