Fitting the OEM Auxillary Heating Ductwork

[Grim Reaper]

Sorry, No, I do have a 7H5 somewhere though.
I bought the right part off Pauly when he was running the shop, but you should be able to get it from a VW dealer/Parts supply place.
They were under £24+VAT in 2019

 

[ma77y]

Yeah thats what I may have to do, I won a few ducting parts on ebay missing the step vent, B pillar coupling and the y ducting.

 

[cflaviu]

Hi there people,

This thread has lots of details about how and where to put the ducts and grills but I didn't see any info on where is the fuel pump fitted in OEM setup.
Does anybody have some pics of the pump and pipe routing in a factory setup?

Any info will on this will be greatly appreciated!

Thanks!!

 

[oldiebut goodie]

All in the manual for the STC.
Plus 3500.


Copy of the manual is here

Fitting Eberspacher D2 - My Experience

Hi All, Not sure if this is of use but I took a few pictures as I fitted my D2 diesel heater, may help people having a go themselves. I’m not a pro at fitting these and this is the first I have done, any criticism is welcome. For reference this is the underslung T6 specific kit and I’m...

www.t6forum.com

 

[cflaviu]

All in the manual for the STC.
Plus 3500.
View attachment 146125

Thanks for your quick reply!
So the fuel pump is located next to the water heater (close to the other dosing pump)?
While in the manual you sent me the pump is on the same side with the air heater

Now how can they maintain an upward slope of the line to the heater if the pump is located on the other side? The line must go up under the car and then down again to the heater inlet, or?

 

[oldiebut goodie]

Just put the pump anywhere where there is an upward slope after it, it doesn't have to be a great slope, 5 degrees is enough. I mounted mine down low after exiting the fuel tank then over and up to the heater thus avoiding crossing above the exhaust. The aim is to avoid any loop up and down after the pump where air bubbles can accumulate and potentially cut down the fuel flow to the heater. When the fuel pump is operating the compression of the fuel causes dissolved air to form minute bubbles on exit, this doesn't occur on the suction side so that does not suffer in the same way.

 

[cflaviu]

Just put the pump anywhere where there is an upward slope after it, it doesn't have to be a great slope, 5 degrees is enough. I mounted mine down low after exiting the fuel tank then over and up to the heater thus avoiding crossing above the exhaust. The aim is to avoid any loop up and down after the pump where air bubbles can accumulate and potentially cut down the fuel flow to the heater. When the fuel pump is operating the compression of the fuel causes dissolved air to form minute bubbles on exit, this doesn't occur on the suction side so that does not suffer in the same way.

So the pump outlet can never be higher than the heater inlet? This is all getting confusing, as I in the manual I see the case where the pump is mounted above the heater (by the way, I have AirTop 2000 STC with DP42 pump).
How can the factory achieve the upslope when mounting the pump on the other side of the heater?

 

[oldiebut goodie]

The manual does say heater up to 1m below pump but best practice is to avoid any likelihood of bubbles getting trapped.
But as I said earlier I mounted mine low down after exiting the tank and then crossed over to the heater all sloping upwards.

 

[cflaviu]

I understand your point but then why did the factory chose to go with the line up and down and like a snake.
I was always thinking the intake (vacuum) side of the line is more susceptible to bubbles but even that, if fully primed why/how could bubbles appear?

 

[oldiebut goodie]

When the fuel pump is operating the compression of the fuel causes dissolved air to form minute bubbles on exit, this doesn't occur on the suction side so that does not suffer in the same way.

Do what you want - after all it is your installation. I'm out.

 

[cflaviu]

I never meant to offend. Sorry if I did and thanks for the time! It is still not clear why would the factory go up and down if bubbles were to form that way...
Also "compression of the fuel" - I learned that liquids take huge pressure to compress even a bit...anyway, my first question was if anybody has any pics of the original setup to see exactly how they install the pump and route the line...

Thanks again and sorry for the misunderstanding.

 

[Grim Reaper]

In my pre installation bench testing (using wide bore tygon fuel pipe) any air bubbles caused by the fuel pump were just pushed through the pipe by the fuel flow, up, down, around corners and so on and fuel feed to the heater was not interrupted no matter how much air accumulated, after all, if you think about it, if you keep injecting fuel into one end of a piece of pipe, it can only come out the other end, it can’t go anywhere else.

 

[cflaviu]

In my pre installation bench testing (using wide bore tygon fuel pipe) any air bubbles caused by the fuel pump were just pushed through the pipe by the fuel flow, up, down, around corners and so on and fuel feed to the heater was not interrupted no matter how much air accumulated, after all, if you think about it, if you keep injecting fuel into one end of a piece of pipe, it can only come out the other end, it can’t go anywhere else.

That's what I can imagine as well !
By the way, what bore size did you use when bench testing? Did you try the bigger pipe on the output or on the input of the pump?
Cheers!

 

[Grim Reaper]

Pardon our interruption...

I’m pretty sure I used the 4.8mm ID tubing, it fits all the metal fittings with no need for adapters, I used Oetiker clamps to secure it.
I have been using it in the van installation for a few years now, I made a tank out of aluminium that sits under the rear left corner of the van, about 13 litres, the pump sucks diesel out of the tank via a standpipe tube that pulls fuel from the bottom but fits in the top of the tank, ebay item around a fiver, the pump is mounted just behind the left rear wheel on a soft rubber mount with a Mahle KL15 fuel filter just before it, then the fuel pipe runs across the van under the metal heat shields and down the right hand chassis rail beneath the plastic covers to the heater under the driver’s seat, I have had no issues with fuel delivery to my 2kW heater using this method.

 

[Grim Reaper]

A bit of a warning, Don’t use copper brake line in the diesel fuel route, a friend of mine tried using old brake line as a standpipe tube into his heater fuel tank and it caused damage to 2 fuel pumps by creating a green gunk type substance that blocked the lines.

 

[Skyliner33]

Pardon our interruption...

I’m pretty sure I used the 4.8mm ID tubing, it fits all the metal fittings with no need for adapters, I used Oetiker clamps to secure it.
I have been using it in the van installation for a few years now, I made a tank out of aluminium that sits under the rear left corner of the van, about 13 litres, the pump sucks diesel out of the tank via a standpipe tube that pulls fuel from the bottom but fits in the top of the tank, ebay item around a fiver, the pump is mounted just behind the left rear wheel on a soft rubber mount with a Mahle KL15 fuel filter just before it, then the fuel pipe runs across the van under the metal heat shields and down the right hand chassis rail beneath the plastic covers to the heater under the driver’s seat, I have had no issues with fuel delivery to my 2kW heater using this method.

Why do you take fuel from this aluminium tank rather than the vans fuel tank?

 

[oldiebut goodie]

I never meant to offend. Sorry if I did and thanks for the time! It is still not clear why would the factory go up and down if bubbles were to form that way...
Also "compression of the fuel" - I learned that liquids take huge pressure to compress even a bit...anyway, my first question was if anybody has any pics of the original setup to see exactly how they install the pump and route the line...

Thanks again and sorry for the misunderstanding.

It is not the actual compression of the fuel per se - it is forced by a piston through a tiny orifice inside the pump and it is this action that allows the dissolved air to escape the liquid. The DP42 fuel pump is of slightly different internal construction to the older DP30 ones and as a result there is less air formation in these but there is still some. ( as a result of the change they are slightly quieter as well )
here is a dp30 - the orifice is just to the right of the red circle on the left - it is tiny.


Don't be tempted to use larger bore fuel pipe - it is 2mm ID for a reason! I have had a couple of customers that thought that they were being clever by using ordinary fuel hose but they complained of low heat output that I couldn't diagnose until I got pictures of their setup and saw the hose used. Once they used the correct line as I supplied normal service was resumed. Just because the large bore works it doesn't mean that it is correct.

 

[Grim Reaper]

I have a separate tank so I can use Red Diesel to make it cheaper, and know that I can not run the main tank low so I can still start the van.

 

[cflaviu]

It is not the actual compression of the fuel per se - it is forced by a piston through a tiny orifice inside the pump and it is this action that allows the dissolved air to escape the liquid. The DP42 fuel pump is of slightly different internal construction to the older DP30 ones and as a result there is less air formation in these but there is still some. ( as a result of the change they are slightly quieter as well )
here is a dp30 - the orifice is just to the right of the red circle on the left - it is tiny.
View attachment 146217

Don't be tempted to use larger bore fuel pipe - it is 2mm ID for a reason! I have had a couple of customers that thought that they were being clever by using ordinary fuel hose but they complained of low heat output that I couldn't diagnose until I got pictures of their setup and saw the hose used. Once they used the correct line as I supplied normal service was resumed. Just because the large bore works it doesn't mean that it is correct.

When I bought my AT 2000 STC (second hand) it came with a short piece (30cm) of original Webasto line that has ID of 1.5mm written on it.
Would then be better to use 1.5 on the output rather than 2mm or even on the input?

I don't mind using the thinner line, or any line for the matter of fact. The most inconvenient thing in my setup is to keep a uphill slope on the oprit of the pump. That would invalidate my preferred place to have the pump

But then, wouldn't a longer output line increase the bubble phenomenon? (Like factory setup chose to do)
Ah, does anybody have any idea of the max pressure spikes that arise at the output of the pump? 10 bar? (145psi) More?

 

[Grim Reaper]

More like 0.0145psi.
The pump moves .22ml on each stroke, so no great pressure, besides, webasto/eberspacher sell a little diaphragm type shock reducer to put in the fuel line, why would they sell that if you needed pressure pulses in the feed?