Old floor heat system
I have an older floor heat system in which the previous owner used rv antifreeze as the glycol in the lines. The system is used for radiant floor heat for the concrete pads. I want to drain the system and refill with cryotek 100 before winter hits.
But what is the best way to drain the system?
My idea is this and please i'm open to all inputs.
- Shut off the ball valve in the system.
- There are two fill valves, one on each side of the ball valve. I was going to hook up a garden hose and use city water to flush the system of all the current antifreeze until it runs clear.
- Then refill the system with 50/50 crytotek 100 and distilled water.
But will having some city water in the lines hurt anything and cause buildup?
Also I'm thinking to do a 50/50 mixture of cryotek 100 and distilled water. The chart shows that has freeze protection down to 10 degrees F. But in michigan our winters do get pretty cold, should i do a higher concentration. Thanks for all help!!
Comments
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Is this floor going to be anywhere near 10°F?
50/50 sounds strong, are you reading the instructions clearly?
Remember the more glycol the less heat transfer.
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Yes it is for a concrete floor at a business that is exposed to the elements all winter. So if power does go out the floors could freeze. Winters in michigan can definitely be that cold.
Good point about the more glycol less heat transfer, I am trying to keep that in mind
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Rarely do folks use distilled water for closed systems. Once the water is in there, you don't change it very often. I was told that the oxygen that is dissolved in that water, and any harmful minerals in that water will do their damage within the first few days. (which is minimal). Then the potency of those corrosives will be spent. Basically leaving the closed system water inert.
Every time you need to open the system for a pump replacement of other repair, you have a real involved process to put distilled water and antifreeze back in it. Are there any special problems with your particular city water?
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Read Freeze protectrion and Burts Protection.
WAG if power fails and the doors are closed it will be several days before that floor gets near the freeze point several days more to get to burst temperatures.
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I'd run a cleaner first, add it to what you have. Flush with clean water. Use pre-mix glycol 30%.
Or if you mix glycol on site it should be DI water as the manufacturers recommend.
If you really need antifreeze protection?
Some RV antifreeze is methanol based, some is PG propylene glycol. Unless you have an empty container it is hard to know.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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All boilers and now Grundfos have water standards in the installation instructions.
A group of us developed a boiler water standard thru IAMPO/ UMC for the US. It was adopted as an ASTM standard. I'm not sure which ASTM number. @heatmeister will know, he was on the committee.
I don't know if you can get it online without $$?
So if you don't have boiler or component water spec, use this. It closely follows the German DIN standard.
3 of the important numbers Hardness, TSD, chlorides. Test whatever water you plan on using for at least these.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream2 -
The stuff sold as "RV Antifreeze" is not propylene glycol, which is what you want to use. The most cost-effective form I've found is Cryo-Tek AG, which the last time I bought it was about $200 for a five gallon bucket. Which may change your calculus, RV antifreeze was about $3.50 a gallon last time I bought that.
Getting the old fluid out means pumping out or blowing out with compressed air what's in there and capturing it. RV antifreeze can be poured down a drain, but you want to measure how much is in there. Because the propylene glycol is so expensive you really want to know the capacity of the system so you can order the proper amount.
Once you've got the old fluid out, you have to put the new fluid in. This will be mixed to a certain ratio with water. You need to make sure the system is empty before you start, otherwise it will be too dilute. You'll need a utility pump to pump the mixture in and pressurize the system. Purging air can be difficult depending on how the system is set up.
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the inhibiters in the glycol will be consumed over time and will need to be replenished or the whole fill changed. there are test strips to test the condition of the inhibiters. It will need maintenance every couple years and annual testing.
A shop vac is a good way to remove most of the residual pockets of water if it doesn't drain by gravity. If there is a lot of residual water in the system you will get a lower concentration of antifreeze.
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not all glycol is created equal. The more expensive products are lower temperature and have better inhibitors. Usually you can blend them down to a 35% mix and have adequate burst protection.
If you have stainless or aluminum in the system you need to use AL or multimetal glycol.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream2 -
If it is standard propylene glycol, it mostly likely only missing the corrosion additives and pH stabalizer.
There are companies that specialize in heat exchange fluid where you send them a sample of what you have and they send you back a kit with all the stuff that is missing from your fluid. Much less cost than swapping out the whole thing.
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There aren't any problems with my city water thankfully. A separate closed-loop system of mine has used city water just fine for years. But I had read that distilled water might be better in the long term.
So you would recommend just using city water mixed in a bucket with the cryotek100 glycol? I thought you were always supposed to use DI water, demineralized water, or distilled water.
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Well this is in a car wash self serve bay. We only have one door and in michigan the ground can get pretty cold.
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Thanks for the reply hot_rod. So you'd run a cleaner in with the current RV antifreeze glycol and run that for a day or so. And then flush with clean water until clear. And then you think I should use DI water instead of distilled water.
The RV antifreeze in the system is propylene glycol.
And yes I really do need antifreeze protection. This is for a self-serve car wash bay in Michigan. So it is exposed to the outside elements all winter. If a pump or something went bad then the lines have a chance of freezing in the concrete. I don't have stainless or aluminum in my system. The freeze protection down to 10 degrees F for crytotek 100 is a 50/50 mixture its showing.
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I would buy 40% glycol, use it straight out of the bucket. It is mixed at the factory with DI water. Maybe buy a gallon or two of straight non diluted if you need to boost the mix %
Dow, Rhomar and Fernox are other common brandsThis Dow Engineering Guide has excellent info on PG
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Yes I'm looking at cryo-tek 100. And purging the air is my main concern with how the system is set up. There isn't an easy way to purge each line individually. And I'm worried about not being able to get all of the air out. That is why I thought I'd flush the system with city water. And then mix a bucket with cryo-tek 100 and water at 50/50 concentration and feed that through the pipes until it is just starting to come out of the return port. I maybe then could test my concentration to see if I need more glycol.
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That makes sense. I will continue to monitor the inhibiter levels each year.
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Well the RV antifreeze is propylene glycol but from what I've read it was never made to withstand constant heating like radiant floor heat glycol. So I think starting over with the fluid will be far better in the long run.
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Believe me any water pipes in that building WILL freeze and burst long before the floor piping!
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Food glycol, technical glycol all starts from the sane base stock, either petroleum based or bio based from corn , canola, etc.
Then additives are added based on the final use, whether it is hydronic, food additive , aircraft deicing, etc. So you want to use the correct product and blend
We had a glycol supplier clear up a lot of questions a few months ago. We have also had Dow, Rhomar and Nobel do glycol webinars for us in the pastBob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
I used to service a Car Wash in southern NJ. they has a buderus commenrcial boiler with a waste oil burner. (they did oil changes also). Someone left one of the outdoor concrete loop pumps off overnight because there was no call for precipitation. That zone burst and is no longer useful. The owner needed to post a very large sign on all the remaining pump switches. "DO NOT TURN THIS SWITCH OFF BETWEEN DECEMBER 1 AND MARCH 30." I understand @MichaelT's situation. The antifreeze must be good for below zero conditions that exist above that tubing if the electric goes out for an extended time in the cold months.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Overnight WILL cause issues. You still don't need 0°F Freeze protection. 30/70 Will give you 10°F Freeze protection with -20°F Burst.
There will be several other frozen and broken pipes long before that floor gets near -20°F.
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If you really are sure that the liquid that's in there is propylene glycol, I would leave it and treat it with additives. There are not different types of propylene glycol, it's a chemical formula for a specific chemical. Propylene glycol is propylene glycol.
I would be sure of that though. Because propylene glycol has gotten expensive you never see it sold as RV antifreeze.
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Exactly my worry - I've seen it happen at other car washes as well. @EdTheHeaterMan so is DI water the recommendation on what to mix with the glycol then? Just double checking as I've read some people to say just use distilled water.
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I would go with DI water for this project. But i yield to @hot_rod as the expert on this part of you system design. I only worked in one small are of New Jersey. Bob has experience from around the world.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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i would not use a bargain brand of glycol, the inhibitors are much weaker, stay with one of the main brands. Flush the old stuff out thoroughly.
There are other antifreezes used in Hydronics, methanol based is still common in GEO loop fields as long as there isn’t a potable water interface,
Ethanol is another product.
Early PB systems used potassium acetate.
There are also some silicone based products, Dow Slytherm for exampleEG glycol is still widely used in larger system that do not have potable water exchangers It is a better heat transfer fluid often seen in ice skating systems. Dowfrost is PG Dowtherm is EG
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Awful lot of poor information out there regarding glycol, and nobody seems to have mentioned that CryoTek -100 is only 55% concentration straight. You can mix that ~1.5-2:1 with DI water (NOT 50/50), or just buy the 45% CryoTek in the light blue bucket from Menards that's already premixed with the proper inhibitors and pump it in straight. No need to reinvent the wheel, but you absolutely do not want anything below 35% concentration for an application like this. 40-45% is even better.
Honestly, if you flush the system with water and then blow the lines out to the best of your ability then dump in pure CryoTek -100, you'll probably end up pretty close to 45% anyway. DI is ideal, but you'll never get the system dry.
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Cryotek AG is straight glycol. Even though it's around $40/gallon it's the most cost-effective way of getting glycol.
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AG Arctic Grade is the concentrate so you will want to blend it some with good, probably DI, RO, or distilled water. Some car washes use RO water for the final rinse, probably the automatics, so that is a source of blend water, they usually have a large plastic tank with stored RO water.
I like when manufacturers show a 3 temperatures. For critical applications you need to maybe pump at the lowest possible expected temperature. So adjust the % accordingly
The richer the mix the more pump you need to move it when it cold and thick. Or maybe you idle a car wash SIM for freezing from the over-spray in and outside the bay?
The car washed I did had the apron on both ends outside melted also. Liability as much as connivence
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Nobody asked that, but okay.
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Cryotek AG is not pre-diluted, but that doesn't mean it's straight PG. It has a corrosion inhibitor package.
"The triple protection inhibitor stabilizes pH to prevent corrosion, chelates, hard water minerals, and inhibit scale and sediment formation"
Is that CI package compatible with everything in your hydronic system?
"Not for use with galvanized, CPVC or aluminum"
If you have an aluminum heat exchanger, you may be better off with Cryotek AL
https://www.oatey.com/products/hercules-cryotek--100al-aluminum-antifreeze--526165088?upc=032628352834
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Thank you for all the help everyone! I greatly appreciate it! I work on most of my equipment but don't have a background in boiler systems.
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