adding tekmar sensor 076 to control 260

CC.Rob_5

Someone suggested I post this here instead of the Wall proper (where it is also). So...

I'm contemplating adding a tekmar indoor sensor 076 to my existing 260. The goal is to get closer to constant circulation and reduce variations in space temp. The present curve gets pretty close to constant circulation, but due to the setback, it's a bit high so we have excess input available for morning recovery.

This is a two-zone system with simple programmable thermostats that do a 2F overnight setback. Otherwise, setpoint is 68F. Thanks to a fortuitously balanced house, and a relatively open floorplan, I've found the sweet spot that represents the average temp of the two zones where the sensor would go.

Is there any benefit to adding the indoor sensor to this system?

From the 260 manual, it seems that the sensor is only active during a boiler demand, so any supply temp "fine tuning" occurs only when the stats are calling.

I am not using a timer, so the 260 is constantly in “OCC” mode.

My primary concern is accumulating errors during setback, when the indoor sensor would see space temps fall, yet OCC is still 68. Would this result in funky behavior during the period when reduced space temps are being maintained? (e.g., thermostat setpoint 66F -> makes a boiler demand -> 260 sees that OCC should be 68 -> jacks up the supply temp until 66F setpoint is reached and the stat removes the boiler demand? If this is a problem, is the only way around it to implement some sort of timer to put the 260 into unocc mode? I would like to maintain the convenience of the zone stats, so everyone doesn’t have to go mess with the 260 just to raise the space temp (not that they should, but sometimes they do…).

Thanks.