Boiler overheat protection loop

If I put 180' of 1/2" pex under the footings before I pour will that work for an overheat protection dump zone? I haven't poured addition on shop for boiler and though that would be an easy quick way to do it. I plan on using a 60kw boiler with 1000 gal storage.

How are you planning to get the overheated water to flow through the pex?

An overheat dump zone should be (rather I should say needs to be) above the boiler - the higher the better. Also, I think you'd be hard pressed to overheat a system in the first place that used a laddomat type loading unit, had a lot of storage (1000 gallons is quite a bit), and had the top of storage above the top of the boiler (as high as your space will allow). That's not saying to not put one in, but if you can design all this like that, you will have good reduncancy and less to worry about going wrong later. So I'd also think about getting your storage up as high as you can and your boiler as low as you can - but still being able to load without taking your back out.

I would agree with Maple on this one. The idea is that water will flow without pumping through the overheat loop in the event of a power failure. With the pex in the footing, the water wouldnt flow anywhere.