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Axiom Feeder Tanks for Hydronic Heating Systems

Many existing hydronic heating systems out there could benefit from the addition of an Axiom fill system– a type of boiler feed tank that provides improved long term performance and ease of maintenance.


Fluid Levels Drop

A hydronic heating system uses a boiler to heat water that is then circulated through radiators, or pipes under the floor. Ideally, such a system would be totally closed and never need any fluid added to it, but in practice, this is not possible. Over time, some water will always be lost to evaporation (and perhaps leaks). In addition, any volume of water will have some air dissolved in it. As the water circulates, these dissolved gases are eventually liberated and bled from the system, with an attendant drop in the fluid level. Accordingly, these systems eventually need to be topped up.



There are two methods for maintaining the fill of a hydronic heating system. Many boiler feeds are just connected to the municipal water supply; this requires the use of an automatic water valve with a backflow prevention mechanism, regulating the water level inside the system while preventing that water from flowing back out. It’s crucial that this backflow prevention device be checked annually to ensure there is no cross-contamination between the water you drink and the treated water inside the system.

The second method is to use an Axiom feeder tank to store a mixture of glycol and water for the boiler, allowing a total separation of the heating system from the potable water supply. Routine service of one of these tanks just entails stocking it with fluid and maintaining the optimal water/glycol ratio.


Why A Water-Glycol Mix?

The use of inhibited glycol in your heating system prevents freezing, reduces corrosion by minimizing oxygen levels in the water, and improves the heat transfer properties of the system. These are essentially all the same reasons we use antifreeze in our cars; it means better efficiency, longer life, and fewer breakdowns.


Better Over The Long Term

There are a couple of advantages to using a glycol feed tank versus a municipal water feed. It allows for easier testing of the glycol levels, which should be no lower than 30% and no higher than 50%. It’s also a simple retrofit, and if you compare its installed cost to the annual maintenance cost of backflow prevention, the Axiom tank can pay for itself in about five years, with a life expectancy of about fifteen years.


Give us a call!

Axiom is a Canadian brand manufactured in Saskatchewan, and represents the industry standard for glycol feeder tanks. We here at Instant Plumbing have oodles of experience with hydronic heating systems; give us a call to arrange a free consultation on how to improve yours.

George Pinel
George Pinel

These blog posts are brought to you from George Pinel & the Instant Plumbing team.

2 thoughts on “Axiom Feeder Tanks for Hydronic Heating Systems”

    • Hi Gerald,

      No, if it is inhibited glycol you can add in right out of the pail

      You can always call us if your are unsure.

      Take Care!


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