Long story, but indirect tank probably needs to be replaced. Not sure what to get...

I'm I correct in assuming that having it piped as a zone is beneficial with hard water because the reduced time with water flowing through the HX reduces scale build up?

Are there any disadvantages to having it piped as a zone? If not, is the advantage of piping it to the bypass simply that 1 fewer zone valve is required, which in my case doesn't apply because I already have the separate zone?

Does the controller operate any differently in the 2 cases, other than not needing to open the DHW zone valve in the bypass-piped case? For example, is the circulator always running the same amount of time in both cases?

If the HX were piped as a zone, would I keep the existing 3/4" pipe or change the whole loop to 1/2"?

IF I asked my plumber to do this, would he be able to do the wiring between the system manager for the domestic water circulator and make any other required changes, or does an electrician have to get involved?Obviously, even with a regular indirect, he'd have to at least touch the aquastat wiring.

I talked to an experienced local EK installer and he was not aware that the plate heat exchanger could be piped as a zone rather than on the bypass. Is the separate zone option a relatively new thing?

I'm doing more research into the cons of the EK system:

The EK system is very similar to a booster tank connected to a tankless coil, which has gone out of style. Is that because tankless coils have gone out of style, or because of the increased complexity of having another circulator that can fail, or something else? The EK system would also be susceptible to a DHW circulator failure, while an indirect has fewer moving parts that can fail. I understand that a circulator failure can be diagnosed and fixed without having the replace the whole setup.

The EK tank is warrantied for 10 years while a stainless steel indirect has a limited lifetime warranty. I recognize the irony of me pointing this out given that my failed indirect has a supposed warranty that I'm unlikely to be able to take advantage of due to my water conditions and also having not filled out the registration card. I'll also point out that the Superstor warranty is more forgiving than the Megastor such that my water conditions fall within the acceptable range for the former but not the latter. On the other hand, I also recognize that parts-only warranties will only cover a fraction of the entire cost of replacement, especially with labor rates continually going up. Anecdotally, I've talked to at least 2 knowledgeable installers who claim that stainless indirect tanks tend to significantly outlast EK tanks, and would prefer them in their own homes for that reason despite the reduction in fuel efficiency.

EK tanks have an anode rod that needs to be changed out periodically, while many stainless indirect tanks have no such requirement.

It's curious that a simple storage tank with no internal heat exchanger coil would not be able to easily outlast an indirect under identical conditions.

So, the glass lined won't last as long with my pH of 8.27?

I just noticed that the house pressure is going above 80psi (!) when the boiler is heating the indirect. Is that only because of the heat exchanger leak or would it be happening regardless of the leak due to thermal expansion while heating, meaning that I definitely should have a DHW expansion tank?

Since I'm only intermittently running the boiler while supervising it, I can crack open the faucet at the slop sink while the indirect is recovering in order to relieve the excess pressure.