Would an loose breaker make your gfi's kick off? Is hooked up with the heater/air unit.

All depends on exactly how it is wired, Can you provide more detail, as I do not understand your situation regarding the HVAC unit and how it relates to a loose GFI breaker

Seems they are on the same breaker. Is a rooftop propane unit.. replaced the thermostat on wall last year. This year heater would not fire up. When tried it popped the gfi's in kitchen, garage, bathroom(wallplugs). Ended up replacing the ignition switch box up in unit. They said it was bad. After twice starting up it wouldn't again. Then it tripped the gfi's again. The breaker doesn't trip but is loose(in panel). Why would the gfi's pop if they aren't supposed to be on the same breaker? We are confused and have been screwed over for a few hundred dollars already. I know how to work with electrical, have for years but not into the chances with the house current things. Going out there today to rewire on the thermostat that (is my friend's mom's house, been 22 degrees at night the last week here) that she put on this last summer. Hoping this could be the problem. Any help and will try to have a better info after I get back. Always very careful with the power. Propane guys won't check it and PG&E would only just look at the breaker and say nope nothing wrong there. Shouldn't they do a continuous power test? We wonder if the electrical power is steady to the unit. Thanks for trying to answer. Jp

I am not sure every thing is clear now. You have a regular breaker that is loose? It feeds both the heater and some GFCI outlets? I will leave the real electrical issues to tkrussel and look at the heater.

If the heater is tripping the GFCI, something in it is shorting to ground. You need to follow the sequence and note what happened last before it shuts down again. There is always power to a 24 volt transformer in the heater. Much of the circuitry in the furnace is powered by it, and I don't think a short in the secondary of a transformer would trip a GFCI supplying its primary. In a modern furnace, the 24 volt power from the thermostat, or DC from the board first closes a relay to the 120 V inducer blower, then the ignitor, gas valve, flame detector, and after a delay, the blower. In most furnaces, only the transformer and the 2 blowers are connected directly to the power supply. If it kicks the GFCI off when one of the blowers starts up, you need to check it and perhaps replace it.

I think tkrussel is going to say you need to replace the loose breaker and add another to give the GFCI circuit and the heater each their own. He and I will support choosing to have an electrician work in the breaker box.

I wish I could get a better idea how the circuit is wired, but I get the impression that there may be a crossed neutral or a neutral to ground short to cause a GFI for the kitchen to trip.

This situation may require a good service electrician with troubleshooting skills to find the cause of this problem, as it does not seem to be a simple problem of a loose breaker.

Yes I agree with Labman that any breaker in a panel that seems loose is a potential cause of hot connections or intermittent power loss, and needs to be checked and repaired as necessary, as ignoring it may cause more damage.

If you can describe the circuit better perhaps I can get closer to a cause and solution.