I have been asked over the years “What is a boiler horsepower” and what is the design criterion of square feet of heating surface per boiler horsepower.

 To understand boiler horsepower it is necessary to review the genesis of the term “boiler horsepower” (Bhp). The term originally related to the quantity of steam necessary to operate a one horsepower steam engine. Due to variations in engine efficiencies, this quantity of steam was itself a variable. Tests conducted in 1876 on a modern (for the time) steam engine determined that it took approximately 30 pounds of steam per hour to produce 1 horsepower (mechanical) of work. In 1889 the American Society of Mechanical Engineers (ASME) standardized the term “Boiler Horsepower” as being based on a conventional steam engine steam rate of 30 pounds of steam per hour (PPH) at 70-psig pressure and feedwater of 100 degrees F. This definition was later modified to: “Boiler Horsepower = the unit of capacity expressed as equivalent evaporation of 34.5 pounds of water per hour from and at 212 degrees F (33,475 Btu per hour.)”

In the early days of brick firing surfaces the rule of thumb was that it took 10 square feet of heating surface to create 1 boiler horsepower. In todays modern boiler designs the heating surface necessary to create 1 boiler horsepower has been reduced to 5 or in some cases less that 5 square feet of heating surface.

HORSEPOWER ?

As we all know before machines we did all the heavy work… then “Joe” one day hitched a horse to a rock to move the rock. Without knowing it at the time “Joe” created the term motive power. Motive power is a term used to describe something (air, water, steam, or the horse) that has the energy (power) to create movement in something else. So, as steam engines replaced the horse as a means of motive power steam engines were were rated in horsepower instead of “Joe Power”. Sorry Joe !

Hope you enjoy this bit of horsepower history.

We have written many articles about flame safe guard controls on Control Trends but we have not really given an explanation on the basic principles of these controls.

The programmer, (also called the blue box, the FSG, the fire eye and the brain) is the mastermind that controls the starting sequence and the firing cycle of a burner. The programmer controls the operating sequence of the blower, burner motor, ignition system, fuel valve, and all other components also called interlocks in the control system.

The programmer also provides, if necessary, a suitable purge period before ignition and after burner shut down allowing for the removal of explosive combustibles. The programmer is designed to de-energize all fuel valves within 4 seconds after loss of flame signal. In addition, the programmer automatically restarts a new cycle each time a temperature controller or pressure controller closes or after a power failure, lock outs must be reset manually after any flame failure.

Example of basic operation of programmer on steam boiler:

When the steam pressure within the boiler drops the pressure controller, (like Honeywell L404F1102), completes an electric circuit which starts a timing sequence in the programmer. The first timing sequence closes and starts the burner motor that rotates the primary air fan. The primary air fan blows air into the furnace to purge any unburned fuel present in a gaseous condition in the furnace.

This process is called pre-purging the furnace. By pre-purging the furnace before pilot ignition, the danger of a furnace explosion is reduced. The purge cycle is controlled by the time card (ST7800) in most programmers and can last varying lengths of time depending on the furnace size.

The programmer is still operating and when the second timing sequence contact closes, the circuit to the ignition transformer (similar to Donagan AO6-SA) is completed. The ignition transformer creates a high voltage spark in front of the gas pilot tube. At the same time, a solenoid valve is opened in the gas pilot line, allowing the gas to flow through the gas pilot tube and be ignited by the transformer spark. The scanner ( like the C7027A1023 or similar) is located on the front of the boiler and positioned in such a manner to sight the flame from ignition.

Sighting the pilot through the will verify that the pilot is lit. This process is called proving the pilot. The programmer timing sequence is still operating and the next contact closes to complete the circuit to the main fuel valve, which opens only when the scanner proved pilot. The main fuel valve is then opened and the fuel enters the furnace and is ignited by the pilot.

The programmer continues to operate for a few more seconds, securing circuits to the ignition transformer and the gas pilot. After the circuits are secure the programmer stops. The burner is now regulated by the pressure control and modulating pressure control. If the scanner senses a flame failure, the system is purged and secured. The programmer is then manually reset to restart the cycle.

The programmer needs very little maintenance. Most common failures are due to heat and moisture causing corrosion to the contacts of the programmer. Care must be taken to eliminate these factors. Check all wiring to the programmer sub-base for loose damaged connections or cracked wiring.

NOTES:

Please be aware this is a GENERIC ARTICLE on the workings of a burner programmer. There are MANY variations of these controls and many applications using these controls. Extreme care must be exercised when working with FSG CONTROLLERS and refer to factory and manufacture’s guides when working with these controls.

When your needs turn to the flame safe guard control please give Stromquist and Company at call at 1-800-241-9471.

Proper boiler blowdown is an essential part of firetube boiler operating proceedures. It is necessary to control the amount of TDS (total dissolved solids) in the boiler water.The total TDS should not exceed 3500 parts per million in a scotch marine boiler. If the blowdown is not controlled, excessive dissolved solids will have a tendency to increase and concentrate to a point that will cause a foaming or a carry over condition which will contaminate the  steam.

High concentrations of TDS in firetube boilers have a tendency to collect as SCALE on the heat transfer surface. Scale is an excellent insulator and its collection on the heat transfer surfaces of a boiler reduces the efficiency of the boiler. Scale thickness between 1/50 of an inch to 1/9 of an inch depending on the type of carbonates or sulfates present can reduce boiler efficiency between 3.5% to 16%. As you can tell just a small amount of scale build up can cost thousands of dollars a year on fuel costs.

Boiler blowdown frequency and duration is recommended by the water treatment contractor and can be accomplished either manually or automatically or both. Manual blowdown involves the operating personnel opening the boiler blowdown valves for a predetermined length of time at proper intervals. Automatic blowdown can be accomplished by many means. The most common method is the use of a surface blowdown skimmer attached to a calibrated blowdown valve which permits a continuous preset amount of boiler water to be blown down.

Proper blowdown rate can be easily figured when two factors are known. It is necessary to know the TDS in the feedwater and the amount of makeup water the boiler is using. The amount of TDS in the feedwater can be determined from a water analysis. The quantity of make up water is determined by installing a water meter in the make up water supply line that serves the feedwater unit. The correct amount of boiler blowdown, as a percentage of feedwater can be figured with the following formula.

TDS in feedwater / 3500-TDS in feedwater X 100. For example if the TDS in the feedwater = 200 divide this by 3500-200 or (3300) the result is .06 the multiply .06 X 100 for the amout of 6% of makeup water for proper boiler blowdown. I hope this is clear as the mud you will now be removing from your boilers.

NOTE: Because of the many variations of boiler plants, boiler, valves, pumping systems, and control systems proper maintenance of these systems should follow manufacturer’s recommendations and federal, state, and local laws that govern these proceedures. Boilers and Boiler maintenance can be dangerous and should only be preformed by Boiler professionals that have the proper training. When in doubt defer to the Boiler manufacturer.

The following is a list of what causes a LWCO switch to malfunction taken from the McDonnell & Miller Service Guide.

   1. Burner motor having greater power requirements than the LWCO switch

   2. Feed pump is not properly balanced for the required fill rate resulting in rapid cycling of the switches.

   3. Shorting of power wiring in control circuit.

   4. Switch submerged in water

   5. Lightning striking electrical service to building, causing electrical overload

   6. Overloaded circuit in building, resulting in low voltage conditions which in turn causes higher amperage draw and consequent switch failure

   7. Other limits like pressure controls, relays, thermostats, etc., may short circuit, overloading all switches in the same electrical line.

   Pump motor having a dead spot, may stall and generates heat, causing overloading of switch

The most common cause of switch overload is incorrect application. Check the electrical ratings of the switch against ratings of the equipment controlled.

If ypu have any other questions about McDonnell & Miller controls please call Stromquist at 1-800-241-9471 in Atlanta or 1-800-678-7828

Honeywell Burner Boiler Flame Safeguard Training Classes

Stromquist and Company is inviting you to our Honeywell Boiler Burner Flame Safeguard Training Class in Jacksonville, Florida.

Date: Tuesday October 4^th 2011

Time: 9:00 am till noon

Location: University of North Florida (University Center) Bldg. 43 Parking Lot 16 on Alumni Drive. http://www.unf.edu/map/

Cost: FREE

Host: Stromquist and Company

Featured Speaker: Dave Krause Honeywell’s Burner Boiler Factory Representative.

Attendance Requirements: Representatives from your facility whose responsibilities are or include the boiler and burner controls and systems.

Registration: http://www.controltrends.org/training-classes/

Questions: Call Bill Jones at 904-334-5938

We have registrations for the Duval County School Board, University of North Florida, and Mayo Clinic so REGISTER SOON to reserve your spot !!

Questions have been asked about the proper mounting of a Low Water Cutoff on a steam boiler.

Notice: The measurements given in this article will be close to the measurements necessary for the installation and may not be the same as the recommended measurements by the boiler manufacturer or the manufacture of the Low Water Cutoff.  Care MUST be taken to follow installation measurements supplied by the manufacture of the boiler and control.

The first issue to answer is…Is this installation for a primary or secondary LWCO?  The Primary LWCO is the operating LWCO and the Secondary LWCO usually incorporates a manual reset and is used for a safety backup for the primary.

Note: on a steam boiler please make sure you have a set of water gauge cocks in the installation. The “center line” of the visible glass should correspond with the boiler’s COLD WATER LINE.

The next issue for the service person to identify is the location of the COLD WATER LINE on the boiler. This is the “normal” cold water fill line as established by the boiler manufacturer. After the boiler’s cold water line is located, look at the LWCO and locate the level mark on the body of the LWCO. With these two marks established installation can now begin.

Primary LWCO Installation:

As a primary LWCO the level mark of the LWCO should be placed for mounting between 1 3/8” to 1 ½” below the boiler’s cold water line which will establish the boiler’s normal operating range.

½” to 3/8” below the LWCO’s level mark will be the burner’s “cut-off level”

Secondary Safety LWCO:

As a secondary safety LWCO the level mark of the control should be placed for mounting between the 1” to 1 ½”area below the primary LWCO’s burner cut-off level. Careful attention MUST be made not to let the float drop below the lowest visible level of the site glass.

Before commissioning the boiler for final usage PLEASE test the Primary and Seconday LWCO levels and make adjustments as needed for proper levels.

I would like to thank Peerless Boilers for their help with information and drawings supplied in this article.

 So you might be asking why are we doing three different posts on Testo Combustion Analyzers ? The main reason is that we have three different videos on the Testo Combustion Analyzers, and I did not want to put them all in one post. The first video focuses on combustion testing, the second video on the Testo 327 combustion analyzer, and this post highlights the Testo 330 combustion analyzer.

As you can see the Testo 327 and Testo 330 are very similar, with the main difference being

whether or not you need to test for CO and NO ( Nox). Unless they work on only residential type heaters, our customers invest the extra money and purchase the Testo 330. The Testo 330 is rugged and durable enough to withstand the day to day wear and tear of tuning boilers and burners,  the sensor (s) last longer than any others that we are aware of, and replacement of these sensors is very easy.

Testo is offering a fantastic fall promotion on the Testo 327 and Testo 330 analyzer kits.  Between now and December 15, 2010 you can get a $200 rebateon the following Testo combustion analyzer kits:

PN:400563 3271:           Testo 327-1 Kit 1 combustion analyzer, probe, power supply, and spare filters

PN 0563 3203 72:          Testo 327-1 Kit 2 combustion analyzer plus carrying case      

PN 0563 3203 71:          Testo 327-1 Kit 3 combustion analyzer plus case, IR printer and spare paper      

PN 400563 3274:           Testo 327-1 Kit 4 combustion analyzer plus case, IR printer, spare paper and smoke tester

PN 0563 3371 70:          Testo 330-1Kit 1 combustion analyzer (graphic display), probe, spare filters,  power pack and carrying case

PN 0563 3371 75           Testo 330-1 Kit 2 combustion analyzers (graphic display) plus printer and carrying case

PN 400563 3303            Testo 330-1 Kit 3 combustion analyzer (graphic display) plus smoke pump, printer and carrying case

PN 400563 3304            Testo 330-1 Kit 4 Combustion Analyzer (graphic display) plus NOx upgrade module, printer and carrying case

PN 400563 3305            Testo 330-1 Kit 5 combustion Analyzer (graphic display) with easy heat software, printer and carrying case

PN 0563 3372                Testo 330-2 Kit 1 Commercial/Industrial combustion analyzer (graphic display) with probe, spare filters, power pack and carrying case

PN 400563 3372            Testo 330-2 Kit 2 Commercial/Industrial Combustion analyzer (graphic display) plus NOx sensor upgrade kit

In addition to this amazing offer from Testo, Stromquist & Company is offering an additional 10% off on these items just by ordering these products on our website at www.stromquist.com. This additional 10% discount is only available through the end of October.

There has never been a better time to buy a Testo combustion analyzer so place your order today.

Note this is a dated post to see current Testo offers please click here

Of all the combustion analyzers we handle, which include great combustion analyzers by Bacharach and UEI, I love the Testo Products. Testo Instruments is a world leader in combustion and HVAC measurement equipment. The design of all the Testo products is well thought out and engineered;  Testo’s quality is unsurpassed. Check out this video by Value Testers Jim Bergnann to get an idea of what I am talking about.

As you can see the Testo 327 combustion analyzer has a lot of great features that an HVAC technician needs when working with combustion equipment. But is it the right tool for you?It depends on what type of service work you do. If you are primarily a light commercial or residential type of contractor, your primary concern is combustion efficiency, and you are only concerned with O2 settings then the Test 327 is a perfect fit. If you work on boilers or burners and you need to measure and record not just combustion efficiency but also need to measure O2, CO, and  NO (Nox) then you want to look at the Testo 330.

The great news is that Testo is offering a $200 rebate on both the Testo 327 and the Testo 330 through December 15,2010. As  an added bonus Stromquist & Company is offering an additional 10% off for our customers if they order either the Testo 327 or the Testo 330 on line at www.stromquist.com

Whatever your combustion analyzer needs,  Stromquist and Company will have a combustion analyzer for you. If you are in Georgia or Florida or if you are a Stromquist customer you can contact your Stromquist factory trained professional for more information. Others can contact one of our affiliates at Controls Group North America.

This Fall Testo is offering a $200 rebate on its 327 and 330 Combustion Analyzer kits, so if you’re in the market for a combustion analyzer now would be a good time to get one.  If you purchase a kit between now and December 15, 2010, you will receive a $200 rebate on a great quality product.

The Testo 327 Oxygen Analyzer quickly measures and makes better O2 adjustments with its simple, intuitive operations.  The pre-calibrated sensors use the most modern materials and come backed with a 3-year warranty.

The Testo 330 Combusion Analyzer combines advanced sensor technology with rugged electronics to measure O2, CO, and NO (NOx).  The long-lasting sensors offer an industry-best 4-year warranty.

You can learn more about these and other Testo products at www.testo.com.

If you are a Stromquist customer in Georgia or Florida, you can order any Testo products from Stromquist.  If you are not a Stromquist customer or located in Georgia or Florida please contact one of our affiliates at Controls Group North America. As an added bonus order your Testo 327 or Testo 330 combustion analyzer on line at www.stromquist.com and get an extra 10% off Stromquist’s already low price. This web promotion will run through the end of October so there will never be a better time to purchase a Testo Combustion analyzer.

Over the years I have been asked how to properly pipe a steam heat exchanger. I developed the drawing below to help answer this question. There are other piping additions that can be added according to your needs, and this drawing does not cover all the additions but should serve as a good workable starting point. A few points to remember…1. A vacuum breaker and/or vent should be installed…. 2. The steam trap should be properly sized for the amount of the pounds per hour steam capacity of the heat exchanger, and the trap should be sized for the pressure at the trap not for the inlet pressure of the control valve…3. A properly sized relief valve must be installed on the hot water outlet side to protect the heat exchanger from possible damage due to volumetric expansion.

I hope this answers some questions you may have. If you need more answers please call Stromquist and Company at 1-800-241-9471, and we would be happy to finalize an answer for you.