Thermostaticmixing valve temperaturesetting

American Society of Sanitary Engineers publishes product standards of safety for plumbing systems.  There are 5 major standards for mixing hot and cold water.  Four of these standards are mentioned specifically in both the IPC and UPC Plumbing codes as well as the four states that use their own codes (California, Illinois, Wisconsin, and New Jersey).  Commercial building require ASSE certified valves. Click below to understand how and when to use these valves. As always, you may contact a Leonard Sales/Engineering Specialist for assistance.

Thermostaticmixing valvehow it works

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Another potential problem when dealing with compression tanks is water logging the tank.  Thru gravity recirculation air can be reabsorbed from the compression tank.  Water-logging occurs when the compression tank reaches the point where all of the air has been removed from the tank and there is no room left for expansion. The addition of an Airtrol Tank Fitting helps prevent this recirculation.

ThermostaticMixing Valve15mm

We like to add one more to the list: The system component with the lowest pressure rating.  Obviously, you don’t want the system pressure to ever exceed the pressure rating on the boiler or other component, lest you blow the ASME relief valve!

ThermostaticMixing ValveBath

After you know these values, choosing an expansion tank for the system you are designing is a matter of completing a relatively simple manufacturer’s sizing worksheet or plugging in a few numbers into a sizing program. But before you get to that point, it’s important that you understand the logic (and physics) that dictates the sizing of your expansion tank.

ThermostaticMixing Valve28mm

Our expert team of sales engineers can help you with all stages of your project — valve design & selection, plumbing & building code and specification assistance.  Some of our professional installs are shown here.

Remember Boyle’s Law?  Boyles Law, and its associated equation, p1V1=p2V2, states that the absolute pressure exerted by a gas (such as air) is inversely proportional to the volume it occupies within a closed system, assuming the temperature and volume of the gas remain the same.  In a closed hydronic system, the volume of water changes constantly as a result of even the slightest temperature change.  As this water volume increases, the volume air within a bladder tank decreases, as the free-floating molecules of air get squeezed together.  As the volume of the air and water changes, so does the pressure. As you decrease (“squeeze”) the air volume in the expansion tank, you actually increase the pressure within the system proportionately.  If you decrease the air volume by half, you double the pressure within the system.

Building Quality Mixing Valves is what we do at Leonard. At the same time we offer the industries best Service. It starts with the Best Engineers, followed by the most technically knowledgeable Regional Sales Managers, topped off with the industries best Specification Reps.  Our team of experts are easily accessible and have decades of market experience and knowledge on Mixing Valves and Mixing Valve Systems.

Every building is different and all manufacturers of mixing valves pipe recirculation uniquely. We have a video to help explain the basic design of a tempered recirculation system with a Master Mixer. This video will help the plumbing professional select the proper piping method for the job.

REMEMBER - Size and pipe your expansion tank correctly, and you will never have to worry about a water-logged tank or a blown relief valve!

ThermostaticMixing Valvetap

Here’s another way to think about it. In sizing an expansion tank for a hydronic system, we are actually predicting the expansion volume of the system and determining how much of an air cushion is needed to keep the system pressurized under low operating temperatures and provide enough space for expansion under higher operating temperatures to avoid over pressurization and blowing relief valves.

ThermostaticMixing Valve22mm

Properly sized expansion tanks (standard or bladder/diaphragm) are critical to a successful air management in a hydronic system.

Since delivering our first thermostatic mixing valve over 100 years ago, we have focused exclusively on designing and manufacturing the highest quality water temperature control valves in America. At Leonard Valve Company, craftsmanship isn't a lost art – it's something we do every day.

Our Production Team is committed to manufacturing the finest water temperature control valves in the industry. Today we supply high/low master mixers, complete water tempering systems, emergency mixing valves, and shower valves, along with a myriad of other valve products to meet the stringent demands of today's commercial buildings.

The tank (whether it is a bladder tank or a standard tank) must be sized such that it can store the required volume of expanded water without exceeding the maximum pressure allowable.  It must also be able to maintain the required pressure when the system is cold and water volume is at its lowest.  That’s where an old chemistry lesson comes into play.

Every expansion tank manufacturer has a written form that provides the steps and calculations for sizing an expansion tank.  Most, if not all, have developed software that does the work for you.  Bell & Gossett has a great one, ESP-Plus which can be downloaded here.  But regardless of whether you use software or charts and longhand calculations to size an expansion tank, there are a few pieces of information you’re going to have to have either way.  These key values are: