Cast Iron Boiler Vs. High-Efficiency Stainless Steel

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Cast Iron Boiler Vs. High-Efficiency Stainless Steel

When it comes to heating and cooling high-efficiency is always good right? Yes, but in the world of boilers used for radiant heat it’s not quite that simple. Merts Heating & Air Conditioning wants to make sure you have all the information you need to make the best decision for your Illinois or Northwest Indiana home.

It’s a case of materials


Most standard grade boilers are cast iron. It’s heavy, durable, and relatively inexpensive. Most high-efficiency boilers are called 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 boilers.

So, what’s the point?

While energy efficiency is always an admirable goal, this is one of those cases 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 (90% or higher) condensing boilers must be made of stainless steel. They are going to cost much more than a standard efficiency (80%) cast iron boiler.
  • 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—While understanding every situation is different and blanket statements don’t always apply, a stainless steel boiler does seem to require more maintenance during its lifetime than a cast iron counterpart.

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. Just be aware the lower fuel costs may not offset the upfront cost and shorter life expectancy when compared to a cast iron boiler.

Depend on Merts

If you need more information to determine what boiler is best for you, call Merts Heating & Air Conditioning. Whatever type of heating system you have in your Illinois or Northwest Indiana home, our technicians can perform annual maintenance to prevent breakdowns during a frigid Great Lakes winter. Be sure to like and follow us on Facebook and Twitter.