I have no recent experience with hydronic heating and none at all with electrical boilers (what I had was oil burning) but if the water only circulates when there's a heat call, I'd wonder if anything more than turning down the thermostat to a low setting would be needed. But I don't know. If this system has been serviced by an HVAC contractor in the past, why not call them and ask.

Should I Turn My Furnace Off Over the Summer?

https://www.heating-air-conditioning.net/

Summer is coming, and with it comes thoughts of shutting off that system and enjoying open windows or cool air conditioning.

What Does It Mean to Turn Off Your AC?

You may be thinking that you’re already turning off your furnace when you switch from “heat” settings to “cool” settings when the weather warms. While this does stop the furnace from running, it does not turn it off altogether. Turning the furnace off means turning off the pilot light so it does not run at all during the summer.

Why Turning Off the air conditioner Makes Sense.

So why should you consider turning off your furnace? Even when the furnace is not running, the pilot light burns gas. That adds up to a small amount, but it’s still an amount that you have to pay. You can save around $50 or so, depending on the overall amount you pay per unit of natural gas over the course of the summer. You will also save energy because you won’t be wasting gas burning a flame that you don’t actually need. Finally, if your kids accidentally bump the thermostat to “heat,” you won’t end up accidentally heating your home when it’s 80 degrees outside.

Does Turning Off the Furnace Have Drawbacks?

Turning off your furnace requires turning off the pilot light. That means in the winter or in an unusually cold summer day, you’d have to re-light the light. That can be frustrating, especially if the pilot light is hard to get to, but it’s not something that’s impossible to do.

Well, Marc, my boiler is electric so there's no pilot to turn off. But, I had forgotten about my other home which does have a pilot for its gas-fired boiler. I do have it "prepped" every fall by a professional, so I guess if I turn off the pilot (and the gas) now, the prep will properly start it up again.