Tilbehor timer for early eberspacher gasoline heater

[oneeyedducky]

I just bought this tilbehor timer for my early eberspacher gasoline heater .
I was wondering if someone could tell me the proper way to hook it up. anyone with one of their car?

The timer has 2 terminals on the back. to use it, you turn the clear face to have the time you want it to start on the right side of the red area, then you turn the knob to the current time (in military time) and then it ticks happily away. once the knob gets to the red area it closes contacts inside, then they open after the knob gets to the left side of the red area and the knob snaps to the left.

on the eberspacher heater itself (not talking anything about the timer just the heater in stock form)-- is a rod that goes thru the dash with a ivory knob on it, pull this and the duct opens and simultaneously the fuel pump runs, glow plug burns and the heater fires with fan running, when you push the knob in the heater duct closes and vents the hot air to the trunk and continues to run the fan, but power is killed to the glow plug, and fuel pump, once the heater reaches a certain temp it shuts off automatically.

i wonder, to hook up the timer, does it just go inbetween the heater and the fuse box in that power circuit? -- this would reguire turning the timer to the red zone every time i want to use the heater. and also if i dont turn the heater off to its cool down cycle and its on the timer, the timer would just shut off the heater hot with no cool down cycle.

there has to be a better way to wire this in with a dual pull relay or something. any ideas ??

[Motorhead55]

I would say that you are right about the hook up of the timer.
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2012 Jetta TDI Sportwagen. Tornado Red, Black interior.
2007 Dodge Cummins Diesel 4x4 6spd stick
1977 Mercedes 240D, 1939 WILLYS pickup

[oneeyedducky]

[Zwitterkafer]

The cool down cycle is essential since it also evacuates unburned vapors from the burn unit. The manual says not to attempt a re-start while the 3 minute cool-down is running and the warning light is still on. To do so may risk a backfire, something that Eberspacher would have us avoid.

Your heater likely has the pull-handle attached to a 3 terminal rotary switch, with terminals 56, 30, and 58.

56 = fused from +6V source, and also goes to the quartz rod thermoswitch
30 = switch output to heater fuel pump only
58 = switch output to fan, glowplug, (via thermoswitch) and warning lamp

How it works:
At rest, heater off, the 3 terminals of the switch are isolated from each other. When switched on, all 3 terminals are connected to each other, and get power from the +6V source connected to 56. The fuel pump comes on, the fan comes on, and the glowplug gets current through closed contacts on the quartz rod thermoswitch. After ignition, the burn chamber heats up, and the thermoswitch eventually trips, cutting off power to the glowplug. The plug stays hot enough to maintain combustion. As the power is cut to the glowplug, the warning lamp comes on, since it has +6V at terminal 58 of the switch, and ground through the glowplug.

When the heater is turned off, the 3 terminals of the switch are isolated from each other, so 30 and 58 no longer get 6V, but 56 still does. The fuel pump goes off immediately, but the fan and warning lamp continue to get power, but now from 56, through the still tripped thermoswitch. The burning stops, cooldown begins, and about 3 minutes later the thermoswitch trips back to it's "at rest" state, which cuts off the fan and warning light from the power source at terminal 56. Cycle complete.

The timer is designed to pre-warm the car, running through a complete cycle on its own while you are having morning coffee. To accomplish this, my suggestion would be to wire it in parallel to the normal switch:

Connect timer power source terminal to heater switch power source (56).
Connect timer output terminal to heater switch terminal 30, for fuel pump.
Connect timer output terminal also to the control winding of a normally-open relay (relay contacts must handle >> glowplug + fan current!).
Ground the other side of the relay control winding.
Connect power source (56) to one of the relay output terminals
Connect heater switch terminal 58 to the other relay output terminal.

Sketch it out on paper first to convince yourself that it could work!

The (10A?) timer contacts only have to supply the fuel pump and primary winding of the new relay....the new relay handles the glowplug & fan.

To prevent normal operation of the heater switch from unnecessarily operating the new relay from terminal 30, you could get fancy and try a steering diode between Timer 30 and heater switch 30.....on your own there.


Legal disclaimer: Attempt at your own risk, I cannot be responsible for any mishaps.

Cheers!
H
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"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC

[oneeyedducky]

[Zwitterkafer]

Did you look up the B2 wiring diagrams on this website? Just pencil in the mods I suggested, and you'll see how it works. The relay is essential in order to isolate 58 from 30 after the timer shuts off. This is the key to a normal 3 minute cooldown run using power from 56, though the quartz rod thermoswitch.

Your switch may have been part of a larger kit that included wiring instructions and a relay. Having spade terminals makes me think that it is a later accessory from the 60's.

H
_________________
"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC

[oneeyedducky]

The only issue I see here at this point is the flap connected inside the heater ducting to the rotary switch. It's is for a pre b2 Eberspacher. When off and hot and motor is exhausting chambers the air,flap closes and vents air to the trunk. When on th Hester blows hot air into the cabin cause the flap opens. Sofia the supply to terminal 56 is off due to heater rotary switch and flap being close and I wire the heater timer in parallel, the heater will run for the time on the heater and heat my trunk. That's no good. The timer will kick off and and allow cool down.

If I wire it inline from the car fuse block to 56 and leave the flap on, it will heat the inside of the car as normal but then shut off with no cool down cycle. I also have to run the timer EVERY TIME I WANT THE HEATER RUNNNING. It's will wear out the timer fast. I would have to rewind it every half hour on long trips to and wait 3 minutes In between to prevent backfiring- lame!!! I need the heater wired so the on off standard rotary Swich and cool down works as normal and is separate fm the timer but the timer allows cool down. A relay with dual circuits may solve this by allowing the second circuit to provide power to the fan when the timer kicks off allowing cool down.
c
One way around this is to wire as the first way and remove the flap. But then I can never seal the heater when off an with all the car windows up cold air will be forced thru the heater and into the cabin- this would suck!!!!

Got to be a better solution- I'm still confused. It's has to be simpler than all this.

In a bus heater his is not a problem- there's no rotary flap

[Zwitterkafer]

Your timer switch, with PUSH-ON terminals, is for the later version heater without the flap valve in the outlet elbow. If you insist on trying to use the flap valve version, you are going to create problems. Substitute a later elbow and you will be fine; just make sure that the rotary switch is exactly the same and switches as I described. The serial wiring method does not make sense to me, and I can't see the factory ever approving of it.

The fresh air intake for cabin heating is actually rearward facing, behind the lower edge of the spare tire. A special baffle (often missing or omitted) replaces the usual round shift rod access cover, and mounts with a screw or two. With this in place, and a hood seal that is sealing properly, you should have no problems.......especially in California. They made thousands of heaters this way before upgrading to a J-shaped plastic intake duct that also takes air from the cabin. I can attest to the fact that the old style still worked very well, down to at least -20 deg C.

H.
_________________
"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC