Owners in Humid climates, how do you keep you car from rusting?

I ask b/c I have a job opportunity in Houston and I'm considering taking it. Haven't work out all the details yet but I should know more by the end of next week.

I lived in Houston for 10-years (1980-1990) and now live in Kansas City (which I love by the way). I know the climate sucks for old cars down there and I'm wondering how much of a problem it is for the guys with older cars? I have a '77 GTB and we all know the older cars had not rust protection on them. My car has a few spots you can see in the engine bay, and one small bubble by the lower drivers side door (right behind the front wheel). I know here that I'm pretty much have no worries b/c I don't drive it in the rain, or on the roads after snow/salt. Only on nice days. The car was in NJ before I bought it (I'm the 2nd owner).

My dad had an Austin Healey 3000 when we lived there and I remember how much trouble he had dealing with rust.

I'm worried that as soon as summer hits, the humidity will show all kinds of fun rust spots up where I least expect them.

I told my wife last night I was going to have to sell it, and get a 84/85 QV GTB b/c they have rust protection on them! She didn't think that was too funny.

thanks

(I put this in the texas section, but realized Houston isn't the only city with a humid climate).

 

I've lived in Florida (pretty humid here) for the last 13 years and I have never seen humidity rust cars here. It is the salt near the ocean that is bad. The sun causes the next damage. Unless Houston has a different type of humidity I wouldn't be overly concerned about it based on my experience here.

 

for humid climates, you may also want to use soemthing for the interior especially if you keep the car parked in the garage for a while. it is called "damp-rid". comes in a plastic container and absorbs the moisture in the drivers compartment. you change the contents periodcally and see how much moisture it collects.

Hello Ken!!!!!!!!!!!

 

Its all a question of removing moisture from your storage area. You need to either condition the storage location or make provisions for dehumidification. You can either purely dehumidify via mechanical means, or use an air to air heat exchanger to recover the energy spent cooling or heating the air in the garage. Our firm has designed and implemented many systems like this for collectors garages. They're not that hard to do, they just have to be properly engineered.

Remember that energy (heat) and moisture will always move from an area of greater concentration to one of lower concentration in an effort to equalize. So in general in a hot, humid climate, heat and moisture will try to move from outdoors to the relatively cooler,drier indoors. Wherever the first point of condensation is is where that exterior moisture will accumulate indoors.

If you have a very effective thermal and vapor barrier in your exterior wall construction, you should be able to keep the moisture out. As far as ther humidity in the environment you will be driving in, the car itself should always be at a temperature equal to or higher than the outdoors, so moisture shouldn't condense on it.

 

Haha, I'm an HVAC engineer so I understand what you are talking about.

As far as Houston climate, their is a lot of salt air as the ocean is only about 90-miles away. However, why does everyone say CA is the best place to keep a car b/c the climate is so nice? Most everyone lives pretty close to the Pacific, but it's a lot drier there than on the gulf coast.

 

Well thanks for letting me run on at the mouth!

I would guess that the salt would be the biggest culprit as far as the potential impact from the driving environment. As for the storage area.... well you dont need my advice!

 

Sean, do you do residential design? I have been told that if I install a dehumidifier in front of the return air that this would result in a big drop in humdity, all other things being equal. Have you heard of this?

Dr "Humid" Tax

 

Dr. Tax,
While Im not Sean Ill throw you an answer.

You would theoretically be mixing two different air streams with different relative humidities, creating a mixed air condition with a lower end RH than that of the higher one statred with.

That being said, I would recommend identifying WHY you have excessive RH to begin with. Generally speaking, use of an independent dehu is necessary when an HVAC system is either poorly designed or is poorly operating. Supplementing HVAC systems with a dehu in say a basement area, typically happens when an HVAC system is unable to accomodate the conditions present in the problem area.

 

Well that is true, a dehumidifier would result in a drop in the humidity of the return air, but it won't change anything on the delivery side of the A/C unit (you're talking about your A/C for the house, right?).

The A/C coil for your house is basically a big dehumidification coil. It takes inlet air (on a house, this is mostly taken from the space you live in) and cools that air. By cooling the air, the coil itself removes the humidity from the air. This is why there is a pan (called a drip pan) and plastic tube off the side of said pan running to a drain. All that water is humidity being condensed by the A/C coil, and dripping off. I can go into the whole psychometrics of this if you really care, but I don't think you do.

If you're talking about a residential A/C-Heater unit, I don't really understand why you would do this. The coil itself already removes the moisture from the air. Now, if you A/C is too small for the house, then it won't be able to keep up, the air being supplied to your house (out of the register) will not be that cold, and will not be as dry as it should be. Your house will always feel warm, even if the temperature is 75° inside, b/c it will be too humid.

Rule of thumb in the HVAC industry is a supply air temperature of 55° and ~50% R.H (relative humidity). You're car will be about the same (which is why I always laugh when people post that their car A/C is 30° - first off, they probably don't have a thermometer that will measure that low that accurately, and second, their car A/C coil would freeze and they'd have NO cold air !)

Now if you're just talking about a fan unit that supplies air to a space then sure, a dehumidification coil will make the air dry. But, like I just said, a dehumidification coil is basically just a cooling coil. (note that a stand alone dehumidifier is different from something you would put in your A/C unit)

If you're talking a heater only, then I'd have to wonder where you live that it's so humid, and cold at the same time that you'd need to dehumidify the air, and heat it up too.


** - When I say A/C I'm talking about the part on the inside of your house, the outside thing is called a condensing unit.

EDIT - What Dopplymax just wrote is correct.

 

I leave my car out in the rain, so the fresh rainwater washes off the salt I got on the car, from going surfing at the beach.

If you leave the windows down, it washes the dust of the leather, as well.

Speedy "Hang Ten" 308
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"Relative Humidity" does in some circles refer to sisters.

 

Thanks to both you guys for the non-technical update. Here's the problem that all homebuilders in the Houston area are struggling with -- mold.

The typical summer day in Houston is 98 degrees and 98% RH and rain. Add to this 12 hours of strong daylight, and you get mold. We have mold everywhere, it's in the air, it's in the ground, it's here, there and everywhere.

When mold gets in the home, it starts attracting that other pest -- lawyers.

How does mold get into the home? The point of beginning is, of course, during construction. But when you add hard rains, floods, plumbing leaks, well you get the picture.

Plus, when you have a poorly insulated structure that has lots of single-pane windows and is pressurized with 68 degree air, it doesn't take too much imagination to visualize the result -- the cool dry air wants out and the hot wet air wants in.

Because the home-buying public will NOT pay the freight for a well insulated home, this means that we need to consider other relatively inexpensive fixes.

So if you HVAC guys are interested in making some real money to go Challenge Racing (note mandatory Ferrari content), all you need to do is come up with an affordable solution to this problem. You gin up the idea, and I'll show you (for a bite of the apple) how to make mucho bucks.

Dr "AC is God" Tax

 

Your point is too well know by me. See www.patuxentenviro.com, and you'll know what I'm talking about. One of my largest client groups is the Homebuilding industry.

That said, short of actually "fixing" the envelope problems, if you really want to just remove the moisture instead of keeping it out in the first place you have a few options.

In order for a DX (refrigerant system) to remove moisture, it has to run long enough to do so. This is due to latent heat (temperature you can feel plus moisture) removal taking a ton more energy than sensible heat (temperature you can feel) removal. So, in a house that isn't too hot, the system frequently stops running because the thermostat is staified long before the moisture has been removed. Several things can be done. You can install as system that has a dehumidification cycle (Carrier has one) that varies fan speed to force the system to have to run longer; you can install a re-heat system, you essentially cool the air more than you need to to remove the moisture and then you heat it back up to what you wanted in the first place, or for a while, you can potentially reduce a system capacity by changing the system charge to force it to have to run longer (worst idea, and will eventually break something).

 

I have a 2,000 sq ft garage in Sarasota Fl. on the west coast. I use an Ebac freestanding Neptune model dehumidifier - about $800. ( http://www.dehumidifier.ws/ebac.htm ). It is about the same size of a $200 Sear unit but removes much more water, faster, and uses less electricity. I ran a permanent hose through the side wall of the garage. It keeps the garage at 50 percent and it does not even run all the time, probably about 40 percent.

I hooked up it's 20 foot line-cord to a Honeywell 46 C or maybe E humidistat. It plugs in to an outlet and has a receptacle to plug the dehumidifier into.

It has been running for 2 years and even in cold humid temperatures where other dehumidifiers will not work at all.

You cannot see it but it is in the left hand corner in this picture, behind the Powermatic table saw.

aehaas

 

I try to keep the humidity in my garage around 30-40% in the summer and in the winter the humidity is around 15-25% in the winter. Will this amount of humidity have an adverse effect on the car. I guess my main question is what is the optimal level of humidity for a garage which have the least effect on the car in form of detoration.

 

Dr Tax, it sounds more like a construction issue than anything else. Is it mostly in new homes, or old homes too? As I said, I lived there for 10-years and we never had issue's with mold in our house (1980-1990). Of course, we weren't in a low area of town and when it rained, their was no water coming up to our door step like a lot of other homes. As Dopplemax pointed out, if you don't have an effective vapor barrier on the house, you'll have moisture problems no matter where you live, but especially in a climate like Houston.

A stand alone dehumidifier may help in your situation. Putting it in front of the A/C unit itself probably won't help as much as putting in in the house somewhere. A first floor area would be the most effective. Since you're house is already built (?) it may be hard to find a hiding place for it.

Are some area's in town worse than others or is it all over (I need to know this if I'm going to move there so I avoid the problem area's).

One other thing to check is your A/C coil inside the house. If it's got mold on it as well that will only make the problem worse. The mold is fed through the ducts in the house, and in effect feeds any spots of mold inside the duct, and inside the walls. If you do have mold in the unit, the most effective solution is to put a UV light inside the unit to kill the mold on the coil, and this will also kill mold down stream in the duct. The UV lights are about $400 + installation, and you'll have to buy a new light every 24-months for ~$100 because they degrade over time. As it degrades, it looses effectiveness and the mold can come back.

F550 - low humidity will not aversly effect your car. If the air has little or no moisture in it, their is nothing to condense on your car and no water means no rust. Also, as we pointed out above, it's the combination of salt air and moisture that causes more problems than moisture by itself. Just look at CA, everyone says that is the ideal climate for a car. 70°F and low humidity year round.

 

Sean, I was asking the question in a broader context. For reasons that I find hard to explain, I keep getting in and out of the home building bidness. Lately, I find myself getting more in.

Our problem in Houston is getting engineers to understand that what works in other parts of the country doesn't work here. Houston is in one of the most extreme humid climates in the country and also has one of the lowest building standards. Then when you add soccer moms getting hysterical about "killer mold," the situation is not good.

Until someone can come up with a cheap "clean room" building process, every home in Houston will have mold. There's nothing that can be done about that. The search is for tecnhologies that minimize the growth of mold so that it doesn't become a problem.

Dr "Moldy But Not Oldly" Tax

 

You mean you're supposed to put the roof on, BEFORE you hang the sheetrock??


Aye, carrumba! How would you say THAT in espaniol???


Speedy "Instant Construction"308

 

No, you're supposed to spray it with water before you hang it, you idiot!

Dr "I'm Outta Here" Tax

 

I'm very happy with the Therma-Stor air purifying dehumidfier that I installed in my garage workshop... see http://www.ultimategarage.com/UltGar2g.htm . There's also a Unico A/C system for the room but they are on separate circuits and can be run independently.

The shop is still not finished but the HVAC and lift are operational. SD
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Sean, the only caveat I would add to the UV concept is application. Its a sound science when sized properly and installed correctly. The only applicability though is to control growth on a coil that starts out clean, so on a new install its a good idea. It wont have any effect on microbial organisms in the airstream, there simply isn't enough contact time, but it can control growth on a surface such as the coil or condensate pan. The other limitation is that while changing an organism to a non-viable state, or for simplicity "killing" it, is useful for preventing disease such as in a hospital, in most cases people are concerned about allergenicity and toxicity, both of which are completely unchanged by killing the target organism. If it was allergenic or toxic when it was alive, it still will be when it is dead. This means that UV is a good supplement to mechanical air filtration, but cant be a replacement.

 

UV can also kill mold on a coil that is dirty/moldy. It will also kill mold in the supply duct b/c by killing the mold on the coil, the mold in the supply duct no longer has a "food" source (for lack of a better term). But you are correct that it will not replace mechanical filtration. Everyone wants to save $2.00 and get the cheap filter, when a better one will help them more, not to mention buy the minimum A/C their house needs and save $100 on a $2000 furnace/AC install and get the inferior unit. First cost is usually an issue on the industrial side as well (which is where I work and see it all the time - let's save $10,000 on a $1M construction job so we can replace that equipment for $50,000 in three years - not to mention the extra energy cost..UGG!).

Dr. Tax. I don't know that a single, cheap technology will solve the problem you describe. It sounds more like a construction issue than operating issue. You're trying to close the gate after the horse has already left the barn. I don't know what is different now than from 20-years ago though. As I said, when I lived in Houston my parents house did not have any mold problems that we ever discovered. Of course, we did not look for it, and none of us got sick all the time.

I've got a few questions and I'll try to PM you later tonight or tomorrow. I have to think about it a little bit first but I have a few ideas.

 

Take your time. I'm headed to the airport right now. Next week is fine.

Dale

 

Well, we've certainly examined all pertinent aspects of HVAC technology here...

But how about the car? I mean - when it's not at home? On the road?
Salt, slush, rain, water?

Has anyone ever seen those devices that are claimed to prevent rust via an electrical current running through the chassis? I remember some of the A&Ps at the hanger shop remarking how they weren't able to install one to try it "in sito," because it would gauss or otherwise interfere with the instruments.

Doesn't sound believable, or everyone would use them.

 

Don't drive it in the rain. And if you happen to get caught, be sure and wash and DRY it thoroughly (especially underneath) when you are done. I know some here have said they use their leaf blower in the engine compartment after a wash to make sure and get all the water off.