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Improving the heater


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Laying in bed last night, i had an idea about improving my heater in my defender. One problem i've got is whenever i turn it on to demist the window, it does the opposite, and makes it much worse, i think this is due to water getting through the wing top grill and into the fan. So to solve this problem and try and impove the output, i thought about making an intake duct which points towards the turbo / exhaust so the fan pulls in warm dry air from under the bonnet.

Any comments / suggestions about this idea ?

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Drawing underbonnet air might end up with the cab being rather smelly with oily fumes from the engine.

Perhaps a good start would be to ensure the heater box isnt full of water and that the drain holes in the intake ducting are clear?

Steaming up windows when you turn on the blower could also indicate a leaking heater matrix, so its worth checking your not losing any coolant.

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One problem i've got is whenever i turn it on to demist the window, it does the opposite, and makes it much worse,

coat the insides of all the glass with cheap silicon based car polish - Mer wax works brilliantly.

Stops the windows misting up at all, means you dont even need to put the heater on "screen" and can leave it blowing on your legs. Also works great on yer spectacles so they dont steam up when you walk into the pub on a cold evening, on bathroom mirrors, insides of your house windows so they dont get condensation etc

:lol:

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sounds like a good idea to me. what about fabbing up a plate that bolts to the manifold with an outlet on it, then running some ducting to the standard heater inlet, that way you would get a better intake of warm air.

bit like the old heat shields they used to use on carburrettor cars to warm the carb up.

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have to say that whilst me heater struggles to fill a 110 with heat, one thing it is very good at, indeed better than many modern cars, is clearing the screen. in part it is probably due to the screen being quite wee, but it does seem to do that job very well. In any case, i think you should give your heater a thorough check over before making bigger modifications, might save you a bit of time/hassle.

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Steamed up screen when the heater is switched on is a tell-tale that the rubber drain/vent thingy in the bottom of the heater intake is blocked. Water that finds itself drawn into the heater intake is supposed to drain away though the vent. The vent fills with crud and traps the moisture. Reach under the heater to find it. Squeeze the rubber vent and you'll hear/see a trickle of water as it empties the heater intake. It's worth removing it altogether to give it a clean since if its trapping water it'll be packed full with crud. The rubber vent is just a push fit although due to its location it can be fiddly to fit.

I'm not convinced by heater intake cowls. Had one once that made not a jot of difference to heater efficiency.

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heard a few people say cowls make not much difference. i fitted one as i found that the heater was ok at low speeds, but at 60-70mph i was getting cold. i assumed this was because at high speeds the intake was in a bit of a dead zone so fitted a cowl to improve it.

After fitting i found i was no longer getting cold at speed as air seemed to be getting in better. i went to the effort of cutting out the grill of the old vent cover first before fitting the cowl on top, so maybe that's the difference. who knows...

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Steamed up screen when the heater is switched on is a tell-tale that the rubber drain/vent thingy in the bottom of the heater intake is blocked. Water that finds itself drawn into the heater intake is supposed to drain away though the vent. The vent fills with crud and traps the moisture. Reach under the heater to find it. Then throw it away, if you wade deep enough for water to get in the bottom of the duct, it won't be long before it coming in through the top and at least when it does come in at the top the hole from the missing rubber valve will let it drain away quickly

I'm not convinced by heater intake cowls. Had one once that made not a jot of difference to heater efficiency.

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Steamed up screen when the heater is switched on is a tell-tale that the rubber drain/vent thingy in the bottom of the heater intake is blocked. Water that finds itself drawn into the heater intake is supposed to drain away though the vent. The vent fills with crud and traps the moisture. Reach under the heater to find it. Squeeze the rubber vent and you'll hear/see a trickle of water as it empties the heater intake. It's worth removing it altogether to give it a clean since if its trapping water it'll be packed full with crud. The rubber vent is just a push fit although due to its location it can be fiddly to fit.

Agreed except the best solution is to remove it and pelt it across the garage, never blocks up again after that, I have 2 or 3 surplus fanny valves which should be lodged in various corners of my garage :)

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That is still widely used on small airplanes as a heating device, all Cessna`s, Piper´s etc are using that method. Collector around the exhaust manifold connected to a blower or using pitot pressure. Very effective, but as mentioned above could be harmful if not fatal when cracked. That´s why some airplanes have carbon monoxide detectors/indicators. Leaks are not very common though, and possible cracks are investigated in every maintenance.

So don´t let them crush you down totally with your idea. :P But also my opinion is to get rid of the water inside the heater box and those possible leaks inside your car. Once you get rid of the water ingress and dampness in upholstery, your problem will disappear.

You could still fit an airplane type auxiliary heater... it´s fast and effective and surely no-one else has it in Defender. Vw:s do have them, but the blower is as effective as the final sigh from a dying man... :D

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I'm liking this idea, it makes sense, suck in warmer air rather than cold air, at the very least the heater won't have to work as hard. and i'm not worried about any oily smells, defenders are supposed to smell like oil, grease and deisel (IMHO!)

i might give it a try, i've just been making a blanking plate and wingtop vent out of chequerplate for our 110 (they look great but it was a right pain drilling the holes! -i basically copied the Rebel stainless ones.) so while i'm fitting them tomorrow i might have a fiddle with some ducting and see if it makes a difference....

i'll let you know how it goes ;)

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Didn't 2cv's have an exhaust powered heater. To avoid the fume issue, could you not just make a simple heat exchanger on a straight section of exhaust and duct the air through this.

Yes, 2cv, VW beetle, bus, and other air cooled engines have heat exchangers on their exhaust manifolds/downpipes.

Typically the beetle type have a mild steel pipe carrying the exhaust gasses, around which an aluminium finned section has been cast. This whole casting is enclosed in a sheet steel outer shell with a pipe/hose stub welded at either end. Air is blown in one end and warm air comes out the other. Heater control is by means of a cable operated flap.

Regards,

Diff

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