19 - Hot Water Loop

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When you are done with this air loop, you can move to plant loop, which we created some time back. This plant loop is, here. You can see all those hot water reheat coils from the reheat boxes. When you create, when you linked these diffusers here, to this plant loop 1, they automatically, the OpenStudio software automatically shows you all those reheat coils, even in the plant loop. You can see it, here. You can rename them, you can change the connection, here. In case you have multiple plant loops, hot water plant loops, you can change the loop by just unchecking one, and checking it to some other one, the new one, let's say. First thing that I'm going to do is, I'm going to click on this dotted line. And, I'm going to rename it to something, let's say, hot water loop. Then your fluid type as water, the default option. The other options are steam, glycol. What else do you have? You can change the maximum and minimum loop temperature. Let's say your hot water loop. The maximum temperature goes only up to 180 degrees. You can change it, let's say, 180, minimum, let's say, 150, in case it's hot water loop. You can also change the maximum loop flow rate. It’s gallon per minute. If you have some values given by your MEP designers, please put those values. You have some common pipe installation value. You can size the system, here. Like, the loop type is heating, the default option. Loop exit temperature, design loop exit temperature, let's say it's 180. What is loop design temperature difference? ASHRAE 90.1 appendix G says 20 degrees. You can change it as per your design. And that's it.

Once we are done with sizing we can move to the supply side. First thing that we need to bring is a pump, okay. Again, as like, fan, you have multiple options for pump. You can either bring it before this main sub loop, or you can put it off after sub loop. In this sub loop here, I'm going to provide some hot water boilers. I'll show you how you do that. But, the first thing is pumps, okay. Again, everything here in library is alphabetical, so look for pumps. Let's say a variable speed pump, you're constant speed pump, as well. You have a constant speed headered pump option, as well. For now, I'm just going to bring variable speed pump. Drag it and drop it, here. And then, the next thing that I need to do is, I need to bring one boiler, okay. Again, you have some options for boilers too, in OpenStudio. Let me just find the boiler, here. Again, sometimes I get confused. I think it should be with B. Yes, boiler hot water. You can drag it and drop it, here. In case you have solar thermals, you can also drop them. I'm not going to show you solar thermal. But, again, you have an option, even for solar thermal flat plate collector. They also can work as hot water supply.

Once you are done with hot water. Let's say, do we want to bring multiple hot water boilers, you can do it. Let's go to boiler, again. Bring it in series to these existing boiler, the first one. Or, in case you want to bring it in parallel, you can also do it. Drag it and drop it here. You can see this one is a parallel boiler to these two, okay. In case you want to bring a bypass pipe, in case this hot water loop is not working at all, you also want to provide a bypass pipe. Then you can do it here, in OpenStudio easily. Let me just find a pipe for you. Let me just see. I'm sorry guys, like, this library has so many options. I know there is some challenge, here. But like, you know, when you get familiar to this, you will be like, it will, you'll find it very easy, okay. It's in pipe. I'm going to bring an adiabatic pipe, and drag it here, and drop it. You can see, this pipe, here, is working as bypass pipe. You can rename it to bypass pipe. You can rename these boilers if you want. The next thing that I need to bring, again, is a set point schedule, okay. Like air loop, you also need to provide one set point manager for plant loops too. Let's say I want to bring an outdoor air reset set point manager, drag it and drop it, here. Click on this. You have all those values which will change later. And what else do you need for one plant loop? I think that should be good.

Click on this pump. You can rename it. You can provide some flow rate. You can provide the pump head. You can also do the calculations for wattage, or of this pump head, based on ASHRAE 90.1 Appendix G. You can provide motor efficiency. You can provide the pump control type, either it's continuous or intermittent. Do you want to provide other values? Like, something like, performance curve value. You can see these are the coefficients here for performance curve, the part load performance curve for pump. You can change it as per your design, or as per your manufacturer information. Or, you can always use the ASHRAE, or, I’m sorry, PNNL data. You can go to Google Chrome, just perform a search. You remember which one I am talking about, you just need to search PNNL 25130 document. And, this document gives you performance ratings. Or, some standards for performances for different components like, pumps, or fans, boilers, and so on, okay. Now you can go to pump, I'm sorry, hot water boiler number 1. You can change the fuel type. Let's say, it's natural gas, that's the default option. You change your electricity. Diesel, coal, so many options. Change the nominal capacity. If you want to hard size it, do that. You want to provide normal thermal efficiency, all these default values are as per ASHRAE 90.1 system.

What else? Do you want to provide some efficiency curve? You can actually change the coordinates or coefficients of this boiler efficiency curve, here. The default one is 100% efficient, which isn't correct. You can use your manufacturer data, or you can use the PNNL 25130 data, here. Same with other boilers. And then, you need to click on this set point manager. The default value is bit crazy it seems, for one hot water boiler. Let's see what other options do we have. Do we have something for one hot water boiler? Looks like, not. You can just click on it. Go to my edit. And, change the values. Let's say, set point outdoor air low temperature, let's say it's 180. And, outdoor low temperature, let's say, is 20 degree Celsius. Set point at outdoor high temperature can be 150. And, outdoor high temperature can be 50 degree Fahrenheit. I'm sorry, all these values are in Fahrenheit, okay. I think, if I'm not wrong, these values are closer to what ASHRAE 90.1 appendix G talks about. If not, please check. You can always create a schedule. You can create another set point manager.

Well, I think for now it's good, okay. We have provided all the information here that you need for hot water plant loop. What else we can do, we can go back to the air loop and check things, again. Click on this diffuser, here. Go to this link, here. And, you can see somehow these diffusers are not connect to hot water plant loop, that's a bit weird. Let me check for others, again. They are connected. Somehow the first one is not connected. I'm just going to connect it, here. See, that's the benefit of doing QC again and again. You should always QC your model again and again, very important. One more thing here, I also need to connect this primary heating coil to my hot water plant loop. Click on it. Go to link, again. And, just click, here. And now, you can see, it shows you to these tiny linkages directly on this primary coil. Even if you click on this, those two linkages, it says, go to attach to. It will bring you to the plant loop. See, it's a shortcut, okay. You can see, this primary hot water loop here, or coil here. And, these reheat coils from diffusers, okay. Once you are done here, you can save this model. Save it.