Ttalk Tech

Lazarus' Heater

Periodically I get questioned about the Arnolt Heater that I've installed in Lazarus, so I found it best to devote a separate page to those issues.

I have the heater 'plumbed in' using one of the diverters that fits into the bypass hose.  The original thermostat innards have been removed from my housing and the upper surface has been relieved to allow a conventional thermostat to mount in the neck of the housing.  The water flow is through the bypass opening, through a length of 1/2" copper pipe to the rear of the engine, thence through a length of hose to the fitting on the back of the heater.  The return from the other fitting on the back of the heater is connected via a short piece of hose to one side of a control valve (NAPA 660-1140).  The outlet of the valve is then connected through hose through the other firewall opening and then to another piece of 1/2" copper pipe that continues forward to reconnect with the other opening of the diverter.  The control valve is operated by a choke-type cable suspended below the edge of the dashboard, near the center.  Opening and closing the control valve allows me to emulate the opening and closing of the vane in the OEM thermostat as well as allowing me to control the heat.


I started out with the conventional, lighted rheostat control for the heater's fan.  After a bit I realized that I never used the rheostat as anything other than a switch.  On top of that, I had it connected directly to a white wire, i.e., drawing power through the ignition switch.  What I have ended up with is a system wherein the power for the fan is taken directly from a source of 12 v (Fuseblock terminal A1), through an automotive relay and a 5 amp in-line fuse.  The relay is controlled by an illuminated switch (suspended below the center of the dash) with power to the switch coming from a source of ignition-switch power (Fuseblock terminal A3).

Here are a number of images showing the things spoken about: (they're thumbnails, give 'em a click)

Control Valve


Power Source


Fan Current