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Antifreeze installationinto a heating boiler Heating Boiler Anti-Freeze FAQs

Heating boiler antifreeze types, installation, questions & answers.

This article series describes how to add anti-freeze to a heating boiler and to the hot water or hydronic heating system piping, baseboards, convectors, radiators, etc. to protect the system from freeze damage.

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Q&A on How & Why do You Add Antifreeze to a Boiler?

Input feed to a heating boiler riser pipe (C) Daniel FriedmanThese heating boiler antifreeze questions & answers were posted originally at ANTIFREEZE for BOILERS - be sure to review that information.

On 2018-10-13 by (mod) - Lowering heat transfer rate from heating pipes to the occupied space will always increase the system heating cost.

Vlad

You're right;

The aquastat control turns on the oil or gas burner based on boiler temperature (and a few sophistications on that)

while
the thermostat, on a call for heat, in most installations, simply turns on the circulator pump to cause hot water to circulate through the various heating zones.

An exception is in some countries such as Canada where custom is to wire the circulator to run continuously during winter weather; in that case (giving more even heat and improved freeze-proofing), the thermostat will turn the burner on and off.

The "heat loss" that you cite is not necessarily undesirable, depending on where those heating pipes are routed, as they may be delivering heat to areas where it's actually needed, for example to avoid frozen pipes or to keep a crawl area dry.

Lowering heat transfer rate from heating pipes to the occupied space will always increase the system operating cost.

On 2018-10-13 by Vlad - lowering heat transfer will also lead to lower heat loses when no call for heat.

There is a thermostat inside boiler that turns on boiler burners by water temperature inside the boiler, not just by call for heat.

When temperature drops beyond the certain level (it depends on boiler settings) AND there is a call for heat, burners will start. Burners will stop when boiler temperature will reach the settings. Therefore, lowering wetting action by adding antifreeze will just delay heat transfer.

It will cause longer times to release the heat from water and from the boiler, not to burn more gas or oil. In other words, boiler will keep its water temperature longer.

There is some heat loss during journey of hot water to radiators though. It means that extra energy will only be used for

(1) additional time to run the circulation pumps (which is minimal in residential heating) and

(2) on extra heat losses during water journey via pipes to heat exchangers (like radiators etc).

On the other hand lowering heat transfer will also lead to lower heat loses when no call for heat.

On 2017-10-14 by Anonymous

I also discovered antifreeze in the drinking water (luckily non-toxic antifreeze was used). I don't have a tankless heater, but I do have a Boiler Mate water heater incombination with a Well Mclain boiler. Is the water heater the only location where antifreeze could mix with fresh water, or are there other possibilities in the boiler itself. I see a

On 2017-09-27 00:03:53.974827 by Pat

Can't get antifreeze replaced until spring. Is there anything we can add to keep the corrosion down through the winter??

On 2016-12-01 23:27:10.106935 by Anonymous

is it normal to lose glycol during the winter months

On 2016-05-14 18:58:05.780693 by (mod) -

Check with your HVAC or plumbing suppliers

On 2016-05-14 05:02:23.042699 by George marty

Where can I buy 60 gal of glycol?

On 2016-05-04 18:08:43.613484 by (mod) -

Stop using the water immediately as you may be drinking poison.

Replace the leaking tankless coil used on your boiler to make hit water for washing.

Or

If your boiler has no tankless coil it's probably missing a backlog preventer valve.

On 2016-05-03 20:09:07.700382 by Anonymous

Antifreeze is leaking into our drinking water. What can be done about it?

On 2016-03-26 15:02:19.899086 by (mod) -

Milan

The boiler and piping are full of water - there should be no air in a hot water heating system boiler and its piping.

On 2016-03-25 22:48:41.365834 by Milan Petrusich

how much water should be in boiler for heating system

On 2016-02-09 15:23:55.338291 by (mod) -

NO, Bob, if you are having to add antifreeze I suspect there is a leak somewhere. A hot water heating boiler leak that causes water to have to be added to the system will dilute its antifreeze concentration. And of course none of this pertains to steam boilers.

On 2016-02-09 15:22:55.961308 by (mod) -

Re-posting

AUTHOR:Bob (no email)
COMMENT:Does antifreeze in a hot water boiler have to be added on a regular repeated basis, in other words boosted every 2 or 3 years?

On 2015-09-07 23:53:45.888138 by (mod) -

Hugh,

Which type of heating system to install is as full of opinionated argument as arguing about religion. Consider your view as a religious choice rather than one based on objective data.

That is to say each approach to heating has advantages and disadvantages.

Hot water heat is quiet, tends to maintain more even temperatures, is usually more economical to distribute in a building (piping rather than ductwork), and has been in use in various forms for so long that there are plenty of people who understand how to install and maintain it.

Forced warm air offers a particular advantage if the ductwork is to also be used to provide air conditioning and in buildings where instead of being worried about stirring up dust by blowing air around the occupants want to benefit from continuous air filtration that can reduce dust and irritants.

Forced air also makes winter air humidification a bit easy to achieve though there are sometimes snafus with mold in wet ductwork.

It's also the case that the system we understand less well often looks more daunting and troublesome.

In sum, polite rants are welcome but let's try to distinguish between opinion and objective fact, data, and evidence.

On 2015-09-07 22:24:34.741005 by Hugh Myron

Why would anyone install boiler heat in a residential home? Its such a pain in the ass, sure it might be slightly more efficient than Forced Air, but you know what? Air doesn't cause a disaster compared to water or glycol.

End Rant.

On 2015-09-03 by (mod) - propylene glycol is leaking into the drinking water?

AJ

For space and citations I've moved your question and given a detailed reply at

PROPYLENE GLYCOL DETECTION & POISONING SYMPTOMS

Post a question there if you need more information

On 2015-09-03 by AJ

How can you tell if the propylene glycol is leaking into the drinking water? What are the signs? Can it be seen, tasted or smelled?

Question: use of the Propylend Glycol that is put in RV's,Cabin systems,etc. (Uni-Gard-50) sold in Home Depot,

(Nov 16, 2012) Ron said:
Why can't the use of the Propylend Glycol that is put in RV's,Cabin systems,etc.(Uni-Gard-50) sold in Home Depot, be used in the Hot Water system of a home.

Reply:

Ron,

In the article above that is exactly what experts recommended.

Question: oily look in boiler water after installing antifreeze

(Jan 23, 2014) Marni Olsen said:
My plumber recently drained my Weil McLain Boiler & I have a Sid Harvery McDonnell & Miller cut-off. He put in what I believe is anti-freeze the water color is a light green & when I drain the water its slightly oily looking. I need to know if this is toxic since I toss the water outside into the ground.

Also is this the right anti freeze to use? THe plumber will not return calls & will not speak to me of what he did.

Reply:

Marni, there are two different types of antifreeze used in heating systems, one toxic and the other using food-grade products is non-toxic. You will need to ask the installer what product was used.

Installers may use either propylene glycol (non-toxic food-grade antifreeze, recommended where a tankless coil is used on a heating boiler and in some other cases), or ethylene glycol (automotive type and highly toxic antifreeze).

Leave a polite message for your plumber noting that you just want to know the brand and product of antifreeze installed.

About your comment "when I drain the water" - I'm unclear why you would ever be draining water from your heating system - that's not a normal step except for steam boilers which surely is not your case. What's going on ?

Let us know what you are told and I can comment further.

Question: other uses are there for boiler glycol

(Oct 5, 2014) Fred said:
What other uses are there for boiler glycol. I just changed boilers and have about 15 gallons left over

Reply:

Food grade antifreeze products are also used in winterizing RVs and plumbing.

Question: How do I turn on the circulator pumps without the heat on?

(Nov 22, 2014) Ed Roy said:

I have the right antifreeze, pump and hoses. I connected them as described, the problem is without the furnace turned on the circulator pumps do not turn on therefore blocking the transfer through the lines, the antifreeze only goes through the boiler.

How do I turn on the circulator pumps without the heat on? they only turn on when the temperature gets above a certain level and the thermostat is up demanding heat. I can't find anything that addresses this question.
Thank you, Ed Roy

Reply:

Ed you may need help from your heating service tech to turn on the circulator pumps or open zone valves - that can be done regardless of whether or not the boiler's burner runs.

Typically if power is on to the circulators it is also on to the boiler because they're usually powered off of the same electrical circuit.

But it's trivial to disconnect the power to the oil burner or gas burner, leaving it off while allowing the circulators to run either by calling for heat at the thermostat(s) or by jumping the thermostat terminals at the circulator relay.

Question: add antifreeze after minor plumbing work

I replaced a relief valve on the boiler, losing about a gallon of boiler water in the process. I added that water back. Do I need to add more antifreeze?

Reply:

Probably not - unless the total volume of your heating system is very small the reduction in freeze protection is likely to be slight.

Question: after adding antifreeze as a winterizing of the heating system, can I leave with the temperature set belo 55 degrees?

29 April 2015 Ron said:
after you have winterized your system ,does that allow you to leave for an extended vacation with the temp.set at lower than the 55 degrees f. that I set it at now.

Reply:

Ron:

The purpose of winterizing is to prevent freeze damage to building plumbing & other systems.

But there are choices to make between "heat on" and "heat off" winterizing methods. And the decision about the safest "low" setting of the thermostat depends on the particular home and what other winterizing steps were taken.

If heat is to be left ON in a partially winterized building see the procedure

at: WINTERIZE - HEAT ON PROCEDURE

If heat is to be turned OFF and the building completely winterized, see the procedure

at: WINTERIZE - HEAT OFF PROCEDURE

The temperature at which you can safely leave your heating system varies depending on many factors:

- the house insulation level or rate of heat loss

- the routing of or location of pipes that may be exposed to cold spots

- whether or not you've placed antifreeze in the heating pipes

Details are in the two articles I cited above. Don't hesitate to ask if after reading those you still have questions.


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