State of MNWI Small Boilers Dan Chudecke Mulcahy

State of MN/WI Small Boilers Dan Chudecke Mulcahy Co

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 Boilermaker

Preview • Discuss modern condensing boilers – Design – Installation – Inspection – Maintenance • Mc. Donnell and Miller LWCO – Recent Mishaps – Solutions

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

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

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

Typical Condensing Boiler Efficienciesi. e. Laws of Physics Rule 100% Efficiency, % 98% 1/3 Input 96% 1/2 Input 94% Full Input 92% 90% 88% 86% 84% 82% 60 80 100 120 Return Water, F This is what is advertised! 140 160

ENERGY CONTENT OF NATURAL GAS LATENT HEAT 10. 2% SENSIBLE HEAT 89. 8% Latent – Definition: Latin for “hidden” Comes from the difference between the Higher Heating Value and the Lower Heating Value of the fuel. Heat that can be measured or felt by a change in temperature Comes from the Lower Heating Value of the fuel.

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

THEORETICAL PERFECT NATURAL GAS COMBUSTION OR STOICHIOMETRIC The CO 2 = 11. 9% The CO = 0 ppm Excess air 0% 1 part gas 9. 7 parts air by volume Foil 11 Nov 2005

REAL WORLD NATURAL GAS COMBUSTION WITH GOOD BURNER TECHNOLOGY The CO 2 = 9. 5 to 10% The CO = 0 to 20 ppm Excess air 20 to 25% 1 part gas 9. 7 parts air What can cause the amount of excess air to change after start-up? Foil 12 Nov 2005

Lambda Pro Technology

VITODENS 200 WB 2 B Lambda-Pro self calibration Physical principal 110 Rich Combustion (Bad) Lean Combustion (Good) 100 Calibration 90 r he ric 80 76 Pct 70 r ne lea Gross Flow [ % ] 120 Io-Signal [%] 60 50 40 30 20 10 Excess Air = 1. 3 0 0. 4 0. 6 0. 8 1. 0 1. 2 Lambda [ - ] 1. 4 1. 6 1. 8

Air/Fuel Coupling premix air/gas 1 to 1 ratio gas valve P G= P A PG PA VFD air

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

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

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 2100 T Control • Spectacular turndown – 6: 1 (150), 8: 1 (200)

The Vitodens 200 -W, WB 2 B 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.

Composite Controls

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

Giannoni Heat Exchanger

Giannoni Heat Exchanger 316 L Stainless Steel

Equal ? ? Viessmann corrosion resistant high grade 316 Ti stainless steel. 1. 5 mm wall thickness. The Giannoni 316 L stainless steel oval section measures approximately 25 x 7 mm with a wall thickness of 0. 7 mm Not even close!!

Giannoni Heat Exchanger condenser primary combustion chamber

GX Combustion condensate

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

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

Inspect Burner

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

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

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

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

Counter Flow Arrangement

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

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

Air/Fuel Coupling premix air/gas 1 to 1 ratio gas valve P G= P A PG PA VFD air

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

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 p. H to 7 • Sealed Combustion – Boiler Designers don’t really know what -20 F is like – Outside Air temp can easily get below a conditioned spaces dew point

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

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

Combustion • Setup should be per manufacturers recommendations • O 2 readings are generally MUCH lower than what older boilers are setup for • For example – We set our boilers up for 3 -5% O 2 at high fire and 5 -6% at low • Old guidelines were 4 -10% • 8 -9% will likely cause C. O. problems

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

Boiler Questions?

Mc. Donnell and Miller LWCO • Brief history of …. . Issues.

Mc. Donnell & Miller • Mercury Phase Out • Overload Issues – Current 150/157 carries the same load capability-7. 4 Amps @ 120 V – The old switch was actually capable of more • Float Sticking – Changed bellows manufacturing process in June of 1999 (Last known modification) • “MD” Application

Questions