Domestic Hot Water Recirculation in High Rise Buildings

the broadcast is now starting all attendees are in listen-only mode hello everybody thanks for attending today's coffee with Coletti webinar domestic hot water recirculation in high-rise buildings I'm Kevin frite with Coletti North America sitting in for Bob Rohr who was travelling somewhere in Pennsylvania he may join us if he gets an opportunity later anyway I'm very excited to welcome our distinguished guest speaker a colleague and an industry expert Claudio our Tetsuya from our headquarters in Italy welcome Claudio hi Kevin hi everybody I'm very piece of being here to participate in this webinar thank you a couple that are related to today's presentation are these two number 21 and 22 recirculation balancing and then master mixing bouts the the one you see on the right there so those are awesome if you don't have those you'll want those so here's Claudio he is a mechanical engineer with over 30 years experience in design and development of hydraulics and plumbing products and HVAC systems - so very strong background Claudio is instrumental in the certification and approval process of products for North America the European Union and Australian marketplace - so he's a global guy he's an active member of a technical committee in Europe which is dedicated to the prevention of Legionella in domestic hot water systems and we're very excited to have them here and in just a few slides I'm going to turn it over to him so let's go ahead and get started the topics today number of different topics will talk about static pressure we will talk about recirculation loops do we have one large loop or do we have to divide those into zones the water heater where do they get located on the roof in the basement somewhere in between we will talk about P RVs it gets tricky when you talk about P RVs and recirc and high-rise and cardio will tell you all about that do you need them in the research piping this is a question that we get sometimes here do we put P RVs in the research piping and the answer is coming soon how do you balance in in high-rise the recirculation risers what about master mixing valves how do they work so these are all the topics we'll cover in the next hour and the importance of Legionella to of course a hot topic right you're seeing articles we're talking about that and we have a very detailed presentation for another day if you've seen it or not but we'll touch on that today in high-rises too so to kick it off let me just start by Framing the importance of static pressure okay so if we look at a column of water that's 1 foot in height that will measure point 4 3 3 psi this is some basic stuff but I think it's good to set the stage for Claudio's discussion so if we set a floor in a high-rise you know is somewhere around 12 feet what we can do is you know round off and just say that's 5 psi so those of us here in the states it's kind of an easy rule of thumb just to estimate things without using the calculator and if we do that we can look at a stack like this a static high-rise would look something like this let's assume a couple of things first that the minimum pressure we need for our fixtures is 35 and the maximum is 80 what that means there is one PRB could serve about five floors so let's say we had a supply at the top of the building and we we had the pressure set at 35 now as you go down from floors 30 to 29 28 you know 27 26 what happens that static pressure builds up right so when we get down to floor 21 we're at 80 psi ok anywhere past that we have to put a PR B we have to reduce that pressure because I told you our fixtures can't handle over 80 so as you drop down further you're going to have to put a PRV in there so we could put it here on floor 16 or we could put it here on floor 20 to handle this group and keep these circuits in between 60 and 80 and the same goes for all these other loops coming down here so this is just you know your basic understanding of head pressure static pressure in the building and the same rules apply if you're coming from the ground floor up okay it's no different you're just starting off with the high pressure at the bottom and making sure that the upper floors have at least 35 psi so that those fixtures work as well so all these things you have to consider right the building height you need to know the municipal water pressure the fixture requirements and flow requirements some of those fixtures require 45 psi to work properly for example so you have to know that if we need booster pumps we need to talk about that and and the water heater system so there's a lot that gets involved here and we're going to get into some of that in good detail so so what I want to do at this point is turn turn it over to Claudio and so again welcome Claudio thanks thanks for being here we are literally in the same office we're sitting next to each other in my office in Milwaukee so I'm going to pass the baton over to Claudio hi thanks Kevin we I would like to start with this presentation directly with some real examples just forgiving an idea a general idea an overview what we will see later on so the typical example we start with first 20 stories building so normally 8 is ok 28 feet as a maximum height and you have a maximum pressure the bottom levels 120 psi so normally in this type of buildings one loop for a circulation hot water that's enough second example we double the number of stories more or less so we reach 48 feet in terms of 8/8 of the building and 40 stories normally is the average but at this this type of buildings are quite tricky because the maximum pressure of the bottom levels reaches 200 psi and here important to to consider this can be one of two loops third example is a week when with the 8th of the building is so high so 90 stories one on 1100 feet it's difficult actually to manage the maximum pressure at the bottom levers it quite impossible so we we need to split the system in two or three or even four loops just for overcome the pressure example here just a diagram showing where the hot water production is armed on top of the building and we have one large recirculation loop for more than 30 stories in this case at the bottom level we can reach critical levels in terms of pressure so the bottom floor would have inlet pressure above or roughly above 150 psi and the pressure limits of the equipment and fifties have to be considered and roughly for the right selection of the fittings and prvs have to be installed a branches of the recirculation line so another possible alternative way of controlling the the pressure and the recirculation is to F is to create a zone using indeed exchanger so in this case a secondary loop pressure is control with a POV station here operation of the circuit can be open or closed we have this configuration in a possible different way of applying in a real system in a single or multiple zone and the control of secondary loop we dedicated for expansion vessel relief valve drives the system to be a little bit expensive and obviously requires a correct commissioning it is that the control has to be accurate and serve it several times at other example more or less with the same logic so we have here the same principle but with all the equipment in one single box heat exchanger pumping station expansion vessel and so on and then distribution it can be multiple zone for instance or another application of the same principle same concept but single zone and the main riser divided in split in two parts where the first top level act as a primary and on the heat exchanger and on the secondary loop we reach the bottom levels controlling the pressure with the same principle with a high with a PR V station second another of the questions was where's the water heater located in a high-rise well hot water production can be located on the roof in the basement or at intermediate levels example here was a heater is on the roof and obviously we have to consider design for the hot water distribution so either static pressure is the limit mainly the limit of the equipment boosting station have to be selected and for the proper pressure okay and service work alik topic rain so we have also to consider that when we reach how at the top level you need a leak Akhter to move equipment or big cranes so also those things have to be checked and obviously who if we split the the loop in two parts and the system in two part because of the height of the building we have to consider the cost of the dedicated technical level and for some residential area this disease are very appreciable cost another example instead of the roof we can have the production of the hot water system with or without the storage at at the base in the basement at the bottom lever or in case of high-rise building we can split it in two parts so we have a dedicated level and the system with its own booster pump station serving the top the intermediate level so the system is split actually in two part and we control the pressure in a bad way now I would like to take the occasion for introducing and considering an important point within the use of pure V's and in a high-rise building special where you have if you have high hydrostatic inlet pressure so cavitation cavitation occurs where is a physical phenomenon that most people most designer know of course when local static pressure in a fluid reaches a level below the water pressure of the lipid at that actual temperature typical example of cavitation we have a POV that control the pressure and obviously the POV works on with an operator and on the seat and the stem and the flow passage through the to the seat in case of a very low flow or an high pressure difference between the inlet and outlet can drive the system and the POV to create cavitation so we are bubble formation and implosion of the bubble after after the reduced section and you can obviously experience following this phenomena you can experience Li vibration noise and damage to valve and piping so cavitation is a sort of how to say general overview on what is happening and we have method for controlling cavitation so we work on the under pressure ratio observing the downstream so to be kept under control and ideally in two to one or no greater than three to one and all manufacture they make those those type of diagrams available for the right selection so you have a good working area where the PRV has to work in case you exceed these this values it's good to have a HUD design review or at the evaluation of a different strategy so including the first staging of pressure using first the HB RVs there's a typical example so the first stage POV is camp can be one of the other possible solution so the high pressure drop between Inlet and outlet is split in two part the first valve is the first stage so called first stage where B controls the drop of pressure between the inlet and the end to an intermediate level so for instance from 240 down to 120 psi and the second stage acts as a traditional PRV normally set at 60 psi are the old led but we didn't come in pressure limited to 120 so in this case all problem created to a cavitation is a solved because the two pressure the two pressure reducing valve are working in pair to combine and to accommodate it so high pressure ratio another thing that we have to consider in this installation can be high low demand in terms of flow rate in terms of flow rate change and flow rate condition so we have this possible solution as a bypass solution so you have a small valve up normally half-inch valve set for 60 psi and in parallel working in parallel with a one inch and a quarter valve set for a lower set pressure 50 psi so automatically if the flow rate is a small just the the single valve that half-inch ball and to a level in such a way that the the valve itself is able to manage this reduce flow when the flow rate increases automatically because of the friction loss and the set pressure the difference in South pressure drives the second bar to open output automatically to manage the full flow these are one of the possible use a very simple system and with really proven proven effect very good very good very efficient depending on the configuration hot water recirculation loop can be located at a riser or at the branch circuit POVs this is a rule have to be installed off the loop in a range depending on the user circuits recirculation pump can be sold at the water heater level it is it normally did a condition where it is installed a couple of diagrams just showing a possible use of the first stage and second stage POVs working together so we can have recirculation of the riser and then the POVs are a branched off the riser so you have the first stage pure be controlling in parallel or single single control the first pressure reduction then you have the second stage appear v they can work individually or they can work in parallel so this is a one of the possible configuration in terms of depending on your network another one can be the recirculation at the branch circuit so in this case which is the the distribution that person I like really much because it has given a proven proven good behavior is to have the branch circuit and recirculation at the branch and every branch balance in the proper way with balancing valve here and then you have the first stage and the second stage branched off the loop now the question is do I need pressure reducing valve in the recirculation pipe in this is a tricky thing the difficult so you have a typical schematic taken from literature on some some real real design and design schematics you can see that this is absolutely wrong so it means that the the recirculation pump can't manage the high pressure drop created by the the PRV which is installed in series with the pump if the pervy is in stone the recirculation pilot heavy pressure drop it can be 100 psi between inlet outlet doesn't allow water to circulate and the calculation of the flow rate is normally based on the heat losses from the hot water supply to the first point in the supply piping normally quite normal way of calculation and the pumper had is selected based on the pressure losses of the entire closed loop so with talking about 10 15 psi Maxima so so high difference and the high-rise buildings this is important use the same calculation method so no special rules for high-rise buildings in terms of calculation of the loop itself another example more lassic trying to explain the same principle the same problem so even though even this one is clearly wrong because the P R V here is in serious with a pump this in this case the right the right configuration or the network should be this one where you are free circulation of the of the hot water through the loop and all the periods are branched off and separate from the recirculation loop then another main topic related to the good sizing the good behavior of the network so how do i balance the recirculation riser in high-rise applications and for this thing I will come back go back to to karyn's and he will continue with this presentation all right thanks Claudio so let's talk about balancing a little bit this is of course very important for a number of different reasons first I want to just touch on the three types of balancing valves we have static balancing valves and here are a bunch of products that are available in the market today some some different brands they all with the exception of that one on the bottom right they require a commissioning tool so they all have differential pressure caps and require a tool of some sort of manometer or digital differential pressure meter to set the flow so those are static balancing valves been around for a long time and they work great at a certain point dynamic balancing flow rate fixed flow rate balancing valves actually maintain a constant GPM so they're different they have a cartridge inside that moves back and forth opposed by a spring to maintain a constant GPM as the differential pressures fluctuate so they are different compared to a manual valve in that they have this the constant flow rate and something that we've been really talking to a lot of people about is dynamic thermal balancing valves again I have a lot of information on this by itself we'll just touch on it a little bit here they modulate they actually modulate the flow to maintain temperature so I like to say that they're a temperature solution for a temperature problem you basically install them there is no commissioning or tools required to put these in the system and they're really great for retrofitting you can just put those in we've seen a number of installations where those are installed in existing buildings and they've corrected a big balancing problem so there's that silver one there is manufacturers been around for a long time good product it's all stainless and then the one on the left the collec product is the 1/16 so technologically they're similar so you can use any of these valves in risers or branch circuits that's that's not there are no limitations there but we want to make sure that we you know stress the fact that balancing each circuit is it going to give you better control so what you want to do is balance each of the branch circuits so that's usually a small valve size 3/4 sometimes half-inch which again is going to serve a a circuit that in turn serves a number of fixtures now we need to make sure that we have the the pressure rating required for high rises so as we get into these higher pressures we just want to make sure that the balancing valves that we select are appropriate I mentioned thermal balancing I'm not going to get into a lot of detail but I do want to show you how they work so this is a cutaway of a colorful product the 1/16 and you can see there the the inside the flow comes from the left and it goes through this valve and seat design and then then on through the valve so this is a thermal what I call a thermal motor and it measures the temperature of the incoming water it expands and contracts to open and close this valve seat right here and graphically this is what it looks like for example if we had the adjustment dial set at 130 degrees Fahrenheit the valve would maintain a minimum position at that temperature and anything greater so there's a small flow coming through there with the CV of 0.23 at that point so the the thermal element can always respond to temperature changes in the water if that incoming temperature should drop what happens the the the thermal element contracts to open the valve seat up and the valve modulates open and this valve this particular valve has a 60 degree throttling range so from minimum to full open is is represented by this line here and what does that mean say our for example our water supply dropped off in temperature because maybe it's not size big enough these valves will all work together dynamically where it no matter where they are in the system to dynamically balance that all the flows throughout the system to maintain temperature so it's a great great theory and it works very well we want to stress the importance of having a check valve installed with a balancing device why why do we need to why do we need to do that it's possible to get reverse flow through a balancing valve depending on what kind of fixtures and devices you have in one loop if you get a big draw on a loop that's adjacent to another loop maybe you have a Roman tub or something like that and you open that wide it can actually draw flow backwards through the other loop and cause an imbalance so here's a picture of the the thermo setter with the check valve on the on the outlet of the valve very important here's a picture of one that's installed this is actually a project out in Colorado and this was a retrofit project here's the check valve right here so you want isolation valves of course for any service down the road it's not a matter of if but but when that you have to clean these as any valve and there's the check right there so that's a nice installation picture the switch gears a little bit and talk about the point of distribution mixing valves the master mixing valves what about those in a high-rise do we need one large master mixer or multiple smaller valves let's talk about that a little bit normally it would look like this okay you would have a master point of distribution mixing valve located at the heater and here's a schematic that we could look at for example if we had a storage tank it's very common to see a requirement of 140 Fahrenheit maybe we mix down temper the water and send it out to the building at 1:30 and maybe we bring it back at 120 if we've designed our recirculation system for a 10 degree delta T so that that's a very common schematic here and this is the the Caliph eligio mix product with the controller that has control over the water temperature we're measuring the returned recirculation temperature here the tempered water temperature and any way that that's a schematic that you can find in the in the collector literature and in that IDE Ronix that I referred to earlier so there's a typical system with one valve now you can also put multiple valves at multiple levels and put like one master mixing valve at each level now what happens right Claudio this gets complicated because then you have a recirculation loop for maybe for each master mixing valve right and then just you can do it certainly works fine but it just gets a little more complicated you want to be really careful with your design right I mentioned thermal disinfection or Legionella control this is obviously a huge topic we'd be glad to get into great detail with anyone that's interested just let us know we're just going to touch on it a little bit here relative to high-rise buildings yes it's a proven thermal disinfection elevating the temperature is a proven method that I'm going to show you how that works for all types of buildings it can be a small senior living center or it can be you know a ninety storey high-rise the thermal disinfection principle works in any building but what what's really important and the larger the building the more important the balancing comes into play because the balancing has to be done properly to minimize stagnation now think about if we do a thermal disinfection strategy where we are elevating the temperature we need to make sure that our bouncing valves are able to somehow bypass that high-temperature flow and I'll show you what that looks like here's an example of what that cycle might look like now this is related to our product eligio mix here's here's what it does let's say that you set the program to automatically go into disinfection at 2:00 a.m. for example and you want it to end at 3 a.m. what you do is set a couple of set points one of those being a 30-minute time we could say for example that we want to increase our storage temperature to 160 if it's not already there we want to reset our set point to 150 and we want to do that for 30 minutes so here's what that would look like here this this dark brown line here is my mixed temperature my tempered water the controller will at two o'clock start to elevate that tempered water temperature and get it up to 150 meanwhile it's watching the return temperature this is the really important temperature right here the dotted line and once that valve gets up to 150 it will run that for as long as it takes to get 30 minutes of confirmed returned water temperature at or above 140 okay right here so this these are all parameters that you can set but this is scheduled it's automatic in our product and it will do it whatever whenever you set it up to do this and that's what this looks like in terms of the mixed temperature and the return temperature if the cycle fails for some reason if you don't get thirty minutes of full 140 return you will get a message saying the disinfection cycle was not successful otherwise you'll get a message that it was successful and then the controller will have all that data in the data logging and the building automation system can record all that it's all recorded now this is these these valves are used all throughout the world it's a proven system they work great in high-rises actually any building and I just wanted to show you what that cycle looks like graphically again the importance the important thing is that we measure and record this cycle because then the building manager of the building owner has proof that the water has been sanitized when we're doing this when we're doing this elevated temperature cycle we need to be able to bypass the thermal balancing valves and here's an example of what we do to accomplish that this is a 1/16 series thermostatic valve we saw it earlier and there's an option to put a little zone valve right here in this extra X a part of the the balancing valve and what we can do with that it's a 24 volt 2 wire on/off spring return closed actuator that's a mouthful and you can run a pair of wires around to all your balancing valves and energize those actuators whenever you want to do a bypass so here's an example of what that would look like the valve will open up to a larger CV to allow significant flow through the valve during that thermal disinfection period the other option oh I want to point out one or two other things here this right here is actually a slide in temperature gauge you can if you have a building automation system and a large high-rise you can just slip in pull this gage out and slip in here a little temperature bulb you know a sensor of some type and run the wires back to an analog input on your bas and read all of the temperatures at all of your recirculation circuits and have all that information on hand for the building manager the other way to do bypass is with a self-contained thermal bypass and this one fits in the same location in the 116 valve and what it will do it will automatically do a bypass at 155 degrees so when that water coming down to the valve hits 155 this is a quick opening thermal bypass and it will pop open again to this level and if the water temperature continues to increase it will actually balance when you get up into this range here above 170 so this one is self-contained it doesn't require a control signal out to the valves to to let that bypass work so gosh we went through this kind of fast today again I hope you're entering questions in the questions box I don't have access to that right now but let's go ahead and wrap this up we talked about static pressure and high rises we talked about multiple loops one large loop or different zones and the different ways to do that and remember you can get a copy of this presentation too if you want to get those schematics to refer to we talked about locating the water heaters you know where are they up down in the middle somewhere we talked about prvs right don't put the P RVs in in the research line okay balancing we we talked a little bit about balancing and we can talk about that some more in other presentations just let us know point of distribution the master mixing valves we touched on that we touched on the Legionella I hope and I know we we finished a little early today but I hope you enjoyed this session please send your comments and questions and we'll get back to you and want to thank thank Claudio again for being here thanks very much Claudio thanks Kevin thanks everybody all right well have a great afternoon we'll see everybody in October