Batch Sparging With a HERMS System?

So, I designed and built a HERMS system recently. I have yet to use it for an actual brew but plan on trying it out this weekend. One thing I am confused about is the proper way to sparge.

It seems that most people fly sparge with a HERMS setup but I only have one outlet from my mash tun so I can't drain while sparging. Am I right in that I should be batch sparging then?

My current system is a 2 kettle setup with a mash tun and a HLT. The HLT doubles as a brew kettle (I'll be adding a separate brew kettle eventually). The HERMS coil built-in to the HLT doubles as a wort chiller. The mash tun has an input on the top which leads to a floating sparge ball and has an output leading to a valve on the bottom. I use a chugger pump to move the wort around and circulate the wort through the HERMS coil during the mash.

My plan is when my mash is complete is to then drain the wort into a separate container and then pump the hot (~170 degree) water from the HLT into the mash tun for the sparge. I plan to use 2 qt/lb sparge water. Once the water is in the mash tun, I plan on recirculating using my chugger pump. For how long, I have no idea. When it is done, I will pump the wort directly into the HLT and add in the first runnings and start the boil.

Even though I am recirculating during the sparge, is this still considered batch sparging? Is there any risk of over-sparging like there is with fly sparging? I know that people usually break up batch sparging up into 2 separate batches but I don't really understand why. Is it because they don't have enough room in their mash tun or because it is more efficient? My mash tun is 10 gallons so I imagine I should always have enough room for a full sparge at 2 qt/lb even for high gravity beers and 6 gallon batches. My main fear is over-sparging. As long as I stick to 2 qt/lb, will I be safe even if I recirculate? Also, how long should I recirculate and sparge for?

IMO there is no good reason to recirculate a sparge. Recirculation is done during the mash to accomplish 2 things: Temp control, and wort clarity.

You don't need temp control during the sparge, because the water can vary a bit with no ill effect.

You don't need to worry about clarifying the sparge wort because you've already set up the grain bed as a filter during the mash. Simply divert the wort from going back to the HLT, and instead send it to the BK (or whatever you are going to use to hold it) and send clean wort from the HLT to the mash tun, which will in turn send it to the BK/holding device.

Batch Sparging with a recirculating system kind of defeats the purpose of having a recirculating system IMO.

You shouldn't have to worry about over-sparging if you do the math ahead of time. No more worry than a batch sparger, anyway. Make sure your sparge water is at a low enough pH.

People batch sparge in multiple steps because it can be more efficient. You are rinsing the grains twice and each time draining it out and leaving less sugar behind. The difference in efficiency is pretty small, and I don't usually do it these days.

If your draining your mash into a separate container, just fly Sparge instead. Collect it all in the separate container(lauter tun) and transfer to your kettle for the boil.