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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

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.
    - m463 7y ago
      I wonder if better PID tuning would help, maybe adding stuff like ambient outside temperature or weather prediction as a system input. I know the nest thermostat does a lot of systemic learning and understands the outside temperature. (I'm not recommending that system, just that a little modern control theory might make things workable)
      - Moru 7y ago
        I thought all heating systems had outdoor input for temperature. I know all houses I have lived in has had that the last 40 years at least. But I live in a cold area so I guess that's different. -38 C is uncommon but happens now and then. Also the isolation of the houses are better and that also helps with leveling out temperature differences.
      - xattt 7y ago
        I have a 2nd gen Nest thermostat since they first came out in 2012 or so with a hot water system, so I can speak from my experience. There is a setting on the thermostat (True Radiant) that takes into account the long heat-up times of radiant systems. With this setting off, overshoot is real. On cold days, True Radiant does start the system earlier. For example, it take about 2-3 hours in the deep of winter vs 30-60 minutes now. However, it seems to be based to on a look-up table rather than an algorithm. It doesn’t take into account forecasted conditions, such as a temperature rise overnight, strong winds or decreasing/increasing radiance of the sun over the season. Those latter factors do make a difference in whether the house reaches the target temperature on time or whether overshoot occurs, and whether I am slightly uncomfortable. As far as I can tell, there is an automatic set-back for heat pump systems. I wish this was given as an option for manual scheduling in True Radiant mode. To this day, I can’t tell whether there is an effect on efficiency (based on run-times which the thermostat dutifully displays). I also wish the thermostats (in a dual-zone system with a single boiler) be “genlocked” or run on common firing times with demand prediction for temperatures to make use of boiler run-time, rather than running the boiler just when there is a request for heat in one zone.
- tomkinstinch 7y ago
  Hot water "hydronic" heating with radiators is very common in the US as well, at least among homes in the Northeastern US constructed before the 1960s. It's a shame more new construction does not use hot water heating in conjunction with central air for cooling because radiators are much quieter, more efficient, and better for those with asthma.
  - Declanomous 7y ago
    I live in a house with steam heat. Steam systems often get converted to hot water, but in general I have a few observations related to radiated heat. 1) Steam and other radiant systems don't deal with temperature setbacks well. They take FOREVER to warm up a house after a set back, so don't bother with a deep setback overnight, and if you are gonna turn down the heat because you are going to be gone for a while, expect your house to be cold for a couple of hours while it warms back up, or expect your heat to overshoot by 5-10 degrees. 2) Radiant heat seems to work well in the temperature range it is designed for, but outside of that range you get strong temperature gradients in rooms. Unless you have a fan in each room, expect the ceiling to be substantially warmer than the floor. I have 12 foot ceilings, and the ceiling can be 15 - 20 degrees warmer. 3) I personally prefer forced air with my allergies than radiant heat, because you can upgrade a forced-air system to use better filters, which basically gives you a filter for your entire house. Radiators are a pain in the ass to keep clean, and the air often seems to go stale over time. I have fairly bad indoor allergies and it just feels like over winter the house just fills with allergens. 4) On the same note, you can't get whole-house humidifiers with steam heat, nor can you easily add air conditioning. 5) Steam isn't THAT quiet. An improperly tuned system will bang (which shouldn't count against steam, because that's the fault of whoever is maintaining the system), one-pipe systems (which are common in Chicago) hiss when they are heating up, the valves sputter as they die, and when the system cools back down there is a loud inrush of air. Two pipe systems make noise as they heat up and joints flex, and the valves also make little clicking sounds. Hot water can get bubbles in it and make wooshing sounds, but that's generally a sign of bad maintenance. The sound of air blowing bothers me less in general than one off sounds that occur with steam and hot water though, and unless you don't mind the aforementioned temperature gradients you'll need to have a fan running anyways. 6) It's much much easier to find people who know how to work on forced air in the US. Replacement parts are easier to find, and forced air is usually more efficient. One big benefit to steam is that old systems were massively oversized for the houses they are in. My house had absolutely NO problem getting up to temp during the week we had below zero temps. It was running a lot though, and the leaking shutoff valves and blurbling air vents were starting to drive me nuts, so I shut off the heat for a couple of hours on the coldest day (which got down to -40 or so) to do repairs. It got down to about 40 degrees inside before I turned the heat back on, and once it was back on it got up to 70 or so no problem. I know a lot of people who had more modern systems that struggled to maintain 40 or 50 degrees. Side note: If anyone has a steam heat system in their home, I would highly recommend picking up The Lost Art of Steam Heating by Dan Holohan. As I mentioned, it's hard to find a real steam heating expert nowadays, most of the time you'll just get plumbers who are moonlighting. While steam heat involves plugging pipes together, there are a lot more things to take into account other than whether pipe A and pipe B are connected.
- twic 7y ago
  As an aside, we simply call it "central heating" in the UK. "Hydronic heating" sounds like something i would install in a geodesic dome.
  - TeMPOraL 7y ago
    That would surely be Dymaxion heating :).
- Nux 7y ago
  Pretty much the standard in most of Europe.
- NeedMoreTea 7y ago
  Forced air was very briefly in in the UK. For a few - maybe as few as five - years around the early or mid 60s forced air was fairly commonly seen in new build houses and the type of small blocks that have 6 or 8 flats. By the seventies no one was putting them in new builds any more, and people were already ripping them out - or sealing up the vents - to go back to just a fire - though without a chimney it would have to be electric or gas, or to put in central heating or storage heat. You will never find one of those houses still using it. Doesn't matter who built the house, where, when, what make of components or which fuel. Usually electric, but there were quite a few gas. Effectively all have been ripped out now. You might find evidence of ducting when rewiring.
  - misnome 7y ago
    We lived in a house with this under-floor-air system until we moved last year. We inherited it from my mother-in-law a few years previously. She didn't really think of maintenance, and so turns out it was using the original gas heater system. This was quickly condemned when we got it inspected - it had a crack in the heat exchanger and - these things were apparently only designed to last 25 years. Lasting 50 was pretty impressive/dangerous. You can get replacement heaters for them, but it's pretty niche, needs to be imported from Europe, and because of the age normally involves dealing with asbestos insulation. It's also apparently virtually impossible to get the venting cleaned, as it's embedded in the flooring (under concrete for the group floor). (Edit: And this caused real problems for Asthma sufferers) While it worked though it was pretty good, it heated rooms extremely quickly.
    - NeedMoreTea 7y ago
      I'm really surprised - and a little impressed - that one hung on that long. :) From various encounters over the decades they all seemed to come with feint smell of burnt dust or just dust. By the eighties it was usual to see a radiator in front of or above the old vents, or the vents simply boarded or painted shut. No idea why it was so comprehensively and quickly rejected despite that brief popularity. Maybe the impossibility of proper cleaning or expense? Though I wonder what they do for cleaning in the US. It's the only approach that hasn't managed to keep some spot in the market even after large declines - like storage heaters or, more surprisingly, even coal have.
- egypturnash 7y ago
  You’ve never been to the Southwest or the Gulf South, have you? There are parts of the US where you would die without AC. Seriously, like when you get a brownout on a hot summer day in New Orleans or Santa Fe or Dallas, people start dying. Mostly the elderly and kids.
  - jessaustin 7y ago
    GP is in UK, and specifically allowed for the difference between that situation and situations in USA. Nobody wants your grandma to die. Also, the heat in Santa Fe is much different than that in New Orleans.
- codfrantic 7y ago
  I was really curious to read about this type of heating, then I read your comment. Quickly imagegoogled the term and found that this is the standard in most of north/west Europe.
maxerickson 7y ago
I see the buffer tank is listed as a water heater? Is that hooked up as a backup?

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.
  - m463 7y ago
    I wonder if better PID tuning would help, maybe adding stuff like ambient outside temperature or weather prediction as a system input. I know the nest thermostat does a lot of systemic learning and understands the outside temperature. (I'm not recommending that system, just that a little modern control theory might make things workable)
    - Moru 7y ago
      I thought all heating systems had outdoor input for temperature. I know all houses I have lived in has had that the last 40 years at least. But I live in a cold area so I guess that's different. -38 C is uncommon but happens now and then. Also the isolation of the houses are better and that also helps with leveling out temperature differences.
    - xattt 7y ago
      I have a 2nd gen Nest thermostat since they first came out in 2012 or so with a hot water system, so I can speak from my experience. There is a setting on the thermostat (True Radiant) that takes into account the long heat-up times of radiant systems. With this setting off, overshoot is real. On cold days, True Radiant does start the system earlier. For example, it take about 2-3 hours in the deep of winter vs 30-60 minutes now. However, it seems to be based to on a look-up table rather than an algorithm. It doesn’t take into account forecasted conditions, such as a temperature rise overnight, strong winds or decreasing/increasing radiance of the sun over the season. Those latter factors do make a difference in whether the house reaches the target temperature on time or whether overshoot occurs, and whether I am slightly uncomfortable. As far as I can tell, there is an automatic set-back for heat pump systems. I wish this was given as an option for manual scheduling in True Radiant mode. To this day, I can’t tell whether there is an effect on efficiency (based on run-times which the thermostat dutifully displays). I also wish the thermostats (in a dual-zone system with a single boiler) be “genlocked” or run on common firing times with demand prediction for temperatures to make use of boiler run-time, rather than running the boiler just when there is a request for heat in one zone.
tomkinstinch 7y ago
Hot water "hydronic" heating with radiators is very common in the US as well, at least among homes in the Northeastern US constructed before the 1960s. It's a shame more new construction does not use hot water heating in conjunction with central air for cooling because radiators are much quieter, more efficient, and better for those with asthma.
- Declanomous 7y ago
  I live in a house with steam heat. Steam systems often get converted to hot water, but in general I have a few observations related to radiated heat. 1) Steam and other radiant systems don't deal with temperature setbacks well. They take FOREVER to warm up a house after a set back, so don't bother with a deep setback overnight, and if you are gonna turn down the heat because you are going to be gone for a while, expect your house to be cold for a couple of hours while it warms back up, or expect your heat to overshoot by 5-10 degrees. 2) Radiant heat seems to work well in the temperature range it is designed for, but outside of that range you get strong temperature gradients in rooms. Unless you have a fan in each room, expect the ceiling to be substantially warmer than the floor. I have 12 foot ceilings, and the ceiling can be 15 - 20 degrees warmer. 3) I personally prefer forced air with my allergies than radiant heat, because you can upgrade a forced-air system to use better filters, which basically gives you a filter for your entire house. Radiators are a pain in the ass to keep clean, and the air often seems to go stale over time. I have fairly bad indoor allergies and it just feels like over winter the house just fills with allergens. 4) On the same note, you can't get whole-house humidifiers with steam heat, nor can you easily add air conditioning. 5) Steam isn't THAT quiet. An improperly tuned system will bang (which shouldn't count against steam, because that's the fault of whoever is maintaining the system), one-pipe systems (which are common in Chicago) hiss when they are heating up, the valves sputter as they die, and when the system cools back down there is a loud inrush of air. Two pipe systems make noise as they heat up and joints flex, and the valves also make little clicking sounds. Hot water can get bubbles in it and make wooshing sounds, but that's generally a sign of bad maintenance. The sound of air blowing bothers me less in general than one off sounds that occur with steam and hot water though, and unless you don't mind the aforementioned temperature gradients you'll need to have a fan running anyways. 6) It's much much easier to find people who know how to work on forced air in the US. Replacement parts are easier to find, and forced air is usually more efficient. One big benefit to steam is that old systems were massively oversized for the houses they are in. My house had absolutely NO problem getting up to temp during the week we had below zero temps. It was running a lot though, and the leaking shutoff valves and blurbling air vents were starting to drive me nuts, so I shut off the heat for a couple of hours on the coldest day (which got down to -40 or so) to do repairs. It got down to about 40 degrees inside before I turned the heat back on, and once it was back on it got up to 70 or so no problem. I know a lot of people who had more modern systems that struggled to maintain 40 or 50 degrees. Side note: If anyone has a steam heat system in their home, I would highly recommend picking up The Lost Art of Steam Heating by Dan Holohan. As I mentioned, it's hard to find a real steam heating expert nowadays, most of the time you'll just get plumbers who are moonlighting. While steam heat involves plugging pipes together, there are a lot more things to take into account other than whether pipe A and pipe B are connected.
twic 7y ago
As an aside, we simply call it "central heating" in the UK. "Hydronic heating" sounds like something i would install in a geodesic dome.
- TeMPOraL 7y ago
  That would surely be Dymaxion heating :).
Nux 7y ago
Pretty much the standard in most of Europe.
NeedMoreTea 7y ago
Forced air was very briefly in in the UK. For a few - maybe as few as five - years around the early or mid 60s forced air was fairly commonly seen in new build houses and the type of small blocks that have 6 or 8 flats. By the seventies no one was putting them in new builds any more, and people were already ripping them out - or sealing up the vents - to go back to just a fire - though without a chimney it would have to be electric or gas, or to put in central heating or storage heat. You will never find one of those houses still using it. Doesn't matter who built the house, where, when, what make of components or which fuel. Usually electric, but there were quite a few gas. Effectively all have been ripped out now. You might find evidence of ducting when rewiring.
- misnome 7y ago
  We lived in a house with this under-floor-air system until we moved last year. We inherited it from my mother-in-law a few years previously. She didn't really think of maintenance, and so turns out it was using the original gas heater system. This was quickly condemned when we got it inspected - it had a crack in the heat exchanger and - these things were apparently only designed to last 25 years. Lasting 50 was pretty impressive/dangerous. You can get replacement heaters for them, but it's pretty niche, needs to be imported from Europe, and because of the age normally involves dealing with asbestos insulation. It's also apparently virtually impossible to get the venting cleaned, as it's embedded in the flooring (under concrete for the group floor). (Edit: And this caused real problems for Asthma sufferers) While it worked though it was pretty good, it heated rooms extremely quickly.
  - NeedMoreTea 7y ago
    I'm really surprised - and a little impressed - that one hung on that long. :) From various encounters over the decades they all seemed to come with feint smell of burnt dust or just dust. By the eighties it was usual to see a radiator in front of or above the old vents, or the vents simply boarded or painted shut. No idea why it was so comprehensively and quickly rejected despite that brief popularity. Maybe the impossibility of proper cleaning or expense? Though I wonder what they do for cleaning in the US. It's the only approach that hasn't managed to keep some spot in the market even after large declines - like storage heaters or, more surprisingly, even coal have.
egypturnash 7y ago
You’ve never been to the Southwest or the Gulf South, have you? There are parts of the US where you would die without AC. Seriously, like when you get a brownout on a hot summer day in New Orleans or Santa Fe or Dallas, people start dying. Mostly the elderly and kids.
- jessaustin 7y ago
  GP is in UK, and specifically allowed for the difference between that situation and situations in USA. Nobody wants your grandma to die. Also, the heat in Santa Fe is much different than that in New Orleans.
codfrantic 7y ago
I was really curious to read about this type of heating, then I read your comment. Quickly imagegoogled the term and found that this is the standard in most of north/west Europe.

maxerickson 7y ago

I see the buffer tank is listed as a water heater? Is that hooked up as a backup?