Heat Controller NextGen Thermostat

Heat addition to our new NextGen thermostat.

Please note, the heat relay box can only accept a 12V DC Input (Utilizing Black as ground and white as Fused +12V). 

The heat controller addition adds heat functionality to our NextGen thermostat via a separate relay control box. The relay control box will allow relay control of your hydronic heater, evaporator flow block off valve, auxiliary heat control (120V etc) and control a hot water timer to fire the hydronic heater to make hot water.


It will be available in 3 versions with different timelines, there are software and hardware differences. Version 1 & 2 will be available in April

Version 1 will be software control functionality on the thermostat that adds heat mode, heating turns on two separate relay on the relay box along with the evaporator blower. Relay 1 turns on the hydronic heater, relay 2 turns off the evaporator bypass valve.  It also adds a 30 minute timer to turn on the hydronic heater in any mode to make use of the heater to make hot water, this does not turn on the blower and does not turn off the evaporator bypass valve. In this version we only provide the software, cable to connect to the relay box, and the relay box itself. All other functionality and control will be up to the end user.

Version 2 will be everything V1 offers, plus a custom enclosure that contains the relay box, our canbus Espar interface (direct plug and play), and includes a 4-way electronic valve that bypasses the evaporator core when not in use. The 4-Way valve will include a mounting plate, wiring harness and 5/8" hoses leading to and from the evaporator core. 

Version 3 (available summer 2024) will also include a 2 gallon coolant expansion tank with a 120V 1800W heating element that is controlled by an auxiliary button on the thermostat display allowing you to switch from electric and fuel mode.


Included components explained:

Canbus Espar Module

The canbus module allows for communication with all Espar gasoline and diesel heaters. It eliminates the need for a easystart module or controller and plugs right into the Espar harness. The canbus module adds an altimeter for constant altitude compensation The most important feature this unit adds is wifi communication that broadcast a wifi signal to allow easy viewing of hours, error codes, diagnostics, pump priming and all temperature sensors.


Electric Bypass Heater Valve

This is a 4 way electric valve that works with our relay box to bypass the evaporator mode. Bypass is required when the evaporator is being used in A/C mode (so it's not trying to cool the heating loop) and bypass is required when using the hydronic heater for hot water mode.

Connection 1 & 4 are Evaporator heater core In/Out.

Connection 2 & 3 are part of the hydronic loop in/out.

When in operational mode 2 flows to 1 and 4 flows to 3

When in bypass mode 1 & 4 are blocked off in a loop closing off the heater core, and 2 & 3 flow past the valve and continue to complete the hydronic circuit.

 What is not included? 

Here is a list of items required to complete a heating circuit in your van.

- Espar D5 gasoline or diesel heater with installation kit (includes wiring harness, exhaust, intake and fuel hookup)

- Roll of high quality 5/8" hose (Good Year, Dayco, Continental recommended) and stainless steel gear clamps. 

- Hydronic coolant tank (stores extra energy, purges air from system, etc) basic plastic for cost savings, or aluminum for higher end builds.

- Heat exchanger (plate type for hot shower/sink water exchange)