S3/S4 heater vent orientation, is there a definitive answer?

[robertverhey]

I've searched the forum thoroughly and it's left me more confused. I'm just reassembling my heater box, and there are two ways it can go. The last pic shows what mine was like when stripping the car down. Note that both the demister and face vent exits are close to the dashboard side. The second shows the workshop manual diagram which seems consistent with the way mine was installed. The first picture is a screen shot of the diagram on rdent's site, shows it the other way around, with demister pipes exiting close to the bulkhead.

To change between the two arrangements ( for the demister outlets at least) it's simply a matter of swapping the end plates when reassembling. But which way should I have it arranged....does either way work? Based on posts on the forum, it seems there are examples of both out there. I look forward to words of wisdom and experience!

[AHM]

Thanks for posting this - You have saved me a lot of work.

My early S4 has the air vent pipes coming out by the bulkhead and the water supply on the dashboard side. The air vents are very squashed and don't work properly.

Your water pipes and air vents are on the (same) dash side.

This is the difference between the 2 pictures the holes are in the same piece of metal so you have one or the other. Swapping the ends will make something wrong with the water pipe outlet- you don't say which is S3 and which S4

[robertverhey]

Yes thanks for that I see what you mean, in fact the rdent arrangement is not an option for me i now see. I suppose it's the side plate orientation i'm really questioning. My main body (and hence the water inlet/outlet and angled rubber face vent outlets) will need to stay put as they are. My two side plates (ie the ones with the cabin flap and the demister outlet) are not permanently connected to either the upper or lower sections. They can be interchanged without disturbing the water outlets, face vent outlets or anything else. So I have a choice of having demister outlets adjacent to dash or adjacent to bulkhead.....which is best?

Mine's an S3 36/6858

[oldelanman]

I believe that the eyeball vent tubes were fitted to the rear (dashboard side) of the heater casing when first introduced but were later moved to the front (bulkhead side) to improve the installation - that's how my S4 is. Space is very limited between the dash and the heater casing. Brian Buckland describes in his book how to cut new holes to convert early heater cases to the later design.

So I have a choice of having demister outlets adjacent to dash or adjacent to bulkhead.....which is best?

Nearest the bulkhead would be my suggestion - flaps nearest the dash. With only the heater installed in the car it does not appear to matter which way they go but once the dash, steering column, glove box, underdash trims etc are in place the little handle on the flap is slightly more accessible than it would be the other way round. Again that's how my S4 was put together originally.

[robertverhey]

Thanks for replies, very useful. On balance i've decided to go with a mixture, ie face vent outlets at front and demister vents towards back (bulkhead). I'll reevaluate when re-installing, to avoid/minimise any clearance or cramping issues

Another part refurbished and ready to go back in.....eventually!

[fatboyoz]

Robert,
My early S4 has the eyeball vent elbows on the front (bulkhead) side of the heater box. There are two identical holes on the dash' side that have rubber, blanking grommets installed. The elbows will squash a little if you have too thick insulation between the transmission tunnel and the heater box.
I have orientated the side plates so that the demister outlets are towards the dash. This places the leg vents further forward (toward the bulkhead) so that the air exiting is uninhibited by the under dash trims.

Thanks for replies, very useful. On balance i've decided to go with a mixture, ie face vent outlets at front and demister vents towards back (bulkhead). I'll reevaluate when re-installing, to avoid/minimise any clearance or cramping issues

Another part refurbished and ready to go back in.....eventually!

[robertverhey]

Hmm good point, air being restricted by under dash trims, will keep option open to reverse configuration if that looks like a problem when the dash goes back in. Looks like I might be going full circle!