What Types of Steam Traps Can You Insulate?

 What Types of Steam Traps Can You Insulate?

“Should I insulate my steam traps?” That’s a question we get asked regularly, and there seems to be some confusion about whether or not you can or should do this. The answer is simple — yes.

And no.

Let me explain. There are some types of steam traps that are perfectly safe to insulate, and steam trap insulation jackets can save you a hefty sum. Reduced heat loss from the trap means you’re getting more from your steam system, which leads to increased energy and money savings.

Alternatively, you don’t want your steam system to look like this:


Which could be the result of insulating certain types of steam traps.

So, which types of steam traps are OK to insulate?

  • Float
  • Float & Thermostatic (F&T)
  • Inverted Bucket
  • Orifice Traps

Let’s say you’re a university that’s looking to save some energy and money. You’ve noticed that your steam traps aren’t insulated, and that you’re losing heat from them. All 500 of them. Upon closer inspection, you find out that about 200 are of the type that can be insulated. Go ahead, do your money dance, nobody’s looking.

Of course, that leaves about 300 steam traps that should not be insulated. In this category of steam traps are:

  • Thermostatic  (Balanced Pressure/Bimetallic)
  • Thermodynamic

Why should you never insulate these steam traps?

Thermostatic traps work by opening the valve based on the temperature difference between the steam and the condensate. If you insulate these traps, it takes the condensate longer to cool and the valve won’t open as frequently. This can lead to condensate backing up into the system, potentially causing water hammering or implosions – neither of which is good.

Thermodynamic traps are similar, except they operate based on differences in pressure instead of temperature. Unfortunately, insulating these traps will have the same disastrous results as with thermostatic .

So what should you do with these types of steam traps? Leave them alone and look at other areas to save heat and money – like your valves, flanges, expansion joints, heat exchangers and other commonly uninsulated systems.



About Thermaxx Jackets

Thermaxx Jackets was founded over 25 years ago with a single purpose: to save energy when traditional stay-in-place insulation is not practical. Combining expertise in heat loss, wireless monitoring, insulation design, and several other disciplines, we’ve become the #1 provider of removable insulation jackets and covers.
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4 Responses to What Types of Steam Traps Can You Insulate?

  1. stephen says:

    i am writing a project on steam trapping and your publication i must say, has been a great resource. thanks.

  2. Steve Shostak says:


    I have worked with many of the major steam trap companies for almost 30 years, have participated in over 100 steam surveys in almost every state in the union as well as Puerto Rico. I give seminars to ISA, ASPE and ASHRAE meetings, engineering companies, mechanical contractors, and end users regarding steam specialties.

    Based upon my experience as well as the application engineers I have learned from globally, one of the things I stress is that one should NEVER insulate any steam trap, as they must radiate heat away from the body in order to maintain an internal water seal…which is the real ‘steam trap’ in any design: all the rest is just a difference in actuation methods.

    Much work goes into insuring the proper amount of mass to both maintain a specific pressure rating as well as insuring the production and maintenance of heat loss so there is always (except for a few designs) a water seal.

    While insulation is a fine thing, heat loss is inevitable and a good case can be made for using smaller-design traps rather than large ones due to the waste of heat loss. I have personally solved many problems with traps around the USA that excessively blow-through—simply by removing the insulation and allowing the water-seal to be maintained. Insulation, if desired, can be used on the inlet piping (allowing a typical 6″ gap pre-trap) and the outlet piping (allowing a typical 3″ gap due to cooler condensate temperatures)….never on the trap—any trap….

    Sorry, but that’s physics for you!

    Steve Shostak

    • Will Jones says:

      Thank you for your input on the insulation of steam traps and which steam traps should or can be insulated.
      I agree with much of what you are saying, it makes sense. My experience in this field (44 years) has taught me that:
      1. There are as many opinions on insulating steam traps and steam trap stations as there are manufactures and types of steam traps.
      2. If an inverted bucket steam trap is over sized and it is insulated it will definitely blow through.
      3. Float and thermostatic steam traps respond very well to insulation, they, in many cases are a constant discharge trap. The thermostatic element is utilized on startup and seldom during normal operation.
      4. Thermostatic and Thermodynamic type of steam traps cannot be insulated, the steam trap depends on heat radiating from the steam trap for proper operation.
      5. When approaching a facility we listen to the philosophy the Facility Manager on the issue of insulating steam traps and provide insulation jackets per the site specific philosophy.

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