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Baxi Luna 310fi DHW issue

I have a Baxi Luna 310fi heating / dhw boiler which doesn't seem to be initiating the dhw service unless at least 2GPM of water is flowing. This causes me to have 2 faucets on when doing dishes, a faucet + shower to bathe etc. I have already changed the bladder in the dhw valve and that hasn't helped. Thoughts?

Also, from the manual that I actually have, it states the minimum required to initiate DHW is 0.66 gpm here in the US. Most of my faucets are rated at 1.5 gpm (trying to be nicer to the environment) and even with one open at full I still have to have a second one open just to get the dhw to kick in.

Any help is appreciated!


  • LordMael
    LordMael Member Posts: 2
    I'm wondering if it is the spring inside the DHW assembly is too tight or if I need to replace either the DHW assembly or the whole 3 piece valve assembly along with the positive and negative pressure tubes :| (this would be over $500 in parts alone not including labor) and finding a plumber in my area that knows what these are and also knows how to work on them has been difficult.
  • Tom_133
    Tom_133 Member Posts: 888
    If my memory serves me correctly the 310 has a rubber diaphragm that when water enters swells and triggers a microswitch. That rubber is probably worn out, typically thats what happens and you can just replace the rubber for very little money though it's easier to replace the whole thing, actuator and diaphragm assembly. I don't know where you are located but its not hard to find a good local guy, call your local Baxi wholesaler and ask who they recommend. To find the wholesaler go to Baxi's website. Wallhungboilers.com or something like that
    Montpelier Vt
  • superdave
    superdave Member Posts: 155
    What town are you out of?? Also did you make sure that diaphragm was in properly and that the spring is ok last what about the needle did you sand it up and grease it. If you turn on one faucet douse the needle com out all the way??