Waterbath Vaporizers, Corrosion, and Antifreeze

Written by Rick Gladding

Time for a little refresher on Waterbath vaporizer antifreeze. Waterbath Vaporizers work in much the same way as a residential boiler. You take one medium (in this case Water / Antifreeze solution) heat it up and transfer the heat from the liquid LP changing it to a vapor. However, if the antifreeze is not maintained and tested, it wears out over time from the constant heat and cool cycles. I have seen antifreeze that ignored over time will turn black and muddy. This is not good for the unit and also an expensive proposition to change. Anyway, back to the basics.

All Waterbath Vaporizers regardless of who the manufacturer is share some common things. For one, they are an open system. Unlike a boiler, they do not need pressure in the Waterbath. So, don’t go looking for a pressure reducing valve to fill the unit. You will notice a tank mounted over top of the vaporizer with a sight glass so you can see the level. These units also have a circulating pump to keep the heat transfer fluid at an even temperature from top to bottom of the unit. This next item is very important. You should see a ground rod that is connected to the chassis of the vaporizer. Fail to provide this and you will be kissing the vaporizer goodbye sooner that the Bruins winning the Stanley Cup again. Since these units are connected to electricity, you must ensure they are grounded and protected with di-electric unions or flange isolation kits.

Now, let’s talk about Antifreeze. You CANNOT run to your local automotive supply house or box store for antifreeze for these units. I have heard of one Waterbath that failed in my neck of the woods due to this. When this unit was installed, it was initially filled with the correct Anti-freeze but over time as it evaporated they went to the box store and added RV anti-freeze… That was a $35,000 no no and the heat exchanger rotted out within 7 years. Thankfully, it was the end user doing this and not the gas company. Again it boils down to training and proper maintenance practices.

There is a multitude of anti-freeze products out in the market place for use. Most of these commercial products have corrosion inhibitors in them. However, if you plan on using a glycol / water mix, remember you must add your own corrosion inhibitor. Plan on leaving behind 5-10 gallons of whatever you fill the unit with for topping it off as needed. One further thing you must be cautious about – If you fill the unit in question, make sure the antifreeze you are putting in is compatible with the material the unit is constructed of. There is a new packaged boiler-vaporizer unit on the market that has an aluminum heat exchanger and you must use an anti-freeze that works with aluminum. Also make sure the water you are adding is Distilled or Deionized water. There are way too many additives in regular tap water.

You must test the antifreeze PH and corrosion inhibitor. One manufacturer recommends testing immediately after installation, then after 2 months or 200 hours (whichever comes first) then every 6 months or 500 hours after that. Just remember that at some point the antifreeze will have to be completely drained and replaced. A Waterbath vaporizer is happy with a PH between the 8-10 range. Make sure your test strips have a range at least 7-10. If your PH is above or below the 8-10 range you must make adjustments to the fluid. Depending on what brand of antifreeze you installed, there will be adjustments that you can make. Please consult with the manufacturer of your specific antifreeze to find out how to adjust it. If all else fails, there are companies out there that do nothing but deliver install, test and maintain antifreeze. I know of one located here in New England that specializes in this and I bet there are more companies out there.

Stay safe and practice good service techniques…

Rick Gladding

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