Comparable product here might be a gypsum concrete. https://en.wikipedia.org/wiki/Gypsum_concrete
Makes more sense to me, thanks.
Radiant in floor heating system
- Thread starter OzSolar
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Makes more sense to me, thanks.
BentleyJ
Solar Wizard
No vapor barrier?
Oh my gosh...that is way too funny. Thank you! ?rotating phone sideways should show signatures
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eXodus
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similar, but no the same but I'm not in building science, just a home-owner with radiant floor heat
. As far as I know the German product stays dry for the life of the building - it's a granulate. You can just scope it out with a shovel. We had once a water leak and needed to dry the Schüttung, so a company drilled a couple of 50mm air holes in the perimeter of the slab - and put blowers on one side - on the other side of the room the air comes out.
Way back in the day 1200-1800s Schüttung was really just random fine gravel from around the building site. Only in the last 200 years it got a uniform industrial product. And in the 60s or so people started adding radiant heat to it.
there is a vapor barrier underneath the slab. Otherwise a long time German builders designed their buildings around "Breathability" Not very energy efficient, but long lasting. So there are ventholes in windows, and the roof is usually vented. No airtightness
Around the turn of the 19s century people started to experiment with cooper radiant floor. and somewhere in the 70s PEX came along
OT Ducati
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It's a small one at 1000 gallons.
OzSolar
Whatever you did, that's what you planned.
Do you operate it like I do mine? You can probably get the storage water much hotter than I can in my home built tank using ICF blocks.
EG: I build 1 or 2 fires per week. It takes about ~6 to 8 hours to go through 3 big arm loads to get my storage tank is up to 160F. The next day I clean out the boiler, reload it and then cost for at least 3 days.
OT Ducati
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Water temp below 180 is due to it being an unpressurized system. The fire box in the tank you run the risk of boil.
So, 1 fire a day 2 to 3 hours with outside temps 20's at night. As the outside temps drop through the winter the burn time increases,
due to the zones call more.
Teens during the day zero at night usually burn twice, once in AM and one in PM.
I'm heating 4784 sq ft of insulated slab this includes a 4-bay garage. This is 4 years old, insulated with closed cell foam and ROXUL.
Been using about 8 to 9 cord wood a season. Mixed soft and hard doesn't matter to me as long as it's seasoned well.
I just get the trees that are dead or dying, blow downs and what not on the property.
Thanks for the tip on The Radiant Floor Co. in Vermont. They were really helpful on the phone. We have a super simple radiant floor, one loop, one pump, one Differential Controller (to Rule them All, sorry, couldn't resist). The Differential Controller has one sensor on a water heater, and switches a Grundfos pump on and off at a set point. Unfortunately, the lowest set point is 100 F and the floor is usually 50-60 degrees, seems like the temperature difference is to wide to be efficient. Maybe more importantly, the high set point may reduce the number of times the pump circulates. Our heat source is hydronic solar panels so we only have a narrow window on winter days to heat the floor. Radiant Floor suggested we may only need a floor sensor which would be a cheap fix, rather than up-sell us to an expensive unit.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
I use the Floor Sensor which is within a tube (7/8" Pex line actually) that runs to the center of my slab. I have it set so it starts heating at 24.5C/76F and stops when the floor / slab is at 25.6C/78F. Now I do have 4" of HD-Type-II EPS Foam under the entire slab and up the sides, as well as 24" side wings to prevent frost creep under the slab. Building Code only requires 2" of foam for an FPSF Foundation.
The house we live in is 5 years old and the radiant floor heat is such a headache. We weren't the original builders as we just moved in 2 years ago but I already dread winters here. It's zoned in 5 areas. And the Northeast corner bedroom never keeps up. We live in South Dakota so it gets really cold here. -10 today and that room will drop to the 50s. That room and the other spare bedroom on the Northwest side are both carpeted. I imagine that is the issue. What I can't imagine is why the heck the builders would allow the owners to lay carpet if it causes the heat to be ineffective. Our living room had difficulty keeping up today too. That's stone tiled with a large area rug. Is that the issue there? The living room is much more insulated as the center focus of the house and I haven't noticed issues here before. But I was disappointed to see 66 degrees on the thermostat for the living room today. I'm tempted to put in a forced air furnace b/c the annoyance of radiant floor heat never keeping up is making me crazy. Anybody relate? Any tips? Suggestions? I feel bad wasting such expensive work but a 5-year-old house should not be having this many heating issues, right?
OzSolar
Whatever you did, that's what you planned.
Hmnn... Let's look at the easy things first. Can you monitor supply and return temps? Supply and return flows? What size is your house? Heat source?
Have you had someone beside the original installer take a look at the the system? Did a professional design the system to begin with?
Edit: to fix typo
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Zwy
Emperor Of Solar
Plenty to digest there. How is it zoned and how is each zone controlled? By room? Can you provide pictures of system? What is the square footage of the house and what is the btu rating of the boiler?
Have you had a professional come look at it if you have no idea how it works? I'm referring to a professional that is highly recommended, look online, search your area and read reviews. Sometimes they even write a blog on their website, these usually the type that are a step above others.
One thing with all radiant heat is there needs to be air purged from the system. If a zone has air in the tubing, there won't be any flow with other loops open. Usually there is a manifold on the return where you can close valves and shut off those loops of tubing. I will close all valves but one on the return manifold with the circulator pumps running. You will know if air was present, usually you hear a gurgling sound as the air in the open loop is forced out. Then open the next valve and close the first one, repeating to process down the line leaving each loop run for some time to clear small air bubbles out. If you have a inlet manifold with a flow gauge, you can see when the flow starts as the air is forced out.
Radiant heat is great with a properly working system. I've seen many improperly installed systems. Issues range from boiler not large enough, closely spaced T's set at the wrong distance (use a low loss header and this won't be a problem), air entrapment without a means to remove it, not using primary/secondary loops, improper installed loops (lengths differ on a manifold) and thermostats. And I'm not a residential/commercial heating technician, I just happen to see systems in various shops and had installed my own. I learned plenty in the process, I researched heavily and knew how a system should be designed and operate before I ever installed mine. The boiler shown in this photo https://diysolarforum.com/threads/radiant-in-floor-heating-system.51401/post-653492 is not installed now, a leak developed in the heat exchanger and I swapped it out over New Years weekend.
I often heat my house to 25C (77F) with my radiant floor heating, especially when someone feels ill. As others have said, what is your incoming temperature and your return? Also, are you pumping pure water, or water with antifreeze - and could it be you have a burst pipe somewhere if the former (e.g., if the house has remained cold for a winter)?
Personally, I never had any issues warming my place with radiant floor heating, with a wood gasifier as energy source - and that's a log house with lots of glass, so not exactly a great R value for the walls (roof and floor are very well insulated however). Perhaps it's a matter of some air in the pipes (as suggested), a bad pump (or wrongfully configured), bad mixing valve (or broken sensor), or just a wrong configuration for your incoming water temp.
Key word is that it is a *radiant* floor. Carpet kills the radiant effect, so you need to rely on less efficient conductive heat transfer. That requires a significantly higher water temperature-- at least 3F, but it could be up to 10F.
If there is nothing under the carpet as a flooring material then you will likely need to add a mini-split heat pump or something for comfort.
It is written in lots of literature on radiant heat that it is more efficient to have a smaller difference, deltaT, between the temperature of the circulating water and the temperature of the slab. How much difference can it really make?
Currently, my system only circulates at 100 degrees and the floor is usually not above 60 degrees. We are operating on "if it ain't broke don't fix it", but if it would make a big difference I'd try to find a way to change the set points of the differential controller.
Currently, my system only circulates at 100 degrees and the floor is usually not above 60 degrees. We are operating on "if it ain't broke don't fix it", but if it would make a big difference I'd try to find a way to change the set points of the differential controller.
If you compare the cost of adding some electric heat sources for your cold rooms to your installed radian't floor system it would be cheaper than a whole new furnace system. Forced air leaves cold areas too, and near the floor is always colder than the ceiling, if that is any comfort for you.
I think you also need to look at the delta-T between hot water supply and return to see how big of an issue you have. A low hydronic delta-T means you don't have much load and you are wasting energy heating up the water too high; you could either reduce flow or reduce temperature. A high hydronic delta-T means that the start of your loop has much higher heat transfer than the end, which can make for an uncomfortable house especially if the start of the loop isn't where you have the highest loads.
Once your hydronic delta-T is reasonable then you can look at its differential to the slab temperature.
Transport losses, pump losses, etc. You have to move the hot water from the tank and back again. The tank is well insulated, the pipes less so, and losses occur. The lower the water temperature you have to send, the lower your losses will be. You should aim to have a delta T between supply and return as low as possible, and having the supply temperature also as low as possible.
In addition, having a large delta T between slab and water in normal operation probably means the slab is losing the heat faster than it should. This could be due to bad insulation, or other losses (e.g. cold bridge between slab and outside).
