Boiler Heat Exchanger: Aluminum vs. Cast Iron vs. Stainless Steel

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Boiler Heat Exchanger: Aluminum vs. Cast Iron vs. Stainless Steel

Energy efficiency is always good when it comes to heating and cooling your Denver, CO home, right? Yes, but in the world of boilers used for radiant heat, the answer isn’t always quite that simple. Builder’s Heating & Air Conditioning wants to make sure you have all the information you need to make the best decision for you.

It’s a case of materials


The heat exchangers in boilers can be made from cast iron, aluminum, or stainless steel. Each has advantages and disadvantages. The most efficient boilers are condensing boilers. The process that makes them efficient also produces an acidic condensate which requires stainless steel construction. The acid would quickly damage cast iron or aluminum boilers.

So, what’s the point?

While energy efficiency is always an admirable goal, this is a case where it comes with a pretty high cost and may not pay for itself in the long run. Here are some of the factors to consider:

  • Upfront cost—As noted above, high-efficiency condensing boilers must be made of stainless steel. They are going to cost much more than a cast iron boiler. Aluminum is the least used material and falls somewhere in between in terms of upfront costs. It does have the advantage of being much lighter than the other two and transfers heat more efficiently than cast iron.
  • Life expectancy—A cast iron model can easily last 25 to 30 years with proper maintenance. Twenty-five year warranties and limited lifetime warranties are common on cast iron boilers. Even with stainless steel construction, the acid produced during the condensing process in high efficiency models will shorten the expected lifespan. Most warranties are for 10-15 years. Chances are you will be replacing a stainless steel boiler while a cast iron model is still going strong. 
  • Maintenance—Understand every situation is different and blanket statements don’t always apply but cast iron boilers generally seem to require less maintenance than the other two materials.

Bottom line

If energy efficiency, a smaller carbon footprint, is important to you, then, by all means, go with the high-efficiency stainless steel boiler. A good second choice is an aluminum. Just be aware that in both cases the lower fuel costs may not offset the upfront cost and shorter life expectancy when compared to a cast-iron boiler.

Depend on Builder’s

If you need more information to determine what boiler is best for you, call Builder’s Heating & Air Conditioning. Whatever type of heating system you have in your Denver, CO home, our technicians can perform annual maintenance to prevent breakdowns during a frigid Rocky Mountain winter.