solar closed loop

Man with a question

Dowfrost is readily available and is rated "food grade" by the FDA. Dowfrost HD has much better freeze and hi-temp protection and is rated "Generally Recognized as safe". I think it is a good compromise. Always dilute! 50% is about right. Tyfocor has very similar characteristics at 2+ times the price.

rene_3

Solar Hot Water Closed Loop

I have a solar hot water system with a closed loop. The loop is filled with 100% glycol. What are the pros/cons of using 100% or should I be thinning it down a little let's say 50/50.

Mike Dunn

Whoa!

The mixture should not really exceed 50 to 55% non-toxic glycol. You need to take some glycol out and add some distilled water. Please.

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rene_3

Mike,
Do you know what harm it would do if any or are there any dangers I should know about

Ray

hot_rod

You really need to look at

the manufacturers spec for the fluid. The protection rate varies, widely, from brand to brand and sometimes from different versions of the same brand!

Here is an example of the Nobel HD (heavy duty) I feel 40% should plenty for most areas.

Notice the slush and burst protection number, both are important.

Remember some brands are pre-blended and used straight from the bucket, usually the less expensive products as they contain water and glycol.

So check the spec sheet when making comparisions, not just %'s.

hr

Rudnae

100% actually worse!

Most of the glycol that we deal with gets worse with any concentrations over 50 - 55%. It will gel faster and lead to some issues I'm sure you'd rather avoid. Check your manufacturer.

Also, what about heat transfer? The more glycol in the mix, the worse the heat transfer. That slippery stuff doesn't like to carry heat very well.

Finally, what is the upper end. At what tempurature does the glycol you are using degrade? Most glycol used in traditional heating systems can handle up to 250F or so. This is most likely not going to be good enough. If the glycol over heats it begins to degrade, becomeing acidic and possibly chewing up your collectors, pipe, pumps etc.

Just some additional stuff to consider. The good news is that once you have this stuff all figured out, it won't change too much. Have a Great Day!

hot_rod

The challenge with higher temperature glycols

is the inhibitor package required to run higher temperatures starts taking the glycol away from a "non toxic" rating. The glycol itself is non toxic to the point of being used as a scent and flavor enhancer in many food products. And the blend water is non toxic, generally.

But the components that must be added to handle PH, O2, and elevated temperature operations are what limit the non toxic-ability.

With the use of evac tube collectors and very high stagnation temperatures possible, the upper working temperature of the transfer fluid becomes a concern.

Ue a good brand of product, test the fluid yearly and inhibit or replace as required for best protection and component life.

hr

Constantin

I would follow the manufacturers' specifications.

For example, some pre-mixed glycol products like Tyfocor are not supposed to be mixed with any other liquids, including water. While Tyfocor may not be the default liquid of choice in America, it is what Viessmann ships with its rebranded Thermomax/Vitosol 300 product.

So, rather than run with any advice you can get, I'd contact the manufacturer and get their tech teams to help you. That's what they're there for!

rene_3

I used a product called cryo-tek. My guy who helped with the plumbing purchased it a local plumbing supply house. I just read the fine print and it says "Not recommended forevacuated tube collectors". GREAT. That's just what I have. I just E-mailed cryo-tek to get their advice.
Anyone out there have a recommended brand of anti-freeze? I live in New Hampshire and the temperature can get down to a balmy 25 degrees below zero. BRRRRRRRRRRRRRR!!!

Unknown

A Viessmann rep told me that Viessmann is now doing it's own manufacturing of the vitosol300 tubes.

As far as re-branding.. the tubes were Thermomax, but the counterflow header was always uniquely Viessmann.