Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Pumping antifreeze into a heating system

I have to fill a heating system with antifreeze. I have a Liberty 331 transfer pump. Can someone suggest the best method to pump it into the system?


  • Brad White_203
    Brad White_203 Member Posts: 506

    I am not familiar with Liberty pumps, personally I use a Silver King Force Pump, sort of a bicycle pump for juice... great tool. Regardless...

    I would drain the system entirely and blow it out with dry air just to be sure. You MIGHT capture the water in a measurable drum to get a sense of system volume OR do a metered re-fill to obtain the same information.

    You might also take the opportunity to clean the piping. One never knows what is in there and what that might do with the glycol. Anaerobic bacteria love the stuff, not saying you have any. But a cleaning, (Rhomar is one company) is good policy for a fresh start.

    Only then would I fill it with pre-mixed glycol to your locally required percentage. Buy it by the drum in the volume you need. Some left-overs are good to have but keep them sealed and if a void, top off with dry nitrogen before sealing.

    Now, you CAN go about adding glycol to existing water, but that is a nightmare of adjusting, draining down (potentially losing a partial solution), adding more glycol, testing, adjusting... You never really know how much to add for sure.

    Be sure to test for pH to whatever your boiler or system requires, usually 8.0 to 8.5 I have seen for most systems, sometimes higher; a little on the alkaline side, never acidic.

    But assessing your volume and percentage and insuring the integrity of that is essential.
  • hot_rod
    hot_rod Member Posts: 22,483
    That's plenty of pump

    for most residential work. I've used the Grainger version of that pump (cast iron) for 20 years now.

    It does have enough psi to pop a 30lb relief valve. I installed a gauge and ball valve on mine for quick shut off.

    It's a little weak for large snowmelts or geo loops, not quite enough gpm. Use an old pool pump for those large gpm requirements.

    A ball valve with a full port hose bib on either side is a goos way to assure a good purge. webstone has nice valves for this purpose.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Norm Harvey
    Norm Harvey Member Posts: 684

    Ive always done things the hard way aka Brads "Nightmare" scenario.

    I estimate the amount of concentrate I need and put that into a 5 gallon pail, then isolate the zones, drain an equal amount of boiler water out into a different pail to match the volume of the glycol I want to put in, and lastly pump the glycol into the system through the boiler drain.

    Id let all the zones run to have the circulator mix the glycol through the system. Go to lunch then check the PH.

    I try to estimate less so that if my PH is off I would add more rather than subtract more to get a desired PH level.

    The 55 gallon drum idea as brad suggested is something Ive never thought of, but could work very well to get things right the first time.

    There was an error rendering this rich post.

  • Watch out,,,

    for what you're getting from the mfg. Some (if not all) glycols are actually glycol and water mixed, not 100%. Here in CT they only way for me to get 100% was to order it special, they only sell that stuff in the extreme north (or south) climates. THEN they wanted me to buy a whole PALLET. I "sweet talked" them out of that one, if you know what I mean. My big mistake, after carefully measuring what water went into my sysetm for cleaning and then how much was removed again after rinsing, was to add 40% system volume of the "glycol" from the can and add 60% water. Turned out WAY WAY WEAK when I did an analysis. Why? Because the &#$% "glycol" in the can was actually already 50/50 glycol to water. And yes then came the aformentioned nightmare of removing solution, adding more, removing more, adding more etc etc until I FINALLY got it where I wanted. Cost me a whole lot of time and extra glycol that came out of and killed my profits on the job. The system held 125 gallons! So yes, it hurt, a lot! Make sure you know exactly what mixture is coming in your cans. Do an analysis on what's in there before you decide how much to dilute by. Or call the mfg's chemist and ask.
  • Darrell
    Darrell Member Posts: 303

    Maybe I'm not as fussy as some of the others but on an existing system I try to make sure it is clean first. Then I run it with straight water for abit cuz the air comes out tons easier than with glycol. Then I use a five gallon bucket and a standard issue sump pump with a washing machine hose. I get the premixed stuff that is dyed and just pump it in, usually at the drain on the boiler, through the boiler and then through each zone and out the zone purge valve. As soon as I get color at my drain hose I know it is full. The mixing with the system water doesn't seem to be a problem, wasting is held to a minimum, no air is introduced to the system, the pump goes at a nice pace that I can keep up with and it doesn't have enough guts to pop the relief valve if I get distracted for a minute. I get the pre-mixed glycol in five gallon buckets because I can fill my pump bucket with one and then up-end another on the top of the pump bucket and as long as the spout on the upside down bucket is in the fluid in the pump bucket it won't dump...until the level in the pump bucket goes down enough to let air into the upside down bucket and then it will dump until the spout is covered again...I work alone and this gives me lots of time to watch things going wrong. I can also add additives if they are called for the same way.

    No muss, no fuss. I pumped 120 gallons of un-cut glycol into a 40 year old system that I cleaned all summer just yesterday. On that one I looked up the capacity of the boilers, stepped off the length of the 2" mains and calculated their capacity. I WAG'd the capacity of the unit heaters, (8), and the baseboard zones and piping all of which are on monoflo tees. Then I calculated how much un-cut glycol I needed for the 60/40 mix using the water in system for the 40%. I filled all three boilers, and then the downstairs main, and then the upstairs main, (had to use a boost pump for that...not enough lift), until all 120 gallons was gone. I checked today after running 24 hours and the system is protected at 56/44 ration...perfect. The sump pump rate was slow enough that it went past the monoflo tees without going into the individual zones.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • World Plumber
    World Plumber Member Posts: 389
    pdrainsump bypass

    I like to build a bypass loop on the pump. I use a tee at the inlet and outlet with a ball valve in the middle then ball type boiler drain valves at the inlet and out let of the tees. This allows you to keep the pump running and circulate the water/antifreeze thru itself while you refill the bucket so you don't pull air into the system.
This discussion has been closed.