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Mixing valve on Tankless...?

kcoppkcopp Member Posts: 2,746
Anyone ever heard of an inspector requiring a Mixing valve on a tankless WH such as a Noritz or a Rinnai?

A coil I can see...and would do. But an appliance that has the control set to only do the HW.....hmmm. What code would he be thinking of?


  • icesailoricesailor Member Posts: 7,265
    edited April 2014
    Mixing Valve on Tankless:

    What State are you in? If he can't show it to you in writing, and you are in Massachusetts, call the Board, ask for an inspector and get a ruling.

    In MY personal opinion, I think that every water heater, indirect heater or instantaneous  water heater should have then, regardless of their thermostats. But that's only my opinion and isn't what the code says.

    The only thing that IS absolutely required is a listed temperature and pressure relief valve.
  • heatpro02920heatpro02920 Member Posts: 991
    I would just throw one on

    Probably cost less in gas and time going back and forth, just throw it on, it won't hurt...

    t if the unit was limited to 120 degrees and had a t&p I don't see why they would ask for mixing...
  • icesailoricesailor Member Posts: 7,265
    One way of looking at it:

    That's one way of looking and addressing the problem.

    But if an inspector can't show you a listed and published code that says so, the AHJ shouldn't be allowed to be making up code in an arbitrary and capricious way.

    It is MY experience that thermostatic mixers do NOT work well (if at all) when the incoming hot water isn't over at least 140 degrees.

    So, wouldn't the advantage of tank less "On Demand" water heaters be defeated by raising the temperature to a level to make a mixer work properly?

    Just because some AHJ thinks personally, that it is a good idea, doesn't mean it is. If you gave a price for a Tank Less install and it didn't include a mixer, who pays for it, YOU? If it creates a problem, who pays to have it removed. YOU? The AHJ?

    Someone needs to consult the Tank less manufacturers about this. It might void warrantees.

    IMO, AHJ's should be more interested in the fact that very few are using PVC cleaner to clean PVC pipe and fittings before solvent welding fittings together.

    If you see the writing incised on the side of the pipe with no interruption, going inside the fitting,  it wasn't cleaned. All codes say to follow the manufacturers recommendation. EVERY manufacturer says to clean the pipe and fittings. Few are doing it. There's something in the code that needs to be enforced. Thermostatic Mixers on Tank less heaters are not one of them.
  • kcoppkcopp Member Posts: 2,746
    Its NH...

    I don't see why its needed.... but ya some folks just make it up to be extra safe....all it does really is add to the cost of an install.
  • icesailoricesailor Member Posts: 7,265

    Ask them what their logic consists of, and what about the mixer needing 140 degrees incoming hot water to work properly. And where the energy savings comes from by running the Tank less at 140 degrees just to get the hot water to a safe temperature.

    Then, ask them why they aren't requiring Mixers on tank type water heaters. the thermostatic gas control could fail too and cause scalding. Especially the dual use where they are trying to heat a building with a potable water heater.

    Where do they draw the line?

    Please post the answers. Inquiring minds are interested.
  • heatpro02920heatpro02920 Member Posts: 991
    edited April 2014
    Ice I see where your point and agree

    I mean do they make you put mixers on a 40 gallon gas fired tank? Its the same thing, BUT like I said around here, I don't argue, me and my partner own the company and learned long ago, we have a bunch of bosses, they are inspectors, just do what they want and be polite... I am young'ish and wont shy away from an argument if I feel I am rite, BUT I put inspectors in the same bin as you would put your wife or mother when it comes to arguments, just bite your tongue and try to get out with as little sacrifice as possible, lol...

    I have good luck with inspectors, the work looks good, they wont say much, I tend to remember what each wants, I learn fast, so if I know the Cumberland inspector wants LWCO's on mod cons with them built in, I install them in Cumberland, but the Cranston inspector could care less, so I don't do it there.... I know an inspector that wants a firepmatic directly over the burner not on the ceiling so I install them directly over the burner when I am in his area, I know an inspector that wants sprinklers over all new boilers and direct fired tanks, so I install them in his area, others dont ask for it so I don't... Live and learn, next time you do a tankless in this guys back yard, make sure you price a mixer...

    Years ago a local inspector would have to find something, he wouldn't leave until he found something wrong, he was an old timer and just would not sign off on the first visit, he did it to everyone, and the first few times, I made sure everything was perfect and I noticed he would just make something up, lol... Like he made me put hangers on a smoke pipe that was 18 inches long and went rite into the chimney {it was fastened to the flue and boiler with screws and l sheets, but he wanted something from the ceiling, lol...

    So another old timer in the business told me, leave the pressure relief valve not piped down so he has something to find.. So I did, and it worked, I did 10-15 boilers that he inspected before he retired and everytime I would leave that pipe off and he would never mention that I left it off everytime...

    I later found out he did it for the over time, he would come back after hours and get a little pay boost, but what ever, I just do my job as well as I can for me and my customers...
  • kcoppkcopp Member Posts: 2,746
    They do require...

    them on tanks....
  • heatpro02920heatpro02920 Member Posts: 991
    edited April 2014
    I never install mixers on

    direct fired gas water tanks, {unless Its going to be a high temp tank} never had an inspector give me an issue about it..
  • icesailoricesailor Member Posts: 7,265
    edited April 2014
    Inspectors and Codes:

    One nice thing about working over the Boarder to the North (Massachusetts) is that we have a "Uniform Code". That means that the State Board sets the codes/rules and they apply to the whole State, not just in some local jurisdiction. Local Jurisdictions can set local rules as long as they follow the "intent" of the code and the regulation is "stronger" than the original regulation. The same code regulation that applies in Edgartown, MA applies in Great Barrington, MA. You can't use Type "M" copper tubing for Potable water in either place, like they do in Florida. That doesn't mean that you can outlaw PVC and only allow Cast Iron "Because you like it".

    I'm talking about Plumbing and Gas. Heating and Oil Burners get to be another issue because the rules are more open to interpretation. Firedragon is always having  "Come To Jesus" moments with local fire department inspectors.

    Its always been my understanding that a listed AFUE boiler does NOT need a sprinkler over it. Like a Weil-McLain WGO-7 has a AFUE listing. It would not need a sprinkler head. A WGO-8 or larger would need a sprinkler. Local codes may require greater compliance but they can't be arbitrary and.capricious.
  • icesailoricesailor Member Posts: 7,265
    edited April 2014
  • JackJack Member Posts: 936
    ...A solution in search of a problem

    we went through this in VT several years ago when they legislated the 140 and tempering valves on all water heaters. They relented on the 140 for tankless and allowed 120 with the MV/TV. A year or so later they pulled the 140 requirement. I don't recall the model they spec'd but it added probably $250 to each water heater install. The 140 requirement was abandoned but the TV was not. So, you installed it and set the tankless at 120 and the valve at 120. The tankless is more accurate than the tempering valve. Some guys would install the valve and put a by-pass around it. Others dug in their heels, fought it and refused. It was an interesting time. I'm not sure where it is now having been out of the area for a few years. It would bleed over the border into NH though, occasionally at least.
  • icesailoricesailor Member Posts: 7,265

    Who came up with this misguided idea?

    The reason they stopped enforcing the regulation is like Garrison Keillor says about sticking your tongue on a metal flagpole when it is 20 degrees outside. Your tongue will stick to the pole.

    Or what any inquisitive plumber rapidly figured out when they installed a thermostatic shower mixing valve, fed with 120 degree water. The valve needs 140 degree water to mix properly. The hot water isn't hot enough to overcome the amount of cold water the valve is designed to always be passing.
  • kcoppkcopp Member Posts: 2,746
    I finally got around.....

    to installing a tankless WH in the aforementioned town. I went ahead and did piping as I normally did.... no problem. No mixing valve. Apparently it is only on Tank type water heaters that they require them.
  • JackJack Member Posts: 936

    To hear it worked out for you. So many times folks don't come back with the resolution of issues. Thanks for posting!
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