Adding glycol back into system

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Watson524

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Hi all,

We have a Weil McLain Gold boiler up at my mom's. She has a zone that's radiant flooring in her bathroom with a mixing valve. 3 other zones are baseboard hot water and another zone is baseboard hot water but in a sun room that's on peers with insulation under the flooring. Because of that zone being to open air more or less, there's always been glycol in it. Had some issues with the boiler in the fall and one zone appearing to be air locked and not letting heat through to the radiant floor. After many screw ups by the service company and me finally telling them I wanted the old guy tech who had a clue, it got fixed (expansion tank needed to be pumped up, not leaking, but I guess after 12 years they lose pressure). As a result of the boiler being drained, the glycol is gone so I need to get it back in there (company didn't seem interested in doing it tho I told them I had it on hand and a pump to pump it in - we have a boat, it's in my winterizing arsenal). So net net, I need to put it back in.

Her system doesn't have a way to isolate and drain just one zone, so I'm going to tackle that by adding hose bibs and a shut off below the existing shut offs on her return side. For some reason, there's only ball valves there so you can stop water from coming down but the bottom end isn't protected so it drains the whole thing. No big deal, I can practice my soldering. Also, since I'll have it drained, I'm replacing her pressure/temp gauge as we found out in the spring that's not working and I guess we're just relying on the quick fill valve to do its thing and maintain pressure but I'll replace it and it'll make me feel better about filling from a garden hose.

On the glycol, a few questions:
1.) I'm assuming the pink -50F burst point stuff is fine?
2.) Should I assume it'll circulate to all zones and that's just the way it is? I don't think there's really a way to keep it ONLY in the sun room zone
3.) What should I plan to read on the refractometer? Since I don't plan to entirely fill the system with glycol I don't know how much to put in or know what it should read when I'm done filling with water. I assume I'll put in at least a few gallons.
4.) I plan to put it in to the drain point that's now at the bottom of the return side. Figure I'll just pour the stuff in a bucket and use my bilge pump setup to pump it in. Good plan?

If the -50F (Northeast PA) isn't enough, I can add in some blue or purple stuff to make it go to lower burst but honestly, -50F is fine for burst, tho it has a slush point at +10-16F.

Thanks in advance for any advice!
 

Watson524

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And I should add that yes the system does have a backflow preventer (brand new, replaced in the spring by dumb tech who thought that was an issue) so the glycol can't get back into the potable water.
 

DonL

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Don't you add that using a Coffee Cup ?

Sorry, I must watch too much news.

Jim must be sleeping in today.


Good Luck.
 

DonL

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I wish it were as easy as pouring it in from a coffee cup :)


You can do it, With the proper tools.

I miss Jimbo, He knew some shit about some shit.

Do not get confused by the color of antifreeze, And do not use to much, you need the correct amount of H2o also.

And do not drink from your coffee cup until you wash it with Gasoline.


Good Luck.
 
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Jadnashua

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The antifreeze must be one designed for a hydronic heating system or you're asking for problems. But, assuming that's the case, at one time, I had a system that required the antifreeze. WHen the tech installed it, he first calculated how much he needed to get the system at the right percentage, he just attached a short hose to a drain valve near the suction side of the pump and ran the pump until the bottle was empty. Stopped the pump, new bottle, repeat until done. THen, he added enough water to finish filling the system and pressurize it properly. This worked, I do not know if it is the best or even an approved method...I can only report that that is how they did it on my old system. It continued to work for years before it was replaced with a new system that didn't need any (the old one had the actual combined boiler/air-conditioning unit sitting outside - the new stuff is all inside).

FWIW, adding antifreeze to a hydronic system decreases its ability to actually transfer the heat to the room - don't remember the exact number but think it was about 10% hit on efficiency of transfer. But, if you have the possibility of a zone freezing, you either need to redesign or use the antifreeze.
 

Watson524

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You're right, it's about 10% on PG and slightly more loss on EG. From what I've read, EG and PG can both be used and PG only where there's any chance of it hitting potable. Since I have the PG, I plan to go with that and the boiler service guy said that's fine (tho he didn't want to take the time to put it in, annoying). It's got the anti corrosion stuff in it tho I suppose I should check the Ph yearly just to make sure it doesn't need any inhibitor added even if the freeze point itself is ok (i.e. don't need to add PG). They tagged the system when it was built and the system was put in to note the antifreeze but they didn't bother writing on the back the specs so I'm not entirely sure what kind of concentration I need. In theory, the moving water in and of itself would prevent a freeze and we have a backup generator for power outages but when mom's gone away to FL for a month in Feb and someone isn't right in the house to know there's an issue.... well it's not a chance I want to take.
 
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