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navien comi boiler ch240 ng asme

mjfmjf Posts: 5Member
During the 1st heating season my Navien operated at a pressure reading of 21.8 during a call for heat. manual shows an operating pressure between 7 and 30 psi. After I drained the unit (Oct 30, 2014)before the 2nd heating season to clean. the unit operated at the same pressure as the last season. Over the course of the next 2 months the pressure slowly went down, ended up with a reading of 14.2 while producing heat. I checked the crawl space and found no leaks when the circulating pumps were running. During the last week the pressure went up to 16.7 when running. The manual says that the auto feed will only add water when pressure is lower than 7.4 The Navien seems to be operating normal except for the reading on the pressure gauge. Do you have any ideas what would cause it to run at a lower pressure this heating season. I have hot water baseboard. Appreciate your help

Comments

  • SnowmeltSnowmelt Posts: 1,093Member
    Nice little set up I see, nothing wrong with that set up.
    But you don't need the pressure reducer just the back flow preventer.
    Your system and every system out there loses water from natural convection. Without getting into it, flip the handle on pressure reducer, your pressure will go up. One it steadies out I want you to shut the valve so no more water goes into the space heating side of the unit. Then watc day by day your pressure will go down till the machine shuts off on low pressure.
  • IronmanIronman Posts: 5,151Member
    Snowmelt said:

    Nice little set up I see, nothing wrong with that set up.
    But you don't need the pressure reducer just the back flow preventer.
    Your system and every system out there loses water from natural convection. Without getting into it, flip the handle on pressure reducer, your pressure will go up. One it steadies out I want you to shut the valve so no more water goes into the space heating side of the unit. Then watc day by day your pressure will go down till the machine shuts off on low pressure.

    Snowmelt said:

    Nice little set up I see, nothing wrong with that set up.

    I see more than one thing wrong with it besides the PRV inline with the electronic fill valve:
    1. How about the string hanger wrapped around the board supporting the primary loop? If the clamps on the unistrut are secure, they'll hold the piping just fine.
    2. The spacing between the secondary tees is not correct.
    3. There's no discharge pipe from either relief valve to the floor.
    4. The condensate drain hose is not properly supported and is trapped.
    5. The high voltage wiring is not secured.

    I guess other than these minor issues, there's nothing wrong.

    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • SnowmeltSnowmelt Posts: 1,093Member
    You have a point with 3,4, and 5. I was more concentrating with the design of the system. If the poster asked to coment on whole job that's most likely what everyone pointed out. But the fact that the poster was having pressure problems, that is what is wrong with getting a little higher on the pressure.
    but yes the wiring needs to be more secure, the p.r.v. Needs to be extended to 6 inches to the ground, the condensation hose had to be addressed, and the return of the zones have to be looked at closer, to much Pex in picture didn't know what line was what.
  • mjfmjf Posts: 5Member
    When I raise the lever to the straight position where it pushes on the push rod it does not seem to do anything like open the valve to full pressure. I don't hear anything or see pressure increasing on navien unit. I read that you can remove the fill lever cap and loosen the lock nut and turn screw clockwise to increase pressure. Could I also do this by connecting a hose with a pressure gauge from the domestic water inlet port to the primary loop? Is there any disadvantage when operating at a lower pressure of 16 compared to 21. If there is not I may just leave it alone until I service it in the summer. Also I should have mentioned that the pictures were taken before the installation was completed. All issues were addressed except the incorrect spacing between the secondary tees. I did not know anything about that. Thanks for your help.
  • IronmanIronman Posts: 5,151Member
    Since the boiler will automatically maintain the fill pressure, you could simply adjust the screw down on the fill valve so it sends constant pressure to the boiler. It would be like it wasn't in the line.
    Do worry about the fluctuating pressure on the display. It will increase as the boiler gets hotter and will also change as it switches to domestic heating. Just make sure it doesn't go below 12 psi.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • SnowmeltSnowmelt Posts: 1,093Member
    You said you want to add some pressure by adding water from the domestic water side. What I do to quick fill the system is get a washing machine hose and add water from the domestic side right to the boiler side service valve. Don't let the water pressure go above 20 pounds. Around 15 to 20 is fine. If you replace the duel pressure regulater and pressure reducing valve with just a pressure reuducer you will be fine. After that you can do a test you can have a running system. Then take some water out of the system and listen to the fill of the machine let water in and the pressure build up.
  • mjfmjf Posts: 5Member
    Thank you for your help. I will monitor the pressure. If all stays the same I will adjust it when I clean and flush the boiler in the summer.
  • SnowmeltSnowmelt Posts: 1,093Member
    What pressure is it at today? Did you take the pressure reducer out of the equation.
  • mjfmjf Posts: 5Member
    I did not take the pressure reducer out yet. It's now operating between 16 and 18.2 while running depending what zone(s) are calling for heat. I checked out another ch-240 in my neighborhood and his was running at 16 (also on 2nd heating season). I guess this pressure reading is normal.
  • SnowmeltSnowmelt Posts: 1,093Member
    Nothing wronge with that amount, did we ever say it wasn't normal? The machine adds water when the pressure gets low. I think it might go up to 18 and shuts off. I think it adds when it hits around 10 psi
  • mjfmjf Posts: 5Member
    Thanks again for all your help
  • ProblemSolverProblemSolver Posts: 190Member
    edited January 2015
    The pressures between 17 & 20 during heating season are normal.
  • jonny88jonny88 Posts: 1,139Member
    Its a Navien guys at least he tried to make it look pretty.Although a personal peve I hate to see pex ina boiler room.They really make it idiot proof now with their premade primary loop.Lets see in 5 years I am curious if these units are going to stand up
  • ProblemSolverProblemSolver Posts: 190Member
    I also forgot to mention, the Navien boilers come with their own pressure reducing valve. I always install a by-pass water feed into the "boiler supply loop" to simplify purging air from the zones.
  • Paul48Paul48 Posts: 4,492Member
    That's some funky looking P/S. I think it breaks some of the rules, regarding straight run to the tee.
  • RobGRobG Posts: 1,850Member
    Agreed, I have no idea how it works. You've got pumps working against one another. I have no idea what's going on with the pump on the right side of the photo that bridges the primary loop?
  • Paul48Paul48 Posts: 4,492Member
    Rob...I think there's a close tee off the back side....but...wow
  • SnowmeltSnowmelt Posts: 1,093Member
    I have a Navien plumbing diagram book from 5 years ago which isn't out anymore. I remember seeing so etching like this.
  • Paul48Paul48 Posts: 4,492Member
    There's just some mistakes. The primary loop should be bigger, allowing 8x's pipe diameter on the supply side, and 4x's on the return side.
  • jerseyfitterjerseyfitter Posts: 11Member
    Aren t relief valves supposed to be vertical?
  • TraverseTraverse Posts: 1Member
    Is the water pressure into the autofeeder supposed to be regulated or full domestic pressure?

  • byroncheungbyroncheung Posts: 2Member
    hi my ch240 don't have an auto feeder. a tech came to replace a bursted hydro coil in my air handler. it worked for a few hours now it stopped giving error code e02 (low pressure on heating side). do i need to manually add water to the system? if so how do i do that?
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