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Creating negative pressure in flue?

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Peter Bell21/09/2020 13:36:22
320 forum posts
146 photos

I have a vehicle type Webasto diesel heater which really does not like operating on a 3" dia vertical flue due to back pressure. I had thought of making a steam raising type blower with a variable speed 12v motor to put on top of the flue as an experiment. to create a slight negative pressure but have no experiance of these.

However on the steam raising designs looked at all the flu gas passes through the fan, is this decremental on the fan? Was going to put the motor on top

Are there are any alternative designs around using an ejector or similar which means the fan is on the clean cool bit just supplying air?

Can anyone offer any advice before I start? Thanks


Edited By Peter Bell on 21/09/2020 13:37:46

Edited By Peter Bell on 21/09/2020 13:38:37

Dave Halford21/09/2020 15:48:22
909 forum posts
9 photos

Have you considered the carbon monoxide might get you if you do it wrong.

Robert Atkinson 221/09/2020 17:12:37
764 forum posts
17 photos

I concur with Dave.

Put the heater outside and run the hot water inside. If it's an air heater stll put it outside but get a carbon monoxide alarm as well. A relative of mine died from CO due to a modification to a heater. Not the way I wanted to inherit his watch making tools.

Robert G8RPI.

Clive Brown 121/09/2020 18:11:30
498 forum posts
18 photos
Posted by Peter Bell on 21/09/2020 13:36:22:

I have a vehicle type Webasto diesel heater which really does not like operating on a 3" dia vertical flue due to back pressure..


Are you sure that you've diagnosed the problem correctly? Don't Webastos on vehicles and boats normally operate with fairly lengthy exhausts much less than 3" dia?

Peter Bell21/09/2020 18:18:29
320 forum posts
146 photos

Thanks everyone for your help.  Perhaps I should have said it was on a test rig outside but I didnt think I needed to to ask about a fan!   Peter


Edited By Peter Bell on 21/09/2020 18:35:22

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