HERMS kettle size question!

I have a question for HERMS brewers that typically brew 5 gallon batches. I currently have 9 gallon pots, will they be big enough to hold all the water I need to do 5 gallon batches after adding the coils and heating elements to the HLT? I plan on upgrading the pots later but due to cash flow restrictions this is a slow building process.

I have a HERMS coming from a cooler mash tun through a 6gal HLT in a crap ton of copper coil. I fill that to the top for the sparge water and mash out recirculation, and heat the mash water (usually about 4 gallons) separately in the brew kettle before doughing in. Using the HLT to sparge the grains, I usually end up with about 1.6 gallons of HLT water not used for a typical 5 gallon batch (6.25gal pre-boil vol). So I'd say your 9 gal pots are good enough for 5 gal batches.

Fill with 6.5 gallons of water, throw everything in to see how much headspace you have left...

Thanks for the responses, Poppincaps I didn't even think about using the boil kettle to heat the mash water, good advice, and lud thanks for the obvious response that I didn't think of! I should have thought of that already but I think I'll need more than 6.5 gallons with the water loss due to grain absorption and the boil.