7 ms·

Have we forgotten to make heat traps? (2012)

104 points by vq 7y ago

sctb 7y ago
Since the submitted link has a download disposition we've updated it from https://www.esbe.eu/it/en/~/media/ESBE%20Public%20web_BRserver/Documents/News/Heat%20traps/Heat%20traps%20in%20installations%2020120508.ashx https://www.esbe.eu/it/en/~/media/ESBE%20Public%20web_BRserv... to the abstract.
- floatingatoll 7y ago
  This could use a (2012), per the article date.
  - sctb 7y ago
    You got it. Thanks!
thefourthchime 7y ago
Seems like something trivial to make with PEX these days. I have no idea if it's regular practice or not. The only downside I can see is if there was recent hot water, it might take slightly longer to reach the faucet.
- gregmac 7y ago
  My water heater has one made from PEX. From memory, I would guess it adds about 18". With 3/4" PEX at a relatively slow 1.5 GPM flow rate, that adds about 1.4 seconds to 'hot water delivery time', though that's not entirely accurate, because the loop itself has some heated water trapped in it.
  - gpm 7y ago
    Shouldn't you also adding the length of pipe/water you are preventing from being heated to that 18"?
    - gregmac 7y ago
      I actually don't think so, because you end up with only a gradient of lukewarm-to-ambient temperature water, which you still have to purge in order to get actual hot water. Even if you're going for just warm water, you still have to purge some of it, then after a few seconds start continually adjusting cold until the hot water from the tank gets to you.
- kragen 7y ago
  Wouldn't it be better to make the heat trap itself with 45 cm or less of copper, then hook up the PEX to its output? Copper will last centuries in continuous contact with hot water, but I'm not sure PEX will.
  - 781 7y ago
    I'm pretty sure a house is not expected to run centuries from now with present day electrical/piping systems. It's a bit like people from 200 years ago debating what to make the candle holder from so that it lasts 100 years.
    - SECProto 7y ago
      My parents house is hot water heated. Originally was coal fired, then oil, then a replacement oil heater, now electric. All the pipes and radiators are original. It's 115 years old. The whole house is built (and maintained) with a different mindset. (I think they removed the last knob-and-tube light socket a couple years ago)
    - kragen 7y ago
      There are a lot of cases where piping problems have totaled houses. A substantial fraction of houses built with polybutylene piping have already been demolished because of it. My concern is not so much that a sample of 100 PEX heat traps installed today will all burst on the same day in 2059 or 2159. It's more that if the average lifetime of PEX under those circumstances is only, say, 50 years, maybe there will be a few percent that burst in 5 or 10 years, depending on how variable the corrosion rate is. So if you can protect yourself from that with 45 centimeters of copper, which will cost a heck of a lot less than the water heater does, maybe you should.
mcmatterson 7y ago
I designed and installed a complete hydronic heating system in our house last year, replacing a conventional forced air system. It being the first time I'd ever done such a thing (and indeed, the first time I'd ever really been exposed to hydronic heating at all) I learned everything through reading (mostly the excellent idonrics series at https://www.caleffi.com/usa/en-us/technical-magazine https://www.caleffi.com/usa/en-us/technical-magazine). I went really deep on the reading so while I had/have a pretty solid theoretical understanding I was/am a complete novice on the craft side of the field. Overall, the practice seems to be very heuristic based, with every installation being a bit different and rules of thumb being the norm. Our system seems to work fairly well in practice, but I've been curious to get a professional's opinion on it (the only pro that's seen it was the gas guy who did the final hookup, who seemed impressed but didn't really offer any specific criticisms). Repo at https://github.com/mtrudel/boiler https://github.com/mtrudel/boiler I've since added an elixir based graphing system to it, at http://mat.geeky.net/boiler http://mat.geeky.net/boiler
- jetbooster 7y ago
  That's interesting, as Hydronic heating is the standard heating method over here in the UK. Reason its not done in the US I image is we don't often ever need AC, so we only need to be able to turn the temp up.
  - LeoPanthera 7y ago
    UK hydronic systems usually use radiators. US systems are almost always under-floor.
    - kevin_thibedeau 7y ago
      Nowadays, but hot water baseboard heat was commonplace for some time.
    - gxx 7y ago
      I once had a new house with hydronic under floor heating - the worst heating setup I've every had - horribly slow to respond and expensive to operate. We turn down the heat to sleep and finally I just shut off the heat to the bedrooms and heated them a different way. Our initial experience with the system was even worse than it might have been. The people who installed it including the thermostats were plumbers and did not realize there was a switch inside the thermostat to choose among three types of heating systems. They left all the thermostats at the default forced air heating setting. We suffered for two years with terrible overshooting and undershooting of temperatures before my own research revealed that the hidden setting existed and that it was set incorrectly. This helped but it was still not great. We were glad to get back to a forced air heated house. I do believe however that hydronic heating with radiators is somewhat better than underfloor hydronic.
gowld 7y ago
Simpler article: https://en.wikipedia.org/wiki/Heat_trap https://en.wikipedia.org/wiki/Heat_trap
- Groxx 7y ago
  It also largely answers the question in the first paragraph: >Newer water heaters have built-in heat traps. So it's "no, they're just done by default and hidden". Seems like a reasonable thing to do.
deleted 7y ago
[deleted]
dqpb 7y ago
> it saves you time and hazzel
- kazinator 7y ago
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104 points by vq 7y ago

sctb 7y ago

Since the submitted link has a download disposition we've updated it from https://www.esbe.eu/it/en/~/media/ESBE%20Public%20web_BRserver/Documents/News/Heat%20traps/Heat%20traps%20in%20installations%2020120508.ashx https://www.esbe.eu/it/en/~/media/ESBE%20Public%20web_BRserv... to the abstract.

floatingatoll 7y ago
This could use a (2012), per the article date.
- sctb 7y ago
  You got it. Thanks!

thefourthchime 7y ago

Seems like something trivial to make with PEX these days. I have no idea if it's regular practice or not. The only downside I can see is if there was recent hot water, it might take slightly longer to reach the faucet.

gregmac 7y ago
My water heater has one made from PEX. From memory, I would guess it adds about 18". With 3/4" PEX at a relatively slow 1.5 GPM flow rate, that adds about 1.4 seconds to 'hot water delivery time', though that's not entirely accurate, because the loop itself has some heated water trapped in it.
- gpm 7y ago
  Shouldn't you also adding the length of pipe/water you are preventing from being heated to that 18"?
  - gregmac 7y ago
    I actually don't think so, because you end up with only a gradient of lukewarm-to-ambient temperature water, which you still have to purge in order to get actual hot water. Even if you're going for just warm water, you still have to purge some of it, then after a few seconds start continually adjusting cold until the hot water from the tank gets to you.
kragen 7y ago
Wouldn't it be better to make the heat trap itself with 45 cm or less of copper, then hook up the PEX to its output? Copper will last centuries in continuous contact with hot water, but I'm not sure PEX will.
- 781 7y ago
  I'm pretty sure a house is not expected to run centuries from now with present day electrical/piping systems. It's a bit like people from 200 years ago debating what to make the candle holder from so that it lasts 100 years.
  - SECProto 7y ago
    My parents house is hot water heated. Originally was coal fired, then oil, then a replacement oil heater, now electric. All the pipes and radiators are original. It's 115 years old. The whole house is built (and maintained) with a different mindset. (I think they removed the last knob-and-tube light socket a couple years ago)
  - kragen 7y ago
    There are a lot of cases where piping problems have totaled houses. A substantial fraction of houses built with polybutylene piping have already been demolished because of it. My concern is not so much that a sample of 100 PEX heat traps installed today will all burst on the same day in 2059 or 2159. It's more that if the average lifetime of PEX under those circumstances is only, say, 50 years, maybe there will be a few percent that burst in 5 or 10 years, depending on how variable the corrosion rate is. So if you can protect yourself from that with 45 centimeters of copper, which will cost a heck of a lot less than the water heater does, maybe you should.

mcmatterson 7y ago

I designed and installed a complete hydronic heating system in our house last year, replacing a conventional forced air system. It being the first time I'd ever done such a thing (and indeed, the first time I'd ever really been exposed to hydronic heating at all) I learned everything through reading (mostly the excellent idonrics series at https://www.caleffi.com/usa/en-us/technical-magazine https://www.caleffi.com/usa/en-us/technical-magazine). I went really deep on the reading so while I had/have a pretty solid theoretical understanding I was/am a complete novice on the craft side of the field. Overall, the practice seems to be very heuristic based, with every installation being a bit different and rules of thumb being the norm. Our system seems to work fairly well in practice, but I've been curious to get a professional's opinion on it (the only pro that's seen it was the gas guy who did the final hookup, who seemed impressed but didn't really offer any specific criticisms). Repo at https://github.com/mtrudel/boiler https://github.com/mtrudel/boiler I've since added an elixir based graphing system to it, at http://mat.geeky.net/boiler http://mat.geeky.net/boiler

jetbooster 7y ago
That's interesting, as Hydronic heating is the standard heating method over here in the UK. Reason its not done in the US I image is we don't often ever need AC, so we only need to be able to turn the temp up.
- LeoPanthera 7y ago
  UK hydronic systems usually use radiators. US systems are almost always under-floor.
  - kevin_thibedeau 7y ago
    Nowadays, but hot water baseboard heat was commonplace for some time.
  - gxx 7y ago
    I once had a new house with hydronic under floor heating - the worst heating setup I've every had - horribly slow to respond and expensive to operate. We turn down the heat to sleep and finally I just shut off the heat to the bedrooms and heated them a different way. Our initial experience with the system was even worse than it might have been. The people who installed it including the thermostats were plumbers and did not realize there was a switch inside the thermostat to choose among three types of heating systems. They left all the thermostats at the default forced air heating setting. We suffered for two years with terrible overshooting and undershooting of temperatures before my own research revealed that the hidden setting existed and that it was set incorrectly. This helped but it was still not great. We were glad to get back to a forced air heated house. I do believe however that hydronic heating with radiators is somewhat better than underfloor hydronic.

gowld 7y ago

Simpler article: https://en.wikipedia.org/wiki/Heat_trap https://en.wikipedia.org/wiki/Heat_trap

Groxx 7y ago
It also largely answers the question in the first paragraph: >Newer water heaters have built-in heat traps. So it's "no, they're just done by default and hidden". Seems like a reasonable thing to do.

deleted 7y ago

[deleted]

dqpb 7y ago

> it saves you time and hazzel

kazinator 7y ago
- '-'---'---,---- '-'---'---,--- ...