Water heater in-floor

PJO

Dave,
I am shocked you jumped in on this thread (G). You are right about Cl2 and biofilms, and also about well water (non-chlorinated systems). Even a UV system on a well source cannot take care of this, although with cold water circulation you are in much better shape.

I mentioned cold water recirc systems a while ago, and I still believe they should be used in a private (well) source with UV lights...and this is not just for battling Legionella. Since UV works instantaneously and leaves no residual, that is good for carcinagens/residuals vs. high Cl2 levels, but bad for areas that have started a colony. A recirc line would, theorectically< prevent this if you started with a clean system and the UV was not turned off. Only problem then is the dead legs...

There are lots of industry that use recirc on cold systems, and it's use for residential should be seriously considered. Lika a lot of you Wallies say, "If they spend the money on _______, why not spend it on heating as well? Fill the space in with what you prefer, and fill heating in with "better wtater".

Take Care, PJO

Bigheadtodd

water heater in-floor

I looked at a job today, HO wants me to fix the radiant floor in his master bathroom that's broke.

The entire house is scorched air, yuck. But there is a zone of in-floor radiant heat in the Master Bath. The source of the water piped through the floor is a loop piped off of the house Domestic hot water recirc loop. Existing piping is a couple tees off the recirc loop just before it returns to the water heaters,primary secondary style with a zone valve piped on one of the tees controled by a t statt in the bathroom.

The reason it's not working is because the zone valve is burned out.

I want to clean this design up some and could use some advise. I relies that the water in the floor is stagnating when not in use, which is a lot in the summer.

What can I do about that? I'm not sure how well this set up works, but the HO says it has always worked fine.

What would be the correct way to pipe this thing? The only pump on the system right now is a small Taco with a clock on it set to run 7 am to 10 pm.

Could sure use some help, and thanks in advance, Todd

Earthfire

stagnant water

Sounds like te water temp in that floor/recirc system is about right for growing LEGGIONELLA virus. If the HO won't go for a seperate heat source for the floor heat (another water heater?) Run don't walkaway from the repair and send the HO a certified letter stating that there is a probable water stagnation problem with his heating loop and that you cannot in good conscience repair his zone valve and Not repair his system to function properly (at HO's expense of course) and safely. The HO may be looking for someone to sue. (Last one to touch the system owns it)Or is it a 20-20 sting on radiant contractors who let unsafe conditions go? Not ME said, Bob Warner! Dang it, I've spent too much time working for that lawyer!

Duncan_2

Zone valves and open systems.

Another point:

Most zone valves are not designed for open systems, the oxygen (and chlorine?) eats the rubber parts in the zone valve, which are probably not designed for potable water.

Honeywell (for one) DOES have a zone valve designed for potable water.

hr

Buy a Danfoss ZCP

that heatboy pictured below a couple posts. They build one for radiant from a water heater. I think you would be wise to seperate the radiant with a HX, and the other problems go away also.

hot rod

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Art Pittaway_2

Recirc is the key

to stagnation and heat. Got called on one that is the same a few years ago. Water heaters on one side of house and bath with radiant on the other. Don't use zone valves. HWH supply goes to tee to split flow for bath fixtures on one side then to radiant on the other. Important!!Put the pump on return from the radiant to hwh with a check valve. Install an aquastat before the tee on supply, insulate it and set it to keep the water to the tee warm. Wire it in parallel with the thermostat. All summer the aquastat flushes the radiant tubing without any excess heat buildup and gives the owner hot water for the bath. In winter the thermostat runs the pump to keep the floor warm. In summer the pump only cycles a few times a day and the slab floor is never warm in summer unless the owner turns up the heat.

Mark Eatherton1

The key to safe hydronicing...

lies in the head of the beholder. I hear what everyone is saying about Legionella and all and I agree 100%. But the problem is, as long as we have potable wtaer distribution systems, we have a significant chance at generating Legionella, or a host of other water borne bacteria and their painful side effects.

It is thought that refreshment is the key to elimination, and I beleive that to be somewhat true, but in the case of where the system is NOT being chlorinated, the chances increase for bacterial growth and survival, and if you're not flushing with a good bacteriacide, like chlorine, then your chances are still pretty good at getting something out of the system.

Now, here's what we at the RPA DHW/space heating roundtable discussion came up with. Install a venturi tee right where the circ return ties back into the cold going into the tank. Every time there's a draw of hot water, flow is induced through the circ return, thereby replenishing the water and theoretically reducing the chances of bacterial formation. This is all true and it MIGHT work to lessen your chances of contraction of a water bourne pathogen, but it will not eliminate them because Legionella has been found in cold water lines too, and the code doesn't address that at all.

A person could use the same venturi tee technology to create a cold water recirculation system too.

I've seen apartment houses where the contractor was from another state where it was OK to run the hot and cold potable lines through the attic. Not here on Colorado. They had to put pumps on the hot AND cold water lines to keep them from freezing. Still froze and broke stagnant side branches.

Todd, if what I think you're saying is true as it pertains to the plumbing, it's only working via gravity. If theres not a pump on the secondary serving the zone, and there's no ball valve with branches on both sides of the ball valve and the valve partially cocked, the only incentive the water has to move through the side branches is gravity. I'm suprised it's working. I'd also get rid of the clock and install an aquastat.

To be 100% sure, you could buy the Danfos panel that was previously mentioned. I wish the heck I'd had thought of that for the HFH home...

Hope that answers your question and fires up your cognitive thinking glands (G)

ME

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ScottMP

recirc replenishment

Is that a word "replenishment", how many points for that word.

Mark, I think I foloow that plan, but, could you draw it out? Is'nt a recirculation line by nature moving ? Dos'nt the water replenish the line very time a hot water tap is open ? I don't follow in my minds eye why the venturi tee, located before it enters the tank would replenish/refresh the line ? The only thing I see being flushed is the short section before it enters the tank ?

Maybe a drawing for the slower members of the troupe

Scott

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Dave Yates (PAH)

Chlorine does not

work effectively against legionella bacteria until the levels are significantly higher than what is safe for human contact and at those elevated levels, the chlorine creates carcinogens. This is due to chlorine not willingly penetrating bio films. Guess the film ratings are NC for no chloirine(G). Chlorine, that is - the residual amounts found in your drinking water, dissapates as the water is heated. There is strong evidence that indicates pitting in copper water lines shares a direct correlation to this disappearing act.

All potable/hydronic systems should be physically seperated. No mechanical device should be relied upon to "exercise" a system to prevent stagnation until one is developed that will last forever with no maintenance.

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Dave Yates (PAH)

PS

Even if chlorine was effective, which it is not regarding legionella, there is none present in well water and the percentages vary between municipal water companies and at different times of the year.

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Dave Yates (PAH)

You guys are causing me to get riled (not Riles)

And another thing! Codes call for any hot water potable system that exceeds 100' in length to be recirculated. Not whenever you feel like it, but all the time.

Now, if you cross-connect a hydronic/potable system and it "uses" the domestic hot water, it has become an integral part of that potable hot water distribution system. The combined total footage of the so-called hydronic loop(s) must now be added to the potable hot water distribution lines. Once 100' is exceeded, you're required to circulate 24/7. Mrs. Jones ain't gonna like that bathroom floor being warm in the summer months.

Anyone who advocates the notion that potable systems can be safely cross-connected with hydronic systems, radiant or otherwise, needs a check up from the neck up.

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Bigheadtodd

Great Post everybody

Thanks for the help guys. I have learned so much in so little time,what a great place this wall is.

This small little project could cost thousands, if its done right.

Phil

Why A Duck?

I agree with all of you fellas that recommend that there's never a cross connect between the potable water and the heating system.

Why not close the bathroom floor loop with a heat exchanger? The heat is to be drawn from the potable hot water recirculation loop. I'm sure you can rig a control to start the closed loop circulator and the return circulator on the potable water supply. Not the best solution but simple.

Good luck, Phil.

Art Pittaway_2

Count to ten Mr. Yates

The piping is copper and the radiant is PEX (Wirsbo) and all of it meets spec. for potable. The Code you referenced, is it UPC or local? I took a quick look in a '97 UPC copy and couldn't find a ref. to it. Even with the radiant in the bathroom it's not much over 100'. I find it interesting that you refer to this as a cross connection. I do not advocate cross connection. Nor do I wish to incubate legionella, but, in the examples I've seen it's been stagnant water that has been given a chance to grow. The above is flushed several times a day all year round. It's city water with clorine. How do you handle a plumbing system after a weeks vacation, or a summer house? Phils point of using a plate HX, pump, exp. tank etc is good and it would have added a few bucks to the job. We chose not to do that. As I think about the jobs I've worked on in the last 10 years this is the only one I did this way, and I think it's just fine. Mr. Yates, I always enjoy your comments, there's always something to learn and many ways to do things better and safer.

Dave Yates (PAH)

I'm done counting!

Mr. Pittaway, I'll go get Mr. Yates (my Dad)! Ignore the grey hair, I'm still 16 at heart(G).

OK Art, here's the deal. Forget about chlorine. It doesn't do much for legionella bacteria. (Neither do super heated hot water flushes, BTW.) Don't know bout UPC, but my BOCA & International codes both reference requiring recirc after exceeding 100'. Both books are at the office (sorry).

Let's see. Is it a hydronic system if it's used for heating purposes? Or is it a potable hot water system? Is Sybil in the house??? If we agree it's a hydronic system, are we not then required to install backflow prevention to protect the potable water? No can do for a cross/connected potable/hydronic system, eh? It can't be both hydronic and potable.

Want to know how this got started? Back when water heaters came set to maintain much higher water temperatures, the folks who wrote the rules were petitioned to allow the inclusion of baseboard hot water heating loops directly cross/connected to the potable water. Bear in mind that this took place back when EVERYONE smoked cigaretts too. No one at that time ever envisioned someone contemplating running a hydronic system at 110 degrees, much less a bacterial issues.

Legionella wasn't even in the picture yet.

They agreed to allow such nonsense because they didn't know any better.

Then came the 70's energy crunch. Throw in lawsuits for scalding. Mix with a good measure of supers and HO's turning down the unitrols. Add gubbermint mandated efficiency ratings. Now add factory set unitrols at much lower temps & reduced gas input - temps that happen to fall within ideal Legionella growth range.

Now add the knowledge that legionella is an opportunistic bug that looks for pH, temperatures favorable, biofilms and last but not least - stagnation. Add long loop lengths and we're throwing open our arms with an invitation to colonize.

Is a direct connection between a heating system and a potable system a cross-connection? Seems pretty straight forward to me.

We didn't know any better back then. We do now.

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Dave Yates (PAH)

P1508.3 Hot Water Supply Piping

(Per International Code)

"Where the developed length of hot water piping from the source of hot water supply to the fartherest fixture exceeds 100 feet, the hot water supply system shall be provided with a method of maintaining the temperature of hot water."
In the explanation section following, they go on to say:

"The simplest method of maintaining the temperature of the hot water distribution system is by recirculating the water. "


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Riles

Life was much easier, but now

I have so much more ammunition. I get quite a few calls with contractors saying I have this small zone of radiant and I want to use a water heater WHICH WILL ALSO be handling the domestic needs of the house. (AAAH)

Often this madness comes as the result of someone receiving information from some internet based "sell radiant product to anyone who's credit card clears" company that proposes this (you know who they are, I won't glorify their existence). Hey this concept sounds good, why not, they included a diagram with the material.

In the past I have said, "I do not in anyway endorse this SHARED practice" and explained briefly. Some people get adament, and I say, "bad decision, but you appear to be set with going with it". It must be the diagram they sent that makes it such a great "economic (haa)" idea.

This post is SENSATIONAL, I printed it. I love when someone backs up their position with such factual detail. Well done. Very informative. I'll just give them a copy and say good luck.

Unfortunately, there is no stopping some people. God help us.

Dave Yates (PAH)

DOH!

That's BOCA, not IPC. Sorry about the mix up.

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Dave Yates (PAH)

If you're in the mood to print...


Add this to your material if you'd like. A direct link to the article is: http://www.contractormag.com/articles/column.cfm?columnid=17

This deals with some of the issues you raised.

Here's Your Sign

BILL ENGVALL’S song, "Here’s Your Sign," plays in my mind at times. Like
when I see a water heater with a 3/4-in. cold water feed line and a 1/2-in.
hot water outlet. Why do that?

Or when I’m told that open-system, cross-connected potable-hydronic systems are so great because
they give you free air conditioning and increase the capacity of your water heater by as much as
50%. All of which can be done without any risk to your health because all the incoming cold water
will be run through the radiant heating system on its way to the water heater and, therefore, prevent
stagnation of potable water along with tempering the colder well or municipal water?

Those were the claims made during a heated e-mail exchange in which I was told, "You just don’t
get it!" In yet another e-mail regarding open-system construction, I was told I’m "just a dumb
(expletive deleted) plumber." We’ll address the slam about being a plumber in another column.
Where’s my sign?

Aside from the potential health risks associated with open-system construction (see
http://www.contractormag.com/ articles/0401/legionair.html), there’s the issue from last month’s
column regarding pressure losses and balanced flow in plumbing systems using potable PEX water
lines. It’s an issue ignored by many proponents of these systems, but one that exposes the customer
to potential scalding or poor delivery pressures as downstream or lower floor fixtures are used
simultaneously with the upstream or upper floor fixtures.

Now before anyone gets his boxers in a bunch, let’s take a minute to examine some hard realities.
Line lengths for 1/2-in. PEX hydronic systems are often 250 ft. Systems connected to a
combined-use water heater will have fairly small Btuh loads in order to permit bathing without
losing too much capacity, right? If not, they need their own dedicated heat source.

At 250 ft. and using the chart from last month’s column, which shows a .208 pressure drop per foot
with a 4-GPM suggested maximum flow rate, these systems are dealing with a potential 52-PSI
drop during peak flow conditions! That’s before adding losses due to elevation changes and line
lengths to fixtures. Here’s your sign.

But let’s change that to heating an area with 1,000 ft. of 1/2-in. PEX using four 250-ft. loops
attached to a manifold.

The shower on the third floor (loss of 10.4 PSI for the change in elevation of 24 ft.) is being used by
Mr. Jones who loves his high-flow, 8-GPM showerhead. He’s adjusted the faucet to compensate for
that long four-way-split-run pressure loss and the differential from the lower resistance to flow in the
cold water line. He’s using an 80%/20% mix of hot/cold because of the 55°F well water and the
heating system, which was already running, has lowered his storage temperature.

With 6 GPM to split between the four hydronic loops, he’s got a pressure drop of 8.5 PSI (.034
PSI/ft. x 250 ft. @ 1.5 GPM). But wait a minute, we’re not including the 75-ft.-long run of 3/4-in.
PEX from the water heater to Mr. J’s shower! That’s another 75 x .082 (3/4-in. PEX at 6 GPM) for
another 6.15-PSI loss. That’s 10.4 + 8.5 + 6.15 for a total line loss of 25.05 PSI!

If Mr. J’s pump system is set at 20/40, he’s toast. Even if it’s set up to operate at 30/50, there’s going
to be trouble brewing the instant a lower floor or lower-resistance-to-flow fixture is used. If you were
water, which way would you go? Here’s your sign.

Well water systems contain higher levels of organic material than most municipal systems, which
means greater odds for biofilm in the tubing and, therefore, more amplifiers for bacterial growth.
Low flow in long horizontal lengths of tubing, no matter the materials used, promotes
sedimentation and biofilm layers. Here’s your sign.

Free air conditioning? OK, let’s introduce that 55°F well water into the 1,000 ft. of in-floor PEX
tubing for the 15-minute duration of Mr. J’s shower. Will this chill the room appreciably? Will the
tubing sweat if it’s installed in a staple-up underfloor application and sees humid basement air?
Will Mr. J need to lay flat on the floor to appreciate the benefits?

If Mr. J is on a municipal system, he won’t be getting chilled water and will likely be receiving water
at or above his room’s air temperature during those peak air conditioning load days. Do the
"benefits" outweigh the pressure, flow and health-related issues? Here’s your sign.

What about the claim that such a system increases the capacity of your water heater by up to 50%?
That assumes the floor is heated to its upper limit, the circulator is running and the water heater
has just finished recovering to full temperature. You know what they say about the word "assume"!
Here’s your sign.












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Dave Yates (PAH)

One more!

This was the article that sprang from research on open system dual use construction that opened my eyes and led to my firm beliefs. Feel free to add this one too.

Direct link: http://www.contractormag.com/articles/column.cfm?columnid=98



BY DAVE YATES, Plumbing Contractor

Legionnaires' disease

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 it.

A wealth of information is available, and I have found the world’s leading authorities are more than
willing to share their knowledge.

In 1976, while attending an American Legion 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 identification of the bacterial strain, the Centers for
Disease Control and Prevention examined some previously collected tissue samples, which
revealed earlier cases of Legionnaire’s disease.

One was circa 1947 from a soldier who had developed and died of pneumonia while at Fort Bragg,
N.C. 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 is derived from
the first recorded outbreak in Pontiac, Mich., which affected 144 people at the Oakland County
Health Department. Flu-like symptoms occur that 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; and aids, heart and kidney patients. Blood
samples have shown that a large percentage of the population has been exposed to legionella
bacterium. As many as 10,000 to 100,000 cases of Legionnaire’s disease occur each year (depends
on whose statistics you believe), and some think those are low numbers. 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 are a virtually perfect
environment for legionella bacteria.

Legionella bacteria need four very basic conditions to survive and grow:

Water temperatures between 68 and 122 F;

A pH between 5.0 and 8.5;

Biofilm (sediment); and

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. In recent years, water heater manufacturers have cranked the thermostats
down in order to stem the tide of scalding incidents and to increase efficiencies. Although
legionella bacteria begin to die above 120 F, they don’t really get kicked in the pants until the
temperature rises above 130 F.

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 is enjoying a radiant revolution. As more and more people discover the
benefits, comfort and reliability of these products, the pressure has increased to find more
economical installation methods. 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 code 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 some believe that this
also contributes to pitting in copper tubing.

High-temperature water flushes (140 F and above) also offer only temporary suppression as has
been documented in numerous locations. In several hospital cases, flushes using 180 F water for
five minutes at every faucet were employed. Many man-hours were required, notices posted to warn
people not to use the faucets 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 two 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 becoming more popular and might eventually be available in residential models.

Maintaining higher water temperatures is the other method. Several other countries have adopted
plumbing codes that require water temperatures to be maintained at or above 140 throughout the
entire potable hot water distribution system and only allow a small amount of cooler water,
typically 131 or above, after the mixing valve.

The only way to prevent legionellosis acquired via mechanical systems is to improve the design
and maintenance of cooling towers and plumbing systems.

Legionellosis has 5%-20% fatality rate in general public exposures and a fatality rate as high as
40% in hospital-acquired cases. 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 and
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. We should be prepared to accept and support these changes.












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Unknown

And it REALLY is happening

In Vermont, right now. Stay tuned...

http://www.concordmonitor.com/stories/news/newengla2002/0808_disease_2002.shtml





State confirms 9 have Legionnaires'

Respiratory illness is potentially fatal
Thursday, August 8, 2002




--------------------------------------------------------------------------------






Vermont




MONTPELIER, Vt. - The state health department has identified two additional cases of Legionnaires' disease, bringing the total number of those infected to nine people, health officials said yesterday.

At least seven of the patients are being treated at Central Vermont Medical Center in Berlin, although Health Commissioner Dr. Jan Carney said confidentiality rules prevented her from disclosing their names or conditions.

"We are continuing our investigation to identify cases and determine whether there is a connection among them," Carney said yesterday.

The department is also continuing to try and identify any other individuals who may have the disease, she said.

Carney said the department expects that additional cases may be confirmed into next week because there can be delays of up to 10 days between when a person is exposed and when symptoms appear.

"We are calling this an outbreak and that's why we're focusing very detailed attention on our investigation," she said.

The incident began last Thursday after a former inmate at the Dale women's prison in Waterbury was diagnosed with the potentially fatal respiratory illness.

After investigators from the Vermont Health Department began looking into other cases of pneumonia that had been identified in central Vermont, two more victims were confirmed over the weekend and four more possible cases discovered.

All seven of those cases have been confirmed.

Two of them - the former prisoner and a patient at the Vermont State Hospital in the same building, the Dale facility - have a connection to the Waterbury state office complex. The others are residents of or work in Waterbury.

Carney said her investigators were conducting extensive interviews with those affected, trying to establish any pattern that might reveal how they came down with the disease.

"We're looking at their home and work lives, medical histories," she said. "We're looking at activities, hobbies. . . . whether or not since these cases have occurred in the Waterbury area, are there any connections between them?"

Legionnaire's disease is caused by a relatively common bacteria, legionella pneumophila. The bacteria and the disease it causes got their name in 1976, when 29 people were killed and 162 sickened at an American Legion convention in Philadelphia.

Humans become infected when the bacteria flourishes in relatively warm, stagnant water and then becomes airborne in mist. Breathing in the bacteria or taking contaminated water into the lungs can lead to Legionnaire's, which is characterized by pneumonia.

Middle-aged and older people are more vulnerable, especially those who smoke or have chronic lung disease, according to the federal Centers for Disease Control and Prevention.