open radiant systems

EJ hoffman

I have no stagnant water in my systems. Constant circulation

Jim Wy.

open radiant systems

Does anyone have an opinion on using a tankless water heater for both domestic use and to heat a radiant system.If we went ahead w/ it we'd keep the water fresh by directing the domestic cold feed through the slab before it could enter the tankless heater or heaters.

[Deleted User]

And, what happens when you are away for 2 weeks on vacation...

The bacteria (Legionella) builds up so when you get back from your trip and hop in the shower, you get a TRIPLE dose of Legionairres disease exposure.

It's not worth losing your or one of your loved ones lifes over is it?

If you absolutely positively are set on misapplying the tankless water heater as a space heating appliance, at least place a heat exchanger to avoid unnecessary exposure to this deadly, omnipresent bacteria. And don't listen to what the internet peddlars have to sell you. They do NOT have your best interest in mind. Only wanting to get your money...

Google legionairres disease and see what pops up. Hopefully, it will soon be illegal to do combination open systems like you are proposing.

ME

Jim Wy.

Is using a tankless for radiant really a misaplication of the product? Is it not the second best choice after mod. con. boilers with a much smaller initial price tag ?

kpc_16

yes...

it is a water heater not a boiler. The flow rates required will force you to put a lager pump/circ. on the boiler for it to work right. The AFUE are not that high (low 80's) on a tankless compared to a mod boiler. If you want the combo set up try a Baxi or a NYT trinity....

Big Will

never in a open system

but I have used a tank less as a boiler twice in my carrier. Never again it takes huge pumps not very good efficiency and will not last long. Noritz makes a boiler now that is a nice in between if you want to cut costs and hang it on the wall. The first Noritz water heater I used for a boiler in a hydro air application is already had a breakdown its less than three years old. Don't do it.


Side note about open systems. All health issues aside. Think of what comes with well or city water. You run it through a manifold and it branches off into many small 1/2 lines. When water slows down that much things settle. I have seen people make systems like you are describing and things get messy. A closed system does not have this problem. Remember you have to live with what you install here. Saving a few bucks here will cost you a lot later. Kinda like financing but you don't get a shiny new car.

Unknown

a tank water heater heater is better than tankless in any application where its output is adequate.

if a tank heater's output is not adequate, or if you have a real heating heating load, a mod/con is the only choice that makes any sense long term.. it will beat a tankless in terms of energy savings significantly.

Unknown

where are you getting an AFUE on a tankless?

Last I knew, they only had a ratings for raising 45 degree water to 115. in a heating application, I don't expect to hit their ratings.

kpc_16

is it not...

a non condensing appliance...in most cases.

EJ hoffman

open systems

Open systems are fine and safe if designed correctly, tankless heaters can be used in open systems if they fit the design. I have been installing open systems for over 10 years no problems. This year alone I have 13 systems using open systems and tankless heaters, but their output fit my deign needs 1 gpm at 90 degrees, make sure you are comfortable with your installer/designer and talk out your questions with them. I would love to put a vito or knight or buderus in every home but unfortunately most of my homes don't require it.

ScottMP

Erik

Please explain to us what happens to the water in your customers systems during the summer time or while they are away for a week or two ?

Please explain how you correct for stagnation of the water ?

Scott

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Dave Yates (GrandPAH)

Open systems are fine and safe if designed correctly?

OK Eric, let's see the design(s) that you stated are 'safe'. What scientific evidence exists to support your notion that open systems are, or can be designed to be, safe?

Fair enough?

Rudnae

Okay, I'll bite...

Alright, firstly I am not a supported of using a dhw device tank or tankless for hydronic heating as I have large issues with the efficiency. However, I don't understand why everyone is so up in arms about open systems. They are legal in Canada, where the conditions have been met. You can only use half of it output for heating applications the rest must be serving multiple fixtures (at least two) and you must have an ability to circulate the slab at least once a week. Most panel products that we use do it once per day. In this case how would that water, that has been circ'd once a day be any more dangerous than your straight tap water left in the piping. After a three week vacation, worst case senario has circ'd your slab three times and nothing has changed the water in domestic pipes. Could you guys please help me with my understanding of this? Thank you. Rod

Unknown

How dangerous does it have to be, to be worth a pump and plate HE (minus your timer devices)?

Is that insurance really that expensive?

It's a poor cost-benefit equation IMHO. Especially after I saw a system gum up from poor water quality.

Rudnae

I totally agree but....

Rob, I totally agree with you about the cost to benefit ratio, I'm a boiler guy not a hot water tank guy. However my main question wasn't about that. It is about the water stagnating and causing/leading to legionaires. What I'm trying to figure out is how is it more dangerous in a sitting heating line vs. a sitting domestic line. This is just one of those things that always makes me wonder why. I'm not looking for an argument, I'm just trying to scratch that itch.

Unknown

sure.

Domestic line = what, 20 feet of pipe? 40?

Heating loop = typically at least 200 feet. Per loop.

Add up surface area (otherwise known as potential bug habitat) and note the relatively small increase in system volume. That would be "concentration level" increasing.

How big a deal is it? I dunno. But it sure makes that HE look like a cheap insurance policy to me

Dave Yates (GrandPAH)

scratch at will!

Rod,

I wrote this for GlobalPipe in Germany in 2002. In 2001, I was asked to host an on-line forum and the subject I chose was using water heaters instead of boilers. I was planning on promoting water heaters to stir the pot. Like the saying goes: a funny thing happened on the way to the forum! After you read this, I would invite you to visit Robert Beans site and read the article on water heaters vs. boilers. Then, if you still have an itch to scratch, go Google "Hot Water + Bacterial Amplification" or "Hot water + Legionella" and if you still itch for more knowledge Google "Legionella: The Coming of the Third Plague"

From 2002:

Last year, I became acutely aware of Legionnaire’s disease while researching the controversial issue of using water heaters for both potable water and hydronic systems. While I was familiar with the 1976 outbreak in Philadelphia, I was not well informed about the disease itself or the bacteria that causes legionnaire’s disease. There is a wealth of information available and I have found the world’s leading authorities on this subject very willing to share their knowledge.

In 1976, while attending a Legionnaire’s Convention at the Bellevue Stratford Hotel, 211 people became ill and 34 of them died from what was thought to be a previously unknown type of bacterial pneumonia. After this outbreak and the identification of the bacteria strain, the CDC (Centers for Disease Control) examined some previously collected tissue samples which revealed earlier cases of Legionnaire’s disease. One circa 1947 from a soldier who had developed and died of pneumonia while at Fort Bragg, North Carolina. Further study revealed an outbreak occurred in 1957 at a meat packing plant.

Another form of infection caused by legionella bacteria is Pontiac Fever. Its name was derived from the first recorded outbreak in Pontiac, Michigan, that affected 144 people at the Oakland County Health Department. Flu-like symptoms occur which last for several days.

So who is at risk? Generally speaking, elderly people with immune systems that are compromised by medication or illness; smokers; heavy drinkers; AIDS; heart and kidney patients. From what I’ve read this past year, a large percentage of the population has been exposed to legionella bacterium which was determined from blood samples. As many as 10,000 to 100,000 cases of Legionnaire’s disease occur each year (depends on whose statistics you believe) and that is believed to be a low number. Unfortunately, many cases go unreported because they are simply listed as pneumonia. Penicillin, a drug often prescribed to pneumonia patients, is ineffective. Erythromycin is the proper medication.

Amplifiers, a term often used with this issue, are devices capable of providing an environment suitable for the growth of legionella bacteria. Some examples include air conditioning cooling towers; potable water systems; humidifiers; whirlpool tubs; spas and domestic water heaters. Any device capable of creating a mist that can be inhaled (vegetable misters, shower heads, aerators) in an environment where people are present, can deliver a potentially fatal dose if the bacteria are present in sufficient numbers to overwhelm the immune system. Human lungs offer a virtually perfect environment for legionella bacteria.

There are four very basic things needed for legionella bacteria to survive and grow and they need not all be present:

• Water temperatures between 55º and 131ºF.

• A pH between 5.0 and 8.5.

• Biofilms and/or sediment and/or rust.

• Stagnation


Biofilms are the slime and layer of junk we find in piping. Plumbing repairs can dislodge large amounts of infected biofilm. Sediment occurs in tanks and in lines where flow is low/slow. Litigation-wary manufacturers of water heaters have done what over these past years? Cranked the delivery temperatures down in order to stem the tide of lawsuits from scalding and increase efficiencies. Right into the range needed to foster growth.

Although legionella bacteria begin to die above 122º, they don’t really get kicked in the pants until the temperature rises above 131ºF. The pH of nearly all potable water systems fall right in the most desirable range for growth. Stagnation is all that we’re really missing.

The hydronics industry in this country is enjoying a radiant revolution of sorts. As more and more people discover the benefits, comfort and reliability of these products, an increase in pressure to find economical installation methods has flourished. The temptation to cut corners and compromise consumer safety, knowingly or unknowingly, has given rise to cross-connecting potable water with hydronic loops while using a domestic water heater as the energy source. As my bride said “Gross, that’s like drinking your own bath water!” What happens when the hydronic system is at rest? Stagnation. Various code bodies and professional organizations want to see timers installed to exercise the system pump to prevent long term stagnation, but like any mechanical device, they are subject to failure and no one is inspecting for codes compliance in my neck of the woods.

Think chlorine is keeping your water safe from legionella bacteria? Think again. Chlorine levels in typical potable water systems are 10,000 times lower than the levels needed to suppress these bacteria cultures. High chlorine concentration flushes of infected systems do not eradicate the bacteria and they are typically back within just a few short weeks. Elevated levels of chlorine in potable water also create carcinogens. Chlorine dissipates in hot water and there is some belief that this also contributes to pitting in copper tubing.

High temperature water flushes (140ºF and above) also offer only temporary suppression as has been documented in numerous locations. In several hospital cases, flushes using 180ºF water for five minutes at every faucet was employed. Many man-hours were required, notices posted to warn of non-use during the flush period and equipment was taxed to its limits keeping up with the demand. Although notices were properly posted, several scalding cases occurred.

At present, there appear to be three effective methods for controlling legionella growth.


• Ionization of copper and silver alloys in the potable water stream for commercial applications is gaining acceptance as a method of killing off the bacteria and preventing its return. These systems are gaining in popularity and might eventually be available in a residential model.


• Chlorine Dioxide has seen suitable results and penetrates biofilms fairly well. However it remains an unstable product that requires appropriate handling and treatment of the potable water to maintain safety.


• Heat Pasteurization: Maintaining higher water temperatures, which eradicates all free roaming Legionella while maintaining suppression of any bugs hiding within biofilms. Several other countries have adopted plumbing codes that require water temperatures to be maintained at or above 140ºF throughout the entire potable hot water distribution system and only allow a small amount of cooler water, typically 131ºF or above, after the mixing valve that is located within 18” of the faucet.


Improved design and maintenance of cooling towers and plumbing systems is the only course of action needed to prevent legionellosis acquired via mechanical systems. Legionellosis has 5% to 20% fatality rates in general public exposures (CAP) and as high as 40% fatality in hospital acquired cases (nosocomial) have been reported. According to the CDC, only 5%-10% of estimated cases are reported.

Clearly our existing plumbing codes must be changed to disallow cross-connected potable/hydronic systems. Manufacturers of water heaters should increase the delivery temperatures and plumbing codes should be changed with respect to requirements for mixing valves and scald-guard faucets. A primary thermostatic mixing valve set for 140ºF at the water heater’s outlet with either thermostatic pressure balanced mixing faucets in bathing areas or thermostatic pressure balanced mixing valves located within 18” of the faucet. We should be prepared to accept and support this change.

Joe_125

Glad I saw this

I just finished installing an open direct radiant floor system in my house using a Polaris water heater as a heat source. It's plumbed so that all new incoming water must pass through the tubing before going to the water heater. I also put in a three way valve so when the heating season is over all incoming hot or cold must go through the PEX tubing before getting to a cold water faucet or the water heater. With all that, After reading the referenced articles/sources I think i will install a heat exchanger and make the heating loop a closed system. Question is can I rely on gravity for the HE or will I need a second pump just for the hot water through the heat exchanger? Thanks for all the info.

Kevin O. Pulver_2

This should make you smile Dave and Brad

You changed at least one person's opinion- and maybe saved someone's life.
(For the record, I agree with you about the HX.)
Kevin

Bruce_26

Dave, Information from the CDC

Your information is good but there are additional factors to consider. This is from the CDC:
Etiologic Agent Legionella pneumophila and other Legionella species. At least 46 species and 70 serogroups have been identified. L.pneumophila, an ubiquitous aquatic organism that thrives in warm environments (32°- 45°C) causes over 90% of LD in the United States.
The critical temperature range that the CDC mentions is 89.60 degrees F to 113 degrees F. With at least 46 species and 70 serogroups (group containing a common antigen). I believe that many people commonly believe that there is only one species and nothing could be further from the truth. It is deadly for the elderly, cigarette smokers and immune compromised individuals.

Unknown

you'll need a pump.

which also makes it real, real easy to add a 356 injection control and really upgrade the radiant system operation as well if it didn't have dynamic mixing before.

Dave Yates (GrandPAH)

right you are

Bruce,

That's by no means meant to be the be-all to end-all! Legionella Sero group 1 is the deadliest strain, but as you mentioned, there are other strains that can cause the diseases known.

Water temps are differently stated by many folks and there's a wide range. It's tough to dial in on specific ranges. So, I used what I researched and found to be the upper and lower ranges.

An open system by its very definition will be a bacterial amplifier. Can't be avoided or denied and I have yet to find a single purveyor/promoter of open systems who can produce scientific evidence to the contrary. That said, if Erik can produce credible scientific evidence - I'm all eyes and ears.

Then there's the absurd notion that using an open system gives the owners free A/C!

Rudnae

Thank you!

Rob & Dave, Thank you for taking the time with me today. I really appreciate the info and can't help but wonder if this information is so readily available why do we still have these systems being installed. Obviously the regulatory bodies are not responding to this as the threat that it is. I work in the wholesale industry and am forced to sell these systems as a part (getting smaller by the day) of my job. I just wish that I had a legal reason ie: code, that would not allow these systems to go in with out a heat exchanger. I shudder to think how many have been sold in the short time (3 1/2 years) that I have been involved in hydronics. There must be tens of thousands of them in my city alone. I shudder to think. Once again gentlemen, thank you. Rod

Unknown

Call your code enforcement department

Ask them to write you a letter that approves these systems in their jurisdiction.

I'd like to hear the response...

Noel

Dave Yates (GrandPAH)

follow the

money for the answer.

Rudnae

Thats a cold, scary place...

Dave those are the same people that quashed our attempt at a national hydronics code (B214).

Rudnae

I've already got it

Sadly I already have it in STANDATA p/g-03-01a-PLBG/GAS. Belive it or not I have to use this to convince people it is illeagal to install water heaters as a heat source only. Sigh...

jrc

I shouldn't stick my nose in here. I'm not a professional. I've been using an open system to heat my house for 20 years.

In response to some of the notions above:

Frugal has a different measure for different people. I paid less for my house than plumber Rich spent on the last hydronic system on TOH. To say that five grand is cheap insurance against a disease unheard of in your locale is a bit much.
To ask those of us who have no evidence of legionella to support its non-existence also defies the laws of logic.
I have read the links provided and do not doubt the honesty of their providers but I wonder who among the professionals might own up to the possibility of system design causing more difficulty than anything else. Mine operates at 130 simply because it wont heat at any less, my tempering devices are in the faucets as they have been since I was a child, my water heater runs most of the time and in the summer water from the street flushes the loop before entering the tank. My capital expenditure for heat amounts to x ft. of pex, a small pump and a light switch. Regardless of the numbers presented my heater runs at 90+ efficiency because it and it's chimney are in heated space.

You as professionals might give some attention to those of us out here who fit a different brand of frugality.

Dave Yates (GrandPAH)

yup, and

cigaretts don't cause cancer!

Chust all depends on what a person wants to believe.

Like I asked Erik: provide the scientific facts that support the notion that open systems somehow get a free pass as a bacterial amplifier, that they can be designed to be 'safe' and I'll gladly listen, read and, if accurate, support that notion too.

Unknown

I agree 5 grand would be a lot to spend just for "insurance".

Luckily, that's a bit less than something like ten times what it actually costs to put in a heat exchanger and a 356 injection control to provide this insurance, as well as to dramatically upgrade the operating characteristics of the heating system at the same time. That means, better and more consistent comfort, all heating season.

Consider again that this is about a seventh of the cost of the water heater that the previous poster was talking about, that would seem to be a pretty small expense in the overall scheme of the system.

Now tell me again how this is a "bit much"? If you're going to make up numbers, make up numbers that make some sense.

You might spend give grand more on a better heat source and water heater setup, but not on a heat exchanger. And, in most heating climates, the difference in cost might pay for itself in a reasonable amount of time as well.

ScottMP

Yup , I agree Dave

How about that mercury we use to roll around in our hands in science class ??

Or the Asbestos we use to put on boilers and pipes ?

Or lead pipes for our drinking water , ya that was good too.

Scott

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Dave Yates (GrandPAH)

why ain't we

dead and without children!?! Loved that mercury(G). Maybe Plumbism is a myth too? White clouds of asbestos dust filling the basement air - breathe deeply.

Don't bogart that Koolaide!

jrc

I think the more appropriate question Dave is "provide the scientific facts that support the notion that a total water system which includes a closed system provides less bacterial amplification than an open system.

The only attempt at that I've seen is Rob's half hearted More pipe equals more chance for bacteria. Unfortunately 0*x is still 0.

Rob: the cheapest water tank I've seen recommended here is the Polaris at well over 3 grand; added to that I presume would be flow controls, tempering valves, air vents and pumps. My heater was 200 bucks, the pump 100.

The cigarettes, mercury, lead and asbestos of course are all red herrings.

Unknown

the polaris has no heat exchanger in it. it is just a huge output water heater.

the act of separating a potable system from a heating system means adding a heat exchanger, pump, and some closed system hardware. doing that adds something like $500 to the system cost, and you're protected, done.

If a more advanced heat source is desired for efficiency... as it should be, on any full size system in a real heating situation, and will pay for itself... that is a an entirely separate issue from the open vs closed debate.

So, is adding $500 to your heater, pump, tubing, and whatever other components really THAT big of a deal for "insurance", not just for you, but for your heating system as well?

Secondly, ignoring that biofilm is where these baddies grow... that biofilm forms on the surfaces of water systems.. that dramatically increasing your surface area without commensurately dramatically increasing your system volume will increase concentration.. well, again, I can't quantify how big of an issue that is. But it's something, and for something like $500 (a small portion of any system cost, no matter how cheap, unless you're doing mini additions), you don't ever have to think about it, at all, ever, whether you have a baby, get old, get sick, have guests, go on vacation, period, ever. Plus you protect your heating system from the constant introduction of fresh water and whatever is in it or might be in it down the road. Plus you don't have to deal with condensation in your joists from cold water screaming around all your joist cavities in the summer, long term helping god knows what grow there.

Finally, you get to avoid this debate, which frankly I would pay $500 for by itself because I am so freaking sick of this topic.

In short:

Open system, seems questionable.

Closed system, there is no question at all, no question possible.

The difference in cost is pretty small.

It's your choice.

Jim Wy.

Where can I find a heat exchanger, pump, comp. tank & hardware for $500 or even $750 ? I'm very interested in finding that competative heat exchanger. Thankyou so much for all of this info.

Dave Yates (GrandPAH)_1

done

If you see it as 0*X, then that's your take on the subject matter laid out for your review. The answer to your question is abundantly clear - just from the limited info contained within this thread. All I've ever asked is that those who are interested take the time to educate themselves regarding the issues and then form their own opinions. It's a free country.

People tend to find reasons to support things they have done - even when the preponderance of evidence is stacked opposite that view.

As was once said about this debate - I have no dog in this fight (with no apologies to Mr. Vic). I have no bias one way or the other, which frees me to objectively look at the known facts. So, if you're inclined to support/install/sell open systems, that's your call.

Just for the record though, no matter the cost to isolate the potable/hydronic fluids - I wouldn't compromise my beliefs. I'd rather walk away from the work.

When you can prove me wrong, I'll listen - with an open mind. I've been waiting for years.

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[Deleted User]

Semi valid point....

If a DHW heater is kept at a constant low temperature (around 120 degrees F) the occupants o f the dwelling ARE exposing themselves un-neccsairily to large quantites of legionella. I know, because I caught legionairres disease from a water heater being maintained at 120 degrees F.

Your question is a bit sily tho. Kind of like asking for proof that seat belts COST lives.

I am personally aware of three people who have contracted legionairres disease from their combination "open" space heating systems, and am also aware of a senior housing center with the same potential problems.

THis is not voodoo science. This stuff is for real, and if you continue to do these systems, you can expect to hear from a lawyer, eventually.

ME

Paul Pollets

Another Case in Point with Lawsuit Attached

Re: the Seattle Housing Authority built these homes with "radiant" heating using a water heater (both Tankless and regular gas fired units were used) ....check out the link. This story appeared Mon. 3/31/08:


DHWT & Radiant Failures


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Unknown

I guess that depends on the size of your project. If it's small enough to make a water heater a good choice, it shouldn't be hard to find. Brazed plate, single wall, a pump, exp. tank and pressure guage/relief valve and hose bibb. 356 just makes it better.

Dan isn't a fan of "push" advertising here on the wall though, so I won't link you to a supplier that I know for a fact can hit those numbers on any system that is appropriate for a regular size water heater.

jrc

Dave and Mark

No one is denying your evidence or your sincerity. What I am questioning is 1-the frequency of occurance. I know a lady who wears rubber gloves all day to protect from flesh eating bacteria--safe and cheap, 2-whether the presence of bacteria is a result specifically of the open system or is the result of stagnant water under 130. There are millions of water heaters out there at less than 130 in conjunction with closed systems, but your crusade seems directed only at open systems.

Saying it's cheap to be safe is not specifically answering the question and reminds me of the oversized boiler a plumber once blessed me with--just in case--cause it only cost 50 bucks more

[Deleted User]

To quote the CDC...

Legionella is the most misdiagnosed disease in the WORLD...

It looks like (and actualy is) bacterial pneumonia.

Again, quoting the CDC, The bacteria is omnipresent. It is in the soil, it is in the water, and when it becomes airborne and is inhaled deep into the lungs, it becomes blood borne.

As for first round versus second round, the first round has been fought, and the results are unknown as of yet. If we clear that hurdle (outlawing the use of open combination systems) then we will address the potable water storage/distribution issues during the code change cycle of 10.

All one really needs to do is look to Europe to see what their thoughts on the disease are. They have ANTI-legionairre settings on their water heaters that takes the water hot enough to kill the bacteria on a regular basis.

As Dave has so eloquently pointed out, open combination systems are nothing more than a guaranteed petry dish growing ground for the bacteria. And the only thing that "flushing" systems does is to guarantee food and oxygen for the bacteria that have colonized in the piping system. The "pump exercise" cycle simply insures that the bacteria is pushed back to the tank, where it can be sprayed out in a shower, or other aspirating device, and then inhaled deep into the lungs.

Anyone with a LITTLE common sense should understand the principles behind this. People like Erik who promote these dangerous systems are doing no one any favors by installing them. Once it is proven that the bacteria thrive under these conditions, will Erik go back to his existing customer base and offer to upgrade their systems to avoid potential health issues?

He may not have any choice in the matter, especially once a lawyer gets a hold of his "system design".

Did you know that most large law firms employ a full time staff bacteriologist, just for these reasons?

Why take chances?

As a master plumber, I am sworn and bound to protecting the health of my customers, and that is what I will continue to do. If I see a cross connection, I am bound by law to disable it and notify the water authority imediately. I and Dave and many other master plumbers take our jobs seriously.

I would love to know exactly what licenses Erik carries and what state he performs his systms in.

ME