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Mod idea, using residual engine heat to keep the cabin warm

vwengineer

Ready to race!
Location
Switzerland
Hello,

I am wondering how complicated would it be to implement this function which exists on the other vehicles such as some MK6 and MK7 here.

My idea would be to install a second electric coolant pump on one of the heater core lines and find a way to power up the HVAC without switching the ignition (I know that webasto made some kind of implementation of this).

That way we could circulate coolant through the engine and the heater core and vent it in the cabin without the engine running although it wouldn't last that long, it would still be useful in some cases.

Now there are some questions:

- I don't know if it's OK the put the pump in-line directly or if it could impede the normal coolant flow
- Not sure if the engine thermostats would be a problem or not, but I don't think, it would be a small loop if the thermostats are closed.

What do you think?
 

zrickety

The Fixer
Location
Unknown
Car(s)
VW GTI
The TSI cars have an aux water pump already...would just need a couple relays to power it up and the HVAC. As you said, it wouldn't last long. I believe the MK7 have an electric heater to supplement the system, saw a post about disabling it with VCDS.
Edit- I would be more worried about the battery...especially in a cold climate. You might be better off to get a remote start or turbo timer to accomplish this.
 
Last edited:

Fred930

Scirocco MK II Track Car
Location
Wisconsin
I recall VW offered a PTC (Positive Temperature Coefficient) ceramic type auxilary heater in some models, for very cold climates. Such devices are electric powered and would offer almost instant-on heat, but require quite high current levels at 12 Vdc - likely supplied from their own heavy duty electrical bus. And certainly it would NOT be advisable to operate them from the battery alone (when the vehicle charging system was not running), as they would rapidly deplete the battery charge.

I think if you look around with VCDS you will be able to find the sub-system control. But I'm doing this from memory and have no idea if the optional PTC heater could be easily added to your car - assuming it could be sourced from Ebay, or such.
 

GTI's

Drag Racing Champion
Location
MD
Hello,

I am wondering how complicated would it be to implement this function which exists on the other vehicles such as some MK6 and MK7 here.

My idea would be to install a second electric coolant pump on one of the heater core lines and find a way to power up the HVAC without switching the ignition (I know that webasto made some kind of implementation of this).

That way we could circulate coolant through the engine and the heater core and vent it in the cabin without the engine running although it wouldn't last that long, it would still be useful in some cases.

Now there are some questions:

- I don't know if it's OK the put the pump in-line directly or if it could impede the normal coolant flow
- Not sure if the engine thermostats would be a problem or not, but I don't think, it would be a small loop if the thermostats are closed.

What do you think?
Have you found a SSP on how this functions in the MK6 & 7. May point you in the right direction.
 

vwengineer

Ready to race!
Location
Switzerland
Thanks everyone for your inputs

The TSI cars have an aux water pump already...would just need a couple relays to power it up and the HVAC. As you said, it wouldn't last long. I believe the MK7 have an electric heater to supplement the system, saw a post about disabling it with VCDS.
Edit- I would be more worried about the battery...especially in a cold climate. You might be better off to get a remote start or turbo timer to accomplish this.
Some diesel cars have an electric heater (PTC) even the Golf 5 which can be retrofitted, however it uses a very high amount of power (1kW) so it's absolutely not possible to use it without the engine running. In very cold climates, VW propose cars with a Webasto heater which burns gasoline or diesel to produce heat which is great if the engine is cold although it also use a lot of electricity so it can only run a few minutes.

The GTI already has an after-run electric water pump, however it's only here to prevent oil cooking in the turbo and I am not sure it circulates water trough the heater core (it circulates water backwards from the radiator to the turbo charger) but that could be an interesting test if there is a way to run it from an input test in VCDS.

Of course it would be easier to simply leave the engine idle but it's not so socially accepted and also illegal here to let a parked car idle ? (and of course also less efficient).

Have you found a SSP on how this functions in the MK6 & 7. May point you in the right direction.
I found an SSP (not for the Golf but for the Phaeton), however they seem to use a complicated pump design (they also have and electric coolant pump active while the engine is running) and they have two heater cores. But I found something more interesting regarding the Webasto unit retrofit on a Golf 5 or Touran:

http://автоотопитель.рф/manual/Volkswagen/Touran/Touran_2006_1.4_1.6_b_E.pdf (yeah never saw an URL like this aha)

They seem to reroute the engine - heater core connection to the Webasto which has a builtin water pump and then also switch ON the Climatronic with the car off. Although the electric part is quite complicated, I don't think it would be necessary. Leaving the ignition ON for 10-15 minutes is probably not going to drain a healthy battery (especially assuming you drove at least 15 min to get the engine warm). Now on their schema, they show two pumps but I think the second one is the mechanical engine pump.

My idea as a first step would be:

- Try to run the after-run pump manually with engine OFF, ignition ON, Climatronic ON and see if it still blows hot air in the cabin (I am not convinced, especially because of the thermostats)
- Install a second after-run pump (about 20$ in China) on the coolant line that goes on the heater core and do the same test
 

GTI's

Drag Racing Champion
Location
MD
Have you taken a look at SSP318 Golf shows both types used in MK5(electrical auxiliary air heater & auxiliary water heater).

May also want to find the coolant flow diagram for your year car and see how it flows if you go the route of installing some type of pump in the HC line. Perhaps a timed relay to control both the pump and blower fan?
 

fastfitz

New member
Location
Murray, SC
VW actually solved that problem in the 60's (or maybe the 50's, I ain't THAT old). A gas fired Wesbasto heater that produced enough heat to get a can of Beanie Weenies steaming hot. The CO poisoning when the combustion chamber rusted was a bit of a drawback though. With the modern ones, A gallon of kerosene (much less maintenance problems compared to #2 diesel) will keep you warm for about 24 hrs (and that's in a roughly 800 cu ft truck sleeper cab). Mount a small aluminum fuel tank, wire it up, and route exhaust and intake air tubes and it's done. Has the option to heat the coolant too, plus using a timer on the control (they have one) allows you to hop in a toasty warm vehicle on cold mornings.
 
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