On 4/7/2018 10:17 PM, J.Albert wrote:
On 4/7/18 12:45 PM, Ed Pawlowski wrote:

I mentioned that he has a boiler and it has a high limit switch that
turns off the burner, but there was no response.

OP here.
If there's a "high limit" switch, it hasn't activated.
(that would be on the aquastat, right?)

I don't really want the furnace cycling on/off repeatedly, just to
maintain a specific setting on the thermostat by (say) +/- 1 degree, or
even 2 degrees.

I don't mind a drop of 3-4 degrees (or even a bit more) between having
it run.

What's really so hard to understand about that?


What is hard to understand is what you don't want to cycle. Do you mean
the burner on and off? The thermostat does not control that. Yes, the
aquastat does.

The thermostat senses the need for heat. It turns on the circulator
pump so hot water moves through the radiators. When warm enough, it
stops the circulator as no more heat is needed.

Meantime, back on the boiler (not a furnace) the water temperature is
sensed by the aquatstat and it turns the burner on and off to maintain
the water in a given temperature range. High limit is usually about 190
degrees. You don't want to exceed that as the pump can cavitate.


You have to clarify what you want to get the best answer. Do you want
the burner to cycle less? Do you not care about burner cycling but just
want to limit the time period is runs in an hour?

Technical terms: Furnaces heat air. Boilers heat water. They have
different controls.