Advice needed on adding antifreeze to boilers

Ken C.

I had a customer today with a house built in 1773. Three of the seven baseboard zones in his system had frozen, and one had burst pipe. Since the loops to those zones are located in unheated crawlspaces or near parts of the foundation with massive air leaks, I recommended adding antifreeze to their boiler.

I know they will need a backflow preventer on the water supply to the boiler, but one thing I am not sure of is how to add antifreeze to a boiler, especially one with several zones. There is only one purge valve and draw-off on the common return. The system is zoned with Taco zone valves on the return header. Other than that, there are no isolation valves in the system.

There is probably more than one way to add antifreeze to a boiler, I'm curious to learn what way works best for you.

Also, is there any "quick and dirty" rule of thumb for estimating the amount of antifreeze needed, without physically measuring hundreds of feet of baseboard?

Steve_35

Get all of the water

out of the system. Mix your antifreeze with water to get your desired dilution (we use 50%) and pump it into the system. Just how you pump it will be dependent on the configuration you have to work with.

Ken C.

Okay, but ...

... how do you purge the system without losing the antifreeze you just put in?

Bill Nye_2

Ken

> ... how do you purge the system without losing

> the antifreeze you just put in?

Bill Nye_2

Ken

Ken, BIG garbage can, a new clean one. We pump from the 30 - 50 gal garbage can through the system and back into the can.

This way you lose the air bubbles but keep the antifreeze. You can "push " the water out of the loops with the stuff you are pumping in, just watch for the change in color when the antifreze comes around

Mark Eatherton1

Articles on glycnoids...

Heres one I wrote. I'll have to dig to find the other...

Enjoy!

ME


EATHERTON ON HYDRONICS


BY MARK EATHERTON , Hydronic Heating Contractor

Why add antifreeze to hydronic systems?

Every once in a while it becomes necessary to use non-toxic antifreeze in a hydronic heating system. The reasons for using non-toxic glycol vary from job to job.
If it’s a home where the occupants may be gone for a long period of time, there’s a possibility that the home may lose its fuel source (propane or oil), there’s a possibility of the long-term loss of power (mountain homes) or there is piping exposed to potential freezing conditions (overhangs). I generally induce a solution of propylene glycol into the heating system for freeze protection.

There are some tricks to doing this right. Too little glycol and you’re not providing adequate freeze protection. Too much glycol and you’ll cost the consumer unnecessary operating costs and possibly create additional problems in the heating system’s performance. Guessing at how much glycol is needed generally results in too much or too little glycol in the system.

You can estimate fluid content in a number of different ways.

First, you can force-purge a heating system into a large container using compressed air and record the number of gallons you removed. This is a guaranteed way of determining the system’s fluid volume, but it is quite labor intensive and can be messy.

Another way is the sodium titrate method. With this method, you test the system for residual parts per million of sodium. Then you completely mix 5 lb. of salt into a 5-gal. bucket of water and pump this saline solution into the heating system. Allow it to circulate for at least two days, then perform another sodium titrate test.

The incremental increase in ppm will tell you how many gallons of fluid are in the system. This method is tricky inasmuch as very few technicians have access to titrate testing equipment. This type of testing is typically performed for free by water treatment chemical companies. Call your local water treatment company for details.

The third method works quite well with new systems but is no more than an educated guess in existing systems.

I have developed a spreadsheet using standard volumetric values for standard nominal tubing sizes from 3/8-in. through 2-in. The spread sheet calculates exactly how much fluid is in the system based on the linear feet of tubing in the system, plus the boiler’s volume.

Once this quantity is known, an accurate approximation of the glycol necessary can be calculated and the appropriate gallons of antifreeze purchased and taken to the jobsite.

A fourth method is to draw a sample of the glycol/water mixture and send the sample to the glycol manufacturer. It can tell you exactly how many gallons of glycol would need to be induced back into the system in order to bring the fluid up to a given percentage.

In order to properly fill the heating system, there must be a means of injecting the premixed glycol/water solution into the heating system, and a place for all of the air-entrained fluid to return back to your charging system. This basically requires the designer to install an additional drain cock, which is actually used as a fill port. This fill port can be incorporated into the make-up part of the system. The purge port can be installed in its usual position.

My friend and associate Robert “Hot Rod” Rohr reminded me that if you are using a boiler drain valve backwards, as in a fill port application, you might want to consider using a standard ball valve with a male hose bib adapter in lieu of the drain cock. The reason is that if you try to stop flow backward through a drain cock, it will strip the bib washer right off the screw. Boy, howdy, have you got problems now! Thanks, Hot Rod.

A word of caution here. If you have a heating system filled with glycol, it is not a good idea to leave the make-up in an automatic fill position. If something goes wrong, and the system starts taking on fresh water without being noticed, you will dilute the glycol to the point of having no freeze protection at all.

This won’t be noticed until it’s too late and the system has already frozen and can no longer provide heat. Unfortunately, in some cases, this can lead to additional freeze damage of the domestic plumbing systems.

Attached below is the spread sheet I wrote for estimating fluids. I've used it many times, and with the exception of guessing boiler volume, it is extremely accurate.

ME

hr

A very important first step

is to clean and flush the system first. If not you may ruin the glycol from the start.

Also you need to check the quality of the fill/ blend water. hard or high TDS water will also ruin glycol as it uses up the inhibitors that are added.

The percentage of mix depends on the brand, and freeze protection. Generally 35- 40% is what I use with Dow HD. Too strong only adds to the pump issues with cold thick glycol.

Find and fix any leaks before you glycol. it will seep out of the smallest of cracks.

Use only PG inhibited glycol and I recommend a RPZ type of backflow. Many codes require this type to the single check, non vented style.

Use glycol only when absoutly needed, it brins additional baggage and expense

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Jamie Hall

RPZ

hot rod -- VERY important point buried in your post. Most, if not ALL plumbing codes require an RPZ backflow preventer, and for a very good reason -- glycol antifreeze is very toxic; the results of drinking the stuff are slow, agonizing, and almost impossible to reverse.

Use an RPZ!!!

Drew_2

Toxciity

Not all glycols are the same.

Ethylene glycol is the primary antifeeze used in automotive applications and will cause kidney failure if ingested. The reason for use is it's inexpensive and high in heat transfer.

Propylene glycol is the antifreeze to use in hydronic heating systems. If ingested in high concentrations, it acts as a diuretic. You will find propylene glycol as a food additive in toothpaste.

Steve_35

> Use only PG inhibited glycol and I

> recommend a RPZ type of backflow. Many codes

> require this type to the single check, non vented

> style.


I've never heard the term "RPZ". What does that mean? Are you talking about something like the Watts 9D?

hr

RPZ

reduced pressure zone. No a watts 9D will not pass. I think the Watts number is 009wt (with test taps)

It's they type you see on lawn sprinkler systems, often above the ground.

Plenty to be seen in Florida. Seems every hotel has a huge RPZ in the front yard

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

S Davis

009

Check the pictures in the thread Buderus Install there is a 009QT in one of the pictures.


S Davis


Apex Radiant Heating

[Deleted User]

Aluminum heat exchangers

Is there a specific glycol mix/brand for boilers with aluminum heat exchangers?

Drew_2

Aluminum

Yes, but not all those that claim to be compatible are.

I won't waste everybodys time here with all the detail.

If you would like the details, call me @ 800-678-6625, Ext 108.

Mark Eatherton1

Drew...

PLEASE waste my time with details... I LOVE details, and am getting ready to utilize some of these new aluminum block beauties. I'd even purchase your product if you have something compatable.

Thanks

ME

George_10

We will be involved in a seminar

in March in Chicago on these topics. Glycol and cleaning and treating boilers with aluminum heat exchangers. Cast Iron Mentality will not work in these new beauties and could actually harm them. For those of you that are going to use these new boilers or have been using them, you are going to also have to learn more about their TLC (tender loving care)

Lack of knowledge can be detrimental to both your customer and yourself. Solid knowledge should bring a win-win situation for both.

house

boiler and RPZ

How many apartment on one boiler before having to use a RPZ instead of a Dual-check valve?

house

boiler and RPZ

How many apartment on one boiler before having to use a RPZ instead of a Dual-check valve?

Alaskabirds

Adding propylene glycol to radiant system

I've read most everything I can find on here and elsewhere about putting glycol into a radiant system.  I have a few questions about the install process.

I will be installing the glycol mix through the boiler drain using a drill pump. The consensus is that the glycol mix should be added with the boiler off and the zone valves open.  I have five zones and two Grundfos pumps (one circulating, one injecting). When I shut the boiler off the Grundfus pumps also shut off. When I open the drain valve with the drill pump attached (but off), water is forced back through the drill pump.

My questions are:

1. Will the drill pump be sufficient to push the glycol mixture into the system and circulate it if the Grundfos pumps are off?

2. How do I know if the zone valves are open when the system is powered off?

I live in Alaska, where we experience frequent power outages and the house will be unoccupied from November - February.  Please skip the lectures about the downsides of glycol in radiant systems.

Zman

Drill Pump?

I don't believe a drill pump will work.

Once the system is no longer under pressure, you should be able to push glycol through you system using a high head circ pump and a bucket.

You will manually open the valve one at a time to purge the zones.

Be sure to read up on freeze temps vs burst temps. I would lean towards a 30% mix

Carl

hot_rod

depends on your pump

and how many GPM you are trying to push in. Ideally pump thru one zone, or loop at a time to get good flow and velocity to purge.



There are some good drill pumps, I use a Zuwa and it will pump 80 psi and about 3 gpm. I doubt the hardware store models are that powerful. Try pumping into a bucket or look at the pump spec sheet.



Also the drill motor makes a huge difference. Mine pump requires 3000 RPM for full capacity. Not many of the larger 3/8 or 1/2" drill motors spin that fast.



Most zone valves have a lever to manually lock them open.



hr

Ron Jr._3

Not too hard to figure

how much water is in the system . Just drain the boiler and zones into 5 gallon buckets and add it all up . Most of the water will siphon out of the zones above . You can get fancy and blow all the water out of the pipes with an air compressor , but I don't think it's that critical with smaller pipes .



We clean the system with 8-Way or equivalent first , then give it a good purge . After the purge we pump the glycol in through the boiler drain , with a pony pump or teel pump . We make sure the relief valve is piped into a bucket and throttle the pressure by opening a purge valve to let excess water out .