Heating issues in my new house
I’ve been finishing the shell of a house, and I’m looking at making the heating system a bit more efficient. I have a few questions:
1) I have a tankless water heater (Bosch 125x), and to supply combustion air, the installer put in two 6″ vents straight to the outside. Since I only need the air when the heater is burning, I’d like to be able to keep the cold air out the rest of the time. What are my options here?
2) The furnace can take outside air for combustion, but the installer didn’t use it because of the vents for the water heater. I can easily hook up the PVC to the outside, but I don’t know what to do with the pipe outside. Can I just put a 90 degree elbow and run it down? Do I need to screen it? Can I find a kit that’s already built for this?
3) The current PVC exhaust from the furnace just stick straight out from the wall. It’s a bit loud outside. Can I put an elbow on this and direct the exhaust up? Or should I just leave it?
4) I have a big 8″ fresh air supply duct coming straight into my cold air return. It’s about 10′ long, and is uninsulated. Should I be thinking of a heat recovery system here, or just insulate the ducting?
5) The furnace has a spot for an electrostatic air filter. How hard is it to install one myself (I’m experience with electrical work, including service panel work).
Replies
1) - MCAD: motorized combustion air damper. Buy and install one. If you have never heard of this or have no idea where to get one, pay someone to do it for you. Insulate the duct.
2&3) - you'll have to explain how the dwh vent affects using outside air for cumbustion for the furnace. I prefer and use a concentric vent (most furnace maunfacturer's make them) that has both the combustion air intake and the vent in a single neat package. Looks like it actually has a purpose in lieu of the two turned down elbows, as is common.
4) - yes, you should consider energy recovery and yes, you should insulate the duct. With or without an ERV/ERU I would recommend installing a MOAD (motorized outside air damper) that opens only when the fan runs see #1 above.
Edited 3/3/2003 3:52:03 PM ET by Tim
Read and follow the manufacturer's installation instructions for the furnace.
Attached is pic of one thing that can happen if you don't: in this case the air intake was above the exhaust. The furnace was short cycling big time and the co levels were astronomical.
_______________________
"I may have said the same thing before... But my explanation, I am sure, will always be different." Oscar Wilde