DDK - Die Deutschen Klassiker

Hi,

I have seen somewhere ( but cannot remember where ), an electric heater unit that fits under the dash or in the trunk and acts as a heater and windscreen blower. I have found some options on the internet but they run off a hot water system.

Basically I want a glorified Hair-Dryer with associated ducting

Anyone have any options?


Cheers
Chris

Hi Chris,

This type of thing http://www.google.co.uk/url?sa=t&rct=j& ... FGzWTPKEdQ

Gwyn.

Hi Chris

Or a heated front screen, these are available.

Kind Regards

Is this any good Chris?
http://www.cbsonline.co.uk/product/Elec ... ater_DEMST

The heated front screen works really well, but you still need to blow air over it to get it to demist.

Gary71 wrote:The heated front screen works really well, but you still need to blow air over it to get it to demist.

Hi Gary,

I didnt on my Caterham or on any rear heated screen, so I would be interested to know why you do in our early cars.

Kind Regards

Not sure if there is any science, but if you want it to demist with any great sucess then air moving the damp away speeds the process up.

Gary71 wrote:Not sure if there is any science, but if you want it to demist with any great sucess then air moving the damp away speeds the process up.

That explains the caterham.

Mick Cliff wrote:Is this any good Chris?
http://www.cbsonline.co.uk/product/Elec ... ater_DEMST

Thanks Guys,

Yes it is something like that.....but I am sure I saw one that had 4 ducting pipes coming out of it. 2 pipes to use as a heater, and 2 pipes to use as a windscreen demister/blower.

I remember seeing it on the internet, but after days of searching I cannot find it or remember who sold it


Cheers
Chris

jury wrote: Basically I want a glorified Hair-Dryer .......

Worth bearing in mind that a typical hair dryer is rated at 1kw. As w= volts x amps, it takes a bucket of amps at 12v to run a heater like that. The electric fan demisters are pretty weak. A heated screen is far superior (if you haven't got heat exchangers).

As Bruce pointed out they take a lot of juice. Would recommend a Alternater upgrade to cope with the draw. Can't think that ive come across one that has 4 outlets whilst been surfing. Seen one with 2 outlets if that helps. Will look as to we're I've seen it.

This is one of the problems with Speedsters with a non standard exhaust to clear the windscreen and for those of us who dont have a posh windscreen (electric).

What about a petrol heater (webasto) etc, can vouch for these as l use one myself and it works well.

I'd stick with some heat exchangers ... or if you are wanting to use headers, I'm sure a man of your talents could cobble together some home brewed heater boxes on the headers

Chris
I used one of these ...


It does take the edge of the cold but that's about it . Obviously no way of attaching any ducting and a bit to big to mount in the footwell . Mine's between the seats wired straight to the battery . Paid about £50 from memory from a place that did caravan and towing supplies in Trafford Park .

Chris,

I spent a good six months on an electric heater project for a 911 without heat exchangers. I was aiming to launch this as a product. Here is the system:

The heater units (1 per side) fit in the kick panels and consist of ducting, a fan and a 420W PTC heater element. Fits behind the carpet and is unseen.



Installed:




A control board replaces the ashtray (but you could place this anywhere) :



Installed:




Here are my observations:

1) The cabin heaters on ebay (as per Russ' post) are a waste of time. They typically have 300W heater elements and have weak fans ( ~20 CFM ). I had the PTC heater elements custom made for my prototype, they are 420W. The fans are 106 CFM and are the most powerful on the market.

2) In use, each heater takes 30A to run, e.g 60A both on. I have an SC with the 75A alternator but this is still not man enough once you consider lights, wipers, rear screen demist etc. The early cars only have 55A alternators. Because of this, my controller monitors the 12V line - if it dips below a threshold, the controller starts a sequencing mode where each side gets pulsed on-off in turn to conserve power. This usually happens when engine idling, lights on etc. When you get the RPMs up again, both heaters resume normal operation.

3) So, does it work? Kinda. The bottom line is that if is below ~10 degrees outside, you really won't get the cabin up to temperature in a sensible amount of time, however, you will still benefit from screen demist. If you have really damp conditions, there is no hope really. If you have a car that lives in a garage and isn't used in the winter much then the system as it stands could be a goer.

4) If the incoming air can be pre-heated just a bit, then the system can provide the rest of the heat required. I did experiment with scavenging heat from the engine bay and also from the oil cooler with some reasonable results. I think the best solution would be a small exhaust clamp type heat exchanger as used on light aircraft ( google "aircraft heat muff"). This could provide enough pre-heat, with the electrics doing the rest.

So there you go. I probably have enough parts to build you a system to play with if you fancy. PM me.

Great car btw!

Looks like a neat solution Jonny, but is there something wrong with the maths?
Alternators are rated at Amps, so yours will be 75 Amp, enough to theoretically provide 900 Watts (12 x 75). Or am I missing something? Your heater elements are only using 60 Watts, same as one headlight bulb