Yea, but low voltage pumps are pushing moving water through pipes (copper, or Pex) throughout your home when the boiler (modern condensing boiler) is on. You w

Yea, but low voltage pumps are pushing moving water through pipes (copper, or Pex) throughout your home when the boiler (modern condensing boiler) is on. You want a efficient release of heat. So I agree with you that stone is a better material for holding heat, by how much--I don't know. Having a stone fireplace might make sence heating one room, but I still have my doubts on energy saved, unless you have some kind of adobe house built around a huge stone fireplace. It just seems more practical to have hydronic heating in your structure than a stove in each room. I have tried to heat a home with a Wolf Stove in a fireplace. A Wolf stove use just a metal stove with a fan in it. It's a fireplace insert. It only heats up the room it's in. It does heat up the bricks on the fireplace, but not enough to keep heat in when the fire is out. If anyone decides to put in a hydronic heating system, you will like it. It's good for allergies too. I put one in a bay area home, and the install is pretty simple. The books make it much more complicated than needed. Basically put down pex piping, or registers (radiators, baseboard) in each room. Soneyinrd you need both. Buy a boiler that has been around awhile. Condensing boilers are new, but efficient. Buy your primary pump, and your sector pumps. Know the difference between primary, and secondary piping. You will need an expansion tank. I used a mixture of copper, and pex. And a thermostat. (In the Bay Area, we use natural gas. An electric heating here is very costly. Stay away from electric. Oh yea, for some reason hydronic heating was stopped in the 50's here. Contractors went to forced air, even though most homes don't have air conditioning. This means many hvac techs do not know how to work on hydronic, but act like they do. So double check their estimates.)