Presented by: Terry Stohs Viessmann Manufacturing Company Inc.

Design Challenges in Commercial Building. Efficiency Regulations Mechanical Room Space Customer Comfort Installation Cost System Design Operational Cost System Longevity System Integration(BMS) Initial Investment Return On Investment

What makes a Condensing Boiler Condense?

Nov 2005Foil 4 ENERGY CONTENT OF NATURAL GAS SENSIBLE HEAT 89.8% Heat that can be measured or felt by a change in temperature LATENT HEAT 10.2% Latent – Definition: Latin for “hidden”

 Simplified Chemical Combustion Formula: CH O 2 CO 2 +2 H 2 O HEAT RECOVERY FROM FLUE GASES How do we capture the latent heat? Water vapor (steam) containing latent heat

MARKETING AND REALITY 99.8 % THE MOST EFFICIENT BOILER 98 % EFFICIENT ….can reach efficiencies of 98% - and more….. Thermal efficiency Combustion Efficiency AFUE

What Are The Test??

Condensate measured for condensing boilers test Heat Exchanger Constant Load ∆T=100°F BTS-2000 Air Input Fuel Input 180 o F 80 o F COMBUSTION EFFICIENCY TESTING For condensing gas commercial boilers >300 MBH Efficiency is manually calculated using formulas in BTS-2000 or CSA B Efficiency is manually calculated using formulas in BTS or CSA B

THERMAL EFFICIENCY TESTING For commercial gas or oil boilers >300 MBH Q IN Heat Input, btu/h Boiler T IN – Fixed water temp ( o F) Condensate measured for condensing boilers T OUT W= Mass of water (lb) ∆T≥100°F BTS-2000 NOTE: In some appliances the combustion and thermal efficiencies are so close that the thermal efficiency can actually be measured higher than combustion efficiency. This can be due to a very well insulated jacket (low standby losses), the testing environment (space warmer than Return Water Temperature) and small errors in the test results. ANSI Z21.13 / CSA

Condensing boiler Sensible heat Condensation Latent heat Total heating value Useable heat Heating system MORE USABLE HEAT THROUGH CONDENSATION What influences the rate of condensation?

Do All Condensing Boilers Perform Equally? Remember, efficiency depends on the rate of condensate formation!

Heating system Govt regula- tion Fuel Burner type Return water temp Effective use of condensing technology Piping layout FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY

Govt regula- tion Effective use of condensing technology FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY

Heating system Return water temp Effective use of condensing technology FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY

Foil Dew Point of Natural Gas Condensing mode Non-Condensing mode Steady state boiler efficiency % Boiler return water temp of 98 SIMPLIFIED CONDENSING BOILER OPERATION 133

How do we get the most from a Condensing Boiler??? Condensing Technology. Rein in the energy savings. Flue gas condensing In contact with the Boiler’s heat exchanger Boiler Heat exchanger Flue gas Latent energy transferred into heating system Make It RAIN!!!

Boiler return water temperature determines condensing operation RETURN WATER TEMPERATURE

2. Efficiency  Eliminate overheating  Three to one rule  Lower standby losses Why use it? 1. Comfort  Slow space temperature changes  Constant heat output  Keep up vs Catch up Outdoor Reset Control

oFoF Boiler Water Temperature Dew point Natural gas Traditional boilers must be kept hot 140 o F Boiler water temperature modulated oFoF Outside Temperature On/off control Boiler water temperature maintained HYDRONIC WATER TEMPERATURES

IMPACT OF SYSTEM TEMPERATURES ON CONDENSATION Supply/return temperature: 167/140 o F oFoF 167 o F 140 o F Dewpoint temp 133 o F Condensation range 11.3 o F System water temperature oFoF Outside temperature 68  Fan  Radiators

SYSTEM WATER TEMPERATURE DROP Typical system 20 o F Temperature drop 160 o F What about a higher temperature drop? 30 o F……40 o F? 140 o F

Air flow 160 O F 140°F Fan Coils For Condensing Boilers Traditional Fan Coil Sizing 150°F

Air flow 170 O F 130°F Fan Coils For Condensing Boilers Fan Coil Sizing 150°F

INFLUENCING THE RETURN WATER TEMPERATURE Let’s get creative

Hybrid System System Return System Supply Condensing boiler Non-Condensing boiler Condensing Boiler

Burner type Effective use of condensing technology FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY

Natural Gas Combustion 1 part gas 10 parts air +Excess air More excess air = Lower CO 2 % Lower C0 2 % = Lower dew point temperature Lower dew point temp. = Less condensation What happens as we increase excess oxygen to achieve better flame quality?

What Methods are Available? Does it Change Efficiency? Turn Down

Higher CO 2 =Higher Dew point =More Condensation Dew point water vapor oFoF Natural Gas (95% CH 4 ) Lower CO 2 =Lower Dew point =Less Condensation  Water vapor condenses below the dew point temperature

Turn Down Methods Single unit multiple gas valves and burners Low Mass High turndown Multiple Gas valves single burner Multiple boilersHigh Mass boiler

Effective use of condensing technology Piping layout FACTORS INFLUENCING EFFECTIVENESS OF CONDENSING TECHNOLOGY

USE OF MIXING VALVES WITH CONDENSING BOILERS 3-way mixing valve Lower boiler return water temperature. CORRECT 4-way mixing valve Boiler return water temperature elevation INCORRECT

CONDENSING BOILERS IN TWO TEMPERATURE SYSTEMS Low temp system High temp system

COMBINATION OF BOILERS LAG BOILER LEAD BOILER System Return System Supply Condensing boiler Boiler

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Thank You!!! Terry Stohs Viessmann Manufacturing Company Inc.