Webasto gasoline coolant heater vs air heater

[avongil]

I have been debating installing the Evo 5 Thermo Top instead of the Thermo Air for cabin heat.

The vehicle is an 2009 Chevy Express long wheelbase Explorer conversion van. It already has the ductwork in place and heats the vehicle just fine when the engine is on. I am thinking it would be much easier to install and implement since I would only have to rewire the hvac circuit to run off the "house" battery.

Let me know if there is a good reason not to go this route over the air heater route.

[booster]

Originally Posted by avongil

I have been debating installing the Evo 5 Thermo Top instead of the Thermo Air for cabin heat.

The vehicle is an 2009 Chevy Express long wheelbase Explorer conversion van. It already has the ductwork in place and heats the vehicle just fine when the engine is on. I am thinking it would be much easier to install and implement since I would only have to rewire the hvac circuit to run off the "house" battery.

Let me know if there is a good reason not to go this route over the air heater route.

I think it work if you had a two way damper setup to feed the ductwork to the house area, but probably wouldn't if you tried to use the vehicle fan because it is all tied to van electronics in the PCM and BCM. This would include some of the control doors in the dash area, including the most important one, which would be the recirculation door, which is left open to the fresh air outside vent when the engine is off. Your van probably has a mix of electric control dampers and vacuum controlled with possibly only the warm/cold mix damper being electric and all the rest vacuum.

[avongil]

I found this:

https://ww2-secure.justanswer.com/up...ac_diagram.gif

So, it looks like if I put a 12v vac pump in and solenoid that would solve the flap issue. How it's tied in to the auto electronics is a mystery. I'm sure someone has done this before though. I cannot imagine this has not been done in the north to warm the windshield at least.

[booster]

Originally Posted by avongil

I found this:

https://ww2-secure.justanswer.com/up...ac_diagram.gif

So, it looks like if I put a 12v vac pump in and solenoid that would solve the flap issue. How it's tied in to the auto electronics is a mystery. I'm sure someone has done this before though. I cannot imagine this has not been done in the north to warm the windshield at least.

It is likely that the doors that are on the selector control for position are vaccuum controlled at the control itself, but may leak so would need a pump and tap into the vaccum line from the ball tank that is probably under the battery under the hood. You would need a check ball to keep all the vaccuum from going back to the engine and leaking out while the pump was running. The only time that the fresh air door is closed is on "Max AC", it will be open in other settings of the selector. You would need to select that each time if it wasn't in Max AC. As long as you don't have the key on, the others may be OK as I don't think any of them have proving or position switches, but is possible a couple might. The heat selector will be electric so shouldn't be powered or confused, but it will depend on where it parked when stopped as to where the air that goes in the dash area. My guess is it won't matter much as it probably will split between the dash vents and the recirculation intake which I think is in the front footwell. With the key off, the vehicle blower will not run an messing with that would be into the electronics which I think are built into the control in the dash and controlled by a temp sensor somewhere in the cab. I think a couple of manual dampers at the tap into the ducts would be much easier and quicker to do, but could be wrong.

[avongil]

I don't think there is any sort of temp sensor. It is a really crude system circa 1996! Just fan speed and air mix. I think I will mess around powering the fan and see where that takes me. Putting the heater controls in whatever desired night time orientation would not be a deal breaker at all. Even just powering the rear fan would be fine! That one is even simpler and just has an intake in the rear left side.

Thanks! That helped quite a bit. Next step is to play around powering the hvac with the engine off and see exactly what works and what does not.

[booster]

Originally Posted by avongil

I don't think there is any sort of temp sensor. It is a really crude system circa 1996! Just fan speed and air mix. I think I will mess around powering the fan and see where that takes me. Putting the heater controls in whatever desired night time orientation would not be a deal breaker at all. Even just powering the rear fan would be fine! That one is even simpler and just has an intake in the rear left side.

Thanks! That helped quite a bit. Next step is to play around powering the hvac with the engine off and see exactly what works and what does not.

You list above a 2009 Expess van, and that likely would have an electronically controlled temp control system that is installed to replace the mechanical cable heat control they had in the old ones. I am not sure when the switched, but in 1996 some of the GM vehicles were already using it as my Buick Road master does.

You can tell by looking at the outside of the panel as the mechanical and electronic look the same, but when you pull them out on the backside of the heat control knob there will be an electronic module that runs a positioning motor on the heat/cool door. I will have to check the factory service manual to be certain, but I am pretty sure that is what our 07 has Express has. The temp sensor might even be in the ducts somewhere, but more likely somewhere around the dash, I think. I suppose that it could be a non temp control electronic, but I don't think so as ours seems to modulate very well.

Here are front and rear of the control panel from ebay that is for the vans, you can check the compatibility chart down the page, too.

https://www.ebay.com/itm/29454834181...ke%3AChevrolet

[GeorgeRa]

Most of hydronic systems use powered heat exchanger or floor radiant heating of passive convection. Passive heat radiators don’t require a blower and cost are low, takes a little longer to heat a van. Heatso sale Kalori heat exchangers with thermostat. https://www.heatso.com/espar-eberspa...kw-cs-version/ https://www.amazon.com/Fin-Clamp-Hyd.../dp/B00U6HLSZI

If you plane to use engine coolant to heat your van you will need to include time delay due to engine large thermal mass, I think independent system from Rixen or Heatso or new Timberline are simpler to install.

I have Espar D5 to heat marine water heater independent of engine coolant.

As Booster pointed above, how would you supply vacuum to control valves?

[avongil]

Well, it seems i have been schooled big time. I see now why everyone just goes the Airtop route! I'm thinking it's not worth the trouble and a separate system is a better idea for ease of repair of the original.

Thanks.

[avongil]

It is this one by the way. Same as the one pictured above just fuancyyer. https://www.ebay.com/itm/16488303971...AAAOSwbiBglYb7

The blower does run on acc power though.

[avongil]

I just cannot let it go. even if its just to turn the fan on in the spring/summer/fall...

I found a wiring diagram for a 2013 Assuming its similar, I am thinking about putting a switch on the dash to provide power to Fuses 13 and 14.

https://f01.justanswer.com/heavy_che...g+G2500+ac.pdf

This is definitely the right style hvac. I just replaced the resistor pack - it had a mouse in it. Grosss...

Does this sound like a bad idea? I have no idea if power the HVAC will cause any unintended consequences.

[klaassybrand]

Hi Avongil,

I just rarely check this forum but noticed your thread. Probably my first post....

I own an older 2002 Express Explorer conversion van. I recently stripped and converted it to a camper with pop top.
As a matter of fact i also recently installed a Chinese version of the Webasto thermo top evo liquid heater. Because of the explorer passenger conversion, the van had all the hosing and auxillary hvac setup in the rear. As i bought the van this was disconnected and the blower motor in the rear was bad.

SO what i did:

- Bought the specific petrol version of the 5KW liquid parking heater (Webasto lookalike)
- Being really carefull i drilled an extra hole in the fuel pump tank lid for the fuel line pickup.
- I installed the waterpump in bewtween the rear heater hoses about halfway of the van. So it would run at first to the rear heating for quickly heating up the iterior.
- I runn the 12v wireing to the aux battery mounted in the middle of the van.
- Somehow i could not figure out how the heater would run and switch the interior blowers without ignition. There was no info available.
TO fix this i just recently i created 2 simple circuits for both the front blower and rear blower motors using 2 separate relay boards with a temp sensor at the heater hose. The relay will switch the "hot in run" 12v wires for both blowers when the temp is above 35 degrees Celsius. The front and rear fans are both selectable in all speeds. I just have to make sure they are not set to "Off" on the dashboard switch but in the desired speed.

This was just a quick reply, I could ofcours provide some photos and more details of the install later on.

Klaas