[roughneck]

No, a chiller could not be used to supply chilled water using the existing hot water piping. You would need separate piping and air handlers. The only method I’ve ever seen for cooling that doesn’t involve air handlers is chilled beams, which is an industrial method and is very complex and expensive.
You’d be best with the mini splits.

 

[papareis]

Thanks. That seemed to be the case. I thought maybe someone might have come up with a unit like the cassettes that mini-splits use that could be applied to air to water systems, but apparently not.

 

[azeotrope]

Thanks. That seemed to be the case. I thought maybe someone might have come up with a unit like the cassettes that mini-splits use that could be applied to air to water systems, but apparently not.

You could do it like you describe with hydronic coils and blowers that get piped to your existing hydronic loop. But you would need to also add a chiller to your loop so you could chill the water, fully upgrade the design and controls to operate it properly, and essentially design it from the ground up so it will operate properly. It’s really not a good retrofit option, or even a good residential option for that matter.

It’s not worth it at all, it’s much more complicated than a ductless split system and it may cause issues with your hydronic setup because the system was not designed for it. The chiller would be located outside where the condenser for the ductless split unit would sit. You are not saving anything and adding complication by adding the chiller and fan coils. Plus fan coils look ugly in my opinion. Maybe you can get nicer looking ones but it’s more of an industrial look used in commercial buildings. The existing radiators wouldn’t work for cooling and the condensation that they produce may end up damaging them (not to mention the pipes in the walls that may not be insulated and cause water damage), etc.

Stick with a multi head ductless split if you want to minimize the condensers outside.

 

[roughneck]

Thanks. That seemed to be the case. I thought maybe someone might have come up with a unit like the cassettes that mini-splits use that could be applied to air to water systems, but apparently not.

They do, hydronic to air heat exchangers come in thousands of shapes, sizes and applications. You’d be into such a system many times over what the cost of minis would be. Not to mention have a chiller to set outside somewhere, pumps and piping separate from the heating side, maintenance on the chilled water system.…..
Things would get very expensive.

 

[Chris616]

I just learned about the existence of air to water heat exchange systems.

Before I ramble on about our newish system, do you mean “air to water heat pump systems”?

 

[www.picturedtile.com]

You have the right idea with a ductless system. Since you have a boiler already doing the heating work, ductless systems are efficient and can be very cost effective. You can even buy them on amazon these days. Just make sure you have a reputable installer, as they can be somewhat complicated to install and set up. Off of one condenser you can have a couple different heads to supply cooling in a large area or possibly two different rooms.

My company has experience installing Mitsubishi units that work extremely well they even carry split systems that can carry heat load as well. I'd say check amazon first for a ductless cooling system to get an idea of pricing on the lower end. Do some homework on different units to see what will work best for you.

 

[papareis]

Yes... I was referring to heat pump systems. Heat transfer was a bit of a senior brain hiccup. It seems, based on the comments above, that air to water heat pump systems are not going to be applicable in my situation, so I'll go back to mini-splits as the likely solution to my attempt to have a more efficient system to provide heat and AC.