Is Boiler Output Sufficient for Second Zone ?

[Abe]

If he has the headroom, this would be a perfect application for floor based radiant heat.

[Vince]

My boiler has a tag saying 112,000 BTU output rating. How might I determine if that is enough to add a second zone? IIRC, the original boiler was rated as 92,000 BTU.

Presently, there is a single series loop zone for the main floor in a ranch style house on Long Island, NY. I am thinking more seriously about finishing off the basement with a second zone heating loop. The basement walls are poured concrete with about two feet above outside grading.

Thanks.

[Edwin Pawlowski]

Step one is to insulate those concrete walls. This lessens the cost of heating as well as the amount of output needed from the boiler.

The proper way is to calculate the heating needs for the house. Only that will determine the actual need. However, you are adding some heat to the basement, not adding more square footage to the house. You also state the new boiler is 20k more Btu than the old one. I'd venture a guess that it will hand the extra heating needed. All you want to do is raise the temperature of the space from say, 60 degrees to 68 or 70 degrees. That does not take much energy. If you were adding a couple of new rooms, requirements would be to raise the temperature from the outside air, say zero on a very cold day to 68 or so.

More complex is how to determine the location and amount of heating surface you need. Balance is important so you'd have the heat on all sections, not all at one end of the living space.

[Abe]

Radiant heat floor systems use water from the boiler going into PEX tubes over the concrete floor and under the finish floor to provide a nice even gentle heat. It's great for basements because the floor tends to be cold, and because the heat is gently rising from the floor, you get nice even temperature throughout. The system takes up about 1 inch of floor height, in addition to whatever finish floor you put on top of the radiant system.

Take a look at the following search results to find out more.

[Abe]

Quite correct. As long as the correct reflective/insulating material is laid under the PEX, heat absorption by the mass underneath won't be a problem. (At least that's what they tell you on TOH and the various radiant heat sites.)

[Amun]

As long as you install the second zone correctly you should have no problems. A basement is not going to require a great amount of heat to keep warm, and the "waste" will be heating the rooms above, so will lessen the load needed on the existing zones. Insulation is every bit as important in a basement as it is above grade so don't skimp there, including the floor.

AMUN

[Vince]

Abe:

Please expand on "floor based radiant heat" and what amount of headroom would it need ?

The height from the cement floor to the overhead beams is approximately 7 feet. I feel that is a low finished ceiling as it is, and has caused me to pause when thinking about finishing off the basement into a den/playroom area.

Thanks.

[Edwin Pawlowski]

Is this good in a retro though? In new construction, the floor will be insulated and the heating atop it. In the case of a retrofit, the heat will also be trying to bring the rest of the earth up to temperature too won't it? Unless, of course, insulation is part of the installation.