Joined Nov 2005
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Forum Thread
Source to compare efficiencies of heating methods
November 30, 2021 at
10:03 AM
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Odd to post this in Finance but it's really a finance question. There are many methods to heat and cool living spaces, and I'm trying to find a source that allows comparing them all in terms of ultimate cost - factoring in efficiencies and local prices of utilities (electricity, etc).
Basically what I am looking at is - here in New England it's common to use home heating oil (which is really just diesel), NG (boiler or forced air), wood stoves and heat pumps for heating, and AC is generally regular AC (some people have geo but that's pretty rare). The combo "minisplit" units are popular, but I'm concerned that in the winter, if the unit defaults to pure electric heat (as in resistance/toaster) it will be outrageously expensive, vs. a true heat pump (which will only work down to a certain temperature), since our electricity is very expensive.
Basically what I am looking at is - here in New England it's common to use home heating oil (which is really just diesel), NG (boiler or forced air), wood stoves and heat pumps for heating, and AC is generally regular AC (some people have geo but that's pretty rare). The combo "minisplit" units are popular, but I'm concerned that in the winter, if the unit defaults to pure electric heat (as in resistance/toaster) it will be outrageously expensive, vs. a true heat pump (which will only work down to a certain temperature), since our electricity is very expensive.
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So, do the proper heat loss calculations for the house (there are specialized software apps for that), then pick the right-sized boiler (Viessmann for larger BTUs, Lochinvar for smaller BTUs i.e. < 40,000 BTUs), buy the wall radiators, copper or PEX piping, and a good ECM water pump (Grundfos Alpha highly recommended). Do not purchase an oversized gas boiler, i.e. with much higher BTUs than the calculations that your house needs. Because otherwise such boiler will short-cycle (start and stop too often, with shorter operating cycles) which is sub-optimal in terms of getting to the right heat efficiency curve, and not wasting gas uselessly.
And you will be set and happy for life. Forget about oil, electric, or scorched air "furnace", or even "water barrels" colloquially called here in North America "heating systems" and "water heaters". Because those are kindergarten, wasteful and inefficient technologies from a hundred years ago. Learn from the European and Asians! U.S.A. is a resource-wasteful country. The U.S. utility company simply doesn't care about your otherwise wasteful consumption. And the fact that your so-called "Forced air furnace" CRAP leaks air thru non-pressure-proof "air ducting" - afterall "air leaks" do not create any damage to the surroundings, including your neighbors (comparing to gas leaks), right? WRONG!!! There is a key leak to not forget - LEAKS TO YOUR WALLET. And how the heck to use damn AIR, which is typically used as a heat INSULATOR (that you place in between windows glass plates) and not as heat CONDUCTOR. Not to mention that Physics clearly show the thermal conductivity of water is about 4,000 higher than air's.
I had a system like this (including also a separate tankless water heater brand name Rinnai - made in Japan), installed with my own hands, and with the help of my father, while being in Ontario, Canada. That system rocked in terms of energy efficiency and monthly gas and electricity bills. And Canadian winters are no walk in the park...
Boo, all the "traditional" water and winter heating "technologies" are a big piece of shaite, both in U.S. and Canada. Primitive technologies, from the woods, and for the American uncivilized, and uneducated rednecks. Sad to say this, but unfortunately so true...Similar to those "wooden barracks" that are called "residential houses", made of wood sticks and glue, bleah.
Also, don't get me started with the stupid hot air climbing up the room and staying high and not uniformly heating a volume space.
Hydronic heating (and probably thermal pumps as well) is superior to the "scorched air heating" shaite, in all points. Check also ... the hospitals ... and see what type of heating do they have - circulating air can propagate and transmit pathogens so easily, fauci-19 included.
Also, don't get me started with the stupid hot air climbing up the room and staying high and not uniformly heating a volume space.
Hydronic heating (and probably thermal pumps as well) is superior to the "scorched air heating" shaite, in all points. Check also ... the hospitals ... and see what type of heating do they have - circulating air can propagate and transmit pathogens so easily, fauci-19 included.
Uh, literally the same amount of time. Boilers eventually heat the air. They're not creating a hot water bath for you to sit in. Once the air is hot, the amount of time it stays hit depends on insulation and room geometry.
True, hot water in pipes will stay hot for the same reason it takes a lot of energy for them to get hot in the first place. That means your room will stay hot even if you don't want it to, like if you're going away soon. Modern furnaces solve this with an ECM fan. If they need to keep adding a little hit air at a time to maintain a comfortable temp, they'll efficiently burn the fuel and then gently run a fan by powering it off and on with varying lengths of time.
Hospitals have different HVAC systems than houses so that the disease in the infectious disease wing stay there. If someone in your house has typhoid, you're all in trouble regardless of if you have a furnace or a boiler.
The wall radiators do tend to have an inertial heat aspect to them, and to your point, it's the rads that tend to keep the heat for long, even when the water is recirculated. Sometimes, those old-fashioned ("ugly"?) cast-iron radiators make make a better job at keeping the heat for longer. than the aluminum ones.
The air in a room gets heated in a hydronic heating system thru 2 components: One is convection (like heat produced by an oven) and the other is radiating heat. None of these 2 useful components manifests in a forced air system.
You are saying that you are interested more in a system that can cut off the heat more rapidly, i.e. to cover a use case like you mentioned - leaving the house. And by the same rationale, expected to produce heat (when starting with a super cold heat) more rapidly.
I for one, am not interested in the use case you have mentioned. I am rather interested in keeping heat for long, and I simply don't consider important the fact that I have to wait a tad longer for the heat to feel its presence first. If, overall, I also get a higher operating efficiency (translating to lower bills).
Actually, with a well-sized ECM water recirculating pump, and well sized BTUs for each radiators, and with a system operating at transfer temperatures that are much lower (50 degrees celsius aka 120F and not 180F), and good electronic thermostat, and optionally, via a multi-zoning concept, one would not feel the time needed to get to operating room temp, as being significantly long!
I've heard the same (strawman) argument in tankeless water heaters vs. "water barrel" primitive water heaters: the fact that one would have to wait for the water to get warm and hot, much longer with tankless. Well, that's laughable - I do have a water barrel in the 2-bedrom attached, 1400sqft house that I am currently renting, and waiting for the water to get hot, for ever! I miss my tankless water heater from Europe, and from Canada. Which was heating water almost instantly, and having a proper 200 kBTU line setup.
And I gave the example with the hospitals, as a hint that forced air based heating systems can create health problems much easily (not to forget allergens etc). A hydronic heating is simply quiet, effective, and much more energy efficient. And it gives a sort of heat that I personally like MORE: more uniform, longer lasting, more pleasant to the body (like those in-floor radiant system heating systems).
But I get it - I know why hydronics is not favored here in North-America: It is not efficient to ... builders and contractors profit margins. Because hydronic requires true work, not just replacing a box (called furnace) at each 10-15 year period, with another, and relying on some air ducting which nobody cares too much to be pressurized and leak-free. It is a more labor-intensive system to install, and detrimental to those contractors chasing the quick buck.
Also, the utility companies aren't too interested in home owners lowering their gas and electricity bills, for obvious reasons.
Don't get me started also with the water barrels, with their "sacrificial magnesium bar" or whatever, and which rust and requiring replacement at each 10 year maybe, due to danger of flooding your basement...
The primitive sliding "windows" vs. the European, tilt-and-turn windows. Subject to comparison, are 2 definitely different Physics / mechanical principles: former is achieving tight-closing (heat insulation grade) via FRICTION of 2 parallel window panels, while the latter is achieving it via a panel pressing / pushing AGAINST the window frame. Same thing with stupid "modern garage doors" vs the so called old-fashioned one (carriage doors).
Parallel Friction will never get you good heat insulations and U-transfer coefficient factors. Pressing one panel against a frame (like a classic room door) WILL. But hey, tilt-and-turn windows don't make those curtains look good in a room ("Honey, what the heck are this windows doing - tampering my nice curtains", or "Honey, let's strip all these wall tall radiators out because they also don't look good with my drapes"! UN-freaking-believable - what a primitive thinking, typical of North-America)
Here where I live just northeast of Phila; we have to have 10 neighbors on our street agree to bring gas down the street. It's been done on a few streets. They had to pay PECO to do so, per household, iirc it was between $7-$10 each. Then replace their oil burner, which supplied hot water as well.
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The wall radiators do tend to have an inertial heat aspect to them, and to your point, it's the rads that tend to keep the heat for long, even when the water is recirculated. Sometimes, those old-fashioned ("ugly"?) cast-iron radiators make make a better job at keeping the heat for longer. than the aluminum ones.
The air in a room gets heated in a hydronic heating system thru 2 components: One is convection (like heat produced by an oven) and the other is radiating heat. None of these 2 useful components manifests in a forced air system.
You are saying that you are interested more in a system that can cut off the heat more rapidly, i.e. to cover a use case like you mentioned - leaving the house. And by the same rationale, expected to produce heat (when starting with a super cold heat) more rapidly.
I for one, am not interested in the use case you have mentioned. I am rather interested in keeping heat for long, and I simply don't consider important the fact that I have to wait a tad longer for the heat to feel its presence first. If, overall, I also get a higher operating efficiency (translating to lower bills).
Actually, with a well-sized ECM water recirculating pump, and well sized BTUs for each radiators, and with a system operating at transfer temperatures that are much lower (50 degrees celsius aka 120F and not 180F), and good electronic thermostat, and optionally, via a multi-zoning concept, one would not feel the time needed to get to operating room temp, as being significantly long!
I've heard the same (strawman) argument in tankeless water heaters vs. "water barrel" primitive water heaters: the fact that one would have to wait for the water to get warm and hot, much longer with tankless. Well, that's laughable - I do have a water barrel in the 2-bedrom attached, 1400sqft house that I am currently renting, and waiting for the water to get hot, for ever! I miss my tankless water heater from Europe, and from Canada. Which was heating water almost instantly, and having a proper 200 kBTU line setup.
And I gave the example with the hospitals, as a hint that forced air based heating systems can create health problems much easily (not to forget allergens etc). A hydronic heating is simply quiet, effective, and much more energy efficient. And it gives a sort of heat that I personally like MORE: more uniform, longer lasting, more pleasant to the body (like those in-floor radiant system heating systems).
But I get it - I know why hydronics is not favored here in North-America: It is not efficient to ... builders and contractors profit margins. Because hydronic requires true work, not just replacing a box (called furnace) at each 10-15 year period, with another, and relying on some air ducting which nobody cares too much to be pressurized and leak-free. It is a more labor-intensive system to install, and detrimental to those contractors chasing the quick buck.
Also, the utility companies aren't too interested in home owners lowering their gas and electricity bills, for obvious reasons.
Don't get me started also with the water barrels, with their "sacrificial magnesium bar" or whatever, and which rust and requiring replacement at each 10 year maybe, due to danger of flooding your basement...
As for on-demand vs tank, it again depends on what you're talking about. If you have a boiler, having an indirect heated tank is extremely efficient and reduces wear and tear on the boiler vs a combi. If you have a standalone tankless, they can be great...as long as they're plumbed correctly. Without a mini-tank, you can get strange situations with an on-demand, like having multiple people shower in a row and everyone after the first getting hit with a slug of cold water (from when the first person turned it off).
And, finally, you seriously misunderstand a few basic things about these systems. Yes, a boiler circulates water through the system. However, once it stops circulating, the water doesn't instantly return to room temperature or leave the pipes. The water sits in the pipe, heating the room. Which keeps the room warm for a long time, which isn't necessarily bad. (This is the payoff for needing a lot of energy to get the water warm in the first place.) However, as I point out, the downside is that in many situations, you don't need to have the heat last awhile, so this is a waste. And, yes, boilers work by conduction and convection (and radiation, too, of course)...but so does a furnace. A boiler has natural convection. Furnaces have forced convection -- a fan. Again, the entire point is to replace the air in the room with hot air from the furnace. And that can be done very efficiently. Further adding to the efficiency is that you can close down the vents in rooms that you don't want to heat/cool. Very rarely are boiler systems set up where you can easily turn off the flow to a particular room. You might be able to control the heating with the radiator cover fins, but that just means that you're wasting energy sending it through the pipes and then not using it.