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Concentric Vent modification.
Wondering how I can achieve greater height off roof with my concentric vent for my Modcon boiler. its currently 14in from roof to bottom of rain cap where intake air goes in. My boiler manual states I can go as high as 20in above roof line. Now what I think ive read is that theres no way to cut the concentric kit (above the elbow where the two pipes join) and extend it for safety reasons. As in cutting the inner and outer pipes and attaching longer lengths. I will post pictures when lighting is better but i looked in my attic where it runs and theres not much length left until it hits the joint section where both pipes converge. I may be able to extend it that way. Reason for it is that where the vent terminates i get realy bad snow drift in the winter. Just want a little more insurance so i dont have to climb up there late at night because it got clogged. I have a tall ladder and rake i used last winter.
So what is the best way to modify? Cut concentric up top and add pieces there. Leave the concentric whole and extend as high as it will allow till the joint reaches bottom of roof.
Other options which i really dont want to do but run two separate for intake and exhaust, that way id be able to go to max height as listed in manual. But then id have to re seal original hole from concentric.
Also, sidewall is a no go. Soffit overhang is too far and where boiler is mounted in the house doesnt allow for an easy run.