Outdoor Reset Concept - Raypak TempTracker mod+ Hybrid Installation And Operation Instructions Manual

outdoor reset concept

The TempTracker mod+ Hybrid has multiple operating modes that satisfy most
hydronic systems. It changes the System Set Point based on outdoor temperature
(Outdoor Reset). The TempTracker mod+ Hybrid varies the temperature of the
circulating heating water in response to changes in the outdoor temperature. The
heating water temperature is controlled through the modulation or sequencing of the
stages.
The TempTracker mod+ Hybrid also controls the system circulating pump with an
adjustable Outdoor Cutoff. When the outdoor temperature is above the Outdoor
Cutoff, the pump is off and no heating water is circulated through the system. When
the outdoor temperature drops below the Outdoor Cutoff, the system pump relay is
activated and the heating water circulates through the system. The temperature of
the heating water is controlled by the Reset Ratio, Water Offset, and changes with
Outdoor temperature.
reset ratio/outdoor reset
When a building is being heated, heat escapes through the walls, doors, and windows
to the colder outside air. The colder the outside temperature, the more heat escapes.
If you can input heat into the building at the same rate that it is lost out of the
building, then the building temperatures will remain constant. The Reset Ratio is an
adjustment that lets you achieve this equilibrium between heat input and heat loss.
The starting point for most systems is the 1.00 (OD):1.00 (SYS) (Outdoor
Temperature : Heating Water Temperature) ratio. This means that for every degree
the outdoor temperature drops, the temperature of the heating water will increase
one degree. The starting point of the curves is adjustable, but comes factory selected
at 70 F Outdoor Temperature and 100
°
a 1.00 (OD):1.00 (SYS) ratio, if the outdoor temperature is 50
temperature has fallen 20 from the starting point of 70
°
water temperature will increase 20
Each building has different heat loss characteristics. A very well insulated building
will not lose much heat to the outside air, and may need a Reset Ratio of 2.00
(OD):1.00 (SYS) (Outdoor:Water). This means the outdoor temperature would have
to drop 2 degrees to increase the water temperature 1 degree. On the other hand, a
poorly insulated building with insufficient radiation may need a Reset Ratio of 1.00
(OD):2.00 (SYS). This means that for each degree the outdoor temperature dropped
the water temperature will increase 2 degrees. The TempTracker mod+ Hybrid has a
full range of Reset Ratios to match any buildings heat loss characteristics.
A heating curve that relies not only on Outdoor temperature but also on the type of
radiation will improve heat comfort. The following are suggested initial settings for
different types of radiation based on average building insulation and heat loss. The
contractor can fine tune these adjustments based on the specific building need.
type of radiation in Building
Radiators (Steel & Cast Iron)
Baseboard (Finned copper tube& Cast Iron)
Radiant (High Mass/Concrete)
Radiant (Low Mass/Joists)
Fan Coils & Air Handlers
TempTracker mod+ Hybrid Installation and Operation Manual
F Water Temperature. For example with
°
F. Therefore, the heating
°
to 120 F.
° °
reset ratio
1.00 (OD) : 1.00 (SYS)
1.00 (OD) : 1.00 (SYS)
4.00 (OD) : 1.00 (SYS)
130
2.00 (OD) : 1.00 (SYS)
120
1.00 (OD) : 1.00 (SYS)
110
100
70
Outdoor Temperature
With a 0° Offset, the
Reset curves begin at
100° Water Temperature.
F, this means the
°
With a -20° Offset, the
Reset curves begin at
80° Water Temperature.
With a +20° Offset, the
Reset curves begin at
120° Water Temperature.
offset
0˚F
0˚F
1:4 1:1
-10˚F
Warmer
-10˚F
20˚F
Colder
4:1
60 50 40
1:4 1:3 1:2
220
210
200
190
180
170
160
150
140
130
120
110
100
50 30
70 60 40 20 10
Outdoor Temperature (in °F)
Reset Ratio is Presented as
Outdoor Temp. : Water Temp. Ratio
Reset Ratio Curves
1:4
130
120
110
100
70 60
Outdoor Temperature
1:4
110
100
90
80
70 60
Outdoor Temperature
1:4
150
140
130
120
90
100
70 60
Outdoor Temperature
5
1:1.5
1:1.25
1:1
1.25:1
1.5:1
2:1
3:1
4:1
0 -10
-20
1:1
4:1
50 40
1:1
-20 Offset
4:1
50 40
1:1
4:1
+20 Offset
50 40