Munchkin Boiler No error code

Phil Yarbrough_2

Hi Guys, I'm out of town and one of our techs is trying to troubleshoot a munchkin 80m. The unit will fire in DHW mode and satisfy the thermostat. However it will do nothing in heating mode.It's as if there is no demand signal, We've even changed the board with no result. I tried to walk him through everything I could think of over the phone, but you know how that goes. I'll be back in the AM, but I was wondering if anyone had any ideas?
Any help will be greatly appreciated.

Phil Y

jwade55_3

Any chance you are using a vision 1 kit.

Check that it may be in WWSD mode.

J

Guy_6

Outdoor

If it has the outdoor sensor, disconnect 1 of the leads to it, disabling it. You will also want to be sure that the high operating limit is properly set. Press S3 until you see "C", alternating with a value. That value has to be set as the highest water temp for your emitters REGARDLESS of what you set in the Vision programming.

Next, disconnect the indirect sensor, as it may be picking up electrical interference and throwing the signals off.

If nothing else, completely disconnect the two grey TT wires from your end switch and connect them together.(for diagnostic purposes only). Actually-be sure that they are connected to an end switch or T-Stat. If they are dead ended, there is no heat call.

One of these things should put you on track towards the problem. My money is on the outdoor sensor area, which is usually just the reset curve programmed improperly.

jerry scharf_3

What's the code for function 1

If the unit has a vision 1 controller, have him check function 1 and make sure it is set to "de". It is possible to set the unit to DHW only, which would produce exactly the result you are seeing.

jerry