Water Furnace problems

[gsxrsquid]

Water Furnace Premier II
ATV045D110CLT #NG8575

I have worked on commercial water source heat pumps but never water furnace. I got the call it wasn't working. The drain light was on so I vacuumed out the drain. I pulled the covers and the pan was bone dry and I poured water in the pan which drained freely. I powered it up and it ran fine.
I got a call to go back for the same problem. Again the Drain light was on and the unit was bone dry inside. Drain line clear. I killed power and restarted it. It ran for a couple minutes and an amber DHW light came on. This unit has two water inlets and 2 water outlets. the top in/out is marked DHW which I am guessing is domestic hot water. Admitting I know nothing about this thing I didn't want to get too involed. I did turn on the hot water in the kitchen to see if the light would go out which it didn't. After a period of time the compressor shut down. The blower kept running. Then after a little while the DHW light went out and the unit started up again. The unit did trip off on the Drain again and when I checked the unit was bone dry.
While it was running I noted the top of the accumulator was warm to the touch rather than cool or cold.
One item of note that may mean nothing. This H/O has been using diposable filters for years. Recently he changed to a washable electrostatic filter. the filter was not dirty.

Also while looking at the control information I saw a dip switch selection that let me switch trouble codes to LEDS on panel. when I turned it in the on position the unit did not start and had Drain, HP, and LP lights on. When I put it back to off it returned to the previous behavior. If it is something simple I'll give it a shot otherwise I am tempted to refer him to water furnace dealer. As always any help is appreciated.

[Milk man]

The condensate sensor is a three part system: a wire, air coil and water in the drain pan. The wire (spade terminal) and air coil act like a set of normally open contacts, and the water is the switch. When water in the drain pan fills up and touches the spade terminal, the unit will lockout on Drain.

To check condensate sensor:
Jumper between C and Y2 and O to start 2nd stage cooling. Observe the water level in the drain pan. If the unit is locking out on condensate and the drain pan is dry, remove the condensate wire from the drain pan and tape it out of the way. Be careful to not ground the wire out because that will cause the unit to lockout on drain overflow. If the unit is still locking out, check the brown wire all the back to the logic board for a short to ground. Remember that the condensate sensor is just a wire looking for a ground. If it touches any metal in the cabinet, the unit will see that as a drain fault.

If removing the wire from the drain pan stopped the false drain lockouts, put the condensate sensor back in place in the drain pan. Pay close attention to how far the spade terminal sits down in the drain pan. If the terminal is pushed all the way down so that it is touching the bottom of the drain pan, this will cause a drain lockout it there is any trace of water. If the spade terminal fits loosely in the drain pan, spread the terminal open to make it fit snug in the drain pan.

[Milk man]

The drain light was on so I vacuumed out the drain: Make sure the clear vinal drain tube forms a trap in the bottom of the unit. Add a vent in the outlet of the drain cabinet.

amber DHW light came on: Think this means hot water limit thermistor > 130º F.

trouble codes to LEDS on panel. Drain, HP, and LP lights on: Did you have SW2 #1 off, #6 off, and #7 on ? If so this shows thermostat inputs. Drain = Y1, HP = O, and LP = G.
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"Current Fault Display Mode" Should be used when troubleshooting a lockout condition while the unit is going through a fault retry.

Place SW2 DIP switches #1 off, #6 on, and #7 on to see if board is see any faults during a fault retry. It retrys three times before locking out.

[gsxrsquid]

I checked the spade and it wasn;t pushed more than about 1/2 from the bottom.

I know there is a curve in the clear vinyl hose but not sure if it actually forms a trap. This system has been there a few years and it is a new problem. I'll let you know what I find.