Cabin heating

[FFMan]

I'm getting round to one of the final steps and putting cabin heating in the EV, based upon an Outlander HV heater.

At the weekend i hooked up a coolant loop though cabin matrix, pump, heater and Teed in a small expansion bottle.

I struggled to get good flow through the matrix using one of those VW aux pumps https://www.ebay.co.uk/itm/204365441881

I wondered what pumps others have used, is mine undersized or do i have a blockage somewhere ? I ran out of time to investigate with a hose etc

I verified the old control valve is no longer present, that was in the engine bay and is long gone.

[arber333]

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I struggled to get good flow through the matrix using one of those VW aux pumps https://www.ebay.co.uk/itm/204365441881
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I wondered what pumps others have used, is mine undersized or do i have a blockage somewhere ? I ran out of time to investigate with a hose etc.

I used those old 12v audi pumps with two pins. I think you use one of those PWM controled pumps with 3 pins in a connector. Maybe it works in default at slow speed without signal connected?

[FFMan]

I used those old 12v audi pumps with two pins. I think you use one of those PWM controled pumps with 3 pins in a connector. Maybe it works in default at slow speed without signal connected?

my version has only 2 pins

[arber333]

my version has only 2 pins

I find that hard to belive, P/N 04L965567 is 3 pin. Observe the rear plate diagram. You should see - + S schematic for connection.

Ok this is the pump i use P/N 7L0965561D and it provides quite enough pressure to feed either heating or cooling system
https://www.ebay.de/itm/283846097712

Did you investigate your heater matrix by connecting tap water pressure to hoses and observe the output? Maybe your heater matrix is cloged?

[mane2]

I used this https://evshop.eu/en/miscellaneous/33-4 ... 1700w.html

Mounted inside the original airbox.

[FFMan]

ok this was actually the pump

https://www.amazon.co.uk/dp/B098NRBXPL? ... ct_details

only two pins, came with a small loom

but now i read the comments, the word pathetic springs to mind - buy cheap buy twice !

[arber333]

ok this was actually the pump

https://www.amazon.co.uk/dp/B098NRBXPL? ... ct_details

only two pins, came with a small loom

but now i read the comments, the word pathetic springs to mind - buy cheap buy twice !

Hm... i actually have that pump too. I didnt use it for cooling as its tubes were not aligned with what i need. But from what i did test with heating i would say this pumps impeler needs to be completely flooded. I think you need to make this pump the lowest point in your system and it should provide enough pressure then.
Also air bubbles will degrade the flow dramaticaly so make the highest point of your system your bleed point.
You can buy brass bleed valve and solder it to the top of a copper tube. I use a blowtorch and plummers paste with solder.

[FFMan]

I used this https://evshop.eu/en/miscellaneous/33-4 ... 1700w.html

Mounted inside the original airbox.

that's an interesting option - how do you control the temperature ?

[mane2]

that's an interesting option - how do you control the temperature ?

It’s on or off for me. Using only two “phases”, it’s still very effective.

[PatrcioEV-ATX]

I am also using that pump and have no issues with flow. I did have to run it quite some time to get all the air out of it. It will get very quiet once all the air is gone.

[FFMan]

I am also using that pump and have no issues with flow. I did have to run it quite some time to get all the air out of it. It will get very quiet once all the air is gone.

thanks - i'll persevere this weekend. I have that same pump on the coolant loop and its ok though flow isn't great, but its not needed really.

[arber333]

thanks - i'll persevere this weekend. I have that same pump on the coolant loop and its ok though flow isn't great, but its not needed really.

Well if you use it for heating then you dont really need that much flow. It actually gives heater more time to transfer energy to liquid...
And those heating cores have spiral things inside to restrict flow so they give out more heat... those can get blocked...

[FFMan]

It’s on or off for me. Using only two “phases”, it’s still very effective.

ok - and do you have a stat as shown in their 'datasheet', and does that switch the HV ?

I guess moving air is essential to operations otherwise it'll get real hot real quick.

[arber333]

ok - and do you have a stat as shown in their 'datasheet', and does that switch the HV ?

I guess moving air is essential to operations otherwise it'll get real hot real quick.

Yeah... this is PTC element. It is protected by rising resistance with heat. If you dont move enough air to dissipate heat there will be more resistance and less heat created directly on the element.

[tom91]

Yeah... this is PTC element. It is protected by rising resistance with heat. If you dont move enough air to dissipate heat there will be more resistance and less heat created directly on the element.

Not always the case, I purchased some PTCs from the same company as the EV-shop ones. The data sheets always show a thermoswitch. It turns out the self regulation temperature without airflow is over 200 degrees. Inquiring with the company indeed confirms that they are designed this way for more power.

So please remember to always use a Thermal Switch when using a PTC unless you can prove it does not get too hot to melt itself out of what ever mounting system you use.

[arber333]

Not always the case, I purchased some PTCs from the same company as the EV-shop ones. The data sheets always show a thermoswitch. It turns out the self regulation temperature without airflow is over 200 degrees. Inquiring with the company indeed confirms that they are designed this way for more power.

So please remember to always use a Thermal Switch when using a PTC unless you can prove it does not get too hot to melt itself out of what ever mounting system you use.

!!!!
Do not forget the fact that you cant just break HV with a simple thermostat. I advise using 12V HV power relay in between.
But then system becomes much more complex and points of failure are doubled.

[mane2]

I have it set so that blower needs to be 75% or higher before it turns on, to avoid it melting stuff

Temp sensor would be nice addition with relay, but then again .. I only drive mine on summer, so heater is not that often needed.

[PatrcioEV-ATX]

If it helps anyone, I'm using a HotStart block heater to heat coolant that flows through a Restomod Air combo heat/AC unit (separate cores). HV power is fused and flows through a HV contactor that is controlled by an Arduino Nano in my HVJB. The Nano gets "Heat" ? over CAN from an Arduino Mega in my center console. I have a temp sensor in the coolant tank, one in the cabin, and one behind the front bumper (this one is really just info). The Mega also reads the value of the fan in the heat/AC unit (5v analog). Heat is called for when the temp inside the cabin is at least one degree less than the value set by my OEM temp lever (another 5V analog provided by slide potentiometer that maps between 65 and 85 degrees), the fan is on, and Climate is on (dual state button on my display). If all that is true, then I send "Heat" and the temp of the coolant over CAN to the Nano and start the coolant pump (from the Mega through a relay).

The Nano closes the relay for the heater if "Heat" is called for and the temp of the coolant is less than 140 degrees. It will open the contactor if the temp gets over 160 degrees, even if "Heat" is still being called for, and will close it again if the temp falls below 140. There is also logic to keep the heater coolant pump running for two minutes past the last time "Heat" was called for. That keeps the coolant flowing even as the cabin temp hits the desired temp.