Installing glycol in the heating system, is it worth it?

georgearoush

Last year, I purchased a new house with a forced-air heating system. The gas boiler in the basement heats water, which circulates through pipes to an air handler in the attic. The air handler then blows hot air to heat the second floor.

Last year, we didn’t use the second floor, so I didn’t bother turning on the heat there (I didn't know I have water pipe going to the attic!) This year, however, we are using the second floor. When I turned on the heat for the first time, I discovered a water leak. After investigating, I found that the water circulating pump, a "Taco 006-BC7-IFC," was leaking. I had it replaced, and everything is working fine now.

The technician who replaced the pump recommended adding glycol to the system to prevent future issues, which would cost $$$.

Here are my questions:

1. Now that I’m using the second floor, do I need glycol in my system?
2. When not using the second floor, if I set the thermostat to 50°F, is it safe to avoid adding glycol? What is the ideal thermostat setting for the second floor when I’m not using it, assuming I don’t add glycol?
3. If I install glycol, can I turn off the second-floor thermostat entirely, for 2-3 weeks, when it’s not in use?
4. How long does glycol last once installed? Will this be a recurring yearly cost?

I’m trying to evaluate the cost-effectiveness of adding glycol versus maintaining the heat at a minimal temperature on the second floor (e.g., 50°F or 60°F).

The house is in Worcester, MA, where winters can get very cold, with nighttime temperatures often dropping into the single digits for several days in a row. Additionally, I have no idea whether the previous owner used glycol in the system or not.

hot_rod

That is probably one of the most at risk hydronic installations. Like you mentioned, a few hours of freezing conditions could cause a problem. Power outage, system failure, etc.

You choices are to condition the space, keep it above freezing, or use antifreeze.

How close to the edge do you want to live 😲

pecmsg

the only real protection in your situation glycol. The question is do you want the entire hw system with glycol or just the attic loop?

SuperTech

I work on a lot of homes with systems like yours. Glycol is a necessary evil for your system. It's necessary because of the risk of the pipes and heating coil freezing without it. It's evil because of the expense, the fact that it becomes corrosive if the inhibitor levels aren't maintained religiously or the glycol replaced regularly. It causes the zone valves, air vents, expansion tanks, relief valves and every other hydronic component to fail prematurely. I hate the stuff and would never want to put it in my boiler but I wouldn't go without it in your boiler.

Add the glycol, don't put in more than necessary. Check the freeze protection and PH levels annually. Add corrosion inhibitors when needed. A PH level of 8-9 is recommended.

hot_rod

Any idea how many gallons your entire system holds? It may be more cost effective to add a plate HX another pump, expansion tank and isolate the attic circuit.

Figure around 20 bucks a gallon for good quality hydronic PG. Maybe the attic loop holds 5-6 gallons? The boiler and balance of the piping?

There use to be a bunch of small HX modules on the market back in the solar thermal heydays. Everything in a poly insulated case, plug and play. Probably some Euro sources for them.

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georgearoush

Thank you all for your input. I have two remaining questions, and I hope someone can help:

1. I estimated the pipe length, running from the basement to the attic and back to the basement, to be around 45 to 50 feet. With a 1-inch diameter, this pipe would hold at most 2 gallons of water, though let’s assume 5 gallons to be conservative. Given that glycol costs $20–$30 per gallon and the job takes 2–3 (or, did I get this wrong?) hours, isn’t a quoted price of $$$ way too excessive?
2. Once the glycol is installed for this winter, will I need to repeat the process annually, or only when purging air from the system (as the technician recommended doing each year)?

pecmsg

Is the automatic fill to the boiler detached?

Purging air is rear unless your adding fresh water.

Glycol freeze protection should be checked annually as well as the PH level.

We replace the glycol every 5 years as part of a service agreement.

Mad Dog_2

The exorbitant cost of repairing the damage done after a long weekend away after a freeze up??? Nolo contendre. Inject glycol. Mad Dog

pecmsg

https://forum.heatinghelp.com/discussion/comment/1830567#Comment_1830567

Inject glycol.

A Glycol Junkie? 😂

SuperTech

Why would you need to purge air annually? There's no need for that. The boiler should have functioning air eliminators. Even when I drain a little water from the boiler during annual maintenance to check the expansion tank I never need to purge any of the zones afterwards.

DCContrarian

1. We don't discuss pricing here.
2. Filling the system with glycol is pretty labor intensive, you have to get all of the water out and then pump in the glycol mix and get all the air out. It goes faster with a helper. If you figure six-man hours of skilled labor the price you were quoted isn't unreasonable.
3. When you install glycol you assume liability for damage due to freezing. There's a price to that.

hot_rod

know also it takes longer to get all the air, entrained bubbles out of a glycol solution.
A microbubble purger is preferred, they work quickly and efficiently

So a trip or two back to inject a bit more may be required

A glycol fill tank or homemade PIG can be helpful for keeping the system topped off as air comes out.

A quality brand of glycol can last 10 years if it isn’t overheated or put into a dirty system. A yearly check is a good idea.

Kaos

If your power is reliable, one option is wire the air handler pump to always run. The thermostat can still control the heat by driving the fan directly.

Even if the boiler is not running, this will circulate house temperature water through the unit and will avoid freezup.

Running the pump 24/7 will add electricity costs. If this is an ECM pump you can set to low speed, the cost of that is pretty minimal.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1830607#Comment_1830607

Id be most nervous about a power outage with water in a cold attic

A step further would be to add a backup power source like computers use

An ECM running 17- 40w should be easy to back up for a day or two of running.

I think a few if the regulars here have sourced commercial grade battery back up units, not the throw away BestBuy units😂

GroundUp

If you think the cost is too high, call somebody else or do it yourself. I certainly wouldn't spend several hours flushing a system to convert to glycol for that $$$ amount.