Do any of y'all have experience doing this conversion either with a kit or from scratch? As many are, we are looking to add backup power to the house and I currently am narrowed down to a full scale standby generator, or the PowerHorse 27000 "portable" generator from nothern tool. I like the idea of a portable generator because then it gets a bit more utility than just the occasional power outage, and I picked this one because it indicates THD<5% so should be fine with home electronics and has enough power to be able to take a NG derate and still run the whole house. The only issue is this one doesn't seem to have a commercial kit to add NG as a fuel option. Looking at the various parts diagrams, it looks like it maybe has the same carburetor as the GP17500 which does have a commercial NG conversion kit
GP17500 carb assembly:

PowerHorse 27000 carb assembly:


my thought would be to order the powerhorse and the conversion kit for the generac, and first try to fit the adaptor/snorkel straight on, and if that doesn't work then get a machine shop to modify it or make me a new of basically the same design to fit the actual measurements. But before i spent a bunch of money on this, wanted to see if anyone has any experience with this type of work or thoughts on this plan, because if i talk my wife out of the permanent standby and into a portable gen, and then can't get it running on NG, it will not go well for me.

I haven't done it, but several of the companies offering conversion kits state that you can call them if your product isn't listed.

They're probably inundated right now, but you might have some luck figuring out which kit you can somewhat use and maybe have to retrofit some of the mounting, etc.

Actually doing this conversion this weekend with a Predator 3500 inverter and NG kit from US Carburetor .

Will update.

Please update with your results. I'm thinking of 2 Predator 3500s in parallel, but this would let me run the central AC for about the same price as 2 smaller units. Nat gas is a must for me though, esp with a giant gen.

I dont think you'll be able to run central HVAC from a parallel kit. Your HVAC is likely 240V. The parallel kits for the Predator generators are 120v 50A output.

There may be a kit that gets you 240 but I have not seen one.

240v problem and LRA problem. I've spent way too many hours looking at this and tend to think 7kW isn't going to cut it. I have both 3ton and 2ton systems. The Locked Rotational Amps on the 2ton is 62a.

There's more to it then that, but basically the A/C unit is going to draw 240v * 62a = 14.8kW when the compressor kicks on. This could be mitigated by adding an "inrush" capacitor to the A/C to assist with startup but haven't gone too far down that rabbit hole yet.

I've written off AC with the predator option. The parallel kit is 120v.

I have no idea if this kit is a real solution, but its one I would be looking in to if I end up with a gen that would have a chance of cranking the AC.

https://www.micro-air.com/products_easystart_368_softstarter_microair.cfm

So I don't know about that model specifically, but from reading on some hvac forums it seems the soft starts generally perform as advertised. Saw one set of details where the soft start took starting current of a 5 ton Lennox from 90-100 amps down to 30 amps. For reference the full load operating amps of that unit is 23.5.

Did the NG/propane conversion for the predator 3500. Easy and runs quiet. Doesn't even smell.