And the stuff you want is "propylene glycol". It has basically the same chemistry as ethylene glycol, and performs the same. However it is not hazmat, does not require recapture and hazmat disposal. That's a vast understatement; the fact is, propylene glycol is actually food and is found high on the ingredient list of many food products.

There is no reason to use ethylene glycol in any "new design" application. There's not reason to use it anywhere else either, except that some people are paranoid about using "exactly what the manufacturer recommends." But here's the thing. What the manufacturer is concerned about is actually the additives which are added to antifreeze, notably anti-corrosion chemicals. Propylene glycol antifreeze comes with them too. Yes, they do fatigue in about a year, and they must be replenished. They make additives for that purpose. Naturally the antifreeze maker says "replace antifreeze annually", but they don't pay your hazmat charges, do they? We're back to "do you really want to buy a chemical you must dispose of as hazmat, when you can buy a harmless one?"

Bah... I'm talking to a wall again...

The accepted figure for an audience seated in an auditorium is 65 watts given off by each person. A passenger count will tell you how much body heat is in the car.

In a museum operation in a mild climate we use a 5 KW portable electric heater to take the chill off the air and warm the inside of a car without working heaters. Usually one hour or two will do the job. If the car can be parked in the sun, so much the better. Then the heater is removed just before passengers board. Body heat keeps the car comfortable.

So depending on your ambient temperature, car insulation, and air leaks, you may not need any additional heat while passengers are aboard.

fk

This leads one to the conclusion that if you're hauling a group of politicians, you may actually have to use the air conditioner.............:)

No, Robert, you aren't talking to the wall. Another advantage to propylene glycol in any application and especially your cars/trucks is that if you have a spill or leak, the local loose animals can drink it without harm like ethylene glycol.

I am in refrigeration and have to calculate chillers for use in food and non-food applications hence my experince with the glycols. Imagine my surprise when I sold a job to a wholesaler who sold it to a contractor for a choclate factory using calcium chloride! Forunately, the factory was sold and relocated a year later without the equipment. Phew!

Later!
Mr. Ed

Don't laugh. Like I said, I was told BART trains only use the heater on the first hour of pulling out; once they get a trainload of people (68 seated, 200 crush per car), the A/C has to run all-weather to get rid of what, 13kw of passenger heat? Since cold weather often means rain, the dehumidification is definitely a good thing.

And Muni finally figured that out. They ordered the new Breda cars with -- gasp! -- air conditioning. Mark Twain is rolling over in his grave; none of the J-K-L-M-N lines go anywhere you'd need A/C more than 3 days a year. (the new T-Third line goes into the warmer parts of the city.) The first thing you noticed on the first rainy day -- no more foggy windows.