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Mod Con Boilers

Modulating – condensing boilers (better known as mod con boilers) are offered by many boiler manufactures today.  They range in size, shape, price, and system capabilities.  These high-efficiency “mod con” boilers- Modulating & (Condensing –covered below)  which means it’s variably burner automatically adjusts to the lowest amount of fuel required at any given time, based on real-time heating demands.  This modulating feature of the burner & heat exchanger allows for the smallest amount of fuel consumption possible.

What is Turn Down Ratio?

This is a term when explaining the Modulating capabilities for the given boiler in question.
For example.  If you have a 200,000 BTU boiler with a 10:1 turn down ration, the boiler can produce heat @ 20,000 BTUs at its lowest level, and up to 200,000 BTUs at a full firing rate.   Common turn down rations are 3:1- 4:1 – 5:1 & 10:1 being the most flexible.  (The greater the ratio the greater the boiler’s modulating capabilities)   

Mod Con Boilers contain on board computers, perform system diagnosis and are available in a range of BTU output from small residential units @ 80,000 BTU’s up to 2-3 Million BTU “rack systems” for commercial applications.   Mod Con rack systems (shown below) is a series of high-efficiency “mod-con” boilers installed together in a shared, integrated system, pre engineered and sized for each specific application.

What does CON stand for-

Con-  stands for  Condensing –  This term “condensing” qualifies for all boilers over 90% efficient AFUE, because all boilers over 90% AFUE  produces water vapor within the exhaust gases.  As this condensation is produced within the exhaust pipes, slightly to moderately acidic vapors collect and falls back down towards the boiler as a liquid.  This acid water should be dealt with accordingly.  Note- All high-efficiency boilers over 90% AFUE are all condensing boilers, but most (not necessarily all) condensing boilers are also modulating boilers. 


mod con boiler

Seen Here- 
Viessmann Commercial Rack System 

-Three (3) – 200,000 Vitodens 200 Boilers
-Viessmann Rack / Grundfos Pump(s)
-Custom condensate removal

Location:  115 Washington ave, Bridgeport- CT
115 apartments- senior living

System Specs-  Total BTUs = 600,000 BTUs In
95% AFUE

Building Load-
-Baseboard heating for lower 5 floors of 10 story apartment building-  Roughly 55 units water heated (upper 5 floors electric baseboard heat)
-Domestic hot water for entire building 110 units + laundry & common areas.

System Notes/  This viessmann rack was tied into a TECOGEN cogeneration system.   This building is one of the most efficient buildings of its size, in all of Connecticut.   Data will be available in the Fall of 2017 to confirm these claims.

Note-  Commissioning the viessman rack system with the existing Tecogen co gen wasn’t easy, we had over heating issues due to the nature of the 20-year-old Co Gen plant, which had extremely out dated controls and no cold water mixing valve.   With the help of Tony Audio, NE rep for Viessmann-  we were able to get the two system working together.