Thursday, May 6, 2010

Do You Really Want Hydronic Heating?

Hydronic Heating is complicated, expensive and a nightmare when it ages.

Hydronic heating, as its name implies, uses hot water to heat your home. Is this a good thing or not? Hydronic heating is very popular in northern regions of the country where heating is a major issue.

There are some advantages to Hydronic heating of course. But I think these are overstated:

1. Zoning: You can switch off zones to rooms not in use, and thus save energy. Of course, those rooms go cold, and unless you have a large house with unused rooms, chances are, this feature is of little use to you. If you have a large house with unused rooms, ask yourself why. When installing hydronic heating, adding zones adds to the cost of installation, so if you want each room on a different zone, expect to pay for the privilege.

2. Warm Floors: You can heat using baseboard hydronic (sometimes called baseboard hot water) or with through-the-floor hydronic heating. The latter was hyped heavily on "This Old House" in the 1980's and 1990's which is when a lot of these systems were installed. Do you really get "warm floors"? Well, they aren't cold, that's for sure, but they aren't toasty warm or anything. The big disadvantage of this type of heating is that you can't "spot heat" to warm the house on cold mornings. If you turn on the floor heat, it heats the house all day. Even in the dead of winter, this often means the house is overheated during the day and underheated at night, as the system has a very slow response time. In Spring and Fall, you either freeze or roast.

3. Makes Hot Water, Too! Yes, the misnamed "boiler" (more on that later) will also make your domestic hot water. Not very efficiently, as it has to heat the water through a heat exchanger. Plus, this means the "boiler" runs all summer long to make your hot water. And that means a warm basement. So if you have A/C, it will run longer to cool off the house, due to the heat generated the boiler. Not efficient, not smart.

4. Heat with Wood: You can tie in an outdoor wood furnace in to a hydronic system and heat with wood. All you have to do is go outside two or three times a day and load the wood furnace with wood. The neighbors love the smoke, by the way. Makes your house look like a smokey crash site. Wood furnaces cost staggering amounts of money - $7000 and up.  Some as much as $15,000.  The "savings" in heating bills take years to rationalize, perhaps decades.

5. Doesn't dry out the air: Some people complain that forced air heat dries out their house in the winter. Hydronic heating is touted as keeping the house humid (and if you break a pipe, it certainly will!). However, you can add a humidifier to a forced air system for less than $100. It's been done. And as for dust, at least a forced air system has a filter to capture dust. With hydronics, the dust just settles everywhere.  Note:  This site claims that hydronic heating does not make a house drier or more humid than a forced air system, and dismisses this claim as a "myth".

OK, so the advantages of hydronic heating are not all that great. The disadvantages? There are so many, where do I begin?

1. Cost: Running all that piping costs money, and copper ain't cheap. The floor piping is plastic. Um, more on that later. Labor to connect all these pipes isn't cheap, either. The boiler, controls, circulation pumps, and associated hardware are far more expensive than a cheap gas furnace.  A typical hydronic system can cost three times or more than a gas furnace.   If you add a forced-air A/C system as well, the costs get even crazier.

2. Efficiency: The "boiler" is often an actual a boiler, but running at below boiling point. So it runs in an inefficient range. Some folks replace the boiler with a special condensing hot water heater, which sort of makes sense. But such hot water heaters are very pricey - like $6000 or more.  Even a simple boiler can cost a few thousand dollars - and last about a decade before rusting through.

3. Boilover: If the boiler DOES boil, it can damage your pumps and plastic piping. Boilovers can occur if the system runs low on water (more on that later) or if the control unit fails.   We lost six brand new pumps in a boilover incident. $300 each.

4. Water, water, everywhere: These systems, particularly the in-the-floor heating models, run pipes all over your house. What could go wrong? Leaks for one. A freeze for another. Pipes get old and leak. With plumbing that is a problem. With a hydronic heating system, it is a nightmare as there are basically pipes in every single wall, ceiling, and floor. If a pipe breaks, it will dump rusty brown water all over your house, and the take-up water will continue to re-fill the boiler and flood the house. You'll never have this problem with forced air, which when it leaks, leaks air.

5. Aging and Replacement Cost: Unlike a gas furnace that can be replaced easily and cheaply, hydronic systems require regular maintenance of their many parts - boiler, pumps, controls, etc. And when it all needs to be replaced, the replacement cost is staggering.  Few companies work on these systems, so your options are more limited.

6. Hard to do A/C: A gas furnace can be retrofitted with an A-coil in the plenum. Put an outside compressor and condensing unit and Voila! You've got central air! Not so with hydronic heating. Adding ductwork to an existing house is nearly impossible, without a lot of work and sacrificing a closet or two. One neighbor installed hydronic heating in their new home AND ran the ductwork for a heat pump. My question: Why bother with the hydronic if you have a forced air system as well? It's like paying for two HVAC plants - effectively doubling your installation costs.

7. Freezup: If you lose power in an ice storm, the system will shut down. If you are running water in the system, the pipes will freeze, flooding the house and ruining everything you own and destroying the system. Fun, eh? Regular plumbing can be easily shut off, blown out, and winterized. Winterizing hydronics is not as easy. Many run anti-freeze in their systems, but it degrades performance somewhat.

My experience with Hydronic Heating:

Our Lake house came with hydronic heating. The system was 15 years old. There was one split-system A/C unit in the house when we bought it. I quickly had to add three split-system A/C units and two portable A/C units to air condition the house. The split systems and one of the portables are heat pumps, and we find that they work well for taking off the morning chill or making the bedroom warm at night. We never use the hydronic heating in the Spring, Summer, and Fall. But the boiler ran all the time to heat domestic hot water.

Our boiler room.  It was very fancy looking, but also very complex.  I was lucky that I had a friend who got me a replacement boiler for $1500 wholesale ($3000 retail) and that I installed it myself.  The local HVAC guy (the only one who worked on hydronics) wanted close to $5000 for the job.  Each of those circulation pumps was $300 and all five had to be replaced.  Due to a boilver problem (caused by a broken controller) they had to be replaced again.  The boiler is cast iron and rusted out in about 15 years.  Hard water is problematic with these systems.  I would highly recommend using anti-freeze as it includes corrosion inhibitors.

The boiler warms the basement, which makes the A/C unit there work twice as hard. And it is not very efficient for making hot water. This year, we installed a 50-gallon electric hot water heater. This allows us to shut off the boiler in the summer and save on energy, as we are not paying to cool off the basement while the boiler heats it.

One pipe burst in the ceiling this year. Hopefully this is an anomaly and not a sign the entire system is ready to fail. If an in-floor hydronic system starts leaking a lot, the only way to fix it is to tear out the whole ceiling, remove the insulation, and re-install all the piping. Fun, eh? Even repairing a "small" leak requires tearing open the ceiling to get at it.

Many folks, when confronted with this problem, convert to baseboard hydronic heating, as it involves a lot less plumbing, and soldered copper is less likely to leak down the road than all that plastic piping.

We replaced the boiler this year as well.   They are made of cast iron and rust through in about 15 years. Ours is over 15 years old and has started leaking. Newer ones are made of aluminum or stainless steel. But even then, they wear out. The cost of replacing it is higher than replacing a gas furnace. Since they are not as plentiful as gas furnaces, they are plenty more expensive.

We plan on running the system with anti-freeze as well, so we will have the option of leaving the house "cold" in the winter while we are away.  Many folks leave their hydronic heating systems "on" while they are away, convinced that it is "safer" to leave it running than to risk a frozen pipe. But if the hydronic system breaks a pipe, it will pump your house full of water. A winterized plumbing system, shut down, might freeze a pipe, but since it is OFF, the damage is limited to one area.

So, do you really want hydronic heating? My answer would be "No" after owning an older system. The touted advantages of the systems are over-stated and the costs and disadvantages far outweigh them. If you are going to install A/C anyway (which even in colder parts of the country, is becoming a reality for most houses these days) it is simpler and cheaper to just go with a forced air furnace as a heating source than to dick around with miles of tubing and a boiler.

But, the choice is yours. Pardon me while I go mop up.....


  1. Some folks argue that modern hydronic systems are more reliable (well, if they are new, yes. When they get old, no). They argue that new materials, such as PEX plumbing, which is a plastic piping with crimp fittings, won't leak over time.

    Might be true, but I do recall the PEX class-action suit and the ruined homes in Fairfax County back in the 1990's, when townhomes were put up rapidly with PEX plumbing and it all leaked when the crimp fittings went South a few years later. I guess they fixed that. Let's hope.

    Replacing all your regular plumbing is bad enough - imagine how hard it would be with pipes every 12" across your floor? That is a lot of piping!

    It is a very complex and expensive system, that doesn't deliver a lot of benefits. Hydronic heating is popular in some Northern regions, but has a market penetration of only about 1-2% nationwide. It does not "add value" to your home, or keep the home humid, or cut down on dust, or provide warm floors. It just drains your pocketbook. Sorry, but that is the truth of the matter.

  2. To all you haters out there who never actually read my article about hydronic heating:

    1. The house in question was in New York State, in King Ferry New York, on Cayuga Lake. It was not in Georgia.

    2. I am a Patent Attorney, but my undergraduate degree is in Electrical Engineering. I went to S.U. while working for a small company called Carrier Corporation, in Syracuse New York, as a laboratory technician in the heavy machinery (industrial chiller) and air handling labs, as well as the packaged unitary rooftop lab. TR-1, TR-7A and TR-19, for five years.

    3. Prior to that, I worked at General Motors in the industrial Engineering department and studied industrial hydraulic and pneumatics while at General Motors Institute. Yes, that involved maintenance on plant HVAC systems. I know how to turn a wrench - a six-foot pipe wrench, to be exact.

    4. A "boiler" used in Hydronic heating does not boil water. It is designed to boil water, but instead is run at a below boiling point range - which is less than efficieent. If water pressure ever goes low, yes the water will boil and blow out all our circulation pumps. Ask me how I know this.

    5. Hydronic heating is far more costly, complicated and prone to failure than any other type of heating system. This would be fine if it delivered benefits, such as efficiency, that justify the extra cost. Sadly, it delivers no benefits whatsoever.

    6. Google "PEX Class Action Lawsuit" Any form of plumbing embedded in concrete floors is prone to expensive trouble down the road (10-20 years).

    7. Forced Air systems are not "dusty" but rater remove dust from the air. Hydronic heating, however, just allows dust to settle everywhere. Dust is mostly your dead skin cells that you shed by the millions every day. With hydronic heat, this settles on everything. With forced air, it is removed from the house by the filter, which can then be thrown away.

    9. The cost delta is so staggering. A simple furnace can be replaced for a couple thousand dollars. A hydronic system? Each circulating pump can cost a few hundred. The boiler can cost thousands (particularly condensing boilers). Controls, piping, etc. add even more. The labor to install is staggering.

    10. If you've never had leaks, good for you. Unfortunately I have. And the previous owner of the house had them as well (and never told me). If you are not home when the house starts to leak, it can be a nightmare, particularly with hardwood floors. And then there are mold issues, even after the leak is fixed. We're talking about a system installed in the 1990's, too.

    12. Hydronic heating accounts for about 1.5% of the heating market. That says it all. No one uses this - it's just too darn expensive and provides no real benefit.

    12. Hydronic heating doesn't work very well in the Spring or fall. It can take hours for the system to bring the house up to temperature. By then, the sun is out and it is too hot - so you open windows. Not very efficient!

    13. You can't add A/C to hydronic heat, but it is a simple matter to add it to a forced-air furnace. The house I bought had hydronic heat. to add A/C, I had to install four split systems and two portable A/C units. Running ductwork, once the house was built, was prohibitively expensive.

    Sorry guys, but no sale to unnecessarily complicated technology. KISS -Keep It Simple, Steven.

  3. A reader writes: "radiant hydronic heat is more efficient, as you can keep the air temperature colder, but the house will feel warmer!"

    Sorry, no sale to crazy. Cold is cold. And a forced air furnace can be bought that is 99% efficient. It doesn't get more efficient than that.

    Cold? Put on a sweater. Rather than trying to turn your home into a hothouse, wear appropriate clothing instead.

    Hydronic heat makes up less than 5% of residential heating plant installs in the country. That about says it all. Very few people want this - and there are very good reasons why, which I found out after owning one.

    They are about as practical as a steam-powered car.

  4. The same reader, after many e-mails, finally admits that hydronic heating systems are not inherently more efficient than other types of heating systems. So there are no "energy savings" to recoup the 2X to 3X delta in installation costs, repair expenses, and the like.

    So, of course, he goes to a credentialist argument (I know more about HVAC than you!) and personal attacks. What a classy guy!

    Apparently my posting questioning the RELIGION of hydronic heating has the Hydronic faithful ready to burn me in effigy.

    I would suggest that making a religion (and it is a belief system, not science or economics) out of your choice of heating plant, is short-sighted.

    If hydronics were more efficient, less costly, easier to maintain, and less costly to repair, I would be the first to embrace them. Sadly, they are none of the above.

    Throw in the shoulder-season problem, and the A/C problem, and well, it is a no-brainer. Spending tens of thousands of dollars on a "look at me!" heating plant makes no sense at all.

    Just as spending $15,000 on an outdoor wood furnace and spending all your waking hours cutting trees, splitting and stacking firewood, and feeding a smoky wood furnace makes no sense at all (in order to save a couple hundred a month on heating bills!).

    Poverty-think at its worse. Spending money to save money - but just ending up spending more money!

  5. Another argument raised in the hydronic debate is that hydronic heat is a "different kind of heating" - or at lest radiant heat is. The argument goes that the radiant heat is "different" in that it radiates heat which heats objects in the house, and thus the air can be colder.

    In order to believe this, you have to believe there are two kinds of heat. However, scientifically, heat is heat. In Thermodynamics, we don't recognize heat as having "flavors".

    But even assuming this is true, the objects in the house are heating, and the air is also heated. How is heat "different" that comes from the floor, versus a floor vent?

    Answer: It Ain't.

    Another argument raised is that "My buddy Clem converted his house to Radiant heat and cut his heating bills in half!"

    This is hard to parse, because unless we can ACTUALLY SEE CLEM's heating bills, it is just a "Friend of a Friend" (FOAF) story, which as we know are the source of urban legends.

    And the story has a lot of holes. Adding radiant hydronic heat to a building that already has forced air heat is staggeringly difficult and expensive - you'd have to tear out all of your ceiling sheetrock to get at the floors above. Perhaps for a trailer home or a one-story home on a crawl space this might be somewhat practical.

    But also, this story fails to reflect how other factors would affect the heating bill. If you replace an older furnace (running at 60% efficiency, for example) with a newer one (running at 90% efficiency) you may see a dramatic reduction in your heating bills.

    And other factors, such as adding insulation, new windows, etc. affect the mix. Given how dramatic a retrofit of hyrdonic would be, one would have to assume it was part of an overall remodel and thus other factors are involved.

    And then there is the "Your mileage may vary" factor. I can get 40 mpg our of a Ford Mustang and 20 mpg out of a Prius. It is all in how you drive it.

    So, if I have a forced air system and set the thermostat at 80 in the winter, it will use more gas than a hydronic system set at 55. Duh.

  6. Again, the bottom line is HARDLY ANYONE USES THIS form of heating - and commercial interests in particular don't use it.

    If it really did save money, you'd see a lot of commercial installs of radiant hydronic. But you don't.

    What you see is these systems SOLD to homeowners as sort of a hobby-toy heating system in some areas of the country where it snows a lot.

    It is a Cadillac system. Nothing wrong with Cadillac - just stop blowing smoke up my ass (and everyone else's) by claiming it is more efficient than a Toyota Yaris.

    The Yaris may be ugly, but it is cheap - and less costly to maintain in the long run.

  7. If you google "how much does hydronic heating cost to install?" you will get an "answer" claiming that it is about on par with a forced-air system - claiming $3000 in materials and $500 for labor.

    And who says online humor is dead?

    Expect costs to be a lot higher and factor in your A/C costs as well - in an era of global warming, you will need A/C unless you live in Hudson Bay or something.

    The cost of a force-air gas furnace and A/C unit is far less than central air and hydronic.

    And the marketplace reflects this in terms of installs.

    It is a bling system, and if you are fond of $2000 washing machines and $6000 refrigerators, you'll probably like this as well.

    Me? Well, you didn't read the title of this blog, did you?


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