Hi

I understand that if I have a full windscreen I will need wipers and a screen washer for IVA, but am I correct in my understating that no screen de-misting function is required for the IVA?

I know Caterham do heated screens that would demist and many 7 type cars have heaters for the cockpit only but not the screen (a small water radiator with electric air fan in a metal box).

Anyone fitted a heater - and what used - Mini, Westfield, Caterham please? Guess no one has squeezed in Mini heater vents and slots into a scuttle (I remember how feeble they were in a Mini!)

Cheers
Mike

[Edited on 25/1/25 by Mike Wood]

I have a little one of these in the Fury https://www.t7design.co.uk/heating/water-heaters/ducted-heaters.html?gad_source=1&gclid=CjwKCAiAtNK8BhBBEiwA8wVt9xd0kaSb4fw8EhpIjFmM5dylkdPDvoEdIF wvVbPFC2rgF-UKMkC11RoCsqAQAvD_BwE

I've also go a Ricky Evans motorsport heated screen which is not wired in. Best not mention wiring to me

From the IVA:

34 Defrost / Demist Application: All Vehicles fitted with a Windscreen (See section 32)

Method of Inspection Required Standard

Ensure that the vehicle is fitted with a system/systems capable of defrosting and demisting the windscreen to allow the driver an adequate view of the road in front and forward of the nearside and offside of the vehicle

Note: The fitting of a device not permanently incorporated into the vehicle structure i.e., adhered to the windscreen or body surface shall not be considered as a “system fitted to the vehicle.”

1. The vehicle must be fitted with a system capable of defrosting / demisting the windscreen.

2. A system using warm air to clear the screen must employ fan assistance and ducting to direct the air onto the screen, to ensure effective operation under cold weather conditions.

3. An electrically heated screen must provide adequate heat and distribution to ensure effective operation.

There is a reason why the Caterham uses an internal electric heated glass for their windshields Vs hot air for defrosting. The low-pressure area behind the wind shield is so great, that the hot defrosting air only reaches about a 1/3 of the way up the glass, unless you have a fully enclosed cabin. A possible option to pass inspection requirements is to fabricate an under-dash defroster system incorporating an RV 12V hair dryer. You can also find electric car fan heaters on E-bay that draw about 100W-12V. All these options will require a couple flexible hoses that connects to scuttle defroster vents. These unites would still need a remote power switch installed, or a cigarette lighter plug since the heater would be buried under the dash or the center console area. Do not plan on these de-misers lasting very long; they are typically not very durable and probably not able to last running for several continuous hours. But they should get you through vehicle inspection.

Perhaps go for a fly screen for IVA, then consider a full screen afterwards? I'm putting my car through with no screen at all, but I know I'm going to regret that decision the first time I go above 25mph. If I did go for a screen I would choose a heated version rather than a demister.

Thanks everyone for such helpful and informative answers.

Apologies I should have RTFM first before asking this question so asking how people have met the IVA demisting requirement which folk patiently and politely answered including posting the relevant extract from the IVA Manual.

Best wishes
Mike

I made a hot air demister for my car using a small heater matrix, which I think it came from a Mini and a computer cooling fan, with 2 flexible ducts
sending warm air onto the windscreen.
It was not that good at demisting the screen but it satisfied the inspector.

Mal

Some years back there was someone on here who had a conventional heater matrix behind the dash as mine was. A hose blew off dumping scalding water in his lap, I believe he was hospitalised. I rapidly removed mine. I recommend you don't go down that route.

quote:

---

Originally posted by PAULD
Some years back there was someone on here who had a conventional heater matrix behind the dash as mine was. A hose blew off dumping scalding water in his lap, I believe he was hospitalised. I rapidly removed mine. I recommend you don't go down that route.

---

I previously shared my solution as did a few others on this thread: Heater

You'll note that my heater matrix is on the engine-side of the bulkhead - for safety.

[Edited on 28/1/25 by JAG]

I must admit that hoses popping off smacks of incorrect installation, there's nothing inherently wrong with it.

There are loads of cars (Mini’s Land Rovers) with the heater matrix and pipe work in the cabin, tractors have it all above the drivers head! Provided the metal or plastic pipes are beaded and suitable hose clamps are used there is no problem. Google “Kit Car Heater” look on EBay and try Car Builder Solutions and T7 design both of which sell heaters, ducting and vents. If you are still concerned then a shield could be added to direct any leaking coolant downward rather than over someone.