Single 120v element options?

Starting to do my homework to build an eBIAB system. Would like to stick with 120v since I have 120v service in both the front and back of the house. Winter I brew in the backyard in the sun, summer, I brew in the front in the shade.
Can I do 5 gallon batches with a single 120V heater element or would I really need to use dual elements? What is the recommended total wattage to bring 6+ gallons to a boil without having to wait all day for a boil?

Just remembered, I do have 220 service in the garage for a 220 heater I never use. The receptacle is like the one attached. It's about a 40 foot run from the plug to the front or back of the house. Can I use an extension cord for this type of service to my e-brewery if the 120v single heater isn't quite enough?

Thanks.

If I'm not mistaken, that's a 20A 120V receptacle...

It is 20A - 240V:

Receptacles-Commercial-20-Amp-Single/Leviton/5821

P-J said:

It is 20A - 240V:

Receptacles-Commercial-20-Amp-Single/Leviton/5821

Click to expand...

You're right, it is a 240v - I didn't pay attention to the blade orientation.

One 2000w element should boil 5 gallons which will leave you with ~4 gallons finished. Any more and you need to supplement the heat either with a stove or a second 120v source.

-Josh