First, the appliance price is only one factor in the "installed" price and frankly the least of it. There are competitive condensing boilers on the market that we sometimes install for less than their cast iron equivalent.
The cast iron boiler is a high-mass boiler and may in fact last longer than a low-mass condensing boiler with a stainless steel heat exchanger, but the potentially longer life of cast iron is offset by the lower efficiency. Much lower efficiency, in certain applications.
If the question is; which is better, we are back at definitions. The Burnham module is made for the unit and is a sure thing if you are so inclined. The Tekmar must be installed and programmed for each system and is not "plug & play" though the Burnham should be programmed for each application.
The most important consideration when choosing any boiler is getting the right contractor to install and maintain it. Internet "research" is a very unreliable way to choose a boiler, since their is no way for the consumer to assess the quality of a boiler or its real value without considering the ability of the contractor to properly size the boiler, his trade skills for installation, or the local support he may, or may not, get to properly service the unit you find ideal.
As for reliability, we have installed 10 different condensing boilers, most with stainless heat exchangers, with perfect luck. Some have not been serviced in more than 6 seasons. We recommend yearly maintenance for safety, reliability and warranty.
We also install Burnham cast iron boilers for those who value reliability above performance and ROI. We love boilers and don't discriminate.
