Hydronic Example - In-Floor

When we're talking about a hydronic in-floor heating system, it's gonna be pretty similar to the baseboard heating system and the radiator heating system that we were just talking about, but it has a couple of differences. On the in-floor example, if we imagine our floor. We can start to imagine a boiler, there's a lot of different boiler types, sometimes you have specific ones that are designed just for the in-floor, sometimes you just use regular boiler, there's a whole wide range of how those things can work.

But let's say we've got our boiler here on this main floor and again, we're gonna have a series of different zones. So, I'm gonna have a zone that's gonna come out and then that zone is gonna do something like... Where it's gonna be very closely tied together, but then it might do something like that.

And what it's doing there, going back, is in the middle of the building, if I have all of these pipes in the floor heating up all this area of the floor near the perimeter, that's great, but I just don't need that much in the middle of the floor.

In the middle of the floor, if I have all those pipes filled, it's gonna be too hot in those zones. So, they start finding ways to leave sections open, so I've got a little bit of an area here with no piping in the floor, and when I say piping, it's actually tubes, they're flexible tubes. They used to be pipes, there would actually be hard pipes that would be soldered and placed in the place for the framework where the concrete is gonna go and then you pour concrete over it.

These days, you actually use these flexible tubes, you kind of place them in a place, and maybe you tie them a little bit to the form work or to the rebar so they hold in place, and then you pour the concrete over them, it's much, much faster than it used to be, much more cost-effective. And the tubes had been made in such a way that they have metal in them, even though they're flexible tubes, they have metal in them which makes them transmit the heat very quickly, or at least, as reasonably quickly as they can from the water to the concrete.

So, I have these tubes and I'm just winding them back and forth, but then I'm finding ways to leave some of the middle sections of the building open because I just don't need that much heat. I would then have, there's one potential zone and then maybe I have another one that comes out and now I have another potential zone that's going back and forth for a little while. And then it's got its own edge conditions.

And then it goes back, right, so I would have multiple zones. I would try to design the zones so that they have meaning like we're talking about with the radiators and the baseboard systems. So, maybe I might have all the bedrooms on one zone and then all the public spaces like living rooms or something like that on one zone, or I might have all of the public areas of an office space or the library on one zone and then all the classroom spaces that are attached to that, in that library, on a separate zone.

And the reason I would start to have those kinds of meaningful zones is because I may have periods of time I want the building to be open and reasonably conditioned, but I don't need that, because the classrooms aren't gonna be used for the weekend or something like that, I can sort of turn those off except for having just a little bit of warm water running through those systems. So, you can balance the building and zones by the use of the spaces, or it could be that we say, all right, all the floors on the south side, all the rooms on the south side, we'll have those on one zone and then all the rooms on the east side, we'll have those on one zone and kind of do it from a climatic and orientation standpoint.

Either way, you're sort of balancing these systems up for meaningful reasons, you're making sure that most of the warmth is going towards the perimeter because that's where the problems are gonna be and that you're having less piping in the middle of the space either by, like I was showing here where some of the loops just don't go there or maybe you have pipes that are just far apart from each other and as they get towards the perimeter, get closer, something along those lines.

But the pipe always has to have a way to go out from the boiler and then return back and it has to be a short enough distance that it's not giving away all its heat before it gets out to the other end.

There's a limit to how far you can go, unless you're pushing a very big pipe and that would start to get a little weird inside the concrete slab. Most of these pipes are fairly small. The biggest problem with in-floor radiant heating is what happens if something goes wrong. It could be that somebody leaves open a window or leaves a door open, very, very cold day, and so the rest of the building is reasonably heated and doing okay, but because the thermostat is somewhere else, but then that area right next to that open door or that open window gets freezing cold and I get one pipe that starts to freeze and that one frozen pipe, as soon as the freeze goes away, and that has broken the pipe, you've created a leak in the pipe, in the concrete, which is a weird thing.

It may not even show up at first because the concrete sort of holds it in, but eventually, that water will make its way expressed and start causing mold problems and other issues as well as just not being efficient.

So, you can have a break in the pipe from just if the window is open too long near it, or it could be that somebody decides to put up a new bookshelf and they put something in the floor to hold it in place, a lag screw or something, completely not realizing that there's actually something in the concrete.

People may know that there's radiant flooring, but it doesn't mean that they are thinking about the fact that there's tubes inside the concrete when they're trying to put something up, put a sculpture up or something. They're putting that screw in, that lag bolt in, and they're damaging that tube and you're getting that problem again, water is coming out and you have all kinds of damage because now you have to open up the concrete in order to fix it.

The tubes are pretty darn resilient these days, they're pretty good at withstanding all of these kinds of issues, but still, the downside to the system is that if you do get a damaged spot, it's such a big hassle to fix it so as much as I love the in-floor radiant systems, they are problematic if they go wrong. If there's anything that goes badly, it's a big, big problem. Those are the issues, you're trying to balance the perimeter versus the interior.

You have a bunch of different zones, you're trying to make sure that those zones have logical meaning either through the use of the space or the side of the building or the climatic aspects and you're hoping for the best in terms of not destroying the building because if you have to repair these things, it means you're digging up the concrete which is a big problem. I love these systems, but they're not right for every situation. They don't make sense everywhere, but where they do make sense, they're really nice to live with.

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