I have multiple boilers cascaded but now have a bunch of 2" pipes sticking out everywhere. How many 2" can I combine into each other and what size pipe do I have to use. Can I put 3-2" into 1-4" or do I need to jump to 6" 636 pipe .. They are 3 - 120k btu boilers
From the B149.1-10 Gas Code,
QuoteClause 8.10.4 - A special venting system or a BH venting system shall be installed in accordance with the terms of its listing and the appliance and vent manufacturer's certified installation instructions.
QuoteClause 8.10.6 - An appliance that operates at a positive pressure shall
(a) not be connected to a venting system serving any other appliance; and
(b) only be connected to a venting system certified for positive pressure venting.
Some of the new Navien boilers can be common vented.
The NHB-110 and NHB-150
I was curious and had a look at the Navien NHB-110 and NHB-150 installation manuals, and found this on page 41,
QuoteDo not connect the boiler vent to a vent for any other gas boiler or vent stack.
The manuals I read can be downloaded - Here (http://www.hvactechgroup.com/hvacforum/index.php?topic=1941.0)
I did find a document on the net, which seems to allow common venting. It's strange that their installation manuals don't include this information. You can download it - Here (http://www.hvactechgroup.com/files/Navien%20NHB%20Brochure.pdf)
This is from the Ontario Amendments, for now anyways...
"Section 4.1.4 is revoked and the following is substituted for it:
4.1.4 Where a conflict exists between the manufacturer's certified installation
instructions and this Code, the most stringent of the two shall prevail."