HVAC explanations ... air handlers, boilers, cooling...

Factual Questions
1

I’m trying to work out what someone just told me about their home’s HVAC system.

They said:

They have a three-zone system heated by a Peerless gas-fired boiler.

There are three air handlers (one for each zone): one in the basement, one in the attic, one in the garage (the garage’s 2nd floor is finished).

This system also provides cooling in the summer.

Now, how does this work?

I understand the gas-fired boiler. That heats water.

I understand the different zones.

But what do the air handlers do? And how does the heat from the water (heated by the boiler) get to the rest of the house?

I’m sure there’s a simple explanation, but I’ve never heard of such a system before; it seems like it’s half hydronic, half forced-air.

2

Seems like they have heatpump/boiler systems. So, the heat pump provides heating and ac and the boiler provides supplementary heat, instead of the the electric strips a heat pump system usually uses. (Heat pumps have trouble supplying heat below 40 degrees F.) Presubably there’s a coil inside the heat pump that tranfers heat from the hot water to then air.

peerless boilers

3

An air handler is a cabinet with a fan in it. It will also have coils from the boiler and from the cooling system. The air handlers blow air past the coils; this heats or cools the air, which then travels through the ducts to the room being heated. The cooling could either be from a heat pump or an air conditioner.