Series 3™

Gas Fired, Chimney Vented,Cast Iron Water Boiler

• 84%AFUE

• Electronicignition

• EquippedwithIQControlSystem™

• 70–280MBH(7sizes)

• Industrystandardtappinglocations,allows easy,directreplacementforthousandsof existingboilerinstallations

• Solid,reliable,American-madecastironheat exchanger,designedtopromoteturbulentwater flowwithinthesectionforefficientheattransfer

• Lifetimelimitedwarranty

• ConsistsoftheIntelligentHydronicControland IQOptionPanel

Intelligent Hydronic Control• Intuitiveself-diagnostics

• Combineshighlimit,relay,andignitionfunctionsintoasinglemodule

• Twocustomizableintegratedswitchingrelaysforeasyadditionofadditionalheatingzoneorindirectwaterheater

• Energysaving“thermalpurge”,whichworksbycirculatingresidualwarmwater(140°orabove)intheheatingsystembeforefiringtheboiler

IQ Option Panel• Enablestheeasyplug&playinstallationofoptionalfeaturessuchasoutdoorreset,LWCO,andhighlimit

Optional Touchscreen• LCDdisplaysallboilersettings,diagnostics,andtroubleshootinginsentences,notcodes

boilercontrol

optionpanel

optioncard

controlsystem

ANYWHEREUNMATCHED

ANYWHEREUNMATCHED

ANYWHEREUNMATCHED

ANYWHEREUNMATCHED

©2018U.S.BoilerCompany,Inc.-Lancaster,PAPhone:1-888-432-8887

PrintedintheU.S.A.FormNo.USBL10031-15ms11/15 www.usboiler.net

Series 3 Dimensions & Connections

Model

Dimensions (inches) Connections (inches) WaterContent (gal.)Width Height Depth Supply Return

Gas Valve

Relief Valve

303 12-3/4 41 33 1-1/4 1-1/4 1/2 3/4 2304 15-1/2 41 33 1-1/4 1-1/4 1/2 3/4 3305 18-1/2 41 33 1-1/4 1-1/4 1/2 3/4 4306 21-1/2 41 33 1-1/4 1-1/4 1/2 3/4 5307 24-3/4 41 33 1-1/4 1-1/4 3/4 3/4 6308 27-3/4 41 33 1-1/4 1-1/4 3/4 3/4 7309 30-3/4 41 33 1-1/4 1-1/4 3/4 3/4 8

*Addsuffix“N”fornaturalgas,orsuffix“P”forLPgasmodels Allmodelscertifiedforusefromsealevelto10,000feetinelevation.Outputsarereducedby4%per1,000feet abovesealevelforelevationsabove2,000ft. AllSeries3boilersareshippedwith30psireliefvalves,MAWPis50psi.

64”

FLOORLINE

23”**

41”

4” “W” 1”

40”FLUE

34”ELECTRICAL

27”SUPPLY

18”GAS

15”RETURN

FLOORLINE0”

0” 13” 24”29”31”

4”

43”

6”

VENTILATION AIR INLET OPENINGS***

12” MAX

12” MAX

6” MIN*

NOTES:CAUTION: Chimney liner may be required by code requirements* Minimalradialdistancearoundventpipeandbreeching** Addheightrequiredtomaintain6”clearancefromallbreechingcomponents***Areaofeachopening1sq.inchforeach1,000BTUHinput-withminimumof100sq.inches.Heightofopeningshouldbehalfthewidth.

Series 3: Technical InformationStandard Equipment • Insulatedsleek,modernjacket• Integrateddraftdiverter,damperandconnectorincluded• Heavygauge1”and1-1/2”baseinsulation• IntelligentHydronicControl–Simpleself-diagnostic controlsystemwith3-digitreadoutforstatussettings anderrors• IQOptionPanel,acceptsplug&playIQOptionCardsfor –OutdoorresetwithDHWpriority –Autoormanualresetlowwatercutoff –Autoauxilliaryhighlimit• Step-openingredundantgasvalve• Sparkignitionwithcontinuousretry• User-friendlywiringwith120VJ-box• Circulatorwithpipingwithwiringharness• Castironsectionassembly• Resettableblockedventswitch• Boilerdrainvalve• Castironsupplymanifoldwithsafetyreliefvalvetapping

ASM

E

H

IQ insidewith controlsystem

TM

Series 3 Ratings & Specifications

Model Input

(MBH)

DOE HeatingCapacity(MBH)

Net AHRI Rating, Water(MBH) AFUE%

Vent Size(Inches)

Approx. Shipping Weight. (lbs.)

303 70 59 51 84.0 4 254304 105 88 77 84.0 5 301305 140 117 102 84.0 6 353306 175 146 127 84.0 6 405307 210 176 153 84.0 7 464308 245 205 178 84.0 7 514309 280 234 203 84.0 8 564