|Posted by Vince on April 12, 2004 at 18:33:08:|
|In response to Re: boiler short cycles & venting/gas supply question|
This is a really interesting code question in part.
I'll use tha National Fuel Gas Code as the representive code here because it is a little more restrcitive than IFGC.
You do not address if this unit has access to outside or inside air. Big difference in how venting is figured.
Regardless of this fact 2 - 6 inch pipes are just too small.
Any mechanical room, with gas burning appliances, needs 2 vents that have a minimum of 100 square inches. This would be 2 - 100 inch vents in your case. But we are not done yet. You do the math on sizing these vents with cross sectional area.
Now for the fun part.
If this is an equipment room just off a basmeent and uses only indoor air. You need to add all the BTU's from the boiler and water heater and over size the vent 1 inch per 1000 btu over 200,000.
If the vents go directly to outside air in an unrestricted fashion and the vent pipe are vertical in doing this. You add 1 square inch per 4,000 btu's over 200,000.
If the vents go directly to the outside air in an unrestricted fashion and the vent pipes are horizonal. You add 1 square inch per 2000 btu's over 200,000.
This is the minimum requirement for air supply based at sea level.
Now for gas line sizing. Your line may be sized just fine if you are close to the meter.
Your delta temperature should never be over 40 degrees and many manufacturer's have a delta spread called for, which is less, in the instructions.
What you do is up to you. I would check into what kind of warranty or coverage the home inspector has for issues found to be a safety issue.
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