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converting from oil to gas

anthony_24 Member Posts: 25
Hi I'm converting 2 oil fired  furnaces to hot water coiled heat exchangers  heated by a Boderus mod com gas with a indirect domestic hot water as priority. I am getting conflicting opinions that this is not the way to go.  I am also replacing central air as well at the same time.  Am I asking for trouble by doing this? It is going to be a costly conversion and I can't afford to find out it was mistake. Thanks for you help in advance.


  • Steamhead
    Steamhead Member Posts: 16,233
    To get the best performance from that boiler

    size your duct coils so they'll deliver enough heat at design conditions with a water temp of 140° or less.

    Did you do a heat-loss calc so you'll know how much heat you need at design?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • anthony_24
    anthony_24 Member Posts: 25
    converting from oil to gas

    Thanks Steamhead for your reply.

    A Manual j was done. a Boderus 142/30 with a 150 GPH indirect for domestic hot water(4 Baths) was prescribed. BTW I'm in eastern Long Island..
  • ModCon fan-coil options

    The boiler can be set to modulate and operate to 180°F and as low as you like.

    However, forced air gets pretty uncomfortable when delivered air temperature gets below 110F°. The answer is; use a modulating fan coil and the outdoor reset feature of the Buderus GB. Modulate both air and fan using 100 to 160 degree water for overall fuel savings and comfort.

    My fan operates full time - filtering and humidifying - and modulates upward as the temperature outside drops.

    Properly sizing the hot water coil and the air handler is the key to success. The coil will be too big and the boiler will run higher than optimum (140F supply as suggested) but this will occur during design conditions (about one week of the year).

    If this is too complex for your installer,  you may also consider using the indirect water heater as the heat source for the fan coil. In this case the water heater (set to the previously prescribed 140°F and mixed back down to 120 for bathing) may be used as the source for the fan coil insuring minimum water/air temperatures and plenty of load for the boiler. Modulating fans can still be used but it is easier to design and install. Outdoor reset is not used but boiler efficiency is quiet good and comfort guaranteed if done right.

    Welcome to the wonderful world of ModCon natural gas boilers!
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,281

    IF it is too complicated for your installer to do it right get another installer.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Come again?

    This is not a typical  "open" system, but rather a fan coil driven off the water heater (copper all) unless your local code prohibits it, the technology is decades old. The most I find required is an control to "exercise the pump.

    I often use a domestic hot water heater for heating and DHW (for which nearly all are now approved) on small load applications where the smallest ModCon is too big. I use a plate heat exchanger when installing radiant panels but when a fan coil is used all that is needed is a bronze or SS circulator.
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    edited April 2010

    Copper's benefits in an open system offer minimal benefit when the system is new, but are quickly compromised after biofilms form that coat the distribution piping. All potable water systems develop biofilms.

    In my opinion, promoting the use of an open potable/hydronic system is foolish given the known facts regarding bacterial amplification in potable warm water systems operating below 140F and even if over 140F if the system is at rest for any length of time. A once a day or week exercise does nothing more than give the bugs a faster ride to seed the potable tank, distribution network, and distal sites (shower heads and all points of potable use where human contact and breathing in water-vapor mist is likely to occur). Wave the codes in front of folks, but the facts regarding the health risks are well-established and our plumbing codes don't reflect the known facts about this issue.

    Now, if you want to employ heat pasteurization once a day to elevate all components of the combined hydronic/potable system (tank, hydronic loops, & coil) to 180F for several hours, you'd be on the right track.

    Do it once & do it right: keep the potable system physically separated from the hydronic system.

    For those of you reading this who might be a bit unsure about what's the right thing to do, Google "warm water + bacterial amplification" or "water heaters + Legionella" or any number of other combinations. Study, read, and form your own conclusions. Look for the four basic needs bacteria like Legionella need to thrive and multiply. Will all four be present in an open system? Are Legionella likely to be present in potable water systems? If they are and you build a suitable amplifier, will they decide to stick around and flourish or do open systems somehow get a free pass because those who promote their use say so?

    If you're still going to install open systems, I'd urge you to give your customers the opportunity to do the same research and let them make the call. If they choose to go forward and you will be installing the system, I'd want them to sign a disclaimer that I'd forewarned them of the potential health hazards. CYA (cover your ****-sets!), but also be aware that even a first-year law student could rip that document to shreds and expose you to a full measure of liability. Ask your insurer what their position will be if you knowingly installed something that increased your customers' exposure to potential hazards when you had advance knowledge that a few simple measures would have negated the potential risks imposed by an open system.
  • Is there a doctor in the house?

    Though many advocate open systems for radiant floors etc. I

    - like the majority - have railed against them since the 80s. They are just

    silly from a mechanical service and efficiency perspective and to a lesser

    degree "BUGS". I know that Legionella has made for good copy in the

    trade publications, but a few facts may balance the hysteria.

    If you are talking about Legionella pneumophila: it is a bacteria that only

    multiplies actively at water temperatures between 68 and 113°F. Legionellosis

    is usually and correctly associated with commercial facilities and cooling

    towers in particular.


    We as plumbers are warned against dead-legs or dead ends

    when plumbing water supplies, but we all know where they are, and have been for

    decades. In fact we all know people who haven’t flushed that basement toilet or

    used the shower since WWII! These are the equivalent of a dead-leg and no one

    is dieing over or even using sleep over them. Could it be that Legionella do

    not like copper pipe?


    One must remember that the vast majority of water heaters in

    North America NEVER see 140°F, but most are at 120F +, so that cases of

    Legionella in residential applications rare. Since it is a non-communicable

    disease and is easily diagnosed and treated, I believe a certain restraint is

    order where residential water supplies are concerned. In fact the only

    statistical risk is to the elderly, smokers and the infirm. (Of course there is

    an inherent risk the pocketbooks of the rest of us).


    Quoted OSHA control standards (pasteurization) for

    Legionella are hardly necessary for residential applications, but if your DHW

    tank is kept at 140°F, you will not have Legionella growing at threatening

    levels.  The fact is; Legionella will

    only thrive in water temperatures of 85 to 115°F. It is also interesting that

    water stored below 68°F does not support Legionella. (I guess that is why the water

    heater at the cabin (60°F basement) hasn’t killed me yet)!

    By contrast; the system, which I have described, installed and serviced -

    approved and well accepted by many states and municipalities - is not to be

    compared with these systems. This system also operates very much like a

    domestic hot water heating re-circulating system, except that the typical residential recirc. will

    not be at, or near, 140 degrees. I have found a great percentage of such pumps

    (required by code in certain states for certain applications) unplugged or

    burned out and all the occupants alive and well.

    While I’m at it, if you wonder

    about the safety of indirect-fired or companion water heaters: don’t. It is all

    about time and temperature. Since they generally lack the scale and sediment

    that feed the “bug” (or is it boogeyman?).


    The more serious risk (if there is one) is from common

    household humidifiers (I have used hot water from water heaters to serve the

    occasional scorched air system). If we really want to raise a flag it would be

    for scalding injuries, which make Legionella look like a nice walk in the park.

    All told, killing the Legionella bacteria or inhibiting its concentration, is

    not that difficult. I believe that certain circumstances may

    cause a hazardous condition to occur, but the risk factor is hard to determine. The fact is, some of us can afford more safety than others. Fortunately we

    are free to choose.

    We have to be careful, lest good practice turn into religion.
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    your "facts" are skewed

    Your temps are narrower than the facts supported by credible reasearch. And, not one single case has been directly traced to a cooling tower. In every case where anyone bothered to trace the origins, it was the potable water that was the root cause.

    Google "Legionella - The Coming of the Third Plague" and bear in mind that the study was done back at a time when water heater's were factory-set for 140F.

    Hysteria? Hardly. Common sense is all that's needed instead of blinders. I'm encouraging folks to check on the available information from independent sources (folks from the scientific community who don't sell/install open systems) and then form their own opinions. The only hysteria I've seen has come from those who advocate the use of open systems when anyone questions that practice. Find the scientific evidence from credible sources that would indicate open systems will not be an amplifier and I'll gladly read/study the info. I haven't been able to discover any over many years time.

    If it's an amplifier and it's not a necessary required component, then - in my opinion - it has no business being deliberately connected to a potable water system. Obviously there are others who disagree & that's why it's important for folks to gather info and form their own opinions.    
  • anthony_24
    anthony_24 Member Posts: 25
    oil to gas

    My thanks to everyone for their input and knowledge. I still don't know which to go.
  • Steamhead
    Steamhead Member Posts: 16,233
    I think

    you have the right idea. Of course, if it were my house I'd go with a fully water-based heat distribution system, but hydro-air is certainly better than the usual furnasty. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Is there a lawyer in the house?

    Of course it depends on the type of plague you are talking

    about. First Bubonic plague; associated the Legionella bacteria with plague (a disease

    transmitted by fleas) and or perhaps the author was thinking about Pneuonic

    plague; which is highly contagious between individuals and aspirated).

    The only similarity to Legionella then would be that you must aspirate it (from

    a shower for instance) but otherwise a plague - in the classic sense - is an exaggeration

    one might even say hysteria.

    You will note that I did not advocate "open" heating systems for

    nursing homes (where the elderly and infirm often reside). Scientist may

    disagree. I am talking about real threats to human health.

    I do not "sell" open systems. I am talking about a specific

    application where a "residential" water heater is set and tested to

    140°F, driven through a copper fan coil and the potable side scald protected (a

    real, verifiable health risk). Using your numbers (apparently the only valid

    information) the system I carefully described is safer unless those who choose

    to ignore the facts also maintain high water heater temperatures in their

    conventional water heaters and indirects (as I do on all of my ModCon indirect


    Those who "sell" magazines seem to have a lot more interest in

    Legionella than the average plumber, save personal injuries lawyers perhaps.

    Please name three documented incidents of Legionnaires contracted in a personal

  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    edited April 2010
    Seriously? That's too easy.

    For starters, let's start with one of our own: Mark Eatherton. Then there's my cousin in Wisconsin who nearly died.

    More interesting, however, your response reveals you didn't bother to read the one document I referenced. Had you taken the time to read it, you'd have discovered a list of documented residential community-acquired cases.

    It's not a challenge to find them listed on line too:




    An open system is just that. I'm not qualified to determine the degree of safety for one type of open system vs. another, yet the evidence to support the idea that connecting an amplifier to potable water systems presents the potential for bacterial amplification is abundant and clearly stated by micro-biologists and the medical community. On what basis do you claim to have the ability to classify any open system as being "safer". Labeling something as "safer" would seem to imply it continues to house the potential for being un-safe. Kinda like saying you're only partially pregnant!  If it poses a risk, why plug it into a potable water system? You certainly can if you like, but I won't. While it's just an opinion I formed after studying the issues surrounding bacterial amplification and the potential health risks, it is just that - an opinion. I'm not saying you (or anyone else) can't install an open system. Repeating myself again: I'm merely suggesting it's wise to study this issue and then decide for yourself if it's appropriate and that a potential consumer/customer should be provided the opportunity to have the same option - prior to having an open system installed in their home. Not much different from public labeling of cigaretts - they know the dangers yet they're free to continue to smoke.     

    I fully agree the scalding issues loom large & you'll find that detailed under my byline in Contractor Magazine and throughout the 28-minute DVD I produced for Watts Regulator a few years ago. Yet one more issue our plumbing codes have failed to adequately address.  

    I complied with your request. Now it's your turn to comply with my previous request that you've conveniently ignored. "Find the scientific evidence from credible sources that would indicate open systems will not be an amplifier and I'll gladly read/study the info. I haven't been able to discover any over many years time."
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    Anthony: mod con marriage to hydro-aire can be great

    We've installed a number of these and your potential to save fuel (operating costs) can be dramatic. The key, for us and our customers' comfort, has been the oversizing of the hydro-coil to ensure we have return-water temperatures that remain well within condensing range for the boiler. A six-pass coil often grants a 40F delta-T without compromising air-flow for fixed-speed air-handlers during A/C operation. The coil manufacturer can provide the details for your installer regarding resistance to air-flow per their coil design.

    A fairly wide delta-T permits a wider range for your boiler's outdoor reset function, which enhances the fuel savings while maintaining higher comfort levels.

    Supply the coil with the warmest water on the downstream side so that as it is cooled as it works its way up through the onrushing return-air. 140F upper-limit supply temp (and lower) has worked well for our jobs.

    This method grants you the ability to tweak the outdoor reset curve for maximum fuel savings and allows you to adjust over the full upper-range, if required, on design-day (coldest worst weather) conditions. Flexible comfort! 

    Sounds like you're headed in the right direction! I'd be tempted to suggest two smaller indirects piped using reverse-return so that the draw-down is equally distributed and a second tank provides redundancy should one need service/replacement.  
  • The sky is still up there

    Dear Mr. Yates,

    Thank you for the links. I see unconclusive conclusion and language much like the famed lead hysteria used such as, likely, believed to be and so on. I saw no mention of open systems or water heaters in my quick perusal. We live among pathogens and survive if healthy.

    I asked for three cases, I believe you are one short. This is a common symptom of hysteria. It is very

    easy to raise the bar and cast doubt.

    Further; hot water kills the "bug" or it doesn't.

    It is to the advocate to overcome irrational fear and misunderstanding. Since

    no one (scientist or otherwise) has a vested interest in making less expensive,

    efficient combination heating systems, I doubt I will find the irrefutable

    evidence you seek. We live with many risks; this simply isn't at the top of my

    list. You are trying to hold residential applications (for which no public

    health risk exists) to commercial standards. There is a reason the two codes

    don't often match up.

    The burden should always be with those who will not, to include government

    officials and the ambulance chasers that follow their unlegislated statutes.

    It is a common symptom of hysteria. It is very easy to raise the bar and cast

    doubt. It is with the advocate to overcome irrational fear and


    I read with great interest ME's article on his personal experience with

    Legionnaires and the one on electric windows.

    In this particular application a fan coil run off from a water heater would

    insure load to the boiler and warm air to the register. If the boilers is sized

    properly (rare) and the coils likewise (more rare) a modulating boiler could be

    set to 150°F supply, pumped to a 30-35F delta T and happy customer.

    On single coil, small houses it is still water heater and fan coil. Please

    speak to the issue of this specific application of which I am sure you are

  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    Blue skies

    You were given many more than three. Your turn(G).
  • TonyS
    TonyS Member Posts: 849
    Calm down guys

    The "experts" have now given us a new and much more severe BUG to deal with, This one is so bad the WHO has declared a pandemic! The SWINE FLUE... Thank god we have these experts. Lets have a show of hands here.....who here actually believed these EXPERTS so much they had their children injected with this crap?
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    Cool, calm &

    collected here Tony. Pandemics are interesting to study & if you go back to the late 1800's & early 1900's to check out Cholera, Typhoid & a few others, you might be startled to discover it wasn't uncommon for cities - like Chicago - to lose more than 5,000 folks in just a few months! In fact, water-born diseases killed off tons of folks and eventually led to plumbing codes being established so that health of the public could be better-protected. And it was. So much so that our governing bodies have chosen to ignore the past while allowing lobbyists to dictate what changes are enacted and which ones don't see the light of day.

    You can place some degree of blame (perhaps most of it) on the national media for the Swine Flu fears, although it does appear we may have narrowly dodged a bullet after reading several med journal articles regarding the bugs ability to shift gears. Don't know if it has/had the potential to rival 1918, but it was revealing to discover how inept the ability to react with any type of vaccine in any sort of time-frame really was & that bothered me more than the actual Swine Flu. I also believe the national media did an excellent job of eroding the public's confidence in the economy, which accelerated and exaggerated the "recession".  

    All things being equal, I'd take Swine Flu over Legionnelosis any day. But, I'm also unaware of our installing any systems in customers homes that carry the Swine Flu bugs and/or provide an ideal amplification for them and, unlike Legionella. the Swine Flu bugs are not (that I'm aware of) normally present in potable water systems to seed and multiply in bugged-on (sorry, couldn't resist) add-on auxiliary systems.  

    Meanwhile I'll wait patiently (and calmly) for the requested information.   
  • TonyS
    TonyS Member Posts: 849
    Ok Dave heres an article

    you will enjoy  http://www.globalresearch.ca/index.php?context=va&aid=18828
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    edited April 2010
    Thanks, but not the doc(S) in question

    Thanks Tony - an interesting diversion, but not what Audetat owes by way of the documents requested regarding open systems and bacterial amplification issues. He stated several "facts" that should be able to be supported by independent 3rd party credible sources or, in the absense of credible resources, they should be withdrawn and admitted to be his beliefs unsupported by facts. The folks who visit here deserve nothing less than the truth so that they can form their own reasoned conclusions regarding these, or any other ideas questioned.

    Especially where potential degradation of potable water and human health are concerned. The risks are known - why even go there.

    Seems like a silly exercise in futility to argue with the facts when it's so simple and easy to provide isolation of the hydronic/potable fluids to avoid the potential problems. Cheap insurance, in my opinion, that totally avoids any possible issues for cross-contamination when the added components are properly installed.     
  • Diversion from the specific application

    One might look into Complete Heat by Lennox. Not a commercial success I suspect, but no fatalities to my knowledge. The use of a close couple fan coil with a conventional water heater has not been addressed (please correct me if I have missed something). This system is should not be confused with a radiant floor "open" system which would fall closer to the threat posed by Mr. Yates i.e. lots of lukewarm water, rarely over 140°F and often times questionable installation.

    The question was of personal experience. If anyone else can answer the simple question: have you personally known anyone who has been diagnosed with Legionnaire's attributable to a residential hot water heater?

    I know it is hard to consider systems you are not familiar with, when you are so deeply invested in a published idea.

    I have had the opportunity to observe many water-heater-driven fan coils and found them to be sound and safe. Safe enough to install in one of my own homes when a full blown hydronic system was not warranted.  Good value, good sense.

    In my original post I just mentioned in passing that if the load were low enough condensing water heaters will work. The bulk of my work involves the very systems Mr. Yates contends are the only systems for you. I am a ModCon zealot and can't disagree for a moment.

    As for this job, I apologize for not answering Anthony's question more succinctly. Mr. Yates is right-on with his assessment and if you can get a man like Yates to do the job, you are all set remembering that low water temperatures must be driven at low fan speeds or wind chill will occur.

    Just don't forget to "pasteurize" that water before you bathe!
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    edited April 2010
    According to the CDC...

    Legionairres disease is one of the most mis-diagnosed diseases in the world.


    I could give you the names of three people, myself being one, but the other two are pursuing the contractor who installed their systems for the cost to convert them to a closed loop system, and the cost of their hospital stay. Both were an open RFH system. Both said they thought they were going to die.

    If you consider yourself a licensed plumber, charged with protecting the health of your customers, why are you a proponent of open looped heating systems?

    RFH or not, unless you are maintaining 140 degrees F through the whole system, and you are not, there are bacterium growing and thriving in the system.

    In the CDC article, they claim that there are more people catching the disease in the summer and fall. You don't suppose that it has to do with people going on vacation, and not "flushing" their systems out, only to return from vacation and exposing themselves to extremely high concentrations of bacterium. That would answer the summer scenario. The Fall scenario is probably caused by the heating system turning on after having sat stagnant (YUCK) for the whole summer, and again, exposing the occupants to significant amounts of bacteria.

    I think one has to step back and see who has a dog in this fight. Dave and I have absolutely NOTHING to gain in educating the consumers as to the details of this deadly disease. You on the other hand have a lot to lose if they are outlawed.

    I would not wish this disease on my worst enemy.

    Each year between 8,000 and 18,000 people per year are diagnosed with this deadly disease, with a death rate of between 5 and 30%.

    And you think we are generating hysteria?

    Just presenting the facts. Hard facts.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • TonyS
    TonyS Member Posts: 849
    Your welcome Dave

    I was just trying to let everyone get a feel for the" EXPERTS" when it comes to disease and money.
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    hard facts can be hard to swallow

    I was asked to produce three documented cases, not three I personally knew.

    The whole 140F notion would be funny, if this wasn't a serious issue. While water may, and I stress "may", be exiting the tank at 140F, it cools to very suitable bacterial amplification temps while traversing the hydro-air coil or radiant tubing and it's unlikely the entire pathway will see 140F if the system is transferring energy as it's designed to do. Then it enters the base of the tank where it wasn't 140F in the first place.

    But, even if the entire combined potable/hydronic system were at 140F, it takes a full 20-minutes of contact time to kill off most of the free-roaming bugs. The bugs thriving in biofilms, sediment, rust, and rubber components remain unaffected - and survive quite nicely after 180F 15-minute attempts to sanitize systems (Danfoss study). The scenario I see in my mind's eye is a bather or bathers drawing down hot water from the same tank with an at-rest hydronic amplifier being activated for heat and injecting a slug of water now housing free-roaming bacteria that have burst forth (as seen in Global Pipe's video - a segment was included showing this in our Watts DVD) from their nursery. Given the outgoing potable flow, those bugs aren't likely to feel the sting of any 140F water and even if they do, their ride to the shower-head won't take 20-minutes. Slip sliding away!  Add a scald-guard mix vlv at the tank's outlet and that 140F contact-time has the potential to be pretty brief.

    Once past the theoretical 140F storage vessel, they now are free to settle into the distribution piping network's biofilms and raise a family. 140F will keep the numbers in check - with adequate contact-time - but will not sterilize the tank or system. Copper/silver ionization and chlorine-dioxide treatment systems are the only methods that offer a 100% kill rate. Both will penetrate biofilms well (chlorine does not and at 2% to 4% has no affect on Legionella bacteria) and copper/silver ionization offers a residual affect that will help keep unused portions (dead legs and stagnated portions of the potable system) sanitized. UV is only affective for incoming flows if coupled to an ultrasonic bombardment component that breaks apart the cysts of the one-celled animals the Legionella have infected to then expose them to the UV rays.

    From my point of view I only need to ask myself one question: will what I'm proposing to add be a potential bacterial amplifier? If the answer is yes, I'm not going to risk my customers safety or expose myself and my firm to the additional liability - no matter who tells me the risk is minimal. If the component(s) in question offer the conditions required for amplification, then it's an amplifier in my view. Mark & I have both been contacted at various times by lawyers involved in litigation and both of us have seen cases where the lawyers were dealing with open cross-connected dual-use potable-hydronic systems.

    Anyone who wants to install open systems can certainly do so. After all, our plumbing codes allow them. Local codes can, and many places do, outlaw their use. But, one manufacturer bragged to me that he knew every place in the USA where licensed plumbers could not legally install an open system but had no problem selling them directly to consumers while not alerting them to the local code restrictions.

    So easy to do it safely! Think of a mod con with an on-board flat plate to generate potable water and simply reverse the process by letting a flat plate produce the hydronic heating. The loads are small, so the FPHX is too & that keeps the added costs low. NSF-rated on the potable side & plain-Jane hydronic system on the other side. Check your costs for the added components: FPHX; small circ; X-troll pkg; & PRV. Cheapest insurance money can buy.

  • Charlie from wmass
    Charlie from wmass Member Posts: 4,281
    Water heaters are fine for less than code installs

    My Lawyer, Insurance agent , and Father (who is over 50 years in the trade and 45 of those successfully self-employed) all say no water heaters for heating a building. My code also says do it with a proper boiler or stay home. Legionnaire's disease is real and warranties are weak . So take your chances if you like.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • herd mentality

    I'm glad Tony S got my point - while the "experts" run lock-step with the "scientists".

    All should note that I did not say all open systems were OK. I specifically pointed out a common application (for which the water heater manufacturers originally certified their appliances for close coupled fan coils. If a residential water heater is maintained at 140°F (by the experts numbers) it is, in theory, safer than nearly all the domestic hot water systems in North America which are much closer to 120°F!

    You can continue to go on and on about "open" HRF systems (which I have decried for decades) or speak to the question for which I am sure you have no suitable or convincing answer.

    I am not judging your integrity, just the application and significance of the research.

    I am, by the way, a licensed plumber in two states and am still licensed in CO, where I learned at Red Rocks Community College how to think outside the box.

    I will never claim to be an expert on pathogens as I lack the scientific training to admonish others on subjects of such complexity (air gaps, air breaks, back flow preventers, double checks valves and RPZs notwithstanding.

    The point is; how safe is too safe and who will pay for it?

    Let me repeat, I am NOT addressing hydronic radiant floors rather, close-coupled fan coils e.g. Complete Heat.
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    Interesting twist!

    Nice try at the dodge & weave, but not my issue to answer. It's yours as it was in the beginning of this thread and you evidently can't find any credible scientific evidence to support your claims.

    On the other hand, I did provide you with the evidence that any open system offers a virtually ideal bacterial amplification site and I provided the proof that was requested by you regarding documented cases derived from residential water heaters.

    Case closed from my perspective unless you choose to present any real evidence to support your claims.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840

    What in your minds eye makes your close coupled FCU, open, direct DHW powered system any better than the HRF systems as it pertains to avoiding the growth of water born bacteria?

    If you are headed for the excuse that you have a timer on your unit to insure flushing, pumps and timers break, do they not?

    You still have all the components necessary to allow and enhance the growth of bacteria.

    Water, warmth, food and oxygen. Just because you are using copper pipes does not give you a clear system. Municipal water system intentionally induce hardness Langlier Index) into the water that protects the pipes. This gives the bugs a place to hang out, and multiply, covering the exposed copper.

    It is a free world here, and you have been educated, so the choice to continue your practice is your choice. Hopefully, through this thread, the consumer is much more intelligent and won't take the wrong fork in the road. Cheap is not always right or best.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Unknown
    edited April 2010
    My Dad's bigger than your Dad...and older too!


    You can ALL point to "one" specific case where a system installed to my specification has caused illness of any kind? Perhaps one of the thousands of Complete Heats? Or one of the thousands of hybrid water/fan-coil applications here or in Canada.

    As I recall Mark was taken ill (happy to see scrappy again) from a regular-old tank-style water heater. I have gotten deathly ill from old chicken, I am more careful now.

    The point is not whether but  how.

    I added a PRV to a poorly installed buffer tank last year. We must all be vigilant and focused on the most immediate threats to health and welfare while providing value and comfort where it merits.

    I have enjoyed our debate but now must prepare for another ModCon (Viessmann Vitodens) installation. You will all be proud as it is expensive, ASME stamped, AND tied to and indirect water heater.
  • Henry
    Henry Member Posts: 996
    edited April 2010

    I had a "Complete Heat". HAD! But FYI, the hot water storage tank was always heated to 140 to prevent Legionella which can survive up to 139F. When in heating mode, the hot water temperature jumped to 160F. It is part of the programming and there are warnings in the user book of this!

    We have done a number of complicated systems that have a geothermal unit that is supposed to provide Heating/Coling air, radiant heat and domestic hot water.Meanwhile we have snow melt,100 gph dometic hot water requirements, radiant floor, pool heating and unit heaters in the garage. P/S is the way to go. We use Knight boilers for their reliability and ease of control work. We let the outdoor reset of the boiler work. The Knight overide for domestic hot water is engaged. The air handler and radiant get their own Tekmar setpoint control and modulating valve, as does the pool heater. BTW, try to use Titanium HX for pool heating. Marine SS does not work with salt systems if not properly grounded! 


  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,394

    Henry, please don't use foul language in your posts. Even if you blank out some of the letters, people can still hear the word in their head, and that's unprofessional.

    I've edited your post.

    Thanks for your understanding and cooperation.
    Retired and loving it.
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