Radiant Floor Heat Highly Inefficient, I think I messed up somewhere?
Hello guys,
I have been building my own home for almost the last 3 years and end of last summer I commissioned my hydronic radiant heat in a bit of a hurry due to drywall/mud work that was going on. I got everything piped and fired up, and I think I did some adjustments at that time to "balance it", but don't really recall what I did if anything. The system worked and kept the entire place warm during the drywall phase. Since then we have moved into this home full time and have been using floor heat as our primary heat source, keeping the house at a constant 22c (71.6F) The house is always warm, but our gas bills are pretty high….and I think I am starting to see some of the issues, but don't fully know how to address them.
I had loop plans professionally made with LoopCad, and have all the information that LoopCad spits out, and will share if needed. I had assistance with the system design itself from the folks right here at HeatingHelp.com and used their advice to put the system and components together.
Here are my components:
Rinnai i120CN Combi boiler
Taco 0018e Circulator
Taco Zone Valves and Zone Controller
In total I have 4 zones, 4 manifolds (3 in utility room, 1 is remote)
I think I finally figured out my problem yesterday, and that I didn't have enough flow going to the manifolds. I noticed a long time ago that my return was always room temperature at best, but I never had the time to think about it, assuming that it just means the heat is being shed into the slab and that's how it's supposed to be, but then I remembered the magic "Delta T of 20 degrees" and looking at mine, it's VERY far apart. I adjusted the flow valves on my main living room (the biggest manifold) and increased it significantly, and within a few minutes my return temp jumped from 70F to 90F and was actually feeling warm for once.
I believe that the reason my system has been so inefficient, it because the boiler was circulating majority of the heated fluid within the primary loop, with just a bit going to the secondary, and because of that, it was warming the house, but running for way too long, thus burning unnecessary fuel.
When I initially setup the system I bought a 0018e pump as it seemed to fit the bill for flowrate and head numbers as per LoopCAD (assuming I interpreted them correctly). I wanted to tune it to run more efficiently based on zones opening/closing, instead of running it full tilt in "contractor no-call back mode".
So here is my dilemma now, how do I properly tune this system to work efficiently? At this point I feel a bit overwhelmed with all the different moving parts. I have 4 zones, 18 individual loops, and a single pump, and I don't know if I should be opening all 4 zones and all 18 loops on max at this point, or opening one zone at a time and tuning it to some numbers (probably from LoopCad?). I have all the information about everything here, I just don't really understand what I need to do to put it all together into an efficient system. I am willing and ready to answer any questions and provide any information, I just don't know what relevant and flood this thread with too much info all at once. Please help!
Pictures of my system:
Comments
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The key to an efficient gas boiler system is low return temps. So set the supply low, keep return temps low, and you’ll be great. Lower is better if the thermostat is satisfied. You don’t want a 20F delta T for floors, typically you want 10F per floor loop, so raise the flow until you reach that. There is no magic delta T.
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18 loops at at least . 50 gpm? Does LoopCAD tell you the flow each loop needs? So maybe 9 gpm or so?
How long are the loops?
What % glycol?
You need to let the zones run for a while and check delta, it will be wide at first closing as the system warms.
Hydraulic equilibrium is when the supply and return temperature have stabilized, measure the delta at that point.
The tighter the delta, the more pump you need and the glycol hit also. 10- 15 ∆ for radiant floors.
the PPI website will allow you to see the flow spec for the loops.
Here is a 300' loop, of 1/2'' pex, .50 gpm- 40% glycol
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Do you have nay high temperature zones? (by the looks of things you do not.
Are you using the outdoor reset function of the CH portion of the Rinnai?
Are all 4 of the low temperature using the same floor temperature? Should they be using the same floor temperature? Slab on grade should be different temperature from staple up and different from carpeted floor to hardwood to tile. & what @Hot_water_fan said also!
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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And a further point: changes in flow and delta T and all that can make small differences in fuel efficiency — if the boiler is properly tuned, at most 10 percent.
Which means that your fuel use is not related to the "efficiency" of your heating system — that's within 10% of the very best you could do — but to the heat loss of your house. If you want to get fuel use down, tackle heat loss of the structure. There's no other way to do it.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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I will reply one post at time to keep the information contained to the question asked.
Looking at LoopCad data, the flow rates on each loop vary from .13 on the low end, to .72 on the high end. In total the summary page shows the entire system having a flow-rate of 9.35 usgpm
This picture below shows the flowrates and loop lengths. The manifolds are named 2/3/4 in this screenshot, because originally there was an upstairs zone that was removed later. Loops A12/13/14 were also removed from Manifold 3 and split into their own 3 loop zone.
I am running 35% glycol (premixed)
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The house is always warm, but our gas bills are pretty high
When you make the conclusion that the gas bills are pretty high………….on what basis do you so state? This is the very first time you have occupied the house on a full time basis so there is no comparison to previous years.
You can't compare this house to your previous house…………..no correlation there.
You probably have not reviewed the price of gas per therm in the last year……………you might be shocked at the increases. You certainly cannot judge simply based upon the dollar cost.
With a brand new house, if built properly, with a mod-con boiler, I can make a good argument that your gas bills are actually quite low.
You are chasing a perfectly good heating system using the wrong argument and without any data (posted).
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Hello. In my setup, I have 3 zones that are at 22c (71.6F) and one zone (garage) at 15c (59F). As per the picture I posted above, Manifold 3 (with A12-A-14 separated into own manifold, we can call it Manifold 3B) and Manifold 4 are at 22c, Manifold 2 is at 15c since it's just a garage.
I do have outdoor reset hooked up for my Rinnai. This is all slab-on-grade.
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Hi, thanks for you input, but I don't think I have significant heat loss. My entire house is a giant ice cooler basically, fully spray-foamed. My garage would be my worst area due to seals needing some adjustments, but I don't know if that in itself would cause the usage to be so high.
Here are some pics of the loops and foam. There is 2" of closed cell spray foam underneath the 4" of concrete in the pad itself, and then the entire house, top to bottom is spray foamed with 3-4" of foam. This is a conditioned attic system (no roof venting), warm attic, and uses an HRV to circulate air. It's a pretty tight building envelope.
I do have a high Carrier Infinity 98 4-zone furnace in this house as well as a backup heat source (and heats the loft for now) and have been toying with the idea of using that to heat the home for a while and compare, but I much prefer the hydronic heating, it just seems like it's not as efficient as everyone said it would be..so just trying to establish if something is wrong with my setup, or if it's just the nature of the beast.
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All looks good there. Garages can add a bit of load and heating cost. Overhead doors allow a lot of heat out.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
So in theory, I should be going to each one of my loops as shown in LoopCad, and adjusting the flow to what is shown in the chart for each individual loop?
I do have a few other things that I think might be playing into my concerns:
- In each zone I use a Honeywell Hydronic thermostat with a slab sensor. I use the AF mode setting as described here. I have set my floor temperature limit to 24c (75.2F) and I believe majority of the time that limit is reached which causes the system thermostat to turn off, perhaps prematurely?
2. What temp should I be running my boiler at? It feels like it's running very high, perhaps reaches the floor temp limit, and then shuts off, instead of running at a more constant heat and trying to reach a good delta?
Thanks everyone for the help, hopefully I will figure this out or at least put my mind at ease here.
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It might be helpful for us if you define efficiency. What do you mean by that? What were your expectations and what exactly are you experiencing?
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Well I am not entirely sure I guess. I am just going off what I used to pay in my old house, and what I pay in the new house. The old house was smaller, but used traditional bat insulation with traditional vented attic. The new house is significantly bigger, non-vented roof assembly, but much better insulation, yet my bills keep creeping up and up, and it hasn't even been a cold winter. Currently we are in a 2 week -20C spell…and I worry of how this will impact my bills here, and if I am missing something in my setup that wasted heat (maybe in the primary loop?) instead of putting it down into the floor…thus running way too long and wasting energy.
Everyone who has come to my house to do any work always said "you will be able to heat this place with a candle"….yet it seems like it's using much more. Last bill I had showed 24GJ of gas used…and the boiler is the only gas appliance we use (and the furnace, but that's for a small loft upstairs) only. Just seems like a lot for something that was touted as being very efficient.
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What’s the boiler supply temp? If it’s 120F or less, you’re really doing about as well as you can do.
3 inches of closed cell is pretty mediocre insulation! That includes the attic?
I think to this point, I’ve seen no indication that your system is inefficient at all. But also - the furnace is the same efficiency as the boiler. So if you thought radiant would be more efficient than a high efficiency furnace, unfortunately you were misled. A lot of magical thinking exists around hydronics.0 -
@eblend : "I don't think I have significant heat loss. My entire house is a giant ice cooler basically, fully spray-foamed. My garage would be my worst area due to seals needing some adjustments, but I don't know if that in itself would cause the usage to be so high.
Here are some pics of the loops and foam. There is 2" of closed cell spray foam underneath the 4" of concrete in the pad itself, and then the entire house, top to bottom is spray foamed with 3-4" of foam. "
By modern standards that's pretty marginal. It depends on your climate zone, but modern codes will typically require at least 5.5" in the walls and 12" in the roof. Spray foamers are pretty notorious for mumbling some mumbo-jumbo about "equivalent insulation" and putting in half what you need.
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You haven't stated the actual cubic footage, but based on the photos it appears to be quite significant. 24 GJ in freedom units is 227 therms, which is actually great for a space appearing to be upward of 50,000 cubic feet. No amount of flow adjustment is going to save a significant amount of fuel, but the supply water temp coming from the boiler will maximize it. If you were to need, say 16 BTU/SF you'd be looking at a surface temp of approximately 80* which should be easily doable with a 100* supply water temp and the proper rate of flow. For now, personally, I'd open up every loop wide open (balance what's necessary), then keep turning down your SWT until it no longer keeps up with demand. On the coldest day of the year, a properly tuned system will run 24 hours straight at the lowest possible water temp.
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To get a picture of where your losses are you should get an infrared camera and view the outside of the house on a cold day. You might find leaks around the window and pay attention to the slab perimeter, eves and soffits.
Miss Hall's School service mechanic, greenhouse manager, teacher, dog walker and designated driver
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I think, sadly, that your problem isn't the radiant installation — and that, therefore, no other system (furnace, hot water, steam, whatever) is going to make a difference. It just plain is going to take that many BTUh to heat that house. As others have said, the amount of insulation you quote isn't really all that much.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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Thanks for the reply. I believe because it uses an outdoor reset, it runs on it's own curve. I haven't touched this setting, but perhaps I should. Here is what the manual mentions about outdoor reset and the temperature curves. I believe mine is running on Curve 1 as I have seem 168F flash on screen when CH is running, it's the default setting. Perhaps I should be setting a custom curve 4..?
Regarding the insulation, just double checked, and it's 3-4 inch closed cell in the walls, and 4-5" closed cell on the roof deck. The insulation is not extreme by any means, but being that it's closed cell and is a vapor/air barrier, it should perform better than equivalent fiberglass ect. It is what it is at this point. If all other indicators point to all else being okay, then I will accept this as the new reality. Never had a home this big before so don't know what to expect.
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I have been researching spray foam for a long time before I committed to it, so I believe there is some truth to some of their statements. The county had no issues with my insulation amounts, and they are pretty strict here now with whole energy efficiency stuff. My numbers were a bit off, it's 3-4" in the walls and 4-5" on the roof. Still nothing extreme, but it is what it is at this point.
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Those curves aren’t great for slab heating. Can you set it at a constant 100F? With no curve?
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Any chance you had blower door test after moving in?
Any insulation below slab? I see, 2 " closed cell. foam
24Gj, is 227 therms? That does seem like a lot.
What setting do you have the 2ndary loop 0018e circulator set to?
After the system has been running 5 plus hours what is the supply temp and return temps in and out of boiler? What is the return temps from 2ndary loop into primary?
In the photo, the display shows 180 on the boiler. Is that what it's set to?
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Thanks for the reply. So my house specs are as follows, but basically just the main floor and the garage are being heated by hydronics
It is 10' ceilings throughout, except for the kitchen/living/dining area, which has a vaulted ceiling to about 14'. Being that it's a conditioned attic space, there is a huge amount of roof space as well above that, as the peak of my roof is at about 25' high. It's a big bungalow.
Below is a blueprint of the entire heated area:
Entire house for illustration purposes:
Thanks for your input. I have never lived in a house this big, it's our second and final home, so I don't know what to expect when it comes to heating a structure this size. If my numbers aren't completely out to lunch, then it is what it is and it's just the cost of owning a big home, and I'm okay with that, but if my system is misconfigured somewhere, then I would like to know to maximize the savings/reduce costs.
Based on the very last thing you said, about the supply water, as well as what @Hot_water_fan mentioned, it seems like I am running it too high on the default outdoor reset curve and should look at making the switch to curve 4 and adjusting the temperature manually. Do you concur that this would be the way to go? The more I look into this, the more I realize that running 24/7 is the way to go for these systems as you mentioned at a consistent temp, I am definitely not doing that now.
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Thanks. Yah I have a thermal camera, got it recently for a different purpose, and will walk around some more and play with it as I learn everything. So far from everything I have seen, windows and door as expected. No major cold spots visible on any of the walls. Garage doors are cold, they are insulated, but it's only like an R12 I believe. The seals on those need to be adjusted as the door had to be moved in a bit, so they aren't all the way tight, will work on that during summer. Will do an exterior walk around later, it is cold out. My preliminary look on the outside didn't show anything strange, aside from doors/windows. I do see some heat loss around the pad perimeter which is still "exposed" as the grade hasn't been fully brought up around the home. By exposed I mean the metal skirt around the house that is on top of a frost wall. The pad is on the other side of that skirt behind rigid board insulation that makes up the frost wall , 2x6 wall, and a bit of spray foam which was rolled up on the bottom plate just a bit to seal things in. Eves and soffits are all blocked off here as I don't have a vented roof, it's all sprayed shut, didn't see anything strange there, but will look more later.
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Thanks for the input. If it is what it is, I will just live with it, but if anything I can do to improve, I would be all game for it. Can't add any more insulation at this point, so if it takes that much to heat the place, so be it. I was just a bit shocked with some of the bills I was getting and wanted to make sure I wasn't completely out for lunch somewhere in my setup. The house feels a million times more comfortable than our old place (old place was a 2006 build), no drafts, wife isn't always cold like she felt in the old place, so it's definitely better sealed, so if that's what I have to live with, I will accept it :)
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So I was not too far off with my 50k cubic foot guess? With your insulation (roof deck is less than ideal, though walls should be fine) coupled onto the sheer volume of the space, 227 therms is not bad at all. If curve 4 is easy to program, maybe set it so that it's about 70-75*F on your warmest heating day (I usually set the top end for a 65* outdoor temp with 70* supply temp) and then 100-105*F on your coldest day (I use 105* at -20F here in MN for a build like yours). Otherwise just disregard the outdoor reset curve altogether and set it for 100* and adjust from there as needed. You could probably pull 5+% more efficiency out of the system by dropping the water temp, but beyond that, more insulation/ less air infiltration is about your only option.
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Yah, I did a rough online conversion and I think your guess is basically right on. I will play with the settings, the instruction are pretty clear on what needs to be adjusted, and see how that goes. If nothing else, it would reduce the boiler cycles if it runs more consistently at a lower temperature.
Regarding air infiltration, I will ask this just in case you are familiar with other heating options, but my furnace is constantly running circulating air via an HRV. It's just in fan mode for every zone, except for the loft, where it's set to heat as well. There is a wall control for the HRV and the guy when installing it simply said to leave it on low all the time, and that it's interconnected with the furnace. I read online that some people were saying that running HRV in the winter all the time isn't great, as it changes the air inside the house far too often, reducing overall efficiency. Any input on that? Should I be looking at something here, or just leave it as if and let it be? Since my house is pretty sealed, mechanical ventilation is my only controlled way of exchanging air, so I know I can't turn it off completely, but just wondering if something there can be improved.
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99% of people in my parts never use the HRV unless it starts to get stagnant in the house. Many actually remove them shortly after inspection. You're throwing a lot of BTU away by running that thing constantly, but whether or not it's actually needed is something I cannot diagnose from here. Personally I'd turn it off and see what the air quality does, then adjust from there if necessary. I maybe run mine for a few hours per year at most.
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I have to admit I'm not really keen on HRVs — but they are much better for air quality than ERVs, so you are well ahead of the game in that regard. Take a look at the settings for them — I'd try for two air changes per hour to keep indoor air quality something decent.
You have to balance indoor air quality vs. "efficiency". A completely sealed — or well sealed — modern structure, unless there is adequate air exchange mechanically, may well be very efficient — but is very unhealthy.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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You have a floor sensor in the slab set to max. 72° A 72° slab will not do much heating.
.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Thanks guys for that input. I will take a look at what settings I may have access to there.
I will investigate this further as well. Up to this point it has been heating the entire house with that setting in place, perhaps slowly, I am unsure, but it definitely heats. Last night it was -22C (-7.6F) and my house is my standard 22C temp. It is warmer than that in the area where it enters the room, at least has been under my restricted flow, but using my thermal camera since I let more flow in, my floor temps are more consistent throughout. My flooring material allows me to go up to 27C maximum, so I'm afraid to crack that up too much higher. I figured 23C floor could warm up the area around it to 23C…but I don't know how that works, obviously :D
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The floor will give you 2 btu/ sq ft for every degree difference between the floor surface temperature and the air temperature.
so a 80 degree floor in a 70° degree room would give you 20 btu/ sq ft.
Set the floor max to 26C. The thermostat will regulate the room based on air temperature the sensor prevents going to the flooring limit. Think of the sensor as a high limit switch.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Heated garages were common in cold climates in the early 20th century. Most were disconnected due to high fuel costs and the fact that modern cars start much more easily in cold weather than older ones did. I suspect that's where a lot of your heat is going.
—
Bburd0 -
Cool thanks, I will make the adjustment. Originally when I setup these thermostats I had them set to floor sensor mode only, and later found out it wasn't a good idea for general heating. With it set to floor only, it was heating the floor even when the room was already much warmer (sunshine beaming inside from the outside, generally warm day, but floor was under set temp). When I switched it to Air/Floor mode, I used the same concept to prevent it from heating more than the room itself, looks like that was a mistake.
Yah, this is understandable. My old house had a detached garage that I never heated and it was always warm enough for most things, at least 10C warmer than the outside. Right now I am actually not even heating the garage for cars…it's where all my stuff is, including all my tools, as I continue on finishing up the house. I do have a "bedroom" upstairs where we currently sleep which is above the garage, which is what motivates me to keep it warmer than I normally would. Perhaps I will investigate turning that heat down a bunch, since I do use the furnace to heat up there now, which is something I wasn't doing when we initially moved in. At that time, the temp upstairs was always colder than in the main living area as there is no hydronic heating up there. Still learning this new house and how to best set everything up. I suspect that I do have a ton of heat loss there, as the pad lip is also completely exposed directly to the outside. The temps will be a steady -20ish overnight for the next week, I will turn off the heat in the garage and see if the furnace upstairs will keep us comfortable at night. Garage does have spray foam insulation in the ceiling/loft floor, so I suspect we will be just fine.
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Unfortunately there are two common myths out there.
One is somehow spray foam is magical insulation and will make any place efficient.
The other is hydronic heat is more efficient.
Neither is true as you can't cheat basic physics. BTU is BTU and R value is R value.
Truth hurts, it hurts in the pocket book.
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with radiant panels you heat the objects in the room. Anything in line of sight will be warmed by the long wave radiation. Not unlike the sun which is 93 million miles away. Step into the sunshine on a cold winter day and feel the radiation instantly. The energy travels through space releasing the energy when it strikes some object
with any system that heats the air, hot air rises. With a thermometer note temperature at the ceiling is higher than the area where people reside.As such, many radiant owners are comfortable with a lower temperature setting, as their feet and anything they touch may have been heated.
So an argument could be made a comfortable radiant home set at 68 degrees will use less energy than a forced air home at 70-72.
Then there is the energy needed to move the heat throughout the building. 37w with a new ECM circ. A fan in a forced air system will use more electricity.
Zoning is easy with hydronics, so rooms kept a few degrees cooler will be using less energy than, a single zone FA system
Then there is the space required for a ducted system compared to hydronic.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream5 -
I did a ton of research before I committed to doing sprayfoam, and while I don't drink all of the coolaid, I do believe it is a superior product to basically anything else out there. There is a channel on YouTube called Spray Jones, and I must have watched every single one of his videos. He goes into everything in a very detailed and scientific way, so it's kind of hard to argue with what he presents in absence of other facts. He does state that R value is only part of the equation, but more importantly he talks about BTU retention. He isn't just saying these things, he shows evidence, engineer reviews and lab tests ect ect. It's really fascinating stuff, I got addicted to it in the cold months when I was waiting to start my build. One of the reports that he talks about was actually instrumental in my own permitting process, as that report made Alberta (Canada) issue a STANDATA (province wide variance, interpretation or information bulletin related to safety codes and standards) that basically changed the rules of the game, and that was backed by facts and a group of engineers. He also often rants about the big insulation companies and all the lobbying they do to keep the code the way it is, solely concentrating on the R value, as it is their business.
This is just a snippet from one of his videos explaining BTU loss efficiency at different thicknesses, at some point it's diminishing returns, so while you could always go thicker, it doesn't help much more. I find this guy to be pretty good at backing up his statements with facts. He has a whole series of video of why the building codes are rigged to favor traditional insulation. By the way, I would never use open-cell, everything I said is all about closed-cell.
I find this one video particularly good
I like this particular mention if the video above
But anyways, I am not going to argue about it, what's better or worse, just sharing what I learned over the years about it. Right or wrong, the insulation is in and it isn't going anywhere anytime soon :)
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Just another little update. My buddy has a house out on an acreage as well, it's a bungalow but with a walkout basement and a tripple car garage as well. I asked him about his usage and it made me feel better about my numbers. His house is a traditional build with vented attic, bat insulation ect ect. He is at 2550 sqf for the living portion of the house, and his garage is comparable to mine size-wise, but like 14 ft ceilings vs 10 for mine. He uses radiant for his slab in the basement + staple-up for portion of his main floor + furnace, and in the garage he has a large infrared heater hanging on the ceiling. He gave me his usage today in GJ and his last month was at 29 GJ, vs my 24 (don't know if dates are an exact match or not, but it shouldn't matter too much, last few months were very similar around here. He keeps his house at 21C, and the garage at 12C, unless he is working in there, in which case he cranks it to 16C.
He shared this overall graph from his place which includes some of his previous years in there.
So maybe my usage isn't so bad after all. I know you guys said it, but it's nice to have a comparable in the same region. He has a slightly smaller house, heats it less than I do, yet still uses more gas than me, so seems like my setup isn't too terrible after all, and I was just in for a shock owning a big house. He does use a gas stove, so that would add to some of the difference, but don't know how much.
Thanks everyone who has contributed, it was very helpful. Love this forum, everyone is friendly and helpful, unlike some other places where people just troll. Much appreciated.
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@eblend I hope you don't take this as picking on you. Unfortunately there is a lot of entertainment out there that masquerade as science. A good telltale of anything pseudoscientific, say "effective R value" or @DCContrarian favorite "thermal mass", is that it has no units or any way of determining it. It is important to call it out for what it is.
R value works because it is a real property of materials. If you give me a location, a building, how it is constructed, R value of assemblies and air leakage, I can calculate with pretty decent accuracy how much energy that building will take to heat. That is science but doesn't make good entertainment.
There is no mystery, a wall that is 2x the R value looses 1/2 as much heat. Of course you can get into law of diminishing returns but a couple of inches of spray foam is not it.
I like spray foam. Spray foam is actually kind of magic when it comes to sealing up old leaky structures.
There are also a lot cheaper ways to add R value to new building assemblies than spray foam. I like to say if you are using spray foam in a new build, somebody didn't do their design homework, spending good money for not much gain.
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Could get into the nitty gritty of it all, but what you are talking about is a couple % of operating cost at best. Spending real $$$ for those couple of percent, ROI is never.
There are very few heating systems out there running on a 37W ECM. Most you see posted here will have at least a 150W of pump power. A new ECM blower on an air handler is maybe 250W, so not far out there.
Stratification is more of a function of how leaky a building is. Once you get a building event to code min (3ACH @50PA) levels, the temperature delta mostly goes away.
Hydronics is good for a lot of things, we just have to be careful on how we apply it and why.
It definitely is a lot more fun to play with.
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Thanks @Kaos . I debated whether to respond. The house is built, the die is cast. The question was whether to say something to help out another soul who happens upon this thread in the future.
There's nothing inherently wrong with spray foam, it has its uses. It's just a lot more expensive per unit of insulation than other materials. In order to make it price-competitive with other materials, contractors will (sometimes) try to convince customers that they don't need as much. Because if you put the full R49 in the attic that code requires, it's going to cost a fortune to do it with spray foam. And beyond about 3" you're going to need it to be applied in two layers, which pretty much doubles the application cost.
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