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  1. #14
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    It's actually the wrong pump to, should be brass or stainless. The floor is pressurized off the domestic water right? There is no flat plate HX separating them. After looking again I don't see any domestic water lines?

  2. #15
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,003
    A quick read through the installation instructions for this unit (model # as supplied by OP) indicates that the unit is not installed according to manufacturer's instructions (as per pictures) and as such the warranty will be void at least for the heat exchanger. Look under limited warranty, exceptions. Hand your HVAC friend the book and have him read that section. If nothing else have him look at the piping pictures in the book and see if what he did looks like any of the pictures.

    And yes, you're asking pros. What you are asking for is technical help. The part of the rules that others are referencing is where it says (not quoting here) clearly that suggestions or help of a technical nature are not allowed in the Non-pro areas of this forum.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  3. #16
    Join Date
    Jan 2013
    Posts
    23
    Air separator works fine. I can hear it work after I do something with the coolant.

    Pump is in the correct flow position and flow check valve is not stuck.

    Sound is not the pump. Pump has this humming/ambient noise and big clunking is coming from the tankless

  4. #17
    Join Date
    Jan 2013
    Posts
    23
    Quote Originally Posted by Joehvac25 View Post
    It's actually the wrong pump to, should be brass or stainless. The floor is pressurized off the domestic water right? There is no flat plate HX separating them. After looking again I don't see any domestic water lines?
    No - closed loop glycol

  5. #18
    Join Date
    Jan 2013
    Posts
    23
    Quote Originally Posted by firecontrol View Post
    A quick read through the installation instructions for this unit (model # as supplied by OP) indicates that the unit is not installed according to manufacturer's instructions (as per pictures) and as such the warranty will be void at least for the heat exchanger. Look under limited warranty, exceptions. Hand your HVAC friend the book and have him read that section. If nothing else have him look at the piping pictures in the book and see if what he did looks like any of the pictures.

    And yes, you're asking pros. What you are asking for is technical help. The part of the rules that others are referencing is where it says (not quoting here) clearly that suggestions or help of a technical nature are not allowed in the Non-pro areas of this forum.
    I have no clue what you're referring to
    Looking at the manual and cans see anything wrong

    It has 6 items listed under Limited Warranty/Exceptions and I dont see any of them applying to my installation

    PS. Im going by your motto "Never be afraid to do something new. Remember, amateurs built the ark; professionals built the titanic."

  6. #19
    Join Date
    Jan 2013
    Posts
    23
    Quote Originally Posted by firecontrol View Post
    If nothing else have him look at the piping pictures in the book and see if what he did looks like any of the pictures.
    What page?

    Thanks

    Greg

  7. #20
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,003
    Quote Originally Posted by Greg555 View Post
    I have no clue what you're referring to
    Looking at the manual and cans see anything wrong

    It has 6 items listed under Limited Warranty/Exceptions and I dont see any of them applying to my installation

    PS. Im going by your motto "Never be afraid to do something new. Remember, amateurs built the ark; professionals built the titanic."
    I knew that moto was going to come back and bite me someday. To be honest with you, I had been thinking of changing it to "Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit."

    Specifically exception #4. "or if the water heater is not supplied with potable water"

    By supplied they mean always.


    I meant look at the manual to see if what you have there as far as your piping, looks anything like what is listed or pictured in the manual.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  8. #21
    Join Date
    Jan 2013
    Posts
    23
    as far as glycol in the system and also says in this manual that it will decrease the warranty on the heat exchanger. It also says 1 can use this heater for a radiant heat installations.I even went further and called Bosch and asked for which coolant I can use. I was told by customer support that glycol based non corrosive coolant is okay

  9. #22
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by Greg555 View Post
    I have no clue what you're referring to
    Looking at the manual and cans see anything wrong

    It has 6 items listed under Limited Warranty/Exceptions and I dont see any of them applying to my installation

    I think he means that this is a water heater, not a boiler. It's not approved for closed loop use and doesn't have a ASME stamp as such. The warranty is completely void in a closed loop installation. The diagrams show a recirculation application and a combi application. Both of those but HE warranty to 3 years. Regular water reating application have a 15 year warranty.

    I'm not saying it won't work, just that it will likely have shortened HE life. The Bosch already uses a Copper HE. I think a wall mount boiler would alway have a stainless steel HE. Copper is just softer and will errode quicker, but reduces mfg costs a little and transfers heat a little better. A a closed loop boiler, I don't think you'll get more than 8 years out of it unless you're rally careful on flow rates. The Glycol will likely reduce the peak effciency and could cause issues at low fire. COme to think of it, I'm not sure any boiler is approved for direct glycol heating. You normally always see a heat exchanger to seperate them.

  10. #23
    Join Date
    Jan 2013
    Posts
    23
    I don't really care about the warranty. I can even drain it for the summer out of coolant and flush it.

  11. #24
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    725
    The tank-less water heater is flashing to steam for lack of flow. I assume this is an "open" system, running potable water through the floor? How did you size the pump? Low-mass water heaters and boilers should be pump to rather than from followed by the expansion tank and air eliminator.

  12. #25
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Great catch. I thought something was amis in the burner side with that sound.

    I wonder what temerpature this unit is set to? I know glycol has a tendency to aerate... A LOT, when pumped. I'd taken samples on the discharge of a larger circulation pump (like 50HP) and it's almost cloudy. A chiller doesn't mind so much, but a boiler might not tolerate all those little air pockets. IT may also fool the flow sensor into thinking it has more flow than it does.

    I'm still betting on the pump running backwards. But otherwise the less than ideal direction of flow and location of hte expansion tank isn't helping it sounds like.

    I'd get a pro that knows boilers, or look up soem diagrams for wall mount boiler installations.

    Just curious, but what percentage of glycol are you using? I assume it's a snow melt application. You really should have a plate and frame heat exchanger to create a seperate loop. You'll find that every single installation diagram you'll find for snow melt shows a heat exchanger. Rannai has a design guide online wiht dozens of installation examples for theri tankless water heater. However, their domestic potable water models always use potable water in them. IF you did use potable water wit ha HE for snow melt, I'd make very, very sure that the snow melt side had lower water pressure in the loop at all time. Plate and frame HE will eventually fail. Contaminating poteabel water isn't something to mess with. Depending what you contaminate it with, you can kill people. ALL plumbers or anyone messing with a poteable water system should take a class in backflow preventer training.

  13. #26
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    725
    Glycol will create more problems with heat transfer and will de-rate pump performance in any boiler. Tank-less water heaters require more attention to detail and will not typically produce rated output when space heating...even with a plate heat exchanger. You will need a primary/secondary and pump to make it work.

    We design and install radiant floor heating systems daily and never use tank-less "water heaters" and very rarely use propylene glycol except in snow melting systems. We do use condensing boilers and are careful to follow minimum flow requirements, which are often met with a single pump by the way.

    On occasion we will use a Combi boiler, which is more suitable for space heating and domestic isolated with a plate heat exchanger. The argument for using a tank-less water heater for space heating is a short one; they are cheap. But they are not necessarily easy.

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