The Evolution Of Radiant Mixing How, why and when to mix with a valve Welcome to the Evolution of Radiant Mixing, presented by Taco. This program discusses various ways to mix water temperature for radiant heating systems using Taco’s mixing valves. Taco has several options ranging from a simple three way tempering valve and motorized 2, 3 and 4 way set point valves that will maintain a fixed water temperature in the radiant system – to motorized mixing valves with integral outdoor reset controls.

Why Mix? CI boilers Mod/Con boilers Need lower temp for radiant Multi-temp, multi-load Zone by zone mixing Mod/Con boilers Boiler makes hi-temp Need to mix for lower temp radiant So, why do we mix water temperature? Well, radiant systems require lower water temperatures than a typical hydronic systems. Basesboard systems, for example, typically require 180 degree water under design conditions. A radiant system, however, may require water temperatures as low as 90 degrees for a basement slab or 130 degrees for a joist heating system with aluminum heat transfer plates. When using a high temperature cast iron boiler for these systems, some sort of mixing device will be needed. Cast Iron boilers typically operate at a high limit of 180 degrees, and require minimum boiler return water temperatures of 135 to 140 degrees to prevent flue gas condensation. When applying radiant to a Cast Iron boiler, a mixing device will be required, as well as some sort of protection piping arrangement for the boiler. Often in modern hydronics you’ll encounter multi-temp, multi-load systems. These hybrid systems will have several types of heat emitters – ranging from baseboard and radiators to hydro-air to several different types of radiant floor installations – all on the same job. These multi-temp, multi-load systems will require several different supply water temperatures, and will require several mixing devices. In addition, many radiant systems will require two or three different supply water temperatures for different installation methods. For example, there might be radiant in the basement slab that requires 100 degrees, while there may be joist heating in the upper floors requiring 140 degree water. When using a cast iron boiler, each installation method will need its own mixed temperature. You may run into a situation where zone by zone mixing may be beneficial. For instance, let’s say you were installing a joist heating radiant system on the first floor of a home, and part of the first floor was carpeted and the rest had hardwood as a finished floor. The carpeted areas may require 150 degree water while the hardwood area may require 125 degree water. These areas will most likely be zoned separately and should receive separate mixed water temperatures. Low temperature modulating-condensing boilers – known as “mod/cons” are increasing in popularity, especially with radiant systems. These boilers are designed to run at lower temperatures than cast iron boilers. In fact, the lower the supply (and return) water temperatures, the more efficient mod/cons will be. In theory, with low return water temperatures, a mod/con could easily reach the mid 90% range in terms of efficiency. In a single temperature radiant system, a mod/con would not require any additional mixing. For example, let’s say you’re using a mod/con for a joist heating job that requires 135 degree water. Simply set the operating control on the boiler for 135 degree water and pipe the system directly to the boiler according the manufacturer’s instructions. No additional mixing device would be needed. However, what if a basement slab requiring only 95 degree water was included in that same system? The boiler is making 135 degree water, while a separate mixing device would be needed for the lower temperature slab. In addition, zone by zone mixing may be beneficial when mixed floor coverings create wildly different supply water temperatures for a radiant system.

Mixing Options 3-Way tempering valves Motorized setpoint valves Motorized reset valves When using valves to mix for radiant heating systems, there are three basic options. The first is the three way tempering valve – a simple, non electric, thermostatic valve designed to maintain a fixed supply water temperature on the radiant side. Next is an electronic, motorized version of the tempering valve, called the iValve, which provides much more precise water temperature control as well as a boiler protection option. Finally, there’s the motorized reset iValve – which includes and outdoor reset control built right into the control head. The reset valve provides not only outdoor reset, but also boiler protection and a warm weather shutdown function. We’ll discuss all these valves in detail.

Mixing Options 3-Way tempering valve Fixed water temperature Simple, thermostatic, non-electric MUST ZONE radiant system properly/aggressively Must pipe bypass to protect boiler There are many ways to mix water temperatures. The most basic is the three way tempering valve – this is the Taco 5000 tempering valve. The tempering valve provides a fixed water temperature to the radiant system. If the dial is set for 130 degrees, then it supplies a steady 130 degrees all winter long. It’s a very simple mixing device – it’s non-electric, so no additional wiring is needed, and has very few moving parts. It is, relatively speaking, a low-initial cost mixing option. However, since the tempering valve provides a fixed supply water temperature all winter long, comfort in the living space is determined by the zoning package. When using a fixed temperature control strategy, plan on providing an aggressive zone strategy to prevent rooms that are too warm or too cool. Also, when using a cast iron boiler it will be important to protect the boiler from low return water temperatures and possible flue gas condensation. This can be done with either a boiler bypass loop or a primary-secondary piping arrangement. We’ll discuss both of these momentarily.

Boiler Piping Here is a typical boiler piping arrangement for a cast iron boiler with a tempering valve. Note the bypass between the boiler supply and return – this bypass is used to protect the boiler from low return water temperatures when the system is in operation. We’ll discuss this in greater detail momentarily. First, let’s look at the actual operation of the valve…

3-Way Tempering Valve Boiler Supply Radiant Supply Radiant Return Boiler Return Let’s take a closer look at the operation of a tempering valve. The valve has three ports – hot, cold and mix. The hot port is connected to the supply line from the boiler. The mix port is piped to the radiant system, and the cold port is piped to a bypass from the radiant return. The valve’s job is to mix radiant return water with boiler supply water to deliver the desired radiant supply water temperature. Inside the tempering valve is a bimetal thermostatic gland that shrinks and grows based on the water temperature it senses. As the gland shrinks and grows, it opens and closes a shuttle valve on the hot, or boiler supply, port. Let’s say we want 130 degree water in the system. The green dial is adjusted to a setting for 130 degree water. When the system is filled with cold water, the bimetal gland is in the shrunken, or retracted, position and the shuttle valve on the hot port is wide open. As the system heats up, warmer boiler water is circulated through the radiant system. As the water temperature in the radiant system heats up, the bimetal gland will expand. As it expands, it will gradually push the shuttle valve on the hot port closed. Once the temperature reaches the desired 130 degrees, the gland will be fully expanded and the shuttle valve on the hot port will be completely closed. At this point, the radiant portion of the system will be hydraulically isolated from the boiler portion of the system. As long as that shuttle valve is closed, water will only flow through the radiant system whenever there’s a call for heat. However, as the water flows through the system, it will lose temperature. That means cooler and cooler water will be hitting the bimetal gland, causing it to shrink. As it shrinks, the shuttle valve on the hot port will open, allowing more hot water from the boiler into the radiant loop and thereby increasing the radiant supply water temperature back to the desired 135 degrees. However, once the shuttle valve opens, a portion of the cool radiant return water, which could be as low as 115 degrees, will be sent back to the boiler. Radiant Return

Protecting The Boiler 1800 Out Globe Valve Mix Point >1350 The boiler bypass circuit is critical to protecting a cast iron boiler in this application. Here’s how it works: The boiler circulator remains wired to the boiler hi-limit control, and fires whenever the boiler fires. On the supply, a portion of the hot boiler water will head to the three way tempering valve, while the rest will flow through the bypass to head back to the boiler. Meanwhile, when the tempering valve is open to warm the radiant system water, cooler return water – in this example 115 degrees – is being sent back to the boiler. Where the end of the bypass and the radiant return piping meet is a mix point. The hot boiler water will mix with the cooler return water at that point, and temper the water going back to the boiler to above the 140 degree mark most of the time. There will still be instances of condensing with this arrangement, but the idea is to minimize that time. The key to making this work is the bypass valve. Globe valves work best here because they are designed for linear throttling, while a ball valve is designed to be either fully open or fully closed and aren’t really considered balancing valves. Globe valves aren’t expensive, either. Most plumbers know them as stop and waste valves. To set the valve, use the following steps: At system start up, set the valve to the half open position Fire the system, and watch the temperature of the outlet side of the 3 way tempering valve. If the temperature doesn’t reach the desired level, the globe valve is too open, and should be closed incrementally until that temperature is reached. Remove then handle If desired temperature is reached immediately, open the valve incrementally until radiant temperature falls – them close until temperature is reached. A quick work about circulator location – in most hydronic applications it is preferable to place the circulator on the supply side of the system, pumping away from the expansion tank. This will provide better air control in the system and promote optimum system performance. In this example, however, you’ll note the circulator is on the return side of a packaged boiler. In this example, the boiler circulator has but one job, and that is to keep flow moving through the bypass to increase the return water temperature above the condensing point. It’s placement on the return side is acceptable in this example. >1350 1150 Back

A System Sizing Problem Let’s take a few moments and run through the actual pipe and circulator sizing for a simple radiant system. Let’s assume there’s nothing else on this system – just the radiant system. There are some simple math formulas to help us size the pipe and the circulators appropriately, without oversizing. Proper pipe and circulator sizing not only means the job will work correctly, but it also means we can economize the job without compromising performance. After all, 1 inch pipe and fittings and a 1 inch air eliminator are much less expensive than 1-1/4” equivalents. So, let’s assume the total BTU load for the entire system is 30,000 BTU’s…

A System Sizing Problem Find the flow rate GPM = GPM = 6 BTUH ΔT x 500 30,000 10 x 500 To find the flow rate, we use the universal hydronics formula – GPM = BTUH divided by Delta T times 500. GPM is the gallons per minute flow rate needed to provide adequate heat to a structure – it’s like the pulse of the heating system. BTUH is the amount of heat required, and we learn this number when we conduct our room by room heat loss analysis. Delta T is the temperature drop of the fluid as it runs through the heating system, and this numbered is prescribed ahead of time as a design criteria. Typically, baseboard heating, radiators, fan coils, etc are designed at a 20 degree Delta T, meaning the water enters the system at, say, 180 degrees and returns at 160 degrees. Some radiant systems are designed with a 20 degree Delta T, although many are designed to a 10 degree delta t for superior performance and more even heat. For our example, let’s use a 10 degree Delta T. The 500 is a design constant, and it comes from multiplying the weight of one gallon of water – 8.33 pounds -- by the specific heat of the liquid (100% water has a specific heat rating of 1) – by the number of minutes in an hour, or 60. If we multiply 8.33 x 1 x 60, we come up with 499.8, or 500. To determine our flow rate, we’ll divide the heat load – 30,000—by 5,000 (the Delta T of 10 times the constant 500). If we work this out, the total flow rate needed for the job would be 6 gallons per minute.

Sizing The Pipe 6 GPM = 1” pipe 2-4 GPM = ¾” 4 - 8/9 GPM = 1” Based on max velocity of 4 feet per second for copper Pipe sizing is all based on flow rate requirement and fluid velocity. These are the generally accepted guidelines for sizing copper pipe in hydronic systems. From flow rates of at least 2 up to 4 gallons per minutes, use ¾” copper. From 4 to 8 or 9 (8 for L, 9 for M) you should use 1” copper. 8 to 14 GPM requires 1¼” copper, while 14 to 22 GPM requires 1½” copper. Again, this pipe sizing is based on a maximum flow velocity of 4 feet per second. Velocities greater than 4 feet per second will create velocity noise in the system, and should be avoided. In our example, the flow rate required for the job is 6 GPM, so according to guidelines, all the piping from boiler to the radiant manifold should be 1 inch. The 5000 series tempering valve is available in ½, ¾, and 1 inch – so obviously for this job we’d use the 1” model. 6 GPM = 1” pipe

Radiant Tube Head Loss – 5’ Flow & Head Loss Find radiant tube head loss Measure total run Multiply by 1.5 Multiply by .04 4’ head/100‘ equiv. length 60’ x 1.5 = 90 90’ x .04 = 3.6 feet of head Radiant Tube Head Loss – 5’ Next we need to size the circulator based on the required flow rate and the overall head loss the circulator needs to overcome. In this example, the circulator we need to size is the radiant circulator. This is the circulator this will need to overcome the entire system headloss –through the radiant tubing, through the copper piping to and from the boiler, and through the tempering valve. We already know the flow rate the circulator will need to overcome – 6 gallons per minute. We now need to determine the head loss. Your radiant design calculations will tell you the head loss through the radiant tubing. That head loss is based on five elements – flow rate per loop, tube size, loop length, fluid type (water vs. glycol) and fluid temperature. For this example, let’s say that based on the radiant design calculations, the head loss through the radiant tubing is 5 feet of head. Now, that’s just the head loss through the tubing running from the supply manifold to the return manifold. There’s more head loss to overcome. To determine the head loss through the rest of the piping, the first thing you need to do is measure the run in feet – how much pipe does the 6 gallons per minute need to flow through. Next, we take that number and multiply it by 1.5 – by adding 50 percent to the total, we account for most normal fittings, isolation valves and a normal cast iron boiler. This will give us the EQUIVALENT length of pipe. Once that’s done, we multiply the equivalent length of run by .04. If we size the pipe according to velocity guidelines, we know that the head loss will be roughly 4 feet of head for every 100 feet of equivalent pipe length– and this will give us the head loss through the hard piping. For this example, we measure the run of 1” pipe from the boiler to the radiant manifold and back again. Let’s say this totals out to 60 feet of pipe for the entire trip. Next, to take into account the fittings and basic valves, we’ll multiply 60 by 1.5, to come up with a total equivalent length of 90 feet. Then we take the 90 feet and multiply it by .04, and we arrive at a total head loss of 3.6 feet. 60 feet

What About The 3-Way Valve? 5’ + 3.6’ = 8.6’ 1” valve Cv = 3.8 3.8 GPM = 1psi 1psi = 2.31’ head (Flow 4 Cv)2 x 2.31 = head loss (643.8)2 = 2.5 psi 2.5 X 2.31 = 5.8’ 8.6 + 5.8 = 14.4’ Remember that the radiant head loss is 5 feet of head, and the hard piping head loss is 3.6 feet. Since those losses are in series and the pump will have to overcome both losses, the total loss to this point is 8.6 feet of head. We need, however, to take into account the head loss produced by the 3 way tempering valve. The 1” 5000 Series valve has a Cv rating of 3.8. That means that it takes 3.8 gallons per minute to create 1 psi of pressure drop through that particular valve. Different valves have different Cv ratings – so a valve that had a Cv rating of 12 would produce 1 psi of pressure drop at a flow rate of 12 gallons per minute. A valve with a Cv rating of 47 would create 1 psi of pressure drop at a flow rate of 47 gallons per minute. The 1” 500 Series valve, however, has a Cv of 3.8, so it creates 1 psi over pressure drop at a flow rate of 3.8 gallons per minute. And 1 psi of pressure drop equals 2.31 feet of head loss, and any additional head loss through the valve needs to be added to the total. The actual flow rate through the valve, however, is 6 gallons per minute. The head loss through the valve can be estimated using the following formula: Head loss = ( Flow/Cv)2 X 2.31 In this example, we would divide 6 by 3.8 to get 1.58. We would then square 1.58 ( or multiply it by itself) to get a pressure drop of 2.5 psi. To turn that into headloss, we would multiply 2.5 by 2.31 for a total pressure drop through the valve of 5.8 feet. We would then add that to the combined head loss of the radiant tubing and the hard piping to get the total head loss the circulator will need to overcome, in this case it’s 14.4 feet of head. You can see that if the 3 way valve were not taken into account, or the headloss through it merely guesstimated at something lower, there’s very strong likelihood that the circulator would not be sized properly, If we consider the just the hard piping and radiant head loss, at 6 gallons per minute and 8.6 feet of head, it would appear that a 007 would do the job. However, once the head loss of the tempering valve is added to the equation, the system appear to operating on the outer limits of a 008, and may perhaps require a 0011 or a 0014.

iValve Reset Outdoor reset – more effective, efficient system Simple wiring – low voltage Can reset individual zones Provides boiler protection Available in 2, 3 and 4-way models The next step up in mixing control is the ivalve Reset. This version of the iValve has a different control head that has an outdoor reset control package built right in. The reset valve gives your radiant system a higher level of control based on outdoor temperature in order to maximize both the comfort of the system and the economy of operation. As with the Setpoint iValve, it’s a 24 volt valve making wiring very easy, and the valve is economic enough to allow you to apply reset to separate zones, if need be. For example, say you had radiant in the first floor of a house, and half the first floor had hardwood and the other half had carpet. Using two iValves, you could provide separate water temperature control, with outdoor reset, to both areas. As with its Setpoint cousin, the Reset iValve can provide boiler protection if needed, and is also available in 2, 3 and 4 way versions.

Understanding Reset To fully understand the application of outdoor reset, and the benefit to the homeowner, it’s important to realize that the goal of any heating system is to maintain a constant room temperature during the heating season. Now of course, the heating system is designed to heat a given room under design conditions – the “coldest day of the year.” In a radiant system, the radiant design calculations will tell you, based on the heat load of the room, the floor covering, the installation method and the tube spacing what water temperature you’ll need to heat the room under design conditions. Both the 3 way tempering valve and the Setpoint iValve will provide that water temperature for you – but that water temperature will be fixed all winter long. But what happens when the outdoor temperature changes? It should be obvious that the heat loss of a structure is based on the outdoor temperature. The colder the outdoor temperature, the greater the difference between the indoor room temperature and the outdoor temperature. The greater this Delta T, the greater the heat loss of the room will be, so as the outdoor temperature goes down, the room’s heat loss will go up. Conversely, when the outdoor temperature increases, the room heat loss will decrease.

Changing Conditions Heat Loss Heat loss change every day Fixed SWT Variable SWT Heat loss change every day Fixed water temp = variable run times = cycling in mild times Variable water temp = fixed run times = less short cycling = greater efficiency Heat Loss Variable SWT Fixed Run Time So how does this apply to water temperature? Well, obviously if the heat loss of a room goes down as it gets warmer outside, the room doesn’t need as much heat. Since we’re not going to add or remove radiant tubing to a room during the course of the heating season, we’re left with two choices for maintaining comfort and preventing overheating. We could provide either a fixed temperature system with a tempering valve or the Setpoint iValve, or we could provide a variable water temperature system using the Reset iValve. With either option, it’s clear that the heat loss will vary every day based on how cold it is outside. With a fixed water temperature system, the water will always stay the same temperature. The only way to prevent overheating would be to vary the run times – shorter run times in milder conditions, longer run times with it’s colder. This, unfortunately, leads to short cycling of the boiler which leads to lower overall system efficiencies. More on/off cycles will also lead to more wear and tear on all the moving parts in the system. With reset, however, the supply water temperature will vary in lockstep with the outdoor temperature – the colder the outdoor temperature, the warmer the water will be. If both the heat loss and water temperature vary together, then the run times for the system, in theory, would have to fixed all winter long. The system will always think it’s the coldest day of the year out, so system on-times will be constant. This will lead to greater system efficiency since the boiler won’t short cycle, and will also lead to less wear and tear on system components, leading to longer life and lower maintenance costs.

How Does It Know? Four key numbers Reset ratio = Outdoor Design Temp Mix Design WWSD Mix Start Reset ratio = Mix Design Temp - 720 How does a reset control know what water temperature to produce? It’s all based on four numbers used in programming. The first number needed is the outdoor design temperature, or the temperature upon which the heat loss has been based. This is the so-called “coldest day of the year.” The next number needed is the Mix Design number – this is the water temperature the radiant system requires when it’s design conditions. This number will be determined during your radiant design calculations. Next is WWSD, or Warm Weather Shut Down – this occurs when the outdoor temperature is equal to the desired indoor temperature. When that happens, the heat loss of the building is ZERO, and no heat is needed. In warm weather shut down mode, the valve won’t enable, preventing heat from being supplied to building accidentally. The final number required is Mix Start – that’s the water temperature you’ll want running through the system at the warm weather shutdown point. The iValve defaults to 72 degrees. Using these numbers, we can determine the “reset ratio” needed to program the Reset iValve. Use this formula: Reset ratio = Mix Supply Temperature – 720 720 – Design Outdoor Temperature 720 – Design Outdoor Temp

Let’s Do One… Mix Design = 130, Outdoor Design = 0 130 – 72 58 = 72 - 0 = 72 = 0.8 Let’s do an example – Let’s say we had an aluminum track radiant system that required 130 degree water at an outdoor design temperature of 0 degrees. If we do the math we find the following: 130 – 72 = 72 – 0 58 = Reset ratio of 0.8 72 We can verify this by looking at the chart – First, find 130 degrees on the supply water temperature axis on the right, and then find the outdoor design temperature on the bottom. Follow the lines to where they intersect, and it should be at the diagonal line representing a ratio of 0.8.

What Does 0.8 Mean? Radiant water temp increases 0.8 of a degree for every 1 degree drop in outdoor temperature To program: Move dial on iValve to correct ratio So, what does the reset ratio of 0.8 actually mean? Well, by setting the ratio to 0.8, the control will know to follow the line in the chart represented by 0.8. When the outdoor temperature changes, the radiant supply water temperature will change as well, along that line. In essence, the 0.8 means that the radiant water temperature will increase 0.8 degrees for every 1 degree drop in outdoor temperature. Programming the iValve is very easy --- simply adjust the dial on the control head so the arrow points to the desired ratio.

Cast Iron Boilers Reset the delivery Boiler operates on high limit Requires >1350 to prevent condensing Boiler fires more effectively, efficiently Take advantage of thermal mass Can add boiler reset, as well The Reset iValve works very well with non-condensing, cast iron boilers. The iValve will be in charge of resetting the deliver, or the radiation portion of the system. The boiler itself will operate off its high limit and fire to 180 degrees. This is important because cast iron boilers require at least 135 degree return water to prevent flue gas condensation. The Reset iValve has a function and a sensor that will automatically protect a cast iron boiler. The value of resetting the deliver portion of the heating system is that the boiler will fire more effectively, and therefore more efficiently. The iValve makes sure the radiant system effectively uses the heat the boiler creates, taking advantage of the thermal storage capability of a typical high mass cast iron boiler. The cast iron sections hold the heat fairly well, and the ivalve takes only as much heat out of the boiler as is needed on a given day – so that when the boiler does fire, it will fire longer and less frequently, raising is cycle efficiency. In general terms, resetting the delivery portion of the system, as shown here, can reduce overall fuel consumption over the course of the heating season 10 to 15%. Additional savings can be realized if boiler reset is added to the system.

Mod/Con Boilers Multiple water temperature system Resetting off the reset Lower return water temps Greater efficiency Gas-fired modulating/condensing boilers – called mod/cons” may also benefit from delivery reset. Most of these low mass, low temperature boilers come with boiler reset built in to the main control. In a single temperature radiant heating system – an all slab job, for instance – there would be no need for any additional water temperature control. However, if the boiler is being used in a system that has several different radiant installation methods – such as suspended tube in the upper floor requiring 145 degree water, extruded aluminum heat emission plates in the first floor requiring 120 degree water, and tubing in the basement slab requiring 100 degree water – then additional water temperature control would be needed. In this example, the boiler control would reset the boiler and deliver the 145 degree water to the upper floor radiant, and then two iValves could be used’ one for the first floor at 120 degrees, the other for the basement at 100. This “resetting” off the reset will lower the return water temperature back to the boiler even further, and create even greater system efficiencies.

Wiring This Bad Boy… 3 sensors 24v power in Boiler return, radiant supply, outdoor Outdoor sensor on north side, out of sunlight, above snowline 24v power in Zoning/circulator control done externally Wiring the Reset iValve is just as easy as wiring the Setpoint version…the only difference is one additional sensor for outdoor temperature feedback. You have the boiler return sensor for boiler protection. Again, this should be placed on the boiler return piping as close to the boiler as possible. This sensor is used ONLY when boiler protection is warranted – when using a cast iron boiler, for example. If using a mod/con, the boiler return sensor and boiler protection isn’t needed. The system supply sensor goes on the radiant supply piping, downstream from the radiant circulator. This sensor should be strapped on and protected with insulation in order to get accurate readings. Lastly is the outdoor sensor – this sensor goes outdoors on the north side of the building. It should be placed out of direct sunlight and above the snowline. The iValve should be directly powered by a dedicated 24V transformer. All zoning and circulator control is done externally with zone valve control boxes or single or multi-zone relays.

4-Way Valve One more hole… Higher Cv Same wiring For higher flow rates ¾” – 7 Cv 1” – 9.3 Cv Same wiring MUST pipe primary-secondary!!! We’ve seen that the 3-way iValves – both Setpoint and Reset – are perfectly applicable for smaller radiant jobs, or even for zone by zone reset. However, the relatively low Cv of the 3-way valves may limit their use. For instance, say you have an entire first floor with consistent floor coverings, consistent heat loads and consistent water temperatures. Zone by zone reset may not be needed, but it might be beneficial to reset the entire first floor water temperature. Here the 4-way iValve would be of use. There are two major differences between the 3 way iValve and the 4-way iValve. The first is obvious…the 4 way iValve has one more hole, so the piping will be a little different. In addition, the 4-way valve has MUCH higher Cv ratings and can therefore handle higher flow rates. The ¾” 4-way valve has a Cv of 7, while the 1” valve has a Cv of 9.3. The 4-way iValve is available in both reset and setpoint, and uses the exact same actuator head at does the 3-way valve. Valve wiring will be exactly the same. Because of the torque capabilities of the actuator, it’s critical that the 4-way valve be piped in a primary-secondary manner, as we will see.

Piping & Sizing 6 GPM, 5’ head radiant 1” pipe, 10’ total length = 0.6’ head ¾” valve = 1.7’ head Total head = 7.3’ Here we show the proper piping arrangement for the 4-way iValve. Note the primary-secondary configuration, and take special note of the fact that there is no circulator on the piping between the primary loop and the 4-way valve – because of the piping arrangement, none is needed. Also, make sure to avoid putting the 4-way valve in line in the primary loop. The primary circulator will produce too much direct pressure on the valve for the actuator to work properly. Let’s take a look at how the higher Cv rating of the 4 way valve will impact circulator sizing. Previously, using the 3 way ivalve with a radiant system requiring 6 gallons per minute, the overall head of the system was in excess of 14 feet, requiring a 0011 or 0014 to do the job. However, if we use the 4-way valve, we see that a much smaller and less expensive circulator will get the job done. Remember that the system required a total flow rate of 6 gallons per minute, and there was 5 feet of head for the radiant tubing. The hard piping required was 1”, and there was 10 feet of it. Using the head loss formula, we come up with 0.6 feet of additional head for the hard piping. Now let’s look at the 4 way valve, and see what happens if we were to use a ¾” valve instead of a 1” valve. The flow rate required through the valve is 6 GPM, while the Cv rating of the valve is 7, meaning that a flow rate of 7 GPM through the valve would create 1 psi of pressure drop, or 2.31 feet of head. The actual flow rate is lower than that. To find the head loss at the actual flow rate, we divide the flow rate of 6 by the Cv rating of 7, to come up with 0.86. We square that and come up with .74 psi of pressure loss. To find the head loss, we simply multiply .74 times 2.31 to come up with 1.7 feet of head. Add it all together and we arrive at 7.3 feet of head for the job.

Which Circulator? So, which circulator should be use? At 6 GPM and 7.3 feet of head, a 007 or a 008 should handle the job very nicely.

Why No 1” Valve? Could have, but… 1” valve = 1’ head loss Same circulator Why not use less expensive valve? Smaller valve – tighter water temp control Size valve to flow, not line size But why not use a 1” valve, since all the hard piping is 1” Well, you could use the 1” valve, but there are a couple of reasons to use the ¾” one instead. The 1” valve has a Cv of 9.3, and at a flow rate of 6 GPM will only impart 1 foot of head on the system, compared to 1.7 feet for the ¾” valve. That’s not a huge difference, and you would wind up using the same circulator either way – so in this instance, it would make sense to use the less expensive valve. In addition, the smaller valve will tend to give tighter water temperature control, since the valve won’t have as wide of a “hunt.” As a rule, it’s always best to size the valve by closely matching the flow rate to the valve Cv rating, rather than by line size. It’ll work better and save some cost on the job.

2-Way iValve Use for “injection” Higher Cv than 3-way valves ½” = 4.9 ¾” = 10.3 1” = 8.9 Can handle higher flow rate applications The iValve is also available in a 2-way version in both reset and setpoint versions. The 2-way valve can be used as in injection control valve, as we’ll explain shortly. The main advantage of a two way valve over a 3 way valve is a higher Cv rating, and lower pressure drop through the valve, again making it beneficial for use in higher flow rate situations.

Injection “Variation” Injection without an injection circulator Bypass, globe valve needed Size to flow, not line size Here’s a piping arrangement for the 2 way injection valve. Again, we pipe the radiant in a primary-secondary fashion using the two way valve to feed the radiant. The two way valve will open and close as needed to mix the appropriate water temperature on the radiant side, with some of the return water being piped through the bypass, with a partially closed globe valve.

Pipe & Pump Sizing 6 GPM, 5’ radiant head loss 30,000 BTUH 1350 SWT 1250 RWT 6 GPM, 5’ radiant head loss Bypass, manifold supply piping - 1” Injection pipe sizing: GPM = GPM =1.09 Valve/pipe = ½” .11 feet of head through valve ½” 1” 30,000 55 x 500 Here’s the same job – a 6 GPM radiant job, with 5 feet of head in the radiant tubing. To pipe this up with a 2-way valve, the hard piping from the bypass on to the manifold would need to be 1”, but the piping from the primary to the bypass, as well as the two way valve, would only need to be 1/2”. Why ½”? That’s the beauty of injection mixing. We’re only mixing a small amount of hot boiler water from the primary to keep the radiant system water at the desired temperature. The math is simple. Using our example of a 30,000 BTUH radiant system, sized to a 10 degree radiant system Delta T with a supply water temperature of 135 degrees, we would find the injection flow rate using the universal hydronics formula. GPM = BTUH divided by Delta T x 500. In this case, the BTUH is 30,000, but the Delta tee is the temperature difference between the water coming in off the primary loop – 180 degrees in this example, and the radiant return water heading back to the primary – in this case it would be 125 degrees. So the math would look like this – GPM = 30,000 divded by (55x500) or 27,500. If we complete the equation, the injection flow rate would be 1.09 gallons per minute. At that flow rate, ½ pipe and a ½” valve would be perfectly adequate. If we calculate out the actual head loss through the ½ valve, with a Cv of 4.9, we find the head loss through the valve is only 0.11. If we added all the additional head loss together on this job, the total head loss would be roughly 6.5 feet of head. With a flow rate of 6 GPM, a 007 would be perfectly adequate.

Additional Features Min/max system supply water temperature Minimum boiler return temperature Set with dipswitch – 120 or 135 Disable by not installing boiler return sensor WWSD -- 70 degrees or off The entire Reset iValve family has several additional features. Using dipswitches on the side you can set both minimum and maximum radiant supply water temperatures, as well as minimum boiler return temperatures for the boiler protection function. The WWSD function has two options – either 70 degrees or off.