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Agnes Member Posts: 1
I have a baxi luna wall hung dual use system and have been told I need to have an expansion tank installed, is that necessary for it to function?


  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    Yes if it is to function safely!

    Get the installer back.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    the tank

    comes already in the Baxi Luna's. Check your OEM I+O manual for verification. It's a flattish chamber to the left of the cabinet, inside, if I recall.
  • Slimpickins
    Slimpickins Member Posts: 323
    Bob is correct

    I found out about the internal expansion tank on my first Baxi service call 'bout 5 years ago, that already had an external tank installed as well. I was having a hard time purging and happened to read the manual and found out and removed the external and charged the internal tank and got it purged.

    I also got help on here in regards to setting the gas pressure on a badly running Baxi. It was someone on the east coast named Bob I believe, Bob Bona, was that you?
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    I did not know that, see we

    learn something new everyday.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,216
    How do we know

    that an additional expansion tank is needed without knowing the volume of the system?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083

    I had put in a Laars HT330 LP about then. They were having gas line whine depsite slight oversizing. Laars rep came down to the site and calibrated the gas valve. I couldn't be there with him, just heard about it.
  • schoondogg
    schoondogg Member Posts: 2
    edited January 2011
    Baxi pressure stabilization

    I have a Baxi Luna 380 combo boiler.  Installed 7/08.  During the 1st season, I began to get the low water cut off alarm.  My installer, who since went out of biz and moved from the area recommended an auto fill valve.

    After 2 seasons of adding water, it was installed in 11/10 ending the need to manually add water to the system.  There were no signs of leak anywhere.  With the volume of water I was getting daily, I would have been flooded somewhere in the house. 

    The problem now is difficulty stabilizing pressure.  I have attempted to adjust the pressure via the auto fill valve and also lowering the operating temp of the boiler via the front controls.  I now have water thru the prv.  I contacted the installer who is also the only person in my area to have been trained.  He has been trying to help and suggests checking the internal expansion vessel and if further action is needed, installing an external expansion vessel. 

    I am checking to see if anyone has suggestions and to check the solutions suggested by my installer.  The local distributor has been no problem and I am unable to find anyone trained on this equipment.
  • Tim McElwain
    Tim McElwain Member Posts: 4,517
    What does the piping system

    outside of the boiler use as emitters such as baseboard, radiant under floor, radiators, convectors. If radiant under4 the floor you could have a leak there perhaps.

    Give us a little more information. Perhaps some pictures?
  • World Plumber
    World Plumber Member Posts: 389
    PRV on wall mount boiler

    Has anyone had experience using an auto feed on the wall mount self contained boilers? I have 14 of them at our camp the one connected into the original piping that is a maze of welded and threaded pipe goes off on low pressure about every three weeks to a month. Due to seepage in some of the welds that are in the stone walls. Do you think that would be an answer to the problem?
  • schoondogg
    schoondogg Member Posts: 2
    Boiler emitters

    Thanks for the reply.  The emitters are hot water baseboard.  If I had a leak with the volume of water I was losing, there would be a large puddle somewhere that would have shown by now. 

    I had a note from the installer today to re-commision the system.  After purging to install the auto feed, not sure it was ever checked for pressure balance on the internal tank. 

    More after that happens.  Hope that is the solution.

    Thanks again
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