Toe Warmer

Submitted: Friday, Nov 28, 2003 at 06:20
ThreadID: 120263 Views:3029 Replies:3 FollowUps:0
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Webasto visit. The heater, for those that don't know, is a diesel powered unit that in cross section looks like a jet turbine. Its a heat exchanger that has a small diesel 'fire' in its belly, surrounded by a metal tube (imagine an old oil lamp glass on its side). Around this is a heat exchanger. Combustion air is sucked in from outside by a fan, blown through the fire tube which then exhausts outside through a small tube. Meanwhile, another fan on the same shaft sucks air into the unit from where ever it is located and blows it out the other end after it has passed through the heat exchanger. The hot air is usually sent through a duct to where it is needed, all controlled by a simple rotary knob which is on/off and thermostat. With me so far? Right, with all that as preamble, lets get to it. Venting Currently our heater is located under bunk at rear of van on the inside of the sloping surface formed by the departure angle cut-away. A register is cut in the flat vertical surface of the bunk to blow the heated air into the cabin area with another in the ensuite. Both have ducting running back to the heater hot air outlet. No probs. Howerver, inlet air is being drawn from inside the under bunk locker. Two problems. One being that it is an enclosed space, therefore resistance as air has to get into whatever space is in there (after loading up the locker) through whatever cracks and mattress material may be between the unit and the main cabin. Secondly, the inlet faces toward the centre of the locker space giving rise to risk of blockage if anything falls across it. Inefficient at best, going into fault mode at worst. Solution? Cut new vent hole near outlet, with ducting back to air inlet. Much better. Thermostat The flat of the central rotating section should be flush with the surround. If not, pull off and remove nut. Underneath will probably be a spring washer. Remove it. Take surround off, then control mechanism out of wall and place spring washer on shaft of contol mechanism. Replace. Replace surround. Replace nut. Replace knob. Hey, presto. Important because if knob not flush, end stop-pins not fully engaged & could allow over-rotation & possible damage to unit. Exhaust Approx 20mm diameter steel exhaust pipe exits under departure cut-away. Little noisey. Fit muffler, followed by another lenght of exhaust pipe say 100mm long, with a 90 degree bend, AIMED AT THE GROUND. This improves silencing appreciably. Combustion Air Intake Round, black can-shaped object with slots top and bottom at rear near exhaust. Could fill with bull-dust. Do not wash out (water could enter air intake line - not good). Suggest use compressor air to blow dust out if necessary. Alternately, good place to keep spare stubby holder. Just remember to take it off before use (of the heater, that is). Sorry about the monologue. Hope its useful to someone Griff
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Reply By: Noosa Fox - Friday, Nov 28, 2003 at 06:22

Friday, Nov 28, 2003 at 06:22
Griff, Bit surprised that they didn't put an air intake vent into cupboard that the heater was fitted in. In our van they checked that there was an inlet vent, and as we have it under the seat where we previously had a battery there was already a vent in it. When you mentioned the bull dust it made me think of something else. It is unlikely that we will take the van through the depth of water that they are designed for, but the heaters combustion air intake and exhaust could have a problem in deep water. We have the exhaust fitted but I think it really needs to be quieter not to upset nearby campers. I was wondering about adding a lawn mower type muffler after the webasto one. Brian
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Reply By: Deleted User - Friday, Nov 28, 2003 at 06:23

Friday, Nov 28, 2003 at 06:23
Discussed the additional muffler idea, but it was felt there may be a back-pressure issue. Worth a try though if you don't have to spend too much on a possible flop. Inlet is very high up under tail. unlikely to be a problem, but if doing a deep water maybe sealing inlet & outlet not a bad idea. Griff
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Reply By: Turist - Friday, Nov 28, 2003 at 06:24

Friday, Nov 28, 2003 at 06:24
Mate if the water is that deep you will need a propellor on the back of the BT.

An inlet air filter is available for Webasto, do you have one fitted?

I will be testing a second muffler for the Webasto in about a weeks time.
I will post the results when available.
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