Boiler Low Water Cut-Off Mounting

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.

Testo 330-2 Combustion Analyzer: $200 Rebate !

 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 [Read more…]

Testo 327 Combustion Analyzer: $200 Rebate !!

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? [Read more…]

Testo Combustion Analyzer Kit Rebate

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. [Read more…]

Proper Heat Exchanger Piping

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.

Honeywell Controlinks Part 2

The ML7999 Universal Parallel Positioning Actuator allows for a direct connection to fuel valves and dampers in the boiler system, thereby eliminating mechanical linkages. The ML7999 actuator is designed to operate combustion air dampers, butterfly gas valves, oil modulation valves, and flue gas recirculation systems requiring up to 100 lb-in torque. Each ML7999 has its own ID, so when the R7999 communicates with the ML7999 it is communicating with only the ML7999 chosen for commissioning. The R7999 Controlinks Controller is a microprocessor feature driven controller. The controller must be commissioned by using the ZM7999 software on a PC or laptop using a minimum operating system of Windows 95 or the S7999B System Display.

Commissioning consists of five basic steps:

1. Connect the R7999 to the communications port of your PC and logon to the software with a password. The password prevents the changing of your modulation curve without permission.

2. Specify the base configuration: one or two fuels, with or without FGR.

3. Select system parameters such as Low Fire Hold.

4. Specify the characteristics of the actuators (ML7999) and set the valve/damper end points for each actuator.

5. Create a modulation curve (profile) for each fuel and verify it from maximum to minimum modulation. This curve can have up to 20 points on the curve to allow for smooth money saving transitions from start to stop.

ML7999 Controlinks UPPA actuator

Commissioning of the ML7999 basically consists of location of the minimum and maximum open/closed position of the valve/damper and locking down the actuator.

Working together, the ML7999 and the R7999 allow the burner fuel to air ratio to be adjusted independently to maximize burner efficiency and reduce fuel consumption, which typically pays for the Controlinks system within one year.

S7999B1000 Controlinks Touch Screen

Let Stromquist and Company help you with your Honeywell Controlinks needs by calling us at 1-800-241-9471 or contacting one of our many CGNA members.

Honeywell Controlinks Part 1

Yes, there is an answer! The never ending questions from clients about boiler energy savings, maximizing burner efficiency, reducing emissions and reduced excess air, increased equipment life, increased system reliability, flexibility and increased safety can now be answered.

With ever increasing popularity the Honeywell “Controlinks” fuel air ratio commercial/industrial combustion controls are sweeping the market.

To look at the future we need to understand how boiler efficiency was dealt with in the past. When a boiler is first commissioned at a new site the combustion efficiency is set by the installer using a combustion analyzer and adjusting the single modulating motor with jackshafts and their linkages to the fuel valve and air damper to achieve the best combustion efficiency. This “setup” during startup fixes the air-to-fuel ratio over the firing range of the boiler. Over time environmental and physical changes will reduce this “optimum” setup. Changes in temperature, pressure, and humidity, along with physical wear on the linkages and jackshafts, will alter the fixed air-to-fuel ratio causing increased operating and maintenance costs. The weakest “link” in this system is the linkage so let’s go “LINKAGELESS.”

The basic Honeywell Controlinks system consists of an R7999 Controlinks Controller, Q7999 Universal Subbase, ZM7999 Commissioning Software, and the ML7999 Universal Parallel Positioning Actuator (UPPA).

How the Controlinks system works… Four separate UPPAs (ML7999) replace the single actuator used with mechanical cam and linkage systems, providing independent control of the combustion air damper, the primary fuel, the secondary fuel, and the Flue Gas Recirculation (FGR) damper if used. The UPPAs (ML7999) are controlled by the Controlinks Controller (R7999), which responds to the load, and firing rate demands setup by the installer using a combustion efficiency analyzer throughout the boiler run/load cycle.

R7999 Controlinks Controller

ML7999 Controlinks Actuator

My next post will be on commissioning the Controlinks system, followed by a discussion on Controlinks features.

Let Stromquist and Company help you with your Honeywell Controlinks needs by calling us at 1-800-241-9471 or contacting one of our many CGNA members.

New Delphi Video Presentation

Honeywell has added a new Delphi video presentation to its Environmental and Combustion Controls website.

Go to: and look to the left of the page under the “What’s New” section, then click on the Delphi Combustion Efficiency Panel Video Presentation (in red) and follow instructions to the video.

Other Delphi and related Information:

Steam Safety Relief (Pop) Valves

Boiler contractors see these valves all the time when working on equipment.  Generally the steam relief valve is often little understood, often incorrectly installed, and usually neglected. A little refresher on these valves might be in order.

How Relief Valves Work

As the pressure of the steam within a boiler approaches the set pressure of the valve, the steam pressure on the underside of the actuating disc approaches the pressure of a spring applied to the outer side of the disc. When equilibrium is passed, the disc starts to lift off its seat. The moment this happens, steam is suddenly released all around the disc to what is called the “huddling chamber.” This chamber increases the area of the disc that sees steam pressure, thus increasing force. This increased area under steam pressure makes the pressure much more unbalanced in the direction of the valve discharge opening and therefore pops the valve into a wide open position. When the valve opens with a “pop” the valve seat is preserved from wiredraw caused by slow opening.

Closure of the valve occurs only after the boiler pressure is dropped several pounds below the set point. The reduction of the area of the disc seeing steam causes the disc to firmly close against the valve seat.

Relief Valve Installation

Proper installation of a steam relief valve seems somewhat simple and is, as long as two areas of concern are followed.

The first area of concern is valve distortion. Valve distortion occurs when the valve is improperly wrenched in, using the valve body instead of supplied wrench flats. Distortion also occurs when the discharge side of the safety relief valve is made to bear the weight of the discharge piping. To prevent this distortion use a short nipple from the valve to an independently supported bell reducer or drip pan elbow. These valves are precision devices and any distortion will affect accuracy and calibration.

The second area of concern is discharge piping. For a safety valve to do its job it must be sized properly to adequately relieve all the steam the boiler is capable of producing while operating at its maximum. All piping to or from a safety relief valve must be at least as large as the valve’s connections. Also, the restrictive effect of elbows and the friction losses in pipe must be taken into account. For this reason, piping runs should be as short as possible and pipe sizes should be generous.

If you need help in replacing or sizing a steam relief valve please contact Stromquist and Company at 1-800-241-9471. All others can order this product from one of our affiliates at CGNA.

McDonnell Miller Discontinues 150E Series

Due to difficulties in obtaining some machined components and because of declining sales, the M&M Series 150E Low Water Cut-Off and all its variants are being discontinued as of December 31, 2009. This will impact the 150E, 1507E, and replacement heads for those products.

M&M recommends the Series 150S float style Low Water Cut-Off as a direct replacement for the 150E and the new 1575 as an alternative for clients that wish to continue using a probe-style device.

From a replacement parts perspective, the 150S replacement head will bolt directly to an existing 150E body. Some minor wiring modifications may be required, and the user should be aware that the time delays and the pump differential are not adjustable on the 150S.  Keep in mind that it is also good practice to use a relay between the 1501S and the boiler feed pump.