3 ms·

I work entirely remote so, other than travel, there are not many long periods when the house is unoccupied. I target the long run time to maximize efficiency.

I work entirely remote so, other than travel, there are not many long periods when the house is unoccupied. I target the long run time to maximize efficiency. A 160°F pipe will lose more heat to the part of the building that I don’t want to heat as well as more heat to the wall right behind the radiators. It also results in the house going micro too-hot, too-cold, too-hot, too-cold as it cycles. Mine is constantly trickling in just enough heat to replace the heat lost instead of cycling between adding way more than needed then none for a while. Another large effect is that low return water temperatures into the boiler allow for greater condensation of exhaust gas energy to be used in the building instead of sent outside. Walking by my house on a cold day, you’ll see minimal steam plume during operation. All that steam I see my neighbors emitting is energy they paid for and delivered to the outside… (They paid a lot for a boiler with a 95% or 98% sticker and run it at 80% efficiency.) https://kw-engineering.com/how-to-optimize-condensing-boiler-system-maximum-energy-savings/ https://kw-engineering.com/how-to-optimize-condensing-boiler...

Retric 2y ago
> A 160°F pipe will lose more heat to the part of the building that I don’t want to heat as well as more heat to the wall right behind the radiators. You’ve got the first part of that backwards, it’s the walls near your radiators that are your problem and need more insulation.
- sokoloff 2y ago
  Indeed the building is 100 years old and impractical to retrofit insulation in any cost-efficient way (structural brick, lathe and plaster walls with about 1” of air space in the original parts of the building).
frereubu 2y ago
Thanks for the explanation.
eru 2y ago
Btw, a heated blanket would be a lot more efficient, as it warms just your butt.
- sevensor 2y ago
  Heated blankets are ok, but you have to arrange them just so, and then you can’t move without fussing with the cord. It’s the last resort after layering warm clothes before bumping up the thermostat.
  - pests 2y ago
    I use a heated blanket as a bottom layer sometimes. Lets you move around and do whatever you want with the blanket fixed in place and the cord not in the way. I have larger heated blanket that has independent power/settings for each half. I turn one half on max and leave the other off and can roll and find the perfect direct heat and if using another regular blanket on top all that is captured too.
amluto 2y ago
> Another large effect is that low return water temperatures into the boiler allow for greater condensation of exhaust gas energy to be used in the building instead of sent outside. Correct. > Walking by my house on a cold day, you’ll see minimal steam plume during operation. All that steam I see my neighbors emitting is energy they paid for and delivered to the outside… (They paid a lot for a boiler with a 95% or 98% sticker and run it at 80% efficiency.) Please check your assumptions. A boiler operating in condensing mode will produce a trickle of liquid condensate (that may well be drained somewhere that you can’t see [0]), teeny tiny drops of condensate suspended in gas (colloquially “steam”, but it’s more like fog), and some residual water vapor mixed with the exhaust gasses. You can see the “steam”, but you cannot see that residual vapor except to the extent that it condenses further as the exhaust stream cools after it exits, much as you can see some of your own exhaled water vapor on a cold day as it condenses outside your nose or mouth. The exhaust gas is saturated: it has maximum humidity and is at its own dewpoint, so there is a lot of visible fog. The droplets that form inside the boiler and escape with the flue gas do not represent wasted heat: their heat of fusion has been captured. A boiler operating in non-condensing mode will produce no liquid condensate, and its exhaust will be well above its own dewpoint. It will contain far more water vapor than a condensing boiler, but you cannot see that vapor except insofar as the flue gas has a different index of refraction than the surrounding air and distorts the background a bit. Depending on weather, a bit of it may condense later. All of it is wasted energy. [0] This liquid condensate is nasty stuff: it’s basically carbonated distilled water plus some impurities but not usefully buffered, and it’s rather acidic. It will quickly corrode many metals, including copper and many common copper alloys, non-stainless steel, galvanized steel, etc. Non-condensing furnaces and boilers are generally carefully engineered to avoid condensation, because the condensation would damage them. If your plumber is unaware of the degree to which boiler condensate is corrosive and uses copper pipes or metallic fittings (push-to-fit in the style commonly sold as “Sharkbite”), the system will fail. Use plastic pipes (PVC or PEX) and plastic (or maybe stainless steel) fittings such as ordinary solvent-cement PVC fittings, “engineered plastic” PEX fittings, or push-to-connect fittings with plastic wetted surfaces. John Guest makes these, and there is also the somewhat bizarre ProLock brand, which seems to be some sort of joint offering from John Guest and Sharkbite.
- 2y ago

Retric 2y ago

> A 160°F pipe will lose more heat to the part of the building that I don’t want to heat as well as more heat to the wall right behind the radiators. You’ve got the first part of that backwards, it’s the walls near your radiators that are your problem and need more insulation.

sokoloff 2y ago
Indeed the building is 100 years old and impractical to retrofit insulation in any cost-efficient way (structural brick, lathe and plaster walls with about 1” of air space in the original parts of the building).

frereubu 2y ago

Thanks for the explanation.

eru 2y ago

Btw, a heated blanket would be a lot more efficient, as it warms just your butt.

sevensor 2y ago
Heated blankets are ok, but you have to arrange them just so, and then you can’t move without fussing with the cord. It’s the last resort after layering warm clothes before bumping up the thermostat.
- pests 2y ago
  I use a heated blanket as a bottom layer sometimes. Lets you move around and do whatever you want with the blanket fixed in place and the cord not in the way. I have larger heated blanket that has independent power/settings for each half. I turn one half on max and leave the other off and can roll and find the perfect direct heat and if using another regular blanket on top all that is captured too.

amluto 2y ago

> Another large effect is that low return water temperatures into the boiler allow for greater condensation of exhaust gas energy to be used in the building instead of sent outside. Correct. > Walking by my house on a cold day, you’ll see minimal steam plume during operation. All that steam I see my neighbors emitting is energy they paid for and delivered to the outside… (They paid a lot for a boiler with a 95% or 98% sticker and run it at 80% efficiency.) Please check your assumptions. A boiler operating in condensing mode will produce a trickle of liquid condensate (that may well be drained somewhere that you can’t see [0]), teeny tiny drops of condensate suspended in gas (colloquially “steam”, but it’s more like fog), and some residual water vapor mixed with the exhaust gasses. You can see the “steam”, but you cannot see that residual vapor except to the extent that it condenses further as the exhaust stream cools after it exits, much as you can see some of your own exhaled water vapor on a cold day as it condenses outside your nose or mouth. The exhaust gas is saturated: it has maximum humidity and is at its own dewpoint, so there is a lot of visible fog. The droplets that form inside the boiler and escape with the flue gas do not represent wasted heat: their heat of fusion has been captured. A boiler operating in non-condensing mode will produce no liquid condensate, and its exhaust will be well above its own dewpoint. It will contain far more water vapor than a condensing boiler, but you cannot see that vapor except insofar as the flue gas has a different index of refraction than the surrounding air and distorts the background a bit. Depending on weather, a bit of it may condense later. All of it is wasted energy. [0] This liquid condensate is nasty stuff: it’s basically carbonated distilled water plus some impurities but not usefully buffered, and it’s rather acidic. It will quickly corrode many metals, including copper and many common copper alloys, non-stainless steel, galvanized steel, etc. Non-condensing furnaces and boilers are generally carefully engineered to avoid condensation, because the condensation would damage them. If your plumber is unaware of the degree to which boiler condensate is corrosive and uses copper pipes or metallic fittings (push-to-fit in the style commonly sold as “Sharkbite”), the system will fail. Use plastic pipes (PVC or PEX) and plastic (or maybe stainless steel) fittings such as ordinary solvent-cement PVC fittings, “engineered plastic” PEX fittings, or push-to-connect fittings with plastic wetted surfaces. John Guest makes these, and there is also the somewhat bizarre ProLock brand, which seems to be some sort of joint offering from John Guest and Sharkbite.

2y ago