While recently taking delivery of a large Weil-McLain Ultra Oil Boiler, our distributor’s driver commented: “I hate to deliver these boilers, they are so (mild expletive) heavy compared to the Buderus and the other ones.” (This large distributor markets several popular product lines.) The driver’s comment became evident when three of us were needed to tip up the crated boiler dolly in the truck, then four to move it into the building. (The driver normally handles it himself in the truck and then another or two assist him to transit into location.)

This experience prompted us into a little research that confirmed the driver’s observation. Yes, the Ultra Oil is much heavier than its competitors — by 100 to 150 lbs at minimum for the equivalent firing rate (capacity). As Heating Engineers we also appreciate the design integrity of this new boiler “block”. It is a “beautiful beast” in a very complimentary fashion, both in performance and serviceability.

As a lifetime “motor head” (car performance enthusiast) the analogy came to me immediately. “It’s a Hemi!” This term originated in the 1950’s and was recently revived in advertising of Chrysler Engines that have dominated Drag Racing and other racing forms. Originally designed as an Industrial & Marine Engine, it was big, heavy, durable and ultimately very powerful. A modified 180HP automobile motor readily became a 1500+HP racing motor.

So what does this have to do with boilers? Boilers are heat engines in the purest sense of the term. They ignite and burn fuels to efficiently generate hot water (or steam) to warm our living environment. In an automobile heat not converted into mechanical power is wasted. The boiler meanwhile is all heat generation and tempered distribution.

Harnessing heat energy also entails risk. (Boilers are necessarily constructed of “sections” with seals between them. Picture a loaf of bread made up of “slices” with “crusts” at each end.) Controls manage this process but may not ultimately protect the boiler from damage under some circumstances, namely:

  1. Water itself has minerals and contaminants that generate sludge in the bottom of boilers (and piping). (Open your boiler drain valve to confirm, if you dare.) Sludge corrodes, eating cast iron and particularly steel boilers, reducing their life and heat exchange efficiency. Doesn’t help the seals either.
  2. A damaged combustion chamber may permit direct firing onto exchanger surfaces creating “hot spots” that create thermal shocking and failure conditions.
  3. Introducing cold water into a hot boiler, thermally shocking it. Can sometimes occur even during normal operation when large, cold heating zones are suddenly demanded into a hot boiler. The metallurgy of the heat exchanger changes, embrittling it to ultimate failure by cracking, warping the section(s) and causing internal seal failures. Either situation is catastrophic.
  4. Using anti-freeze compounds. Many manufacturers, particularly of older boilers, prohibit their use. Newer seal materials have limited the risk. However, check your Warranties! Even using the recommended anti-freeze increases leakage potential in the system. (Servicemen generally dislike its use.)

Summarizing: Cast Iron and Water Volume = Increased Boiler Life and Performance

The boiler operates at a lower average temperature and accommodates load and surge conditions more readily with no efficiency penalties.

May we suggest that it is also a better value?