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Low flame current and other error codes

Ok folks. New and excited to be here. Bought a house with a hell of a heating system. Here are the details:

basement- in slab hydronic heat (1600 sf),
main floor- 1/3 of area in floor hydronic heat with none under hardwoods in rest of area (1800 sf). Modulating gas forced air furnace for supplement (used to be a hydronic coil in air handler, but exceeded heating capacity of boiler). 

Domestic hot water is from two electric hot water tanks. 

Goods: 70,000btu cadet ND070  (lochinvar) boiler and furnace is a Bryant evolution 98 mod

Problem with boiler is as follows. N05 code: increased fan speed low flame current. So I replaced flame sensor since it looked pretty cooked. It still throws N05  code. Replaced to gas furnace which heats house better than hydronic air handler, also warm outside. No demand on boiler since no call for heat. One zone calls for heat. Boiler heats, but does not stop till it hits setpoint which throws a B01 code. Stops heating so outlet is cooling below set point. Kicks back on then throws a E11 code and/or a B02 code. No flame or anti cycling respectively. 

Does anyone have ideas? My hvac guy is stumped and helping me on the side. Your help would be greatly appreciated. Thank you. I’m sure this won’t be my last heating question in this house. 

Comments

  • earthnsurf
    earthnsurf Member Posts: 3
    I should add prior to replacing flame sensor it was reading about 4 micro amps. Now it’s about the same down to 2 micro amps. 
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,453
    I would start by checking the flame sensor connections including any grounding (the flame current goes through the gas flame to ground and finds it's way back to the burner control)

    and combustion test the burner and clean the burner and boiler
  • earthnsurf
    earthnsurf Member Posts: 3
    That is definitely on the list to do, the cleaning part at least. I checked wiring which looked good. No resistance in flame sensor wire. Can’t see where the ground is. The igniter has the ground with spade connected. Plastic jacket on spade connected is dry and cracking. Is it weird to have that sequence of codes though? How do I rule out the board? Thank you for your reply. Much appreciated.