THIS CATEGORY IS RESERVED FOR BOILERS BETWEEN 88% AND 83% NON CONDENSING MODELS:

Condensing boilers have an efficiency curve that achieves maximum efficiency (90+) only at low temperatures and achieve the maximum efficiency in low fire.  Both conditions make the condensing boiler a tough choice if the system calls for an average temperature of 125F to 190F.  Keep in mind that the high efficiency boilers cost up to 50% more than non condensing boilers so you'll need the low temperatures and optimum operating conditions to turn the increased first cost into a worthwhile payback. 

Representatives who encourage a condensing boiler on a higher temperature application probably do not have another boiler to offer.  Engineer's who use condensing boilers on high temperature systems are probably being misinformed or simply don't understand the difference.  There are great options outside the condensing boiler but all have certain requirements. 

The key things to remember are:

• < 85% efficiency will net standard ANSI category III or I venting (Pressure stack or 'B' Vent) ** > 85% will net an ANSI category II or IV venting (AL29-4C)

• By today's standards it's crazy to consider boilers rated under 83% for hot water and 82% for low pressure steam.  This is today's standard even in steel bentube, watertube, or firetube boilers.  The selection of a boiler below these standards is actually a financial drain for your customer.

• Look for other efficiency drains such as stand by losses experienced in an atmospheric boiler or drains from heat sinks such as refractory bases still found in some older technology boilers.

• Watch the return temperatures.  Copper can handle about 125F and steel will need 130F-140F.  This is important as increased piping may add greatly to the first cost of your project.

Engineer’s Beware:               As the efficiency and boiler types can be all over the board.  Equals may not be equal at all.  For instance, you can specify a bent tube boiler because you've had a good experience with this type before, yet the equals may not be what they seem.  A great example of this is a basis of design Unilux which is rated at 85% in the bent tube design.  UBW and Cleaver Brooks actually share this rating but the area's most popular bent tube boiler is only rated at 80%.  5% over the lifetime of these boilers is HUGE.  To make this worse, the burner can be downgraded and this manufacturer supplies the boiler with a refractory base while all the others supply it with tubes surrounding the firing zone.  Last but far from least, the tubes are 1/2" smaller than the others so is there any doubt this boiler will cost much less?  Let's see, the burner is downgraded, the tubes are smaller, the base is refractory, and the customer may pay up to 5% more for fuel... not counting the increased standby losses.  Funny part is, that model can't even make it into the RME payback center!  So, the most popular bent tube boiler may actually be the worse choice, yet contractors and engineers are tempted to make it an equal because of how long it's been around.  Problem is, the other surpassed the performance and this model can't meet the spec any more. 

STAY OUT OF TROUBLE BY:

Ο      CHOOSE A BOILER EFFICIENCY AND MAKE ALL MANUFACTURERS MEET IT.  (Even the one above makes a model that gets close)

Ο      BE SURE ALL EQUALS ARE THE SAME ANSI CATEGORY TO AVOID VENT MATERIAL ISSUES.

Ο      CHOOSE YOUR FAVORITE BURNER AND HAVE ALL MANUFACTURERS BID WITH IT.  (EX. GORDON PIATT IS OEM FOR ALL OF THE ABOVE BOILER EXCEPT CB)

Ο      KNOW THAT ALL MANUFACTURERS NEED THE SAME PIPING ARRANGEMENT.  SIMPLY AS THE REP YOU ARE WORKING WITH, I'M SURE HE'LL TELL YOU.

 (Go directly to our line of HIGH EFFICIENCY boilers and water heaters)

RELATED ENERGY SAVINGS COMPONENTS:

Exhausto:  When using multiple boilers, you should be sure to do a full venting and combustion air calculation.  Exhausto can save the end user dollars by taking multiple stacks and shrinking them to an affordable AL29 common vent system.  They also provide a wonderful source of combustion air instead of a large open louver.  Last they can limit excessive draft on high chimneys which cause poor combustion and random lock outs!  (Go directly to our line of HIGH EFFICIENCY boilers and water heaters)

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