Opinions on introducing glycol into boiler system


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Old 03-18-08, 08:25 AM
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Opinions on introducing glycol into boiler system

I am in Colorado and have a new home built with a Weil Mclain Ultra gas boiler. The system includes 7 zones operated by circ pumps. One zone is for driveway heat. My question is in regards to introducing glycol into the whole system for the driveway zone to be protected. I was under the impression the plumber was going to isolate that zone so glycol would not be in the whole system but that does not appear to be the way it is done. Is that ever an option and if not, what are your opinions on having glycol in my system? Is the maintenance that big of a deal on a new boiler to have to keep the concentrates accurate? Also I have heard glycol can be good for your system ie: lubricates the pumps, and I have also read some of your sites that lead me to believe it can be harmful to my pipes and boiler. Does anyone have any strong opinions on this? The loop has been isolated by shutoffs and can be "abandoned" if it is more of a problem than not.
 
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Old 03-18-08, 08:58 AM
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Your contractor should have used a heat exchanger to isolate the driveway from the rest of the system. Unless you live in the sticks where you can't get servicing quickly or your house is left alone for long periods without anyone checking it I'd avoid glycol. It reduces the capacity of your heating system and needs to be monitored closely and changed out about every 5 years. You'll need to incorporate a glycol that is specifically rec'd by W-M for use on the Ultra because of the aluminum heat exchanger.
 
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Old 03-18-08, 09:04 AM
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How hard is it to add a heat exchanger and can you explain how that works?
 
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Old 03-18-08, 09:10 AM
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The existing piping from the boiler would lead to a flat plate heat exchanger pretty well as is. The driveway piping would then connect to the other side of the flat plate heat exchanger. On the driveway side, you would need to add another circ (it could be wired with the other circ or off of a relay to the other circ is the combined load was too high), another air eliminator and expansion tank as well as purging and some form of a glycol fill setup.
 
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Old 03-18-08, 05:13 PM
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Glycol

I agree with WHO. Glycol is a double edged sword. It can be great stuff in that it can save you from a freeze up but on the other hand, as WHO said it has to be monitored. The pH of the solution is critical. If it gets too low, it is very hard on copper pipes. The plate heat exchanger with some type of temperature control for the snow melt, in my opinion, is the way to go.
 
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Old 03-18-08, 05:38 PM
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You guys rock! I am so impressed with your timely responses and help. I will do more research on the heat exchanger, (size for this system), additional parts and pricing. If I end up trying to add this into the system I will let you know how it goes. I am extremely comfortable with plumbing but not had much experience with boilers. I am assuming there will be a sufficient installation manual with the exchanger and should be managable. Thanks so much.
 
 

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