Anti-Freeze / Boiler Water Treatment

Hi.
I was reading the install manual for my Harman Hydroflex 60 Boiler and came across something interesting.
It states the following:

Anti-freeze and / or boiler water treatment:
There is no restriction on the type of commercial antifreeze used. When filling the boiler water system, it is
recommended that some form of boiler water treatment be used.

Has anyone done this? What are the pros and cons of not adding it?
And, how would you do it if it wasn't done during installation (a year ago)?

Any input would be greatly appreciated. Thank you.

I don't know if it helps or not. I put 10 gallons in my system because I have underground piping. I drained 10 gallons of water out of my boiler and then removed my temp guage on top and used a funnel for the glycol. They don't give that stuff away I tell you. Cost me about $170, but well worth it.

I don't like to see anti-freeze in a boiler unless NEEDED. It's ongoing maintenance & expense that 98% of boilers do not need. If you want to add a quart or two of anti rust, fine. Just drain one or two quarts from the system then use a 5 gallon bucket, a pump & a washing machine hose & pump the anti-rust in.

Don't do either unless absolutely necessary.

melpeters wrote:Hi.
I was reading the install manual for my Harman Hydroflex 60 Boiler and came across something interesting.
It states the following:

Anti-freeze and / or boiler water treatment:
There is no restriction on the type of commercial antifreeze used. When filling the boiler water system, it is
recommended that some form of boiler water treatment be used.

Has anyone done this? What are the pros and cons of not adding it?
And, how would you do it if it wasn't done during installation (a year ago)?

Any input would be greatly appreciated. Thank you.

CYA statement from the manufacturer.

If you wanted your system to be winterized such that you didn't have to worry about it freezing if there were no power or heat, then the antifreeze would be recommended. However, it is very expensive and should be bought pre-mixed with De-ionized water for purity. It also must be made with inhibitors formulated for HVAC systems. Automotive antifreeze can damage parts of an HVAC system. It is best bought in 55 gallon barrels. I bought a barrell two years ago at $6 per gallon premixed to 40% (wholesale cost) or $330 per barrell plus tax. I used it in my workshop system, so I didn't have to keep the heat on in the workshop all of the time.

Note that antifreeze will "clean" the system and any leak will show up. It is a pain to keep the stuff from leaking from valve packings.

If your system is already filled, don't worry about water treatment. Once sealed, the oxygen reacts and is used up. Adding water treatment in a residential size system after the fact is a waste of time and money.

The reason antifreez is not recommended in a boiler is that most people don't know what they own. If there is a domestic hot water coil in the boiler with pin holes(happens all thr time) the anti- freeze can weep into your domestic water supply.

steamup wrote:any leak will show up.

For sure, anti-freeze is molecularly smaller than water. It will leak where water can not.

Brian wrote:If there is a domestic hot water coil in the boiler with pin holes(happens all the time) the anti- freeze can weep into your domestic water supply.

Well, no..... the domestic coil is at house pressure (40ish or more PSI) the anti freeze would be at boiler pressure (less than 20PSI) If the coil springs a leak, in short order the domestic water will go into the boiler and blow off the pressure relief.

And don't forget that anti freeze is not a one time expense. It needs to be tested now & then & either replaced or additives added if it becomes acidic. One other thing.... antifreeze does not transfer heat as quickly. It will take longer to come up to temperature. It will not use more fuel, but it's slower to move heat. Back when I was doing plumbing if we knew for a fact that a place was going to get anti freeze we would increase the amount of baseboard by 20%.

Correct Freddy,

For Glycol solutions, the specific gravity is greater than water and the Specific heat is less than that of water. Actual values depend on concentration. Net result is lower heat transfer for the same given flow.

I used propylene glycol not ethylene glycol for my antifeeze. Propylene is non-toxic to humans but a little more expensive.

Fred

What if your domestic water pressure went to 0 psi. and you had 20ish psi in your boiler with a leaking domestic water coil where would your anti-freez end up? In my opinion not a good practice.

Thanks guys. We did install a backflow preventer when we hooked up the domestic water supply. No DHW is being used from the Stoker (to far from house). We used a propylene glycol mix and its the mix they sell everyone with Outdoor wood boilers. I'm just concerned that we have a leak as the color is totally gone, and some of our pex lines have turned gray or brown. thanks again. bob

I replied to your other post about the boiler leak. The pex lines should not have changed color if it was indeed oxygen barrier or pex al pex. I beginning to think that regular/potable hot water pex was used in this system. Do you have any small pieces left from the install that you can show a close up picture of the pex tubes cross section. If standard pex was used that could explain the missing antifreeze.