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High Delta T

Hi,

It's been a cold Thanksgiving weekend. No heat since Wednesday night. I couldn't figure out why it constantly getting high delta T (lockout code 14) and occasionally lockout code 4. Have someone came by and diagnosed bad boiler pump. I have replaced a new pump yesterday evening but still getting lockout code 17. Boiler seems to run fine, though return temp can go only as high as 90 F. We live about 20 miles west of Boston and the house is a little bit under 3000 square feet; Burnham Alpine ALP150W with HTP Superstor 45 gal. indirect heater, 3 zones.

I am sorry my message is a little bit cryptic since I am an immigrant and had very little back home so kind of mechanical challenged. Any help will be appreciated.

KC

Comments

  • Leon82
    Leon82 Member Posts: 684
    Can you post a picture of the boiler and any pumps or zone valves
  • Leon82
    Leon82 Member Posts: 684
    edited November 2018
  • NeedHvacHelp
    NeedHvacHelp Member Posts: 5
    Thank you Leon82. My mistake. It was soft locked out code 14 (Delta T inlet/outlet high). I did see 17 but it would clear itself. 14 is constant and the boiler would go into standby delay with red screen.
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 2,686
    edited November 2018
    Sounds as though the water is traveling too slowly through the boiler, unable to pick up all the heat from the heat exchanger.

    Required flow for your boiler is 9.2 gpm at 6.6 ft. head which a small pump can do easily. Now that you've ruled out the pump, I'd say that there's air somewhere in the system, preventing flow.

    Do you have radiant heating in the floor or radiators? What is system water pressure?
    Often wrong, never in doubt.
  • Leon82
    Leon82 Member Posts: 684
    Make sure the pump is pumping in the right direction .
  • NeedHvacHelp
    NeedHvacHelp Member Posts: 5
    Alan and Leon82 thank you very much for the info.

    Water pressure is 20 psi. The house has three zones. First floor has an ADP hydro air handler, basement has 50 linear feet baseboard and second floor also has a hydro air handler but I am not sure the brand.

    I will double check the pump I put in - I believe it was the same direction as the old one I took out.

    KC
  • NeedHvacHelp
    NeedHvacHelp Member Posts: 5
    Boiler pump direction is correct. Finally got heat for about a couple hours. High delta T showed up again.
  • NeedHvacHelp
    NeedHvacHelp Member Posts: 5
    Searched the forum for delta T issue. Mine seems like “Lochinvar WHN085” that has a faulty sensor of sort.
  • Leon82
    Leon82 Member Posts: 684
    Maybe unplug it and inspect the connection, the manual may have some values you can check with a multimeter also
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