Can anyone debunk this article?

ChrisJ

Robert,
Why do you feel hot water boilers, or more properly, water heaters, are designed to boiler water?

Steam boilers are designed to boil water. Hot water boilers are not. There are hot water boilers on the market with a 96-98% AFUE rating.

SWEI

Greetings, and welcome to The Wall.

robertplattbell said:

To all you haters out there who never actually READ my article about hydronic heating

The overwhelming majority of us here are not "haters" and do not engage in ad hominem attacks -- rather, we actively disparage those who do. It's truly unfortunate to see that sort of attitude prevail in many HVAC and (other building sytems-related) forums. I did read your article (twice) and I have issues with several of the assumptions and the majority of the conclusions drawn.

If you're truly interested in dialogue, hang out here for awhile. You might find it interesting.

R2.0

I did read your "article." If we're going to bandy about qualifications, I have a degree in mechanical engineering and spent the first 20 years of my career in project and construction management, focusing on HVAC systems in biotech labs. So I feel qualified to say that many of your statements are incomplete, misleading, or just plain wrong.

As for your qualifications, I'm not impressed, but they do explain your strange confidence regarding the "superiority" of air ducts over hydronics. Roof top units are, to the commercial building world, exactly what you say about residential furnaces: cheap up front costs, simple to control, easy to replace. They also suck at providing proper climate control for anything but a spec office building or big box retail. Any facility that is more complex goes with chillers, boilers, and piping. The single time we tried to install RTU's in a lab, we simply could not get the system to work until we basically ripped out all the factory controls and rebuilt them as custom air handlers.

The same principles apply to residential. The fastest cheapest solution for a spec house is ductwork and a furnace with one stat. But the second you want the system to do more than cycle the whole house up and down, things start going off the rails. Zoning a ductwork system is an of magnitude harder than doing it on a water system. Not only for the install, but the balancing. You wind up with a system that not only won't do what you want it to do, it can't be made to do it without ripping out and replacing ductwork.

Your blog is about living frugally. I applaud that. You might even be an expert at it. But your statements show that, whatever your other qualifications, you don't understand HVAC systems of any complexity. And believe it or not, sometimes complexity IS better.

David Nadle

With a technical background like yours you should know that N=1 (your house) is not enough data to draw inferences. If you read the posts on this thread with an open mind you'll see that many of assertions you made are false. I think if you had come to this site with questions about your system while you owned that house, you would have received excellent advice and could have added controls and safety equipment that would have avoided a lot of the problems you experienced. Properly installed and controlled hydronic systems don't boil over, or overshoot, and leaks are rare.

I don't know what to say about #7. You still have to vacuum and use the duster, don't you? How did #7 make the cut?

Docfletcher

robertplattbell, Any Home Depot would have Cryrotek. I'm fairly sure it's a fact regarding efficiency. Those folks that are out in the sticks may want to consider automatic back up generator. Which, I myself need because power here is not the most reliable Antifreeze should be PH checked every other year. I won't use it again.

ChrisJ

@robertplattbell,

Please enjoy your forced hot air, I have no problem with someone being happy. You will not find any hating on this forum.

I enjoy my steam heat. No fans, no filters, no pumps, no zone valves, no limit switches except for a high pressure limit that never does anything, no antifreeze because the system is empty when cold and no pex since you hate that so much as well. I can do a 10 degree recovery in around 30 minutes and I heat the objects in the room, not just the air so it doesn't end up still feeling cold for hours after the recovery like it does with forced air. My house feels like it's one steady temperature when we are home rather than always feeling slightly cool or slightly warm depending on if the furnace is on or not, you never know what it's doing. Leaks on my system are not a concern either due to the extremely low pressure I run.


Some of us prefer comfort and are willing to pay for it.
Have a pleasant weekend.

R2.0

I actually wasn't attacking you personally but rather your qualifications. You tried an "argument from authority" by citing your academic achievements and employment history. I pointed out that they don't actually qualify you on the subject in which you are claiming expertise.

My biggest issue with the thrust of your arguments is the general claim that hydronic systems have no benefit to them over hot air systems. "No benefits whatsoever" is your quote. In this case you are simply wrong. A properly maintained hydronic system is more efficient, both theoretically and practically, than a hot air system *of equal capabilities*.

Mechanically, hydronic systems have far fewer parasitic losses than a ducted system. Fans are far less efficient than pumps and use much more energy to move the same amount of heat. There are also more heat losses to the environment, due to air leakage and the surface area of duct vs. pipe. And there is always duct leakage. ASHRAE standards have classifications for duct leakage, none of which are "zero cfm." By contrast ASME codes for piping require zero leakage, often measured under pressures 150% of design. This disparity in mechanical efficiency is compounded as the systems get more complex. Zoning a duct system requires motorized dampers, which rob energy from the air flow and introduce more leakage. Whereas valves don't leak if properly installed, and while they do rob energy from the water flow it is much less on a per BTU basis than dampers.

From a practical standpoint, the advantage is more subtle, but more important. It stems from the fact that radiant heat "feels" warmer than convective heat. It's physiology that causes that, not engineering. But engineers can take advantage of the phenomenon. By transmitting the heat into the space via radiation, we can make person feel more comfortable than the same amount of heat moved into the space convectively. Which means that the space temperature in a hydronically heated house can actually be lower than in a ducted house while maintaining the same comfort level. Which means you are using less fuel on a degree-day basis for the same results.

I won't argue that ducted systems don't have certain advantages over hydronic systems. At the base level they have cheaper first costs, which can be a major factor. Which, BTW, is the main reason so few houses have hydronic systems these days: builders have to make a price point. And yes, ducted systems can serve heating and cooling, which can be a major factor in cost considerations. But to maintain, as you do, that hydronic systems have zero advantages besides, as you put it, "dollar signs", destroys whatever credibility you could claim from your education and experience.

R2.0

ChrisJ said:

What is the reason all hot water systems don't use antifreeze?
I'd think it would not only offer freeze protection, but wouldn't it be a corrosion inhibitor as well?

What are the cons to it?

Heat transfer. Glycol doesn't have as high a heat capacity as water (actually few liquids do) so you need to pump more of it to move the same amount of heat from the source to the emitters. Same reason we use an antifreeze mix in our cars instead of straight glycol - it just can't carry enough heat from the engine to the radiator.

kcopp

If FHA is so great why then are almost all heating systems in Europe Hydronic... where fuel costs are more expensive?

icesailor

ChrisJ said:

What is the reason all hot water systems don't use antifreeze?
I'd think it would not only offer freeze protection, but wouldn't it be a corrosion inhibitor as well?

What are the cons to it?

It cost a whole lot more to fill a system with anti-freeze. Including the fact that Antifreeze has a thicker viscosity so it needs bigger circulator pumps, and the heat transfer is lower so you need more radiation.

We won't even get into what a PITA it is to service a system with Antifreeze in it.

icesailor

People who own "vacation homes" and leave the water on while unattended are looking to make an insurance claim. It is far cheaper to have the house professionally drained. Then, if the owner plans to visit for a weekend or a week, have someone turn the water back on. If it is later on in the Spring when the weather is warming, leave it on. Anyone that leaves water on in an unattended house likes going to Las Vegas and gambling.

I drained and winterized houses for almost 50 years. The only houses I ever saw that flooded because of water being on were pure carelessness or negligence on the part of someone.

Don't use that as an excuse. If your house froze up in a winter and there was flooding. you either didn't have a caretaker, or the caretaker wasn't doing their job. And were negligent in doing it.

Usually, it was the former. No caretaker.

Where I used to work, frozen and broken pipe damage has gotten so bad that if you make a damage claim for flooding, and you do not have a paid person watching the property, that has provable records as to how often they checked the property, the insurance company will refuse the claim. And that "caretaker" must now carry liability insurance. Gone are the days when you can ask a neighbor to look in on the house after a storm. The damage comes a week after the storm when the weather warms up and the pipes thaw.

icesailor

Then again. some people are smart. The rest of us aren't.

Leo_I_G

Robertplattbell, you quote 1.5%. Have you checked the European % on installed heating systems? If not you should. When the cost of energy is 3 - 4 times higher in cost then at the present (as in Europe compared to most of N.A.), you will see a drastic falling off of forced air systems, especially in the colder northern and Canadian climates. Why, because hydronic heating uses less energy to achieve the same comfort.

Where I live and work, in B.C., we are at about 15-25% hydronic installs already. Of course we also have rules for proper install of forced air, so the cost difference, though more for hydronics, is quite a bit less of a factor here.

Of course if you want the cheapest way to heat, get an airtight and burn wood!

RobG

Although most of the points have been made in a rather disjointed way, this is the perfect post for ME from the RPA to join in on.

Gordy

Robert,

The original poster asked for an opinion on the article itself. My original reply was to the content of the article in which consideration should be taken in who wrote the article, and their actual knowledge on the subject matter it contains. Your profile says your a patent lawyer not a occupation I would consider to be of an actual relevance to the subject matter. Now you come forth with added "credentials" as if they were to some how support your perception of what you consider actual facts.

On the other hand your negativity to hydronic heat is based on your single personal experience of ownership of such a system. There are hacks in all facets of construction. Even hvac.

I have no desire to counter all your arguments, but I will say a boiler is not designed to boil water for hydronic heating systems. It's called a boiler, but it's designed to heat water to a desired temperature for the requirements of the system its servicing. It's efficiency to do this is based on how much fuel is being converted to usable BTUs at the HX ( that's short for heat exchanger). Not to boil water. Your experience with pumps ruined by water being to hot is evidence that your system lacked proper controls, and limiting devices not functioning properly.


There is radiant cooling for certain climates that lend itself to the method which still requires smaller duct work for humidity control. Much smaller than conventional AC.

Some other arguments show lack of understanding of how a properly installed hydronics heating system does work with proper control strategies in place. Also a lack of understanding how those controls,are,suppose to work.

All homes,experience the shoulder season especially going from summer to fall. A lot of this has to do with our biomechanics as to what feels comfortable, and what should be comfortable. We are exposed to summer temps then when fall comes 60 degrees feels cold. When we come out of winter it's amazing how warm 60 degrees can feel in comparison. During the summer we cool our homes to 78 degrees and we are comfortable. In the winter 78 degrees is pretty darn hot in a home. It's the same perception no matter what type of heating system we choose to use.

It's coined the cold 70. 70*'can feel cold, and it can feel warm. It's,all about MRT (mean radiant temperature) that keeps us comfortable.

Docfletcher

Gordy, Well said. I especially enjoyed your temperture perception analogy.

R2.0

I think I know the source of the whole "boilers are inefficient for hydronics" thing. I remember reading a number of years ago an interview in a trade rag with a mechanical contractor who used domestic hot water heaters for radiant systems. When questioned, his justification was that "boilers" were originally designed to produce steam, and if they aren't making steam they are being inefficient. Since the systems he was installing were using hot water, he was using the equipment designed to heat water - aka domestic water heaters.

While it sounds plausible to someone who has just enough knowledge to follow the conversation, "design purpose" is irrelevant when discussing efficiency - those are numerical values. An 85% efficient boiler uses as much fuel as an 85% efficient HW heater. Period.

Gordy

And you would be hard pressed to find an 85% efficient Tank style water heater.

SWEI

Leo_I_G said:

we also have rules for proper install of forced air, so the cost difference, though more for hydronics, is quite a bit less of a factor here.

There's the rub. Commercial jobs specify (in detail) the performance of ductwork and require testing. When and if these standards are uniformly applied to residential systems, we may see a bit of a resurgence in hydronics.

Sticking to the facts, roughly two thirds of your perception of hot and cold are related to MRT. If you want to make occupants hot or cold, manipulating MRT is the most effective way to get the job done.

icesailor

Massachusetts has instituted a "Sheet Metal License" where they have set standards for installing ducted anything. In HVAC applications, installed ductwork will have to be tested for tightness before a sign off by the AHJ. We'll see how much the added work to be sure that a air HVAC system is tight and how much it adds to cost.

I used to "Test as I went" while installing piping. So, when I was done. I already knew it was tight. I want to see how they will measure duct air pressure leakage and how they will fix it.

R2.0

icesailor said:

Massachusetts has instituted a "Sheet Metal License" where they have set standards for installing ducted anything. In HVAC applications, installed ductwork will have to be tested for tightness before a sign off by the AHJ. We'll see how much the added work to be sure that a air HVAC system is tight and how much it adds to cost.

I used to "Test as I went" while installing piping. So, when I was done. I already knew it was tight. I want to see how they will measure duct air pressure leakage and how they will fix it.

I can say that, from the commercial ductwork installs, it's a PITA. It's not like a hydrotest - fill, squeeze, wait, done. Basically you need to measure the air volume right after the supply fan, and measure the air flow at the outlets, and do the math. The outlets never equal the supply - the difference is the leakage.

Typically a designer will specify the permitted leakage class, and there is a corresponding construction class that specifies sheet metal gauges, joint types, etc. IF a contractor follows proper construction methods there is rarely a problem. If there is an issue, it's typically due to slipshod construction - joints made up without sealant or the incorrect joints used - slip and drive vs tee joints, for example. the solution? Going back over all the ductwork and slopping duct sealant all over every joint. And since it's being applied externally, it needs to go on thick. And it's sticky, nasty stuff.

In other words, very few ductwork installations will actually meet the new codes. Inspectors aren't going to know what to look for - the can't just stare at a gauge for 10 minutes. So it will be a submission of paperwork, which will get filed and ignored and will only be of use in some later lawsuit.