Demist / Internal windscreen fan

[smiles1]

Hi,

Does anybody know of a good (read powerful and useful) internal front windscreen fan/demister that I can wire in without the need for external air ducting or connections to coolant hoses.

I currently have a little 100w electric fan/heater but it wouldn't blow the skin off a rice pudding!

Thanks

[Steve_D]

How about this one from CBS
http://www.carbuildersolutions.com/uk/electric-dem...

Steve

[smiles1]

Thanks, I saw that one and was considering it.

I was ideally trying to find one that people had previously used and could recommend as being upto the job

[kdempsie]

Hi, I used one on my Sylva Mojo and kept the screen clear fine. I didn't have a hood though so not sure if it could have kept up in that circumstance, passed SVA OK too. Initially I bought two but under dash space was tight, two is generally the recommendation.

Keith.

[smiles1]

Thanks Keith

[gtmdriver]

If you don't have fresh air flowing through the car you will always get misting problems after a while as the condensation from your breath builds up in what is effectively a sealed system. For shorter trips though you could fit a small heater from a production car. I always found the Mini unit easy to fit.

[blitzracing]

The problem you have with the 12 volts one is the massive current needed to produce any meaningful heat output- even the Car builders one is only rated at 160 odd watts, thats going to draw 13 amps, so two is 26 amps or about half your alternator output before you even turn on the lights, plus you need make sure the wiring is heavy enough.

have a dig around here- might give you some ideas

http://www.t7design.co.uk/index.php?main_page=prod...

[Mr2Mike]

blitzracing said:

The problem you have with the 12 volts one is the massive current needed to produce any meaningful heat output- even the Car builders one is only rated at 160 odd watts, thats going to draw 13 amps, so two is 26 amps or about half your alternator output before you even turn on the lights, plus you need make sure the wiring is heavy enough.

The 12v electric heaters are all pretty pathetic, which is not surprising when you realise a normal car heater has around 4-5kW output compared to a 150-200 watts for the electric heaters. Well worth while getting one of the compact heater units sold by e.g. CBS, and plumbing it into the coolant lines.

[finishing touch]

If electricity is "pathetic" then only two other options remain.


1. Water. It still involves a fan blowing air through a heater matrix though.
It's the preferred choice of many manufactures, including myself. Can't all be wrong.


2. The other "free heat" from an engine is the exhaust.
Lots of small aeroplanes use this method, not only to heat the cabin but the air intakes to the carbs as well.
Ram air removes the need for a fan once you get going.

[530dTPhil]

What about a heated windscreen? These can be produced as one offs at a reasonable cost.

[Fury1630]

I have a heated screen in my Fury, even with the roof off the screen still mists in the morning espesially if climbing a hill (yes, surpised me too) but the heated screen deals with it quickly enough & adds no weight to the car.

[Mr2Mike]

finishing touch said:

If electricity is "pathetic" then only two other options remain.

I think you may have misread my comment, neither I nor anyone else has suggested that electricity is pathetic, but the 12v heaters for demisting purposes certainly are. The power you can draw continuously from a 12v car electrical system is just too low to be of use for an effective hot air blower.

Obviously the 5-10 amps it requires for a blower motor is not a problem, but to get something remotely approaching the efficacy of a proper interior heater would require 200+ Amps to be drawn whenever the heater is on (i.e. as much or more than a starter motor), clearly not practical.

An electrically heated screen is probably the best compromise, in terms of ease of fitting and weight/space requirements, though they aren't particularly cheap and the heating elements can weaken the windscreen (a friend has been through five heated screens in his rally car, the inevitable stone chips very quickly turn into cracks compared to the non-heated screens).

[finishing touch]

I apologise for my remark.

We all know what a water filled matrix looks like so if I may I'll show how hot air can be drawn off an exhaust.
In this example, an aircraft.

Paul G

[Fury1630]

Mr2Mike said:

An electrically heated screen ............. though they aren't particularly cheap and the heating elements can weaken the windscreen (a friend has been through five heated screens in his rally car, the inevitable stone chips very quickly turn into cracks compared to the non-heated screens).

That's not my experience in 20,000 miles in the Fury, but I guess quality varies between manufactuers?

[Mr2Mike]

Fury1630 said:

That's not my experience in 20,000 miles in the Fury, but I guess quality varies between manufactuers?

How many gravel special stages have you driven your Fury through?

[blitzracing]

Dont forget the good old VW beatle has separate heat exchanges off the exhaust you might be able to modify.

[Fury1630]

Mr2Mike said:

How many gravel special stages have you driven your Fury through?

Probably the same number as the OP is intending doing?

[Mr2Mike]

Fury1630 said:

Probably the same number as the OP is intending doing?

Great, shouldn't be much of a problem then. Doesn't stop it being true though.