Radiant heat Debate: open vs. direct
The debate will go on forever as witnessed by Terry Alsberg’s reader feedback letter. So here is the question: is there at least one (or more) proven case of Legionnaire’s disease that has been traced back to the bugs growing in an open radiant heat system? These mix heating loop and potable water.
I would think that the residential fire sprinkler systems that route potable (cold) water through a long piping path to the faucet could be accused of providing a similar “friendly” bug-growing conditions, if in fact there is a problem in the first place.
And of course, this begs the question of why the municipal water supply systems don’t breed the same bugs, especially in our Southern states.
Terry claims that the risk of Legionnaire’s disease is non-trivial, but with the years and miles of water systems we have, I would argue that it is trivial – unless there have been actual cases of the disease caused by warm water residence time. As a DIYer, the cost difference is not 0.3% and I see no reason to pay extra if there is no risk.
Any good info available? (Not Internet “facts”.)
Replies
Well from a logical point of view, I offer some food for thought. I am NOT an expert in Legionnaire's disease, but have been exposed to the issue on a couple of occasions.
From what I understand, it is an AIR BORNE disease only. You cannot get it from e.g. drinking water. It is particular about temperature, also.
Fire sprinklers should have a back flow device on them to prevent stagnant water from going back into the house domestic water supply ... as should the hose bibs (i.e. anti siphone hose bib). These prevent water borne diseases/contamination from affecting your health, I think.
I did some research with the notion that a standard domestic hot water (DHW) tank might support Legionnaire's disease and that you could get it while taking a shower (due to the aeration/misting of the water). I don't recall the specifics, but the conclusions were ... it is a non issue.
The classic source of Legionnaire's disease is from e.g. cooling towers ... used to cool large buildings ... if you don't treat the sprayed water, it is a great place to support Legionnaire's disease in that it helps it become airborne.
Your concern should be general contamination of potable water related to using an open loop radiant heat. I think during the heating system, this is likely not an issue ... the water is continually circulating (or regularly). It is the stagnant water during the summer that might be an issue. Answer to that would be to pipe it so that summer water supply runs through the slab first and then into the water heater. It helps pre heat the water a bit and cools the house a bit.
Just my 2 cents.
You can also kill the bacteria by periodically running the hot water heater at 160 degrees for 5 minutes including all outlet taps. This works well with a flash heater.
"Fire sprinklers should have a back flow device on them to prevent stagnant water from going back into the house domestic water supply ..."But he is talking about a completely different kind of systems.They use heads with multiple connections. IIRC it is 5. Each head is connected to all of the others in a web.This does 2 things. One the large number of parallel paths reduces pressure drop so that it can easy support large flows with nominal size residential piping.And the 2nd is that cold water domestic water is tapped off this web so that it continously flushes the system.However, this is COLD WATER.Legionair's requires warm water to grow. Not sure, but I think that is the range of 110 - 120..
William the Geezer, the sequel to Billy the Kid - Shoe
Hi,
Just a couple comments. Doing construction work, I'm much more worried about drying on the job-site, or on route to the job-site. Legionaire's disease just sounds like another fear-mongering tactic. If your local code and building inspector is fine with an open direct system, then it's all good. Building inspectors always seem leery about the smallest risks, so if they don't care, it's a good bet you don't need to either. My 2 cents. Sorry though, no actual data on this mystery disease itself.
I've been looking into the different types of radiant systems for my new house since reading that article in FHB. Kudos to the author, I really enjoyed it. I like the idea of the open direct system a lot. I'm not a water guru though, so I'm not sure if there are any issues related to stale water. As other posters have said though, if you are able to continually circulate the water, there shouldn't be an issue. Let's face it, you're mainly drinking cold water anyway, and that's just sitting in your water lines until you use it.
What concerns me most about the open direct system is its relianance on water. If this heating system is going to be in place for the next 100 years, then that's a lot of time for all matter of whoopsie to happen. Bottom line, I think if you freeze your system, it's probably destroyed. Not 100% sure on that, but it stands to reason. And the idea of removing and replacing 2600 s.f. of slab and 1600 s.f. of thin slab just doesn't sit well with me.
Looks like open direct saves $1000-$2000 over the same system that uses a heat exchanger to separate fluids, and obviously, operates more efficiently, as there are no efficiency losses from the heat exchanger. Although I suppose you could argue that as long as the heat exchanger is in the building envelope, its losses will stay within the conditioned space. You could make the same argument about uninsulated water heaters though. My take would be that it's better for the heat to go exactly where you want it.
-Carleton
I know. Just rounding out some of the discussion about stagnant water flow or back flow from another application and issues that are associated with that. Really LD is not an issue w/in the context of the discussion ... at least that is my understanding.
>>I did some research with the notion that a standard domestic hot water (DHW) tank might support Legionnaire's disease and that you could get it while taking a shower (due to the aeration/misting of the water). I don't recall the specifics, but the conclusions were ... it is a non issue.There are, IIRC, a couple of studies that suggest there are issues with electric water heaters on private wells.
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurman
Not sure what electric water heaters and/or private wells would have to do with it. It's not like legionnaire's disease is more present in one condition over the other as far as water source or heater type. Given the very specific condition for it to exist, it will be there regardless of the two conditions you mention. And it does have to be a very specific set of conditions.
the private well thing is because you don't chlorinate your private well like the public utility would.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Doesnt' matter, I don't think. Plenty of instances where chlorinated city water resulted in Legionnaire's disease in cooling towers that didn't have proper water treatment. Again, it is more conditions of use than source of the water.
chlorine is only effective for a short period of time.Usually in a city tied potable system you are cycling that water through fast enough for it to remain effective to some degree, somewhat lessening your risks of any bacterial issues (not just legionella, as Tim pointed out).If not, such as in the case of the cooling towers, or a freshwater heating system, that is not true. Or if you have a private well, that is not true.but all this was posted earlier in the thread.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Good points. A private well, though has little to do with legionella as beyond that, again, it takes very specific conditions for it to be an issue. Much like the human immune system. We are ALWAYS full of bacteria ... some even deadly ... but it is that delicate balance of biology that keeps it at bay. Upset that biology and you have the potential for some serious sh*t happening. My readings on Legionella IIRC is that a shower, while having some of the elements easily supporting legionella (e.g. temperature), that the overall conditions would rarely, if ever be correct/idea for supporting a 'legionella hazard'. That is ... no worries, mate.
DISCLAIMER: My half baked recollection of something I read some time back does NOT make me any sort of expert in any way shape or form. Concerned? Research it for yourselves, folks. :) .... and that's all I have to say about that ...
I am in the middle of a radiant hydronic heating system in my own new home. I looked at the open systems and the products and designs pushed by the suppliers mentioned in the FHB article. To say I was less than impressed by the open systems and the supposed savings promoted by the open system suppliers is a great understatement.
I see absolutely no advantage to the open systems, and quite a few pitfalls. Legionella bacteria is a risk not to be taken lightly. Confusing the issue with cold water, fire sprinkler, and municipal utility issues is really apples vs oranges.
For quality feedback on this serious issue, post your thread on http://www.heatinghelp.com under the "Questions" tab on "The Wall". The author of these links frequently posts there -
http://contractormag.com/columns/eatherton/cm_column_645/
http://contractormag.com/columns/eatherton/cm_column_656/
http://contractormag.com/columns/eatherton/cm_column_668/
http://contractormag.com/columns/eatherton/cm_column_681/
I can provide you the open system vs closed system + indirect hot water tank quotes I have recieved and final materials list I am using and it will clearly show that there is NO cost savings with an open system.
Mis-diagnosis and ignorance to the symptoms of Legionaire's disease are likely suspect in the "trivial" number of cases reported. Try these links - then decide if it is worth it.
http://www.cdc.gov/legionella/patient_facts.htm
http://en.wikipedia.org/wiki/Legionellosis
http://www.mayoclinic.com/health/legionnaires-disease/ds00853
http://www.legionella.org/general_public.htm
I think FHB really dropped the bar by printing that article and shows that the qualtity of content and attention to detail are rapidly deteriorating in the print copy. Why risk it? What are you really accomplishing with an open system? Show me your system pricing and I will show you mine if you'd like - then we can debate the pros and cons based on true costs of materials and installations.
Craig Benson
Great Basin Custom Homes
Your links don't provide cases of disease caused by open systems. Just because Legionaire's disease is bad doesn't mean you are risking it in your radiant heat system. I propose a leak in a heat exchanger could poison your children with glycol. See this link and decide if the risk is worth it!
http://www.mnpoison.org/index.asp?pageID=155
I'll take water over glycol any day!Open systems are flushed by incoming water to the hot water heater, there is no stagnation, at least no more than the rest of the water lines in the house.
Actually, open systems are after the water heater. There may be a problem if there are zone valves in the system. You have to make sure that the zone valves are open in order to flush the lines and if you are flushing the lines, you are heating the house.
So, assuming a standard water heater, you have a system that has an AFUE of about 60, plus you have to have extra cooling to cool down the space after heating it by flushing. And if you don't flush, you have stagnant water which IIRC, is prohibited by your plumbing codes.
So, ignoring the Legionella debate, an open system doesn't make a lot of sense from a pure effeciency point of view.
I was referring to the open system design radiantec (http://www.radiantec.com/systems-sources/open-system.php) uses. They use check valves that give priority to DHW use, the incoming water to the water heater runs through the floor system. It's not bad for small areas. Elegant design.I wholeheartedly agree with you that using a DHW heater is not very efficient unless you go with a condensing heater like a Polaris. I just don't like fear mongering about legionella bugs.
Well, it may be "elegant", but up here it ain't legal. But aside from that, what bothers me about any company is when a picture is different from a schematic.
The picture in the link is a 2 zone heating system with a tempering valve serving who knows what? And why the relief valve when the water heater requires a P&T relief?Condensing water heaters don't have a great reputation, not to mention a vitodens 100 is probably cheaper than a Polaris.
And how do you control the supply temp to the floor when you require heat? If the incoming water is too cold, you need to boost the supply temp of the water heater. Most flow rates for infloor are based on about 1/2 gpm. Depending on zoning, more water is going to flow through the zones than is optimum.
Even if you go with a water heater instead of a boiler, a HX and an extra pump isn't much more.
Every time you make a change, the ripple effects can be significant.
And just for the record, while I think that most modcon boilers are great, there are situations where I don't recommend them.
I am confused. What exactly is an open system?
If my water in my radiant floor is full of Legionaires bacteria, how do I get infected? Bacteria can't migrate through pex piping.
My floor heat is on a dedicated hot water heater and circ pump open to the air. If I am servicing the system should I flush it with Clorox first? How bad is Clorox for my pex or hot water heater? How often do I need to Clorox my system to keep it pathogen free? Is my mother's wonder disinfectant (Clorox) the best thing for the job?
Eric
I believe the contractormag.com articles do show a definitive case of contracting LD via low-temp domestic hot water. Did you read the articles?System design plays a huge role in the amount of fresh water that is circulated through the entire system in order to "flush" bacteria out of the system. Zone valves may cause some circuits to stagnate and legionella is only one of the water borne bacterias that can accumulate in large numbers and be potentially fatal when "incubated" in a low-temp heating system.Look, I personally trust the construction of a heat exchanger or indirect tank much more than I trust the concept of fresh water flush in an open hydronic system.I don't see the benefits of an open system and have selected components in my system to minimize the risks I perceive. Do you have any evidence of heat exchanger failure rates or glycol ingestion from failed HXs?Likely we are all exposed to much higher risks just driving to work than we would ever be with either type of supposed risk in hydronic systems.Engineering a system which provides an ideal environment for dangerous bacteria to multiply, even if the risk is minute, is still opening the door for disaster. Is it worth it - for me no way. Bacterial populations multiply on a logarithmic scale and could reach dangerous levels in a very short timeframe, would you flush the system for a few hours when you return from a vacation or would you be more likely to jump in the shower to relax just as the author of the articles described? Only takes once, just sharing my thoughts and some of the research I did when looking at system design. Gonna go dig out the article and read it again, wanna make sure I'm not really missing the boat or leaning towards germophobia...
"I believe the contractormag.com articles do show a definitive case of contracting LD via low-temp domestic hot water. Did you read the articles?"
Yes the article highlights very well that improper care of any domestic hot water system( even a closed system) gives the possibility of escalating the possibility of contracting Legionnaires.
Yes Haystax, I have read the articles in the past and reviewed them again. Here are some quotes:
"The doctor looked at my pictures, listened to my lungs with a stethoscope and declared, "You've got bacterial pneumonia!"
I was shocked. I'd never had any lung issue in my life. I said, "As in Legionnaires' disease?" to which she replied, "Most likely ... "
and "I EXPLAINED HOW I believe I contracted Legionnaires' disease in my May column"
This would not be a confirmed case of legionella, it would not be a case of an open radiant heat system. It would be a case of a tank of stagnant warm water that might be the cause of the problem. It could be he picked up a bacterial infection from a telephone, someone's cough or any number of places. He also correctly points out "Remember, we are all exposed to the bacteria on a daily basis."If open systems are a problem than, logically, so are hot water recirculators (used in large buildings and on long plumbing runs), that shower in the guest room, and, as Eartherton points out, domestic water heaters.I was kidding about the glycol thing, I thought you might need something else to fear. Even if the risk is minute.Peace!
Okay, fair enough. As for direct causative agent, I believe the author states he did test positive for legionella bacteria. However, the stack of other pathogens and weakened immune system all have to be taken into account. The tepid shower was probably only the straw that broke the camel's back.I still believe there is correlation between this case in a low temp domestic hot water system and an open loop hydronic system. They are basically the same thing. If your tank temp is over 140* in an open system, how are you mixing to achieve floor friendly temps? In a typical tempering valve scenario it is only a small percentage of return loop water that makes it's way back to the tank, the rest is recirculated and goes back to the bacteria nursery for more incubation time. When those zones are closed off, stagnation occurs. Once the zone is opened for a heat call, all of the water from the loops is cool enough to initially return to the tank. Are you at least advocating oxygen barrier tubing in an open loop system? I am curious why you feel so strongly that an open system is the way to go. What did I miss in my research? Have you found a real, tangible amount of cost savings? The cost of stainless or bronze pumps can easily offset the savings from non-barrier tubing.To each his own I guess...
maybe you should re-read the articles, that's why I quoted them:The doctor looked at my pictures, listened to my lungs with a stethoscope and declared, "You've got bacterial pneumonia!"
I was shocked. I'd never had any lung issue in my life. I said, "As in Legionnaires' disease?" to which she replied, "Most likely ...""I EXPLAINED HOW I believe I contracted Legionnaires' disease in my May column"'Most likely' and 'believe' are not the same as stating that he tested positive for the disease. Maybe, in your research, you need to read with a critical eye. If you read the Eatherton articles and came to the conclusion that he tested positive for LD you didn't read close enough. He had pneumonia, but the LD is a guess.I'm not opposed to any radiant heat system design, I'm opposed to fear mongering. I'm all for science!
Am I missing something? Won't an open system be more likely to allow freezing in the PEX embedded concrete floor if the heat goes off? In a closed system here in Wisconsin, I put a bunch of glycol (antifreeze) in my closed system loop just for that reason.
Interesting question. Yes, if pex imbedded in concrete freezes, it may burst and even wreck the concrete. Been there, seen it.
The question is will insurance cover the damage if you know of the possibility and you don't have glycol in the system?
Bill,
In my opinion, discussions concerning hydronic closed systems vs open systems should not be centered on Legionaire's disease. It is an issue for other systems and does not apply to the discussion.
The classic case of Legionare's disease occured when a fresh air intake was located near a poorly maintained cooling tower and people outside smoking near the cooling tower directly inhaled mist/vapor from the water. The American Legion was meeting at a hotel in Phillidelphia in 1976 and this how the disease came to be so named. It is not a waterbourne disease. It is an infection of respiratory system.
Open vs closed systems actually warrant little debate. While Leagionaire's is not a significant risk in a bastardized/open system, other water-borne bacterial based maladies are. (Dysentary comes to mind first, but I'm sure there are many others) Most comprehensive building codes (understand this is the lowest common denominator to keep the unintelligent and the unscrupulous from killing people) prohibit intentionally contaminating potable water systems (that includes the "open heating" system). If you have an independent system (a private well) and your choose to contaminate your water supply, only you and you immediate offspring would be eliminated. This might count as Darwin in action.
To directly address you concerns, you need to understand municipal water systems and some basic chemistry and biology. Municipal water systems provide protection from bacterial infection by means of residual oxidants. Chlorine (or sometimes bromine) to you and me. Anyone familiar with water and its treatment knows that oxidants dissapate over time. If water is left to stagnate for more than a week or so, the oxidants are gone and an anerobic environment develops. Here is the "friendly bug growing conditions". They do not exist in any normally used, municipally fed systems that are not closed (the exception being when due to failures, water supplies become contaminated).
Cost of what? The infloor piping cost is the same. The controls should cost about the same. If you're looking at a domestic water heater as your heat soure, that's as cheap as you can get (That's another debate, but the constant province of the terminally cheap and perpetually challenged).
Personally, I would never connect a heating system to my drinking water supply without a backflow preventer. But then I know a little about water treament and hydronic systems as well as having dealt with more than a few municipalities on the plumbing codes. There is a reason this debate only takes place in the residential arena: commercial construction usually weeds out the unfit and the incompetent from industry. No commercial plumber would ever consider installing an "open system" no inspector would ever pass one and no Engineer would ever put one on plans. But other that that, I'm sure its ok.
Loud applause by professional crowd.<!----><!----><!---->
Well said Tim.<!----><!---->
RB<!----><!---->
Mr. Bean,
Thank you for the kind words.
BTW, I haven't seens any of your publications in the (ASHRAE) Journal of late. I haven't been cover-to-cover in a while, did I miss one?
Tim
Hi Tim,<!----><!----><!---->
I always love your stuff!<!----><!---->
Have been tied up the past 2.5 years doing the research for and writing of HRAI of Canada's Residential IAQ course. It’s all done - we had the pilot course two months ago.<!----><!---->
Have some time and have started another article for ASHRAE - if all goes well it should be out in the fall.<!----><!---->
Thanks for asking.<!----><!---->
Keep pushing up the benchmark.
rb
Well stated.
One quibble. As stated Legionnaires is a caused by aerosolized water that is inhaled to cause a respiratory infection.
Does this perhaps describe my 15 minute morning shower environment if my water has been compromised somehow and is loaded with pathogens?
Cheers
I would be speaking out of line if I claimed a detailed level of understanding of the legionella pneumophila bacteria, where it can and cannot exist. I do know of the major documented outbreaks of LD and all are directly attributable to warm, open water systems, agitated or "aerolized" in some manner, and in proximity of large numbers of people. 3 of the 4 most famous, or notorious cases invlove cooling towers, the other was suspected of hot tubs and/or humidifers.
But to be clear, Legionaire's disease is caused by inhaling the above listed bacteria, usually in an aerosol state. Hot water, as in the 140 degF that your water heater should be providing as a minumum, will kill this and most bacteria in a matter of minutes. This is a reason that domestic tank water heaters are recommended to be set no less than 140 degF and that scald protection be provided at the point of use via the appropriate measure.
I do not know if legionella grows in an anerobic environment, such as a closed stagnant piping system. All of the cases I am aware of were sourced from a very aerobic environment. This does not mean that a compromised domestic water supply would not be full of bacteria (some of which could be pathogens), and that those would not be harmful to you in the shower or elsewhere. It means that legionella is not the pathogen with which you should be concerned.
Hi Tim,
Thanks.
MY hot water tank is definitely set above 140 F but many of my clients regularly turn down their heaters to 120 on the advice of the greenies despite the antiscald valve.
My knowledge of Legionella is also limited but reading Mark Eatherten's column describing his personal experience with a serious illness makes me exceedingly leery of any open system with sub 140 temps.
From what I understand the legionella bacteria is in all water supplies everywhere and just needs a warm, not too hot, with a food source (sludge), place to colonize and settle down.
Not being argumentative, just trying to learn, but would potable water be described as anaerobic? I know the glass of water at my bedside has lots of bubbles up the side each morning despite the absence of the faucet aerator.
Cheers s.
keeping a tank at 140 in an open heating system doesn't guarantee success either. it only takes a few bacteria to carry through the tank to populate beyond it. it's not a "kill all screen", it just makes the water heater itself not habitable. it won't kill bugs out in the biofilm in the rest of the system.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Will my copper pipe help? :)
My tank is probably more like 150+
s.
edit. potable only for me no open heating system nohow.
Edited 4/7/2009 4:57 pm ET by s crough
"MY hot water tank is definitely set above 140 F but many of my clients regularly turn down their heaters to 120 on the advice of the greenies despite the antiscald valve."
It's not just the greenies. The American Association of Pediatrics, CDC, and many other organizations recommend water heaters be kept between 120 and 125 degrees for safety. A lot of children sustain scald burns every year, and the amount of time required for significant burns decreases exponentially with increases in temperature. Most pediatricians that I know make that recommendation regularly.
John
You can see how that advice contradicts a great deal of knowledge to the contrary.
I agree that anti-scald devices should be required by all plumbing codes (and are required by all that I know of).
I do not agree with prescribers (i.e modern MD's) making plumbing systems recomendations. You think it a good idea for plumbers to write drug precriptions?
A little misguided knowledge in the hands of "trustworthy" figure like a doctor is a very dangerous thing. I guess there's alway malpractice suits..
But making recommendations about safe practices is a good part of pediatric practices. We talk about seat belts, helmets, accident proofing the home (I know, it is impossible). This isn't quite the same as plumbers writing prescriptions.
If the antiscald devices are the answer, and are always required, why so many burns each year? Are they not used, do they fail, or what? It would probably be "safer" from an infection standpoint to set it at 210 degrees. Is that practical?
John
Kiddoc, codes apply only to new buildings, in jurisdictions covered by codes officers.That leaves nearly all of our existing building stock not covered by such codes, and/or outside of enforcement range.Needless to say, there are quite a few systems out there without antiscald valves, and still be installed without them. If you've ever been in a house where the water was OW hot, you found one.the correct response is to install such a valve, not to turn down the water heater.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
There are not "that many scalds each year". The occurence is rather rare, actually. The reason they still occur is two-fold, one of which is that homes built before the current codes weere in place do not have any scald protection. I would expect responsible parents to make upgrades to their homes for the protection of their families, but I expect a lot of parents that doesn't occur. The second part of the issue is unattended children of the age that are unable to not scald themselves. Regardless of the protection deveices being installed or not, children have to rely on their parents to do their job.
As far as killing bacteria goes, 210 degrees vs 140 degrees is NOT more effective. Therefore, the postulation is invalid. It is neither beneficial or practical. 140 degree water is not that dangerous and is a prefered setting, IMPO.
Obviously, two conflicting views to which there is no "right" resolution.
"There are not "that many scalds each year". The occurence is rather rare, actually."
I guess it depends on what you consider rare. 17% of all hospitalizations for burns in the 4 year and under age group is from tap water scalds. Here is a link to information about burns (including scald).
http://www.fresno.ucsf.edu/about/CommonBurnsFAQ.pdf
John
"As far as killing bacteria goes, 210 degrees vs 140 degrees is NOT more effective"
I think every microbiologist would disagree, the higher the temp (and pressure) the more effective the sterilization.
As far as 140 degrees being safe, look up the time at various temperatures to develop significant skin burns. 140 degrees can produce a third degree burn in 3 seconds, where 120 degrees is something like 40 seconds?
John
Edited 4/8/2009 9:03 am ET by kiddoc
No domestic water systems are sterile. Ever. Sterile vs prohibiting and limiting the excessive growth of bacteria are two entirely different concepts and one doesn't apply. We're not discussing the operation of an autoclave here, are we?
A water heater at 140 degrees will kill legionella in 32 minutes. While higher temperatures will definitely shorten that time period, there is no practical benefit in doing so (at 151 deF the kill time is 2 minutes). Microbiologists can do the math, too, I would imagine. This is a mute point since you are advocating a temperature of 120 degrees (which will provide the same effect in 8 to 10 hours). At 122 degrees, legionella can exist indefinitely. I am no microbiologist, but I assume similar "results" will be seen for other microbes that might exist in our water supplies and that will potentially cause us harm.
I disagree with the recomendation of 120 degrees for a residential domestic water heater. I have explained why. You disagree. You have explained why. I have an alternative, safe solutuion to your point (installation of commonly available anti-scald devices).
So the kids will not be visiting their prescribers with scald burns, but instead with unexplained and difficult to diagnose respiratory infections. Something I'm sure the makers of antibiotic medications will appreciate. Always know where your bread is buttered, right?
Do I assume that you are a plumber that gets paid to install antiscald devices? I find your last statement insulting. You prefer to perpetuate injury to children until antiscald devices are universal (don't hold your breath) to protect against a very theoretical risk. So be it. You are definitely in the minority. Look at the recommendation of the majority of health and safety organizations and agencies, and it is to lower the temp of the water heater. Obviously you are smarter than they are.
John
John,
I am neither a plumber nor a distributor of the product. I have no interest in this other than I believe it is the lesser of two evils. I do not sell plumbing devices, nor do I sell antibiotics. I am completely unbiased here. I do have a strong opinion on this (and many other) issue. And yes, I am smarter than most of the safety blabberers you reference. Wow, smarter than a government bureaucrat. I bet you are too.
I'm merely saying that the "lower setting crowd" has no solution for the problem they cause. Trade one problem for another. Regardless of the number of the herds of cattle following this nonsense approach, it is still nonsense.
The "higher setting" crowd does have a solution for the increased burn potential. The last time I checked, these are relatively inexpensive. A lot less than the average car seat.
I assume by your taking insult that your are an MD. We'll not discuss that futher here, sorry for the offense.
You do realize that fully 1/3 of the "scald" victims are intentionally burned, as in victims of abuse, and that no preventative measure is possible. The reported numbers are skewed by various interests. I once believed the scald numbers were trumped up by the mixing valve people. They do play on fears, but real fears.
Our house has the water set at about 120 degrees. If our kids accidentally max the hot water in the tub or sink, no damage will occur.
However, the plumber at their grandparents house set the water heater MUCH higher. I think I measured the kitchen tap at 145.
In that house, all it takes for the kids to scald themselves in an errant turn of a faucet. So when they are in the tub, if one of them grabbed the single tub fill valve and pulled, they could get scalded. I'm sure they could get a burn washing their hands if the sink was already charged with hot water.
Parents can control only so much.
Tu stultus esRebuilding my home in Cypress, CAAlso a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
True, parents can only control so much. But some choose to control so little.
You, as a parent, are telling me that neither you nor your parents/inlaws have thought to have an anti-scald device installed at least on the tub that kids bathe in? You have no control over calling a plumber? You are unwilling to spend a few hundred bucks to provide this safeguard?
What am I missing here?
I am telling you, as a parent, my in laws are:
1. Uninterested in lowering the temprature of their water heat.
2. Uninterested in adding new plumbing fixtures inside their walls.
I've told them repeated the danger posed by the water temp, both on their grandkids and on themselves as they age.
I get pretty much the amused smile or the dismissive "Bah!" This is the way they always lived, now I'm apparently telling them it's wrong.
Yeah, good luck with that. I had better luck getting them to reverse the way they placed dishes in their new diswasher... they did it as if they were still using their old diswasher that stacked them all the same direction.
Tu stultus esRebuilding my home in Cypress, CAAlso a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
I understand.
A tankless heater would solve the scalding problem( set at below 120) and also ensure no Legioiaires in a regular DHW system.
Hi Folks,
I don't have any witty or intelligent comments about the current baby-scalding hazard this thread has taken...I'm going to revisit its original purpose.
Still undecided about this Legionnaire's thing...I think the open system has some merits, but obviously, some limitations as well. And like many seem to think, some possible health hazards. I'm not going to open that can of worms though.
After much personal research however, I obtained quotes from both Radiantec and Hannel Radiant Direct. Hannel's prices seemed inflated. Radiantec's were much closer to their advertised costs.
Nevertheless, I also obtained a quote on a closed-indirect system from a large local supplier, which came in about the same or cheaper than either an open-direct or closed-indirect system from Hannel or Radiantec after I took out the unnecessary "up-sell" #### (e.g. 3/4" Barrier XT insulation for $5000...what the hell is that?? Give me 2" of regular styro at $1500 anyday). Between $13,000-$15,000 CDN, all told, but no labour or assembly included.
That is, WITH THE EXCEPTION of a "panel assembly charge" from my local supplier of just under $4000. $4000, to assemble a boiler, controls, pumps, fittings, electrical, glycol tank, etc. on a piece of plywood for a quick install. I was quoted the figures for the components separately...that's purely a labour charge. Now, maybe this is a fair price, but visually, although complicated, I can't see how this panel would take a skilled tradesman even close to 40 hours to put together...assuming he were charging $100/hour. I'm thinking that's more than most of us make. Sorry for the rant, but this is one area where Radiantec, et al, seem to make things easier on a DIY guy. The fact that they're willing to help out at all stages in the process with phone tech support is really helpful too. The mere though of seeing myself slaving away on my basement floor trying to assemble one of these panels is scary, and although I finally know what all the parts do, I'm really not relishing the thought of trying to put it all together. PEX, I like, but not all these convoluted bronze connections.
I should have picked a trade like HVAC, that baffles people, and nobody writes DIY books about. ;)
Either way, by the sounds of things, I'll probably end up going with my local supplier's Trinity Ti-200 boiler, some glycol in the system, five zones, and a stainless indirect water tank to function as my DHW. And puzzling it out myself, which will suck the big one.
Anyway, all this information is only my experience, and is perhaps skewed by the fact that I'm in Canada, and with Radiantec, Hannel, etc, I would have to have all the materials shipped directly to me from the US companies. Exchange rates, duties, taxes, shipping costs, etc.
All parties were nice to deal with - special kudos to Radiantec and my local supplier for their willingness to answer all my questions. I sure can have a lot of them. ;)
Anyway, hope that info helps anyone thinking about one of these systems. It certainly seems to me as though the idea of $4 vs. $14 sq.ft. radiant heat is a bit misleading. My system will cost about $4-5/sq.ft., doing it myself, whether I go the conventional route of closed-indirect, or whether I go open-direct. I think $14 sq.ft. is for that 200,000 btu Viessman boiler, at $8500CDN, zoning for every room, including the linen closet, and a radiant contractor who takes his sweet time laying PEX.
-Carleton
Hi Carelton. Check your local codes. Lots of places up here in the Great White North won't allow an open system. Sure you need a 200? If you can use a 150, compare the price of a vito 100 to a Ti150.
Hey Rich,
Thanks for the idea. I would sure like to use a 100 or 150. Because you're right, the price is substantially more reasonable! Unfortunately, everyone who has done heat loss calculations on my house has said I need a big boiler. (even assuming tri-pane windows, R-50 ceiling insulation, R25 nominal walls). Between the basement, main floor, and garage, there's a tad over 4000 s.f. of slabs to be heated, apparently all with 1/2" PEX. Garage is 12' ceilings, everywhere else is 9' with about 400 s.f. vaulted up to 14'.
Talking to one supplier, he said that NTI Trinities always need replacement parts. Although he carries them, he said they're his most unreliable high-efficiency boiler (great......). He said Viessmann was the best, but it also came with the best bill. :(
You know anything about boiler reliability? Other than Viessmann is the best? ;)
Coupling that heating load with DHW made everyone figure I'd need at least 175K BTUs.
-Carleton
Heating load is seperate from domestic hot water. Hard to believe that 100 wouldn't work. House is what, 1800 sq ft? Are you installing a/c?
Hi Rich,
The house is a walkout bungalow. Well insulated, I'm planning, but still 1600 s.f. in the basement, 1600 s.f. on the main floor, and 1000 s.f. in the garage.
It would sure be nice if a 100BTU would do the job!!
I was going to use the boiler to do all the DHW as well via heat exchanger/indirect tank. You don't think that impacts the sizing of the boiler?
-Carleton
No. Use an indirect tank, and the tank gets priority. When the tank is calling for heat, the boiler ramps up to about 170. When the tank is heated, the boiler goes back to heating temp.
whoa whoa... who did a heat load calculation? I don't believe either hannel does load calcs and I know for a fact radiantec doesn't. for heat loads, I can count on one hand the number of homes I have come across that require boilers your size.you don't add domestic to that (trinity has domestic priority built in, I believe). Unless you have a very high domestic demand and you can't upsize the tank, you probably don't need a boiler that big.and if you do use one that big, you need a buffer tank for the heating system (separate from the indirect).-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Rich,Thanks for the explanation. That makes sense.Hi Rob, nice website, I'll have to have a better look at it later.Sorry, I could be using the term "heat loss calculation" incorrectly. That's a term the local supplier tossed around. Whether he did one or not, I'm not entirely sure, but he had a look at my plans, and took all kinds of supplementary info from me. He came up with the 200K BTU boiler. Hannel told me a 175K Triangle Tube. Radiantec didn't quote me any heat source, as US-sold Polaris heaters aren't warrantied in Canada. I have to buy one locally.If I can go smaller BTUs, I'd love to go Viessmann for the lack of trouble. What do you guys think about boiler qualities?Buffer tank...that's different from an expansion tank? Excuse the ignorance.Another related question...I just had a heart attack talking to my brother today. He said that the HRV system they installed in his buddy's radiant-based house had to have supply/return from each and every room.I'm sure this is code-dependent, but I always thought you could just duct to kitchens, bathrooms, and perhaps between rooms. If I have to run ducts to and from every room, that's going to be a mess. Any info?Thanks again guys!-Carleton
Assuming you're building in Alberta, these are just four of several documents which apply to the design and installation of your HVAC system.
Alberta Standata 06-BCI-012, Hydronic Heating Systems
Alberta Standata P/G-08-02-PLBG/GAS, Requirements for Combination Heating Systems
CAN/ CSA Standard B214 Installation code for hydronic heating systems.
CAN/CSA Standard F326-M91 (R2005) Residential Mechanical Ventilation Systems
Under Alberta regulations, subject to the authorities having jurisdiction, you'll need your hydronic system either custom designed by a professional engineer or use a pre-engineered package which has been stamped by a professional engineer or have the design done by someone who has been certified by CIPH or HRAI of Canada.<!----><!----><!---->
The Standata's are free and you can download them through the various links at this page:http://www.healthyheating.com/water_heaters_as_boilers.htm
The CAN/CSA Standards have to be purchased through CSA at these pages:
CAN/ CSA Standard B214 http://www.shopcsa.ca/onlinestore/GetCatalogItemDetails.asp?mat=2418590&langid=E&currkey=cad
CAN/CSA Standard F326-M91 http://www.shopcsa.ca/onlinestore/GetCatalogItemDetails.asp?mat=2410793&product=CAN/CSA-F326-M91%20(R2005)%20PDF&source=ProductDetailCrossSell
On another note...if you have time...you might want to head up to Edmonton for the Foothills Conference which starts this Wednesday. It's put on by the Alberta Hydronics Advisory Council and has some seminars which might be useful to you as well as a trade show.
http://www.hydronicsalberta.com/foothills/schedule.htm
Hope to see you there.
RB
Hey Bean,You're a code guru! Thanks for all the great info. I'll check it all out a little later tonight.Thanks very much for the link to the conference too. I'll see if I can manage to make it there. Thursday or Friday might work, but it's too soon to know.I saw you were giving some lectures. Would be nice to meet you.Appreciate it!Hey, maybe you know...I posted to another thread last night asking about HRV requirements for a 100% radiant house. I figured I would just need supply/return ducting from bathrooms, kitchen, and a couple other central locations, but my brother said he thought it had to be supply/return ducted from each and every room in the house! Any info?Thanks again for all your time!-Carleton
hi carleton,a buffer tank is a passive resevoir of water to absorb and release heat... basically, to prevent "short cycling" of the boiler. it heats up for awhile, and takes awhile to be cooled down. If you use a large, low mass boiler like the trinity, you'll need one unless you have a small zone count and they are all high mass zones.I personally would consider a dedicated IAQ system that does not provide fresh air directly to bedrooms and the main living spaces to be substandard in most cases. Fresh air while you sleep is pretty important. Pretty important to make sure you've got good airflow in those rooms. don't forget your door undercuts.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Thanks for the info, Rob. You make some really good points about IAQ too!
It sounds like radiant is pretty hard to make cost effective vs. forced air...but, I can't argue with the wife! ;)
Still looking forward to looking at your website. Just not at home for the next couple days.
-Carleton
Hey Bean,
Standatas had some good info. Thanks...good to know Alberta's own specific code regulations!
Would love to see the CSA information, but can't pay $85-$125 for each article. Too bad this information isn't provided for free, as it's certainly for the public good. If it were free, maybe there would be less confusion.
Asked the wife about stopping by the show on Friday. We might be able to make it. I'll let you know.
Thanks again!
-Carleton
"To bad this information isn't provided for free, as it's certainly for the public good. If it were free, maybe there would be less confusion."But it wouldn't protect the HVAC trades... People might start doing it themselves!Here in the US PEX is still outlawed in CA, the pipe fitters union says it's dangerous.
pex is now allowed.
Hey Rob,Just made some time to look over your website.Extremely informative and well done. I really look forward to reading more about you guys when I'm back home.Anyone who's interested in this topic should have a look at Rob's website. Lots of good stuff on there. I especially like the sample layouts.-Carleton
is it no longer 'dangerous'? Was it ever?
None of the certification agencies say it is dangerous.
Kiddoc,
So we exchange a known preventable risk with an unseen potential risk.
I agree with Tim.
Let's leave prescriptions to the docs and the safety of the public water supply to plumbers and plumbing codes.
It is interesting that public sanitation has led to greater benefits to the masses than has public health.
Cheers s.
How about we work together for the safety of kids, and accept that many professions have value towards that goal? Is there any plumbing code that states the temperature should be at least 140?
John
Hi Kiddoc,
I am just a carpenter so of limited use as to a code reference.
However, 140 does seem to some generally quoted standard for sanitizing hot water tanks.
I am sure someone with greater knowedge will chime in.
Cheers
"How about we work together for the safety of kids, and accept that many professions have value towards that goal? Is there any plumbing code that states the temperature should be at least 140?"
I agree, and I don't think so. Good practice vs minimum acceptable practice. Codes typically define system element requirements and some functional constraints. More to the end to prevent people from killing themselves vs accident prevention. User controllable settings, such as thermostats and water heater set points are not mandated, certianly not in residential applications. My plumbing system design experience is limited, so maybe a CPE could step in and clarify.
Not necisarily. Water is atomized in cooling applications, where you are looking to create water vapor. A shower that produced alot of water vapor directly would be a very poor shower! I believe humidity is different from atomized water.
Tu stultus esRebuilding my home in Cypress, CAAlso a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
Hi Paul,
As I understand it the bacteria live in water droplets which I most certainly inhale deep into my lungs after the shower head has created spray/humidity/vapour under high pressure.
I just do not believe in open potentially contaminated systems and am willing to learn more.
Cheers s.
I know this is an argument from a bit ago. But been looking into various ways to set up a hydronic towel warmer (yes must be stainless steel construction) on to an existing water heater for domestic hot water
We added mini splits in the house but at times the master bath can use a bit of a boost.
So had two thoughts:
A) just tap into the water heading to the jetted tub or shower. When they run the water first flows through the warmer.
Probably just going to heat the towel
B hot water circulation pump for master bath sink with water running through the warmer first. Can use a pump with a timer set it to come on in the Am in winter for a long period of time. In summer short periods.
Then I came upon this discussion my thoughts was there anything in code that prevents it?
According to the 2018 IRC which in our area covers homes of 1 or 2 residents and also covers most of the nation, No.
The second part of the code is for an old system. it means you can not take what is previously an closed boiler system remove the boiler and connect it to the hot water heater, for both heat and domestic hot water.
As to water born legionnaires, I worry more about a vacation home on a well that may not have someone living there for 2,3 weeks or a month(s), But is not drained for winter then my primary residence.
Anyway seems nothing against it in IRC.
You might be wise starting a new thread, unless you think there’s important information presented above.
I zoomed down to this post but I wonder if others would lose interest before they got down here.
Was not so much inquiring about my situation that is just what got me here.
I just wanted to sum up that there is nothing in the IRC forbidding an open loop system. I read most of the above and found that code was hardly discussed.
You could also look at electric towel warmers.
Thanks for the good suggestion!
Not trying to make this about my situation just trying to add in the code component to the past discussion.
But feel you are due an reply.
The reason for wanting hydronic is I would need to install a new main panel, mine is max as it is. I have 3 circuits to that bath now. Lighting, sink outlets.jetted tub no more room in the 100 amp box. As it is the toilet has an electric bidet seat and I added a outlet for that off the sink circuit ( we barely use blow drier or curling iron) but have a draw style folding iron board in the vanity and an iron is plugged in the sink outlets more then a hair appliance.. So electric towel warmer would need a 4th circuit for safety.
After being in the radiant heating industry for over 25 years I can say my preference, my suggestion, and the radiant industry's preference are closed-loop systems. There are many factors to consider here so let's just start from the top...One of the major factors when dealing with the corrosion of material is oxygen. What do open-loop systems have?...an excess of available oxygen. This requires the components in an open-loop system to be entirely non-ferrous material such as Stainless Steel, Bronze, Copper, and or Aluminum. But, regardless of material, you're reducing the life span of these products by introducing fresh oxygenated water constantly. The material of these products will increase the upfront cost of your system and in some cases, this can come very close to the same cost as a dedicated closed-loop system using more "industry standard" components.
Another consideration with an open-loop system is the sizing of your heating unit. Most domestic specific products will have very little capacity in addition to the ability to produce the standard amount of domestic hot water for a home. With open-loop systems oftentimes you're having to upsize appliances or install two appliances where one might do the trick. I've run into many customers who have approached me with the idea of installing multiple tankless water heaters, or hat water tanks, for a project and using them for heating and domestic. When you break this idea down, you'll find you are not only doubling down on equipment, but also the infrastructure to handle the equipment, i.e., gas piping, venting, power, drainage, and lastly gas meter sizing or Propane tank sizing. With two tankless water heaters, you are now looking at a minimum demand of 400,000Btus per hour of gas consumption. I could make the case and show you a design where the same home could be reconfigured with the right equipment and have a BTU load of about 100,000BTUs or so. At the very least 50% less if not 75% less overall gas consumption.
When looking into residential water heaters, like standard hot water tanks, or on-demand tankless units you'll find that most of them are designed for a certain amount of runtime, this usually equates to somewhere between 6-10years of standard domestic use. When you use that same equipment under the constant stress of a radiant system, you are reducing the lifespan of that equipment considerably.
We can also talk about the efficiency of the equipment. When you look at all the on-demand tankless appliances touting 92% or more energy efficiency ratings this is specific to creating domestic hot water from a cold start. For example...cold water from the ground comes into your house somewhere between 45 and 55 degrees and its the appliance's job to heat that up to about 120degrees. It's that temperature differential between cold and hot, that will drag down the heat exchanger and burner in the appliance and make it condense and therefore run at that higher stated efficiency. So to put a number on that let's just say the temp difference is 70degrees. With a radiant heating system, a good design might run in the neighborhood of about 20degree difference between supply and return. These higher return temps not only eliminate a water heater's ability to run at the highest efficiencies but will also eventually cook the inside of the appliance. Boiler equipment and Combi-boiler equipment are designed for this load and will still achieve their high efficiency ratings under these conditions. Therefore making the entire system design more energy efficient.
To sum this up...If the radiant and/or domestic water heating industry were so keen on open-loop systems, they'd be making appliances for this purpose. But instead, they are making more and more Comb-Boiler style equipment to fit this small niche. A combi-boiler can do both your heating and your domestic needs out of a single appliance while keeping both water systems separate. There are also boiler and side-arm tank systems that will provide both needs while keeping water separated. This all ultimately depends on the size of the home being built and also the size of the radiant load, but in the long run, you'll spend less money on repairs and replacements when using the right equipment from the start, even if that might cost a small percentage more in the beginning.