Losing pressure in combi boiler

Discussion in 'Boiler Forum' started by Dave636, Dec 13, 2019.

  1. Dave636

    Dave636 New Member

    Joined:
    Dec 13, 2019
    Location:
    Ontario
    Purchased house in the last couple years and it has a Baxi ht 330 combi boiler. During summer months I get the e119 code requiring to pressurized probably once every 2 weeks. Winter time when the floor heat turns on I get the code probably every 2 days. Had a heating guy come out and I think my system intimated him as he didn't touch a thing and said they would have to have multiple people out to run a pressure test on the system. He was nice enough to charge me for the service call. Not saying that does not have to be done to figure out the problem. I see on multiple forums people experience these issues due to the internal expansion vessel, I have no external. Opened up my boiler today and it looks like it has leaked in the past out the side see pic. I mentioned to this heating guy about seeing multiple people indicating expansion vessel issues which he reported if there was a leak it would be coming out the pressure release valve. I plan on getting someone else out to check but what do you think should the expansion vessel be replaced prior to further leak testing?
     

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  2. WorthFlorida

    WorthFlorida The wife is still training me.

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    Retired
    Location:
    Orlando, Florida
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  4. Dave636

    Dave636 New Member

    Joined:
    Dec 13, 2019
    Location:
    Ontario
    I will look into replacing, thanks.
     
  5. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    Given that most boilers are way oversized for their space heating loads, and most combi-boilers are way oversized for the radiation (especially on multi-zoned systems, run both this math and this math before picking a replacement to make sure you don't short-cycle it into low efficiency and short lifecycle.

    The minimum modulated output of a Baxi HT 330 is pretty close to the heat load of my place when it's -15C outside and WAY over my average wintertime heat load, which means it would basically never modulate on space heating calls at my house. YMMV.
     
  6. Dave636

    Dave636 New Member

    Joined:
    Dec 13, 2019
    Location:
    Ontario
    Sorry when I said I would replace I meant I would replace the expansion vessel not the whole boiler.
     
  7. Dave636

    Dave636 New Member

    Joined:
    Dec 13, 2019
    Location:
    Ontario
    Just want to report it was the expansion vessel. To. Anyone that is losing pressure in their system press the the schrader valve. When I took the vessel out it was heavy compared to the replacement. I pressed the valve and water came out. Since replacing pressure holding strong. Was a bit scary filling boiler back up as water kept pouring out of the pressure relief valve, I think just due to air in the system, eventually resolved in a few minutes. Took a few hours for all the air to finally remove out of the system.
     
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