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BOILERS AND EFFICIENCY

Gary Archer

Vice President of Sales

JW Stevens Co.

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BOILERS AND EFFICIENCY

TYPES OF BOILERS – STEAM

Water tube, Fire tube, Cast Iron Fuels – gas, oil, combination Typical Efficiencies – 78-84%

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HOW DO YOU INCREASE EFFICIENCY ON STEAM BOILERS?

Burner/controls upgrades as discussed earlier

ECONOMIZERS!!!!

ECONOMIZERS

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ECONOMIZERS

Take flue gases from the boiler to pre-heat water that can be used for potable use if you have a large need for domestic hot water. (i.e. Hospital, Food Processing )

OR Use the hot water (260 degrees) to be used as boiler feed water. (Typical feed water temperatures

are 160-225) Increases boiler efficiency by 3% or more and

usually have less than an 18 months payback

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BOILERS AND EFFICIENCY

TYPES OF BOILERS - HOTWATER Water tube, Fire tube, Cast Iron Fuels – gas, oil, combination Typical Efficiencies – 78-84%

MODULAR BOILERS!!!!

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MODULAR BOILERS

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MODULAR BOILERS

Gas Only – Natural or Propane Small Footprint Low mass/light weight design Non-Condensing and Condensing

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What is a Non Condensing -vs- a Condensing Boiler?

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Non – Condensing BoilersThese style boilers run in the 85-86% efficiency range

regardless of return water temperatures.

Vessel design must allow for continuous operation @ >130 F return water temperature.

Heat transfer (fireside) surfaces do not consist of materials resistant to acidic condensate and corrosive elements. They are typically made of copper

Less expensive than condensing boilers

Typical Applications are Standard building heat and/or indirect DHW.

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Condensing BoilersTo achieve maximum efficiency a hydronic boiler must fully

condense. This means the return water temperature back to the boiler

must be below 130F. This allows for the flue gas temperature to drop below its dew point. This causes the water vapor in the flue gases to condense or change phase from a gas to liquid therefore giving off more energy

Vessel design must be such that the flue gases are cooled down as low as possible.

Heat transfer surfaces [fireside] must consist of materials resistant to acidic condensate and corrosive elements, typically stainless steel.

Condensing boiler efficiencies can run as high as 99%.

Typical Applications are radiant floor heating, snow melt, heat pump, hybrid heating systems

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Return flow temperature °F

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RelativeBoiler Load

Condensing

Non condensing

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Modular Boilers – Hybrid System

What Is a Hybrid System???

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Hydronic Boilers – Hybrid System

Hybrid Systems Utilize Both Non-Condensing And Fully

Condensing Boilers.

The Condensing Boilers Run In The Warmer Or “Shoulder”

Months (i.e. October, November, March, April) while the Non

Condensing Boilers Run In The Coldest Of Months.

Building management systems can control the enabling or

disabling of the two different type of boilers or most boiler

manufacturer’s have their own stand alone controls that can

achieve the same results.

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84

86

88

90

92

94

96

98

99

6820

80630

1004

1202

140 16058

Return flow temperature °F

Boi

ler

Eff

icie

ncy

%

20%

50%75%

100%

RelativeBoiler Load

Condensing

Non condensing

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Hydronic Boilers – Hybrid System

In conclusion about Hybrid systems,

Use the boilers that condense and get up to 99%

efficient when the outside air temperature is

milder and supply water temperature to the fin-

tube radiation in the occupied space can be lower

Use the non-condensing boilers in the coldest

months when you need high temperature water to

keep the occupied spaces warm. This will achieve

maximum seasonal efficiency.

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JW Stevens Co

Stop by our booth to see a case study on a DVD loop to see an example of a hybrid system we did last year with Oswego CSD.

They will earn well over $100,000.00 in National Grid Incentive Dollars