P61 Exhaust Plumbing


Oct 6, 2014
Ok did a search with no results, picked up a used Harman p61, cleaned it up, replaced a couple motors and swapped it out with a current stove I've been running for a couple years.

Question : Why is the air inlet and the exhaust non-conventional sizes to plumb ? the Air is 2 5/8 so a standard 2" coupling doesn't work ... I've got that one covered but c'mon the 3" exhaust outlet ???? I have to go 3" to 4" for the pipe up my chimney and the 3" to 4" coupling I have actually fits the ID of the stove outlet and is loose .... anyone got any suggestions ????

Thanks in advance



Patriot Guard Rider Moderator
Staff member
What brand/manufacturer of Venting are you using? Have you tried a Stove adapter as the starter piece?


Nov 5, 2011
Kananaskis,Alberta, Canada
Take the exhaust pipe off and weld the size you want on it....and replace the gasket...advice I used from this site.


Minister of Fire
Dec 2, 2017
your 3-4 adapter is going on the inside of your stove outlet? The ones i have seen are clamped to the outside of the stove outlet with a few band clamps.. Pic would be helpful

bob bare

Minister of Fire
Oct 31, 2013
park county montana
Will try to keep this short. The Harman tapered exhaust adapter, was designed that way, so even if people screwed up the exhaust system(flue, pipe) it would still preform mostly properly..the air intake on Harmans was part of the "intake/exhaust". Same as a gasoline engine. Do not under size the air intake. screws up .Going 3" to 4" slightly past the stove is usually a very good thing.