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My 1st Baxi

Bob Forand
Bob Forand Member Posts: 305
Hi Steve, with the description you gave there a couple of things that could be wrong, starting with gas pressures not set up properly. If you email me your phone number to [email protected], I will call you and try to help walk you through it.


  • Eric_8
    Eric_8 Member Posts: 66
    My 1st Baxi

    I haven't paid any attention to the Baxi posts because I've never seen one in my area until today. Got called out on a Baxi Luna 310Fi and of course there's no installation manual. The DHW temp is fluctuating and the burners seem to be short cycling. I turned the temp dial back and forth and the burners don't seem to modulate. I turned on a nearby lav faucet and tried to adjust the temp dial and the temp would either overshoot and be way under the output temp i was trying for. The dial seemed really sensitive because just a slight turn, the temp would go really high, to around 150. The heating side seems to be working ok but I really didn't spend a lot of time checking it out.

    Man, this unit looks hard to work on for a guy with big hands. If anyone can help me out here and tell me how to access parts in the tight area and tell me what to check out, I'd kindly appreciate it.

    Thanks in advance, Steve M
  • Dave_4
    Dave_4 Member Posts: 1,405

    Sounds like the domestic water sensor on the outgoing pipe
    is faulty, replace that and all should be good one of there
    most common problems.
  • Steve M_2
    Steve M_2 Member Posts: 121

    Man, I love the wall!
  • Ralph_7
    Ralph_7 Member Posts: 2
    baxi luna 3.10 Flue/fan fault

    man i need some help...
    baxi luna 3.10 hooked to DHW and Radiant floor system. when the system senses demand it comes to life and the and sometimes the fan kicks on and some times it doesnt. sometimes when it's running it will just stop and then the Fan/Flue fault light will flash.
    the outfit i bought it from has had a falling out with vendor and can no longer get parts. said this was a common problem with about 40 of them he installed for city project and baxi told him there was no manufacture problem. any help anyone can give would be great... i can install parts if need be and i can get them...
  • Bob Forand
    Bob Forand Member Posts: 305
    Hi Ralph

    Hi Ralph, this sounds like an odd one. Sometimes it does, sometimes it doesn't. Strange..the sequence is, the fan comes on, proves draft,pressure switch opens, then the boiler fires. Knowing that the fan, draft, or pressure switch is the issue, lets start there. Is the vent placed in a high wind area ? Are the venting connections tight ? There is a flue venturi inside of the elbow that connects the venturi to the pressure switch, that could be blocked. You could try to stick a pipe cleaner in the port on the elbow to see if it is blocked. It is also possible that the pressure switch is malfunctioning. You can check that by sucking on the tube from the venturi and listening for a clicking sound. I would lean more towards a vent issue above all else because of the symptoms of sometime it does and sometimes it doesn't.
  • Ralph_7
    Ralph_7 Member Posts: 2
    baxi update...

    here's what i'm seeing...
    either the DHW turns on or the heating system kicks on and the circ pump comes on. on the panel it tells you which one it is. then after a couple seconds there will be a "click" from behind the panel and then the fan turns on. a split second later i can hear the boiler fire up and the flame light comes on and all it well. it will heat upto and maintain what ever temp i have it set on.
    Sometimes though i do not ever hear the "click" behind the panel and the fan does not come on, and after a couple seconds the fan/flue fault light will start to flash. there are other times when it will be working fine and then just stops and the fan/flue fault light gomes on. and other times when it is in heat mode and DHW comes on it will try to make the switch but then the fan goes off and then i get the same fault light. always it's the same fault light. I've checked the Venturi, and airflow switch and they're clean, no condesation and seem to work well when i suck on the tube. No clogs or stuff in coaxial vent pipe. I used the standard vent pipe with about a 15" extension with a very slight lean away from the baxi(about 3/8" over the length). vent is in a protected area without full wind or rain. thanks in advance for any help!
  • Bob Forand
    Bob Forand Member Posts: 305
    Hi Ralph

    Hi Ralph, I just sent you an e-mail. I wrote in it that you can take your electronic manometer and pull the tube from the pressure switch off of the venturi, connect the manometer and you should see a negative pressure. That isolates the pressure switch from the equation. The next step is to listen to the relay on the control board when the fan is starting to lock out. You can try to tap on it with a screwdriver to see if it is just sticking. I suspect after reading your last post about the clicking that the PCB board is bad. That relay is non-replaceable.
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