Webasto 7 day timer

[opus]

Can someone tell me how to set this so it wont turn off by itself.  I want to start the Webasto and have it run til it kills the battery or runs out of fuel. 

[Sean]

Remove it and replace it with a switch.  I find these timers of limited or no use on a conversion.  They are principally designed to pre-heat engines before the drivers arrive in the morning to start their vehicles.

Our Webasto is tied to household thermostats, which happen to have program timers, should we need that feature (we do have the temperature set lower when we are asleep, easily overridden at the thermostat).

-Sean

[opus]

I was told that if I tied the purple wire to hot, it would do just that.  In this scenario, the timer would still work as well.  If not, where do I put the switch, the signal wire, which is black...if I recall correctly?

[Sean]

I was told that if I tied the purple wire to hot, it would do just that.  In this scenario, the timer would still work as well.  If not, where do I put the switch, the signal wire, which is black...if I recall correctly?

Well, it's hard to be specific since I don't know how your unit was wired.  Typically the switch presents voltage to terminal B-1, which on a standard harness is where both the black and violet wires are tied.  On systems without a timer, the switch connects black to voltage.

On systems with a timer, the timer operates the black wire and the violet wire can be used to bypass it.  There is also a violet wire on pin 9 of the timer which commands the timer to keep the unit on rather than cut it off after one hour; look at Figure 23 on page 40 of the manual.

You might have to trace some wires coming off the Webasto control box to know for sure.

-Sean
http://OurOdyssey.BlogSpot.com

[opus]

This much I know, the purple wire is now tied to the [hot] red wire.  Guess I need to just fire it up to see how long it runs.

My timer manual has 18 pages and my DBW2010 has 55 pages.  I will look still...... 

[rv_safetyman]

Sorry for a slight thread drift. 

Our AquaHot (Webasto) also uses a house type thermostat- but not digital.  Have tired to find a thermostat that will control to temperatures below 50* for when it is in the shop in the winter.

Do the digital units go lower than 50*?  Looked at the hardware store, but they don't talk about the range.

Jim

[opus]

It would run for 10 mins or so, then cool down and shut off.  I had it wired with the purple wire too.  I ditched the timer and put a switch in.  Runs for 10 mins, shuts off.  Pulled the cover off the box and ran it.  Heard some clicking so I put screwdriver on my ear and started probing for where it was.  Its the control box...clicking like a relay or points.  I called tech service, they said it sounds like a bad ground.  Cleaned the ground off and we shall see.

[Sean]

OK, my apologies for coming back to this so late in the game.  We were in the middle of this discussion when the largest natural disaster in the U.S. since Katrina hit...

... Do the digital units go lower than 50*? ...

Jim, I think you will have a hard time finding any household 'stat with a range that low.  I would order a $5 fixed-point thermostatic switch from, say, Grainger, with a set point at whatever temperature you need, then wire it, along with an SPST switch, in parallel with your existing 'stat.

It would run for 10 mins or so, then cool down and shut off.  ...

There might be nothing wrong at all, as this is normal behavior when the fluid is hot.  Are you sure your pump is running?  Also, is anything pulling heat out of the system, like fan-coil units?

To verify, pull the little plastic shroud off the thermostat housing, and measure voltage on both sides of the operating 'stat (orange wires).  When you first turn the unit on, you should read +12 (or +24 as the case may be) on both sides.  Wait until the burner shuts down and measure again; if you get voltage on only one side, then the 'stat is calling for the unit to shut down because the fluid is already hot.  If so, check your pump operation, and plumbing.

-Sean
http://OurOdyssey.BlogSpot.com

[opus]

It would run for 10 mins or so, then cool down and shut off.  ...

There might be nothing wrong at all, as this is normal behavior when the fluid is hot.  Are you sure your pump is running?  Also, is anything pulling heat out of the system, like fan-coil units?

To verify, pull the little plastic shroud off the thermostat housing, and measure voltage on both sides of the operating 'stat (orange wires).  When you first turn the unit on, you should read +12 (or +24 as the case may be) on both sides.  Wait until the burner shuts down and measure again; if you get voltage on only one side, then the 'stat is calling for the unit to shut down because the fluid is already hot.  If so, check your pump operation, and plumbing.

-Sean
http://OurOdyssey.BlogSpot.com

I was getting 12.3 at the batteries and 11.2 I think at the control box. It turned out to be dropping voltage through the fuse box and a shaky ground.  I replaced the fuse box, and pulled out the timer.  Now I have 2 timers I can sell. 

[opus]

Sorry, I am a little late back to this post.  I tried this the other night when we needed heat and it still ran for only 15 mins or so, then quit.

It would run for 10 mins or so, then cool down and shut off.  ...

There might be nothing wrong at all, as this is normal behavior when the fluid is hot.  Are you sure your pump is running?  Also, is anything pulling heat out of the system, like fan-coil units?

The pump is running, actually 2 pumps.  There are all the normal school bus heaters still.  So that would be a yes.

To verify, pull the little plastic shroud off the thermostat housing, and measure voltage on both sides of the operating 'stat (orange wires).  When you first turn the unit on, you should read +12 (or +24 as the case may be) on both sides.  Wait until the burner shuts down and measure again; if you get voltage on only one side, then the 'stat is calling for the unit to shut down because the fluid is already hot.  If so, check your pump operation, and plumbing.

Pump operation and plumbing is all properly functioning.  I will check the orange wire thing tomorrow.

[Sean]

So, did you do what I suggested and check the voltage on both sides of the operating thermostat both before and after the shutdown?  What were the results?

-Sean
http://OurOdyssey.BlogSpot.com

[opus]

So, did you do what I suggested and check the voltage on both sides of the operating thermostat both before and after the shutdown?  What were the results?

-Sean
http://OurOdyssey.BlogSpot.com

Well, I did.  It never shut down...lol!  There was correct voltage all the way through the 45 minutes or so. 

[Sean]

...  It never shut down...lol!  There was correct voltage all the way through the 45 minutes or so. 

OK, now I am confused.  Is it shutting down after 15 minutes, or running continuously for 45?

-Sean
http://OurOdyssey.BlogSpot.com

[opus]

Initially, shut off after 15.  Now it runs and doesnt shut off [what I want].  I got bored after 45 mins of it running.  We used it the other night when needing heat and it shut off after 15 mins.  Beats me!