How the outdoor sensor works – Hydrolevel OS-100 User Manual

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We warrant products manufactured by Hydrolevel Company to be free from defects in

material and workmanship for a period of two years from the date of manufacture or

one year from the date of installation, whichever occurs first. In the event of any claim

under this warranty or otherwise with respect to our products which is made within

such period, we will, at our option, repair or replace such products or refund the pur-

chase price paid to us by you for such products. In no event shall Hydrolevel Company

be liable for any other loss or damage, whether direct, indirect, incidental or conse-

quential. This warranty is your EXCLUSIVE remedy and shall be IN PLACE OF any other

warranty or guarantee, express or implied, including, without limitation, any warranty

of MERCHANTABILITY or fitness for a particular purpose. This warranty may not be

assigned or transferred and any unauthorized transfer or assignment thereof shall be

void and of no force or effect.


The outdoor reset feature monitors outdoor temperature to continuously adjust the boiler water to the minimum

temperature required to satisfy the heat demand. The feature is activated automatically when the sensor is wired

to the OR and C spade connects on the Fuel Smart HydroStat. When connected, Outdoor Reset overrides the

Thermal Targeting temperature reset method which is built into the Fuel Smart HydroStat. The display will toggle

between boiler temperature (8 seconds) and outdoor temperature (2 seconds). If the sensor becomes damaged or

disconnected, the control will automatically revert back to the Thermal Targeting reset method. The display will no

longer toggle outdoor temperature.

The Fuel Smart HydroStat controlʼs Outdoor Reset feature uses a reset ratio method to control the boiler

temperature. The reset ratio determines how much the boiler temperature is adjusted for changes in outdoor

temperature. A reset ratio of 2.0 means that for each 1 degree increase in outdoor temperature, the boiler

temperature will decrease 2 degrees. Conversely, for each 1 degree drop in outdoor temperature, the boiler

temperature will increase 2 degrees. The control adds 10 degrees to the calculated reset temperature and

provides a 20 degree differential for burner operation. So, if the control calculates a reset temperature of 150°F, it

will set a target temperature of 160°F. It will then allow the burner to fire up to 160°F and draw down to

140°F before re-firing. This operation will maintain the desired average temperature of 150°F. You can check the

current target temperature at any time, by pressing the Test/Settings button in 4 short intervals.

To insure that the heating system always satisfies a call for heat, the Fuel Smart HydroStat control is equipped

with a thermal boost feature. If the thermostat is not satisfied thirty minutes after the boiler reaches the reset

temperature, the control will boost the reset temperature by 10 degrees. It will continue to boost at 30 minute

intervals until the call is satisfied. Once the call is satisfied, the control reverts to normal operation, utilizing the

calculated reset temperature.