If I've got a water cooled chiller and all of my piping is inside in conditioned space - do I need any glycol in that loop?
Do you put glycol in chilled water loop?
Grawburg
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is any of your piping going to air handling units? if yes do they have economizers or fresh air intakes? if any of the previous applies, then yes you must use glycol.
15% to 35% depending if you can run chill water pumps automatically whenever temps below freezing.
is there ANY place in the ENTIRE system where the temperature of a component or fluid that the chilled water will come in contact with could be at or below 32*F?
Think about the chiller evap and the air handler on this!
That will answer your question.
Think about the chiller evap and the air handler on this!
That will answer your question.
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Good investment in cold areas.
I manage a large high school campus in southeast Wisconsin (hot water heating-four Bryan flextube boilers/2 water-cooled McQuay chillers). In December, we had a power failure during a wind storm that resulted in the hot water pumps not running for a long period of time. Due to the high winds and cold ambient temps, we froze up a large heating coil (50-60 broken return loops) that required 3 days of brazing with 2-3 pipefitters, and about 30 lbs of sil-fos rods.
If we hadn't had glycol in the chilled water system, I'm certain we would have frozen the cooling coil in that AHU that too! It's an expensive initial investment, but it saves money in the long run (and you sleep better!)
We used to drain the system every year, but that is time-consuming, and one year, when there was a change in personnel (before I got here), they forgot, and froze several cooling coils-$$$$$!
I manage a large high school campus in southeast Wisconsin (hot water heating-four Bryan flextube boilers/2 water-cooled McQuay chillers). In December, we had a power failure during a wind storm that resulted in the hot water pumps not running for a long period of time. Due to the high winds and cold ambient temps, we froze up a large heating coil (50-60 broken return loops) that required 3 days of brazing with 2-3 pipefitters, and about 30 lbs of sil-fos rods.
If we hadn't had glycol in the chilled water system, I'm certain we would have frozen the cooling coil in that AHU that too! It's an expensive initial investment, but it saves money in the long run (and you sleep better!) We used to drain the system every year, but that is time-consuming, and one year, when there was a change in personnel (before I got here), they forgot, and froze several cooling coils-$$$$$!
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1,008 Posts
We recommend winterizing the coils if they can be exposed to outside air.
2 methods:
Isolating & filling with glycol
(slushing) Isloating, Filling with glycol, Draining the coil.
Anyone else do this?
2 methods:
Isolating & filling with glycol
(slushing) Isloating, Filling with glycol, Draining the coil.
Anyone else do this?
Glycol
Here are a couple of things to keep in mind about glycol:
1. There will be a capacity correction, gpm goes up and chiller capacity goes down.
2. You need to be aware of the corrosive nature of the different types of glycol and the associated inhibitors that are required.
3. You need to have the glycol loop tested for bacterial growth that can cause thread corrosion if it gets out of control.
4. There is a slush point and a freeze point to consider for protection.
5. Can you get pre-mixed glycol with inhibitors?
There is a bit of liability involved with putting glycol into a system that wasn't designed for glycol. Verify, check, ask lots of questions and warrant that you are going down the right road. The chemical salesman is always happy to sell you glycol but it can be very costly to fix the results of loading glycol into any system... Good luck!
Just my 2 cents.
Here are a couple of things to keep in mind about glycol:
1. There will be a capacity correction, gpm goes up and chiller capacity goes down.
2. You need to be aware of the corrosive nature of the different types of glycol and the associated inhibitors that are required.
3. You need to have the glycol loop tested for bacterial growth that can cause thread corrosion if it gets out of control.
4. There is a slush point and a freeze point to consider for protection.
5. Can you get pre-mixed glycol with inhibitors?
There is a bit of liability involved with putting glycol into a system that wasn't designed for glycol. Verify, check, ask lots of questions and warrant that you are going down the right road. The chemical salesman is always happy to sell you glycol but it can be very costly to fix the results of loading glycol into any system... Good luck!
Just my 2 cents.
Didn't even think about the AHU's with O/A on them. This was more of a generic question cause someone asked me and I said I didn't think so. My hydronic experience is limited.
Then again, if the O/A was 32F, wouldn't a freezestat turn on the hot water coil...or am I missing the point of the function of the freezestat?
Then again, if the O/A was 32F, wouldn't a freezestat turn on the hot water coil...or am I missing the point of the function of the freezestat?
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76 Posts
Stats, valves and pumps fail, you also have damper leakage when the unit is off. Water + OA <32 == freeze. You have to prepare for that. Chilled water coils should be drained in the winter months but aren't always. I have a client who just destroyed a 3 year old 150-ton chiller because JCI didn't drain the coil.
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Cooling coil is upstream of the heating coil for freeze protection as well as dehumidification, I always call for my units to be oriented that way even if there is no application for dehumidification. I will usually put a small circulating pump in just for the heating coil that will run continuously if the outside air temp falls below 35 degrees to avoid freezing. I'll also call for freeze plugs, low leakage dampers and strip heaters inside the unit depending upon the location. Since my client with JCI on site is a good client, have money and Johnson is beyond incompetent, if we don't have a penthouse for our air handlers, which is the only way they will get service is if the tech doesn't have to go outside, we will have them do all of the above just for freeze protection on any unit, not just 100% OA.
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32 Posts
freeze protection
ALWAYS protect water piping. Power failure can leave water still. Also I had a store that had a malfunction in the fire system on a weekend, which opened the outside dampers 100%, the below freezing outside air froze all but two of the 6 foot X 4 foot coils, each 6inches thick. This took two men 5 days and a ton of silfoss to fix.
ALWAYS protect water piping. Power failure can leave water still. Also I had a store that had a malfunction in the fire system on a weekend, which opened the outside dampers 100%, the below freezing outside air froze all but two of the 6 foot X 4 foot coils, each 6inches thick. This took two men 5 days and a ton of silfoss to fix.
I think you mean cooling coil is downstream of the heating coil. Otherwise, how do you have freeze protection?
Yes, a simple answer to your question. Typically a freezestat is setup to shutoff the suppply fan, close outside air dampers, and will drive a heating valve 100% open. Unless its steam, then sometimes it will control the heat to a set temperature within the AHU.
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Sorry
typing too fast, yes that is what I meant OA > HC > CC.As far as the preferred setup with PH > CC > HC, I can't say I've ever seen a unit installed with this configuration. I don't see many preheats, and they are usually very old & done with steam, but they are always PH > HC > CC in my observances. Just wondering why you think that is the preferred setup?
As far as the freezestat, pedantically I would say it is there to protect any hydronic coil in the unit, not just specifically the coiling coil.
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76 Posts
Design temp for Chicago is -10 and we've hit it more than once this year.
If you are talking about a permanent addition of glycol read and understand Yipikia's post. If you are talking about adding it just for winter I would follow hvacconsultant's suggestions, especially the strip heater with a stat set around 40* if you setback temps at night and the unit isn't running. We have the same opinion of our JCI people, I see. If you decide to drain a coil just for winter, I would recommend to fill it back up with glycol to mix with any trapped water and many valves leak through and can fill up the coil during cold weather because the drains will freeze shut. Use Proplyene glycol as it can be dumped down drains in most places without violating sewer rules.
PH for protection and extra heating, CC to cool the air down and condense the moisture out, HC to heat it back up. with CC before HC, you get dehum.
Toronto gets very dry and cold winter and also get hot and humidy summer.
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