Anti Rust Products

[Myrtles Man]

The type of dehumidifier that I use is a consendate dehumidifier that works by the refrigeration process and delivers a stream of dried air into the garage. I think that the ones you are using are OK for small enclosed spaces (like inside the car itself) but probably not much use as far as drying out a room is concerned. Mine pulls out up to 2 litres a day from the garage!

[Donald Ross]

Yes you are right about the dehumidifiers.

I have a very old big refrigeration one but it costs a fortune to run. I will look for a new more economical one.

Can you recommend any particular ones?

Thanks
Donald

[Myrtles Man]

The one I use is an Ebac model that I bought in used condition from eBay. It must have collected the equivalent of the North Sea in the ten years or so that it's been in my garage!

[philthehill]

Unless you have a sealed garage damp air from outside the garage will infiltrate the building and the dehumidifier will continue to extract dampness from the incoming air. It is a cycle you will never win.
The most effective way of keeping damp at bay is to have a good flow of air through the garage.

[Bumpy]

"it came freshly painted with underseal but I am not a big fan of it as it tends to flake and rusts under it."

The term underseal tends to cover a wide range of products. I prefer to categorise them as skin forming and non skin forming.

Any skin forming product, when damaged, will allow water under its surface and from there the water will be trapped and have difficulty in evaporating. Hence it will continue to cause damage until the skin itself flakes from the surface it is trying to protect. I suspect this is the sort of product you had on your car.

Non skin forming products such as engine oil, waxoyl, lanolin etc will self heal , which is why I prefer them. They are also very effective at clinging to surfaces and being hydrophobic (water hating) will actually repel water. Think how WD40 is used to chase water off electrical ignition parts.

Like most, my engine, over its history, has delivered quite a lot of its engine oil onto the surrounding underside. There is no rust there.

Equally when setting out to unscrew the outer sill trims to replace them with pretty stainless ones I had to use a screw driver to dig out years of accumulated, dried, packed mud from the contours of the sills and in particular around the jacking points. As I got down towards the metal itself the mud became darker indicating it was sitting against an oily, waxy product put on many years ago. There was very little sign of damage to the bodywork itself.

Engine oil is a great product to cover surfaces with but unlike some of the more modern waxes can soften and age rubber bushes.

As I read through my stuff it seems a little condescending in places, sorry if it comes over as such, I am just trying to capture my own thoughts on paper.

[Bumpy]

Relative Humidity the science

At a given temperature air is capable of holding airborne water vapour. If the air is perfectly dry then this is defined as having 0%RH (zero % relative humidity) and if the air is saturated with water vapour it is on the point of condensation and is at the opposite end of the scale being 100%RH. For every temperature the scale remains 0 to 100%, but the water loading of the air within that scale is different. For instance cold air is capable of holding less water vapour than hot air. Equally if hot air containing say 50% RH is cooled then as the temperature reduces so the the %RH increases until condensation occurs Condensation around windows in the house is the obvious example.

In the context of condensation within a garage we need to avoid the metal bodywork being at a temperature where the air in contact with it cools until it reaches 100%RH and condensation occurs. I will try and debate ways to avoid this next.

[Myrtles Man]

"Unless you have a sealed garage damp air from outside the garage will infiltrate the building and the dehumidifier will continue to extract dampness from the incoming air. It is a cycle you will never win."

Certainly can't argue with that statement but all I can say is that it works for me - no rusting at all, even on brake discs on vehicles that aren't used for months on end plus, as I mentioned above, it provides a very useful supply of 'distilled'* or 'de-ionised'* water which is especially useful in a very hard water area such as the one in which I live.

* Those of a more scientific persuasion than me will doubtless tell me that the water I collect is neither of those things but, whatever, it's jolly useful anyway.

[Bumpy]

Possible ways to avoid condensation on our Moggys in the garage

Some of these have been captured by other posters in this thread.

Lots of fresh air
If all surfaces are at the same temperature, and all surrounding air is at the same %RH, its scientifically unlikely that condensation will occur, so as suggested earlier by another poster, allowing ventilation in your garage is very good. This ventilation will also help to sweep away water vapour from leaks or 'damp' floors and walls as the air inside the garage will attempt to equilibrate with the air outside both in terms of temperature and %RH

Heating
Heating is a good thing as air of a given %RH will move to a lower %RH as it warms and away from the condensation point. But heating an entire garage can prove expensive. Better, if you can just warm the car itself so covering it with (porous) blankets and placing small heaters underneath is good. Doing it this way, you can still ventilate the garage. Don't whatever you do use paraffin heaters as these give off massive amounts of water as the fuel burns.

Dehumidifiers
The electric jobs can be very effective removing about 2 pints of water a day, but if you have windows open and other good ventilation you are trying to dry the World! This will cost you a lot of money on your electric bill with relatively little benefit to the car. So with a humidifier, close up the garage as best you can, and better still is to create a cocoon say in polythene sheeting around the car into which you pump the dry air. Remember that breathing puts a fair bit of moisture into the air. If I went down this route, for economy I would buy a dehumidifier with hygrostat so it turns off when the air has been reduced to the required %RH. I think these devices can be retrofitted by plugging them into the power point. The trays of chemical dehumidifiers have a role to play, buy they are not very powerful and are best used say inside the closed up Moggy to keep it fresh and dry.

Remind yourself that if the car body is colder than the surrounding air then that's where condensation will occur if it does.

[Bumpy]

duplicate post - cant delete

[Donald Ross]

I have been looking into dehumidifiers.

I looks like the desiccant dehumidifiers are the best option as i am in scotland and the temperature is often cold.

Here is a example:
https://www.amazon.co.uk/EcoAir-DD1-CLA ... r=1-5&th=1

From what i gather they dont just dry the air but also provide a amount of heat due to the desiccant process which may benefit also?

My garage has a fair air flow so not sure how effective it would be but as it also heats may be worth a try????????

[Donald Ross]

Hello again

I have decided to get the dehumidifier to replace the 30 year old compressor type on i currently have.

I discovered today the car was damp underneath in the areas the heaters dont cover. The front and rear where the heaters are were dry but the centre of the car was wet. I then put on my big old dehumidifier and moved one of the heaters and problem solved, Dried in about 2 hours.

I am hoping that the new dehumidifier running on a programmed setting will keep the condensation at bay for the short term until the better weather comes about late march at which time i have decided i am going to insulate the concrete garage floor with a 2nd damp proof membrane, 25mm Insulation board with foil on both sides then a 18mm Hardboard on top. That should solve the long term issue as i find most of the concrete floor to be rather damp which i think is causing most of the problems under the car.

Wil update you on how i get on.

Thanks again
Donald

[Bumpy]

Sounds like you've got some pretty challenging conditions - are you in Scotland?

I think you are going in the right direction with the dehumidifier and flooring. For the ultimate you could try building a little retractable tent over the Moggy using something like sturdy polythene sheeting from Wickes. It doesn't have to be very sophisticated, just functional. You could then focus the dehumidifier and the associated heat output to lower the humidity and raise the temperature in that smaller volume. Cheaper to achieve in running costs and the car would be snug as a bug in a rug.

Good luck

[Bumpy]

Out of interest we've had a fair bit of rain overnight in Herts.

Outside its about 4 degC and 90%RH. This type of humidity is perfectly normal in damp winter conditions

In the garage its also 4degC but 98%RH, which is not so good. Thankfully there is no condensation on the car. But, I have taken my own advice and opened the windows and doors until dusk to equilibrate the humidity with outside.

If I can find my second hygrostat I can keep an eye on internal and external %RH simultaneously and ventilate the garage when required. At least doing it this way is free and something to do during lockdown

I feel an invention coming on. An automatic window opener that operates when inside humidity is greater than outside, or a big extractor fan.

[ManyMinors]

Goodness! How complicated it sounds having a garage
I'm glad that my Minor lives outside all the time and is free of all this worry

[Donald Ross]

Yes im is scotland.

I did a fair bit of anti rust work on the car today, it is now fully dried out also.

I have managed to get the humidity down from about 96% 3 days ago to 79% today which is a big improvement in as much as the floor and car are now dry ( i have a old weather station which i use in the garage for humidity and temperature readings).

The dehumidifier is due to arrive next monday so until then i will leave the heaters under the car and try to manage with my old dehumidifier although as it is about 1 degrees it does not work very well.

Although condensation is something to overcome in the garage, which im sure after the new dehumidifier and floor in a couple of months will be sorted, i would fear that in my climate if my car was left outside for 6 months i would be looking at a pile of rust which i would be sweeping up rather that a car in one piece. Obviously if you are in the south of England the climate is much warmer and would not affect in this way.

Bumpy you might be onto something with the automatic window opener. Did you manage to reduce your 98% RH a bit?

I am hoping that once i have the new dehumidifier i will be nearer the 70% mark almost all the time and once the floor is done i aim for something in the region of 55-65%RH. We will see.

Here is a few photos of the underside of the car. Nice and dry now!

[kevin s]

I used bonda primer then stone chip when I restored my tr7V8 back in 1995, 100,000 miles of all year round use later only a few areas have gone mostly seams where the moisture has got between panels. I'm not sure if the bonda primer you buy now is the same stuff though. Recently I have been using epoxy primer which seems to adhere well and is waterproof, for a rust converter I have been using bilt hamber hydrate 80 which I am not entirely sure about, seems to bond ok but does very little in the way of conversion, I have heard very good things about fertan so may try that next.

Until recently I have used waxoyl mixed 75-25 with new 20/50 engine oil sprayed on, this covers well and penetrates extremely well but still sets so doesen't drip like neat oil. On the minor my son splashed out on bilt hamber dynax ub which seems to go on very well, he also bought some 4mm Correx which he used to make front wheel arch liners which also seem to be working well to keep the winter weather out of the all the rust traps.

Kevin

[Bumpy]

Did you manage to reduce your 98% RH a bit?

I am hoping that once i have the new dehumidifier i will be nearer the 70% mark almost all the time and once the floor is done i aim for something in the region of 55-65%RH. We will see.

My internal humidity tracks fairly close to the external humidity but with a few hours delay - I guess with no external influences like heating or dehumidifiers and with a well ventilated roof then this is what should be expected. Even 98%RH is OK. Providing that the temperature of the car (metal) is never lower than the ambient and that there are no local areas of moisture such as the floor then there should be no condensation, but its sailing close to the wind.

The Carcoon, which is well regarded, works on this principal by introducing more sophisticated means to ensure the %RH and temperature around the car is homogenous rather than being controlled. Its worth noting that there is no drying and insignificant heating of the air being pushed into the polythene tent but it relies entirely on having no cold spots or local areas of higher humidity to avoid condensation. Its a sound principal and most customers are happy. It also has very low running costs - just a couple of low energy fans. Don't be over impressed by the inbuilt carbon filters. They do not remove water but simply keep the air fresh by removing smells. They are also consumable and present additional running costs.

Donald. I like the desiccant dehumidifier you recommended. Its a new technology to me but looks a sound principal which gets around the drop off of efficiency of condenser dehumidifiers at the low temps we have in our garages. It also gives off beneficial heat as a by product. Having the ability to set the required humidity at which it goes into standby is great and should reduce running costs. This effect could be enhanced still further by creating you own cocoon or microenvironment around the car with polythene sheeting.

Keep us in touch with your progress

[Donald Ross]

Hi all

I now have my dehumidifier. I am very pleased with the results so far. I have stopped using the heaters for now in favour of this dehumidifier.

I did a trial 2 days ago. The temperature in the garage started off at 1 degrees C and 97 percent humidity.

After the dehumidifier ran on low power for 4 hours the humidity had reduced to 84 percent and the floor was fully dried out. In this time i collected believe it or not about 1 ltr of water to my amazement.

As we have said earlier a by product of the desiccent dehumidifier is heat, so not only did my humidity reduce to 84% in 4 hours, the temperature in the garage increased from 1 to 6.5 degrees C.

I am running it depending on the weather just now and will monitor going forward to see the most efficient run times for it.

I am currently battling rear brake problems ( discovered all the threads on the brake pipes were wrong, UNF like the front rather than the correct BSF thread across the axle.) So i will have to make up new brake pipes with a UNF fitting for the 3 way junction and BSF on the other end for my new brake Unions. Also had a bleed nipple snap off, 1 thing after another at the moment. Will get there in the end.

Regards
Donald

[Bumpy]

Hi Donald
Did you buy the EcoAir DD1 Classic MK5 Blue. Its a bit unclear if you can set your own humidity at which it goes to sleep. Can you advise.

[Donald Ross]

Hi Bumpy

Yes i did purchase the EcoAir DD1 Classic MK5 Blue, it is first class.

You get a choice of 3 humidity settings as follows:

Eco: 50-60% RH
High:40-45% RH
Auto:50-60 RH which automatically reduces and increased fan speed to save power.

I run mine on eco all the time and on that setting it only uses 300Watts of energy, confirmed by a plug in metre i have so is economical.

I am very impressed with it and the difference it has made to the garage is amazing.

Here is a link to the user manual which you may find interesting:

https://cdn.shopify.com/s/files/1/0081/ ... l.pdf?7088

Regards
Donald