Eberspacher D4 warm air duct size

[JimC]

Should it be 75 mm or 90 mm diameter?

 

[Talulah]

The unit is often supplied with 76mm ducting but 90mm is better for longer runs.

 

[pcatterall]

Either!! It depends on the length of run/ number of bends etc involved. Dont have any figures and can't see any in the bible.

 

[JimC]

Thanks both. My D4, which I haven't fitted yet, has 75 mm orifices in both ends. I believe you can also buy 90 mm end hoods at a price. My primary duct run from the heater to the main outlet in the saloon will be about 7 feet with 4 bends in it, each between 45 and 90 degrees. Would there be any benefit in going to 90 mm and, if so, would this need a new end hood on both ends of the unit or just the output end, or is there a step-up adaptor?
Thanks

 

[fireball]

Any reason why you shouldn't use 102mm stuff?

http://www.screwfix.com/search.do;j...tton.x=0&searchbutton.y=0&searchbutton=submit

 

[JimC]

Only that it wouldn't fit the Eberspacher heater outlets or their various Y and T branch fittings and outlet grills etc.

 

[fireball]

We think it's flexible enough to collapse down under a jubilee clip ...

and it was a question ..

 

[V1701]

I don't know how using different size pipes would affect heat loss (which I read in another thread is greatest at bends and joints), with larger diameter possibly more in general due to greater surface area but less at bends and joints than smaller?

I have found that lagging the pipework definitely helps. Cheap as well, did mine with the foil bubble wrap stuff from B&Q and it is surviving the temperature. A foot or so at the very hot unit end I did with strips of an old fire blanket...

 

[Talulah]

A 90mm hood on EBay is £15.
I've just replaced most of the Eberspacher ducting with Silicone heating hose off eBay.
I would not now go back to using Eberspacher ducting.

 

[JimC]

I've just replaced most of the Eberspacher ducting with Silicone heating hose off eBay.
I would not now go back to using Eberspacher ducting.

Would you mind telling me where you get this from?

 

[Talulah]

On ebay the seller is 'AutoPerformanceOnline'
0844 800 5199
web site: http://www.apmotorstore.co.uk/air-ductings/blue-silicone-ducting.html

I have ordered two separate lots from them. One direct, one via eBay. Both were delivered quickly.

 

[JimC]

Thanks for that.

 

[LeonF]

Just found this post after a search.... is it OK to clip this stuff straight onto the heater unit ?

 

[pvb]

Should it be 75 mm or 90 mm diameter?

Check out the air duct calculations in the Marine Installation Guide - it shows you how to work out the airflow resistance of all the bits and pieces. It's almost certain you'll need to use 90mm ducting.

 

[pvb]

On ebay the seller is 'AutoPerformanceOnline'
0844 800 5199
web site: http://www.apmotorstore.co.uk/air-ductings/blue-silicone-ducting.html

I have ordered two separate lots from them. One direct, one via eBay. Both were delivered quickly.

£30 a metre?

 

[LeonF]

£30 a metre?

Must say I shared your view... and do I really need a temp range upto 325C ?

 

[pvb]

Must say I shared your view... and do I really need a temp range upto 325C ?

Of course not! Buy regular hose at more sensible prices.

 

[Ramage]

Only that it wouldn't fit the Eberspacher heater outlets or their various Y and T branch fittings and outlet grills etc.

Eberspacher do 100mm ducting for the D5 so it should be possible.....

 

[JimC]

Of course not! Buy regular hose at more sensible prices.

This looks OK, similar prices to Eberspacher and apparently non-crushable http://cgi.ebay.co.uk/76mm-3-1m-Hea...arts_Vehicles_CarParts_SM&hash=item2eb18d6e1d

 

[pvb]

This looks OK, similar prices to Eberspacher and apparently non-crushable http://cgi.ebay.co.uk/76mm-3-1m-Hea...arts_Vehicles_CarParts_SM&hash=item2eb18d6e1d

I don't think it's big enough. As I suggested earlier, check the air duct calculation. I think you'll need 90mm ducting. If you use smaller ducting, your heater performance will be compromised.