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Condensing vs. Non-condensing Heaters

As the weather starts to warm up, you might not want to think about heating equipment. But now is the best time to plan a replacement for your old boiler or furnace and it’s a decision that will affect your family for many winters to come.

One important choice you have to make is whether to go with a condensing or non-condensing heating appliance. If you have an old boiler or furnace, it’s probably non-condensing since condensing type heaters are fairly new.

So how do you make the right choice? Here are the differences between the two technologies and some tips for choosing the right equipment.

Non-condensing heaters

For non-condensing boilers and furnaces, the heating temperatures are kept high enough to prevent water vapor in the flue gas from condensing.

If it does condense, this condensate causes corrosion due to its acidity. But operating a boiler or furnace to prevent condensate also means that precious heat is lost to the atmosphere as the water vapor is released. This limits efficiencies to the 70-80% range.

Condensing heaters

Condensing boilers and furnaces make use of the energy in the water vapor by using it to preheat the water or air, recovering energy and increasing the heater’s efficiency to 95%. To achieve this, the burner and heat exchanger materials must be resistant to corrosion, and the operating temperature of the boiler or furnace must be lower.

So which one is better?

From an energy perspective, condensing boilers are more desirable, even with a higher initial cost. However, there are other considerations for these systems.

Discharging the condensate

One consideration is that the acid in the condensate needs to be neutralized before it can be discharged to the drainage system. This is accomplished by a condensate neutralization kit, which is a key component of condensing systems.

Operating temperature

Because the operating temperature of a condensing system is lower, this affects the performance of the heat emitters and distribution system for boilers. You may need to change radiators and piping if you are replacing a non-condensing boiler with a condensing boiler.

Venting requirements

Venting for the two systems is different. Because of the non condensing boiler’s higher operating temperatures, a metal type B vent with a vertical termination is required. Condensing boilers are vented with fan powered plastic (PVC) pipes that can be terminated through a side wall. The combustion air for condensing burners is taken directly from outdoors, unlike non condensing systems that take air from the room.

If you’re purchasing a new boiler for your home and you don’t know which one to choose, give us a call and we can help you make the right decision.