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Coolant Shut-Off Thermostats
Shut-off thermostats control fuel temperature for any coolant fuel heater. Coolant flow stops when fuel temperature reaches a certain point to save you money.
Those temperature ranges are:
For all of the S-400 series, full coolant flows when the fuel is at or below +78° F (+25° C), coolant stops flowing when the fuel is at or higher than +95° F (+35° C).
For all of the S-440 series, full coolant flows when the fuel is at or below +104° F (+40° C), coolant stops flowing when the fuel is at or higher than +125° F (+52° C).
It is VERY important that any coolant circuit connected to these thermostats is not also connected to any other coolant dependent device, such as a heater core, fuel fired heater, or APU. Because the coolant flow is shut off, and NOT by-passed. Any other dependent device in the circuit will not receive any coolant until the fuel temperature decreases to allow flow.
Regardless of model, all Arctic Fox Coolant Shut-Off Thermostats operate the same way. They are analog valves, not digital. What this means is that there is a natural hysteresis in their action. Simply put, as the fuel temperature rises, the internal valve mechanism gradually closes until it is fully closed. Likewise, as the fuel temperature decreases, the internal valve mechanism gradually opens. So, it is not an ON/OFF device, but rather a slow acting valve that in cold weather is typically somewhere between fully open and completely closed, modulating the fuel temperature similar to how the engine thermostat modulates coolant temperature.
Another feature that they all have in common is the size of the fuel and coolant ports, they are all 1/2" NPT thread so they can be connected with common fittings.
Arctic Fox does also supply a wide array of fittings to simplify your search for components, and help make your installation professional. Other products to consider when installing a Coolant Shut-Off Thermostat are, Fuel and Coolant Hose Insulation to help retain as much heat as possible, STEEL Tee and Wye Fittings, hose clamps for the coolant lines, and reusable swivel fittings and flare seat fittings for the fuel line connections. Arctic Fox can provide all of these components and more.