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State of MN/WI Small Boilers Dan Chudecke Mulcahy Co.

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Presentation on theme: "State of MN/WI Small Boilers Dan Chudecke Mulcahy Co."— Presentation transcript:

1 State of MN/WI Small Boilers Dan Chudecke Mulcahy Co

2 Background Mulcahy Company 21 Years –Best known for Hydronics –Have been in the boiler business for over a decade – –100’s of boilers installations I am an actual Boiler Maker

3 Dan Chudecke Discuss modern condensing boilers –Design –Installation –Inspection –Maintenance McDonnell and Miller LWCO –Recent Mishaps –Solutions

4 High Efficient Boilers Greater portion of the overall market share At last count 40+ manufacturers offer some form of condensing boiler All are a different from each other All are VERY different from “Old School” boilers they are taking the place of

5 Non-Condensing Boilers Return Water Limit Set By Manufacturer

6 Comparison Natural draft Separate components for each function Minimal moving parts 83 % Max – Nat. Draft 85% Max – Fan Assit High minimum return water limitations Fairly High Mass Forced draft venting Combination controls that are often proprietary More parts and switches 99% efficient possible Lower return water limitations Fairly low mass

7 Comparison Full modulation usually done with full speed blower and damper Burners act like ‘Flamethrower’ Simple controls Full Mod usually done with variable speed blower and ‘Zero Governor’ gas valve Burn is more contained at a mesh or ceramic surface Monitor multiple points

8 Typical Condensing Boiler Efficiencies- i.e. Laws of Physics Rule 82% 84% 86% 88% 90% 92% 94% 96% 98% 100% 6080100120140160 Return Water, F Efficiency, % 1/3 Input 1/2 Input Full Input This is what is advertised!

9 ENERGY CONTENT OF NATURAL GAS LATENT HEAT 10.2% Latent – Definition: Latin for “hidden” Comes from the difference between the Higher Heating Value and the Lower Heating Value of the fuel. SENSIBLE HEAT 89.8% Heat that can be measured or felt by a change in temperature Comes from the Lower Heating Value of the fuel.

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

11 Nov 2005 Foil 11 THEORETICAL PERFECT NATURAL GAS COMBUSTION OR STOICHIOMETRIC 1 part gas 9.7 parts air by volume Excess air 0% The CO 2 = 11.9% The CO = 0 ppm

12 Nov 2005 Foil 12 REAL WORLD NATURAL GAS COMBUSTION WITH GOOD BURNER TECHNOLOGY 1 part gas 9.7 parts air Excess air 20 to 25% What can cause the amount of excess air to change after start-up? The CO 2 = 9.5 to 10% The CO = 0 to 20 ppm

13 Lambda Pro Technology

14 1.8 0 10 20 30 40 50 60 70 80 90 100 110 120 Physical principal Lambda [ - ] Io-Signal [%] Gross Flow [ % ] Rich Combustion (Bad) Lean Combustion (Good) 76 Pct Excess Air = 1.3 richer leaner Calibration Lambda-Pro self calibration VITODENS 200 WB2B

15 Air/Fuel Coupling gasvalve gas P G = P A PAPAPAPA PGPGPGPG air VFDpremixair/gas 1 to 1 ratio

16 Heat Exchanger Materials Wide range of condensing heat exchanger materials However all use a vent material capable of handling the acidic flue gasses.

17 Wall Hung “Mod Con” 50,000 & 400,000 btuh Floor mounted or wall mount Can be direct vented +92% efficient

18 Typical Wall Hung Mod-Con Features Lift off front panel –Easy component access –Floor or wall mount Quiet - less than 45 db Light weight - less than 100 lb. Sentry 2100T Control Spectacular turndown –6:1 (150), 8:1 (200)

19 The Vitodens 200-W, WB2B boilers come equipped with Lambda Pro, the industry’s first intelligent combustion management system. The boiler adjusts automatically to any gas type and quality without the need for a fuel conversion kit.  The fuel flow is checked against the optimum flame signal and the correct lambda setting is determined for the current burner cycle.

20 GX Features Stainless steel jacket SS screws, nuts, studs SS heat exchanger Metal fiber burner Fully modulating

21 Giannoni Heat Exchanger

22 316L Stainless Steel

23 The Giannoni 316L stainless steel oval section measures approximately 25 x 7mm with a wall thickness of 0.7mm Viessmann corrosion resistant high grade 316Ti stainless steel. 1.5 mm wall thickness. Equal ???? Not even close!!

24 Giannoni Heat Exchanger condenser primary combustion chamber

25 GX Combustion condensate


27 Composite Controls

28 Typical Mod Con Venting Option Direct vent only? Solid core PVC, ABS, Poly Pro, CPVC or AL 29-4C piping –for 180° return use CPVC Provision for condensate removal

29 Typical Mod Con Venting Direct vent only, –No inside air –Certified for direct vent –Potential freeze up 12” above snow line 4” lateral separation 18”to 36” vertical separation FOLLOW GUIDELINES

30 Inspect Burner

31 Clean Heat Exchanger Annually for Propane At least bi-annually for Natural Gas


33 Other Mod Con Boilers Aluminum Heat Exchanger Requires special glycol Inhibitors in typical HVAC glycols respond badly to Aluminum Systems should be tagged properly

34 Larger Input Boilers Varying Heat Exchanger Materials –Stainless Steel –Cast Iron –Coated Copper –Ceramic –Aluminum ALL drain off the condensate as it is formed

35 Nov 2005 Foil 35 Condensing boiler requirements:  Counter-flow principle for flue gas and boiler water – optimal heat transfer  Parallel flow direction for flue gas and condensate – uniform flow with self- cleaning effect of heat transfer surfaces Condensing boiler Hot Flue gas Flue gas HR HS Normal heating boiler HS HR CONDENSING BOILER CONSTRUCTION

36 Counter Flow Arrangement

37 Other Condensing Designs? Primary Heat-X Second Condensing Heat Exchanger “2 nd Swipe” type systems often get a few more points of efficiency

38 Compact Designs Thru 6,000,000 input per device Generally fit thru a standard doorway.

39 Air/Fuel Coupling gasvalve gas P G = P A PAPAPAPA PGPGPGPG air VFDpremixair/gas 1 to 1 ratio

40 Start-up and Installation Each boiler manufacturer is different Many require certified start-up for warranty to be valid Here is a partial list of things to consider

41 Installation/System Design Minimum Water temperature Minimum Flow consideration Glycol? Condensate Treatment –Boiler condensate is a low grade acid that can ruin cast iron pipes –Running the liquid through limestone brings the pH to 7 Sealed Combustion –Boiler Designers don’t really know what -20F is like –Outside Air temp can easily get below a conditioned spaces dew point


43 Dilute sulfuric acid reacts with metals via a single displacement reaction as with other typical acids, producing hydrogen gas and salts (the metal sulfate). It attacks reactive metals (metals at positions above copper in the reactivity series) such as iron, aluminum, zinc, manganese, magnesium and nickel. Condensate Neutralizers prevents acidic condensate from corroding drains and sewer systems, Neutralized condensate is more environmentally friendly

44 Testing Blocked flue and blocked combustion air Gas pressure loss going into the boiler Gas shut off going to the burner Loss of VFD/Fan Test Manual reset boiler high limit LWCO Combustion setup at various input rates

45 Combustion Setup should be per manufacturers recommendations O2 readings are generally MUCH lower than what older boilers are setup for For example – We set our boilers up for 3-5% O2 at high fire and 5-6% at low Old guidelines were 4-10% - 8-9% will likely cause C.O. problems

46 Maintenance After the boiler has been in service for a period of time, the boiler should be rechecked (anything changed) An annual checkup (if not more) is usually recommended/required for warranty reasons. Some boilers require periodic parts replacement Annual testing of the glycol is recommended and often provided by the glycol supplier

47 Boiler Questions?

48 McDonnell and Miller LWCO Brief history of ….. Issues.

49 McDonnell & Miller Mercury Phase Out Overload Issues –Current 150/157 carries the same load capability-7.4 Amps @ 120V –The old switch was actually capable of more Float Sticking –Changed bellows manufacturing process in June of 1999 (Last known modification) “MD” Application

50 Questions

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