Hybrid Boiler Systems in Houston, Austin, and San Antonio

Hybrid Boiler Systems

Hybrid Boiler Systems

What is a Hybrid Boiler System?

In short, a hybrid boiler system is one that combines condensing and non-condensing boilers in one system to provide the owner with the best return on investment in terms of energy efficiency, longevity and reduced first cost when compared to an all condensing type boiler system.

Why and where would you consider using this system?

Not every hydronic boiler system is used in the same conditions.  That being the case, here are some facts to consider:

  • Condensing happens ONLY when return water temperatures to the boiler are between 130-140F because the dew point of the exhaust gases is typically in the range of 135F.
  • Boiler cycling is one of the main contributors to both excessive fuel consumption and reduced life span of the boiler equipment.
  • Advanced PID controls are needed to allow the proper operation of a hybrid boiler system.
  • A hybrid system is an acceptable design for both new construction and retrofits alike, given that proper attention is given to the loads present.
  • Here in South Texas, we use approximately 20% of the entire designed boiler system capacity 80% of the time.
  • Condensing boilers are typically made of alloyed stainless steels or high mass metals such as cast iron in order to deal with the acidic nature of the condensing liquid byproducts of the combustion process.
  • Condensing boilers are 20-50% more costly (BTU for BTU) than their non-condensing counterparts.

So, a prime candidate for a hybrid system is one where the typical 160-180F design criteria is not really needed or warranted.   After all, the old 160-180F design was not used because that was all the coils in the system could function properly with, it was used to protect old fire-tube or high mass boilers that could not take return water temperatures of less than 140F.  These temperatures are seldom needed, except for in the coldest of design days.  This is a relic of the past that can now be remedied with a hybrid design!  A plant that must provide temperatures this high to maintain a process, for example, is not a good candidate.  However, a K-12 school, higher education buildings, office buildings etc. are all good candidates!  Why?  Simply because these buildings can usually be satisfied for 80% of the year (reheat) by much lower supply water temperatures, this means you could be in the condensing range for that same percentage of time.  This equates to huge energy savings, a minimum of 20% should be expected and 40-50% can be achieved when controlled properly.  The end result in a retrofit is a more affordable (when compared to all condensing) and a much shorter payback.

So how is the system sized?

If we look back at the fact that we use 20% of our total boiler plant designed load, 80% of the time we get our sizing guide.  A condensing boiler is typically sized to satisfy this 20% of the load with the remainder being made up of lower cost non-condensing boilers.  It is important to note here that in retrofit applications, it is not always necessary to replace all of the boilers if there are multiples.  A condensing boiler can simply be added in front of the legacy unit(s) to provide this ability to drop the loop temperatures.  However, controlling the legacy boiler(s) needs to be addressed properly in order to maximize the system efficiency.

Here are a few of the hybrid boiler systems we offer:

Firebox LPD HF
The Firebox LPD HF design is suitable for applications to produce low pressure steam or hot water in ranges from 3,450 – 20,700 lbs/hr (3.4 mm BTU – 20 mm BTU) output at 15 PSI steam or 30 PSI hot water.

Hybrid RG
The Hybrid RG design is suitable for applications to produce high pressure steam or hot water in ranges from 3,450 – 60,000 lbs/hr (3.4 mm BTU – 60 mm BTU) output from 100 up to 400 PSI.

Hybrid CG
The Hybrid CG design is suitable for applications to produce high pressure steam or hot water in ranges from 3,450 – 60,000 lbs/hr (3.4 mm BTU – 60 mm BTU) output from 100 up to 400 PSI.

Hybrid PF
The Hybrid PF design is suitable for applications to produce high pressure steam or hot water in ranges from 3,450 – 60,000 lbs/hr (3.4 mm BTU – 60 mm BTU) output from 100 up to 400 PSI.

Hybrid UF
The Hybrid UF design is suitable for applications to produce high pressure steam or hot water in ranges from 3,450 – 60,000 lbs/hr (3.4 mm BTU – 60 mm BTU) output from 100 up to 400 PSI.