Anticipator settings - 24 volt system

Charlie_3

I have a 2-zone hot water baseboard system in a rental property. The thermostats are Honeywell round type, the thermostat cicuit is 24-volt. The tenant told me that the heat doesn't come on at all unless she turns it up all the way (10-15 degrees above the room temp.). The plumber who installed the system a number of years ago ('89) says the anticipator should be at minimum setting for this system. So I set the anticipator at minimum (it was at 0.3 before) and turned the dial up. The mercury made contact about 2 degrees above the room temp on the thermometer. Then I watched as the thermostat shut itself off again, apparently as the anticipator heated up. Once this happened, I had to turn the thermostat to 85 to get the mercury to fall back again. When I saw a wisp of smoke near the anticipator, I set the settings back where I had them!
Can someone explain the theory behind anticipators? I am having trouble finding good information. Or maybe there is something else I am overlooking and it's not the anticipator at all. Any input would be appreciated.
Thanks.

[Deleted User]

Oh oh....

Sounds like you might have let the smoke out of the anticipator... You may need a new thermostat.

As the name implies, the anticipator "anticipates" the room being satisfied before it is actually satisfied.

IMHO, it is a throw back to the old days of inefficient heating systems whereby there was a WHOLE bunch of heat left in the heating system to still come into the house after the thermostat was satisfied. Hence, the anticipator shut the heating system down early knowing that there are a whole bunch of btus that hasn't even made it into the room yet, so in anticipation of this, it shuts down early.

Industry practice is to set the anticipator for the actual amp draw of the device it is controlling. Unfortunately, there are some devices out there (older Taco heat motor types of operators) that have a REALLY big amp draw and will cause the scenario you just explained. Although it's probably a poor practice, I usually turn these anticipators completely up to eliminate their function, and I've never had anyone complain of excessivley warm environments.

Just my opinion though...

ME

heatboy

Taco Zone Valves?

These are famous for letting the smoke out of anticipator circuits when installed by..........non-technician types.

hb

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Larry_7

Maybe Too Late

10-15* sound a little far out of whack. The Round is able to be re-calibrated using a special skinny wrench after making sure the stat is level and secure. Needs to be done before smoking the anticipator, though. I have made smoke a coupla times and still saved the sucker by shutting it off in time. There is usually very little time to take remedial action once the first wisp is observed. Ohhh sh.. If you complete the sentence, it's too late.

Larry

D lux_2

IS it level?

I have found the subbase out of level causeing prob.

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