Reversed polarity outlet issue

[Obiwanna]

I picked up an Ampace Andes 1500 solar generator to use as an emergency backup power source for a forced air gas furnace. Plugged it all in (Andes 1500 has pass through AC) and the thermostat and blower fan run but no heat to be had. Noticed the furnace code indicator flashing a sequence that translates to:

Reversed line voltage polarity (control will restart if the error recovers).

I used a plug tester on the Andes AC outlets (all 4) and get “open ground” if unplugged from house AC and “hot/neu rev” when plugged in. Tested the house outlet and confirmed correct wiring.
2 questions:
1 - is this normal for a solar generator/inverter or did they screw it up during the design/build?
2 - if it was wired correctly and power went out, would the ground remain connected?
It works fine for “dumb” electrical loads but not for the one I bought it to serve.
Thanks in advance.

 

[SparkyJJO]

Open ground when unplugged makes sense.
It shouldn't be reversing polarity though. Sounds like a bad unit or bad design

 

[OzSolar]

Was your solar generator grounded when your furnace gave the error?

What voltage does you multimeter report on the Solar Generator for:
L-N
N-G
L-G

 

[mikefitz]

works fine for “dumb” electrical loads but not for the one I bought it to serve.

No neutral to earth bond. The furnace won't like that.
When plugged in you get the bond tranfered through the unit but perhaps they wired the outlet incorrectly .
Take the voltage measurements on the solar generator outlet, both plugged and unplugged from the supply.

 

[robbob2112]

When used as a UPS - it should be getting the ground from where it is plugged in. If you don't have it plugged in you won't get the ground.

The same may be true for the neutral line - in some systems the N line on the input and output are tied together and in others the N for in and out are not tied together unless you do it manually, but it might damage the system.

The safe bet to see if it is going to work is to have the furnace run from a plug and that plugs through your generator unit while the unit is plugged in. That should carry the ground through for the flame detector to be happy and let the generator do whatever it wants.

 

[Obiwanna]

Was your solar generator grounded when your furnace gave the error?

What voltage does you multimeter report on the Solar Generator for:
L-N
N-G
L-G

Yes, the UPS was plugged in to AC and the furnace was plugged into the UPS.

L-N 120
N-G 120
L-G 0

 

[SparkyJJO]

Well that's definitely backwards

 

[Obiwanna]

No neutral to earth bond. The furnace won't like that.
When plugged in you get the bond tranfered through the unit but perhaps they wired the outlet incorrectly .
Take the voltage measurements on the solar generator outlet, both plugged and unplugged from the supply.

Unplugged there is 120v L-N and 0V L-G or N-G, as expected. I presume that the ground remains connected even if the breaker trips or a utility line goes down. Is that accurate? If not, this won’t function as a UPS for my furnace.

 

[SparkyJJO]

Ground is connected always

 

[Obiwanna]

The safe bet to see if it is going to work is to have the furnace run from a plug and that plugs through your generator unit while the unit is plugged in. That should carry the ground through for the flame detector to be happy and let the generator do whatever it wants.

I have wired the furnace with a grounded plug and am plugging it into the UPS which is fed from the dedicated furnace circuit.

 

[Mattb4]

Reversed polarity. Many Chinese wired inverters have suffered from the problem. While not operating in AC bypass your unit would have to have a means of bonding neutral. It would also need to unbond when in bypass. You likely need to open up your unit and swap the L and N wires to the outlets.

Some inverters are claimed to have problems with using a NG bond on output. I have not seen an issue with any of the types that have a transfer switch (AC bypass) type function. However your units manufacturer may need to be consulted.