Danfoss RT 8L Thermostat Installation Guide
Danfoss RT 8L Thermostat

Thermostat Instructions

Thermostat Instructions
Thermostat Instructions

Technical dat

Mechanical differential (DIFF)
RT 8L and RT 16L: 1.5K (2.7 °F)
RT 14L: 1.5K (2.7 °F) / 0.7K (1.3 °F)
min./max. range
RT 101L: 2.5K (4.8 °F) / 3.5K (6.7 °F)
min./max. range
RT 140L: 1.8K (3.2 °F) / 2K (3.8 °F)
min./max. range

Maximum ambient temperature
RT 8L, RT 14L, RT 101L, RT 140L:
-50 °C (-58 °F) − 70 °C (160 °F)
RT 16L: 50 °C (120 °F)

Maximum bulb temperature
RT 8L: 145 °C (290 °F)
RT 14L: 150 °C (300 °F)
RT 16L: 100 °C (210 °F)
RT 101L: 300 °C (570 °F)
RT 140L: 240 °C (465 °F)

Min. temperature variation rate
< 1K/15 minutes.

IP 66 acc to IEC 529.


See switch cover or fig. 10.
The marking, e.g. 10 (4) A, 400 V ~ AC means that max. connection current is 10 A ohmic and 4 A inductive at 400 V ~.
The max. starting current on motor cutin (L.R.) may be up to seven times the inductive load.


A set of Pg13.5 cable gland is attached to the RT in a separate bag. To ensure IP66 (units with automatic reset) or IP54 (units with external reset) grade of RT enclosure it is necessary to assemble this gland as shown in the fig. 10. If this gland is not used with a cable, a metal blinding should be also assembled.

Use the mounting holes item 25.
The thermostat is fitted best with the knob 5 facing upwards.
The thermostat housing and the capillary tube can be placed colder or warmer than the bulb.
In the case of RT 8L and RT14L, the cylindrical bulb can be fixed to a wall by using a bulb holder 26 or it can be fitted in a brine tank by means of a bulb pocket 30 or in capillary tube gland 31. See fig. 1.
If the capillary tube is to be passed through a wall, it can be done most easily by using a grouted-in pipe closed by rubber plugs.

Electrical connection

Cable connection Pg 13.5.
Cable diameter 6 − 14 mm.
The screwed cable entry shown in fig. 11 is used with rigid cable conduit. Earth connection to earth terminal 38.


The required temperature (= break temperature of contacts 2-3) is set by rotating the knob 5. The setting can be read on the main scale 9.
The required neutral zone (NZ) is found in the diagram. On the lower scale of the diagram, the value at which the neutral zone setting disc 40 is to be set, can be read.

Example: RT 8L
Required temperature: -2.5 °C (27.5 °F).
Required neutral zone (NZ): 3 °C (5.5 °F).
The thermostat is set for -2.5 °C (27.5 °F) by rotating the knob 5.
As it can be seen from the diagram, the required dead zone of 3 °C (5.5° F) is obtained by setting the setting disc 40 at 2.4.
The make and break temperatures of the switch (see fig. 5) are then – with the differential fixed at 1 °C (1.8 °F):

Make temperature of contacts
1–4 = -2.5 °C + 1 °C = -1.5 °C (27.5 °F + 1.8 °F = 29.3 °F).

Break temperature of contacts
1-4 = temperature setting: -2.5 °C (27.5 °F).

Make temperature of contacts
1-2 = -1.5 °C – 3 °C = -4.5 °C (29.3 °F – 5.5 °F = 23.8 °F).

Break temperature of contacts
1-2 = -4.5 °C + 1 °C = -3.5 °C (23.8 °F + 1.8 °F = 25.6 °F).


Documents / Resources

Danfoss RT 8L Thermostat [pdf] Installation Guide
RT 8L, RT 14L, RT 16L, RT 101L, RT 140L, RT 8L Thermostat, RT 8L, Thermostat

Leave a comment

Your email address will not be published.