Thimble Sizing Question; 3 or 4 inch?

[Iburnslow]

I've had a Harman for years. I originally installed it direct through the wall in my old house. Moved it to my new house and vented it up the chimney with flex pipe. Now, I'm moving it to my family room out of the chimney. It will go direct through the wall again, but it's been years since I've done this install. Here's the question; I have 3 inch double insulated pipe. Do I purchase a 3 inch thimble? Or, do I need to compensate for the double insulated pipe and purchase a 4 inch thimble? 3 inch double insulated pipe is ~3.75 inch. Just wondering before I purchase a 3 inch and have to return it....thanks for your input!

 

[pete7713]

I have 4 inch pipe that is actually 4 3/4, my thimble in 4 inch and the pipe goes through with little play around it. I would think you would use the 3 inch thimble

 

[Iburnslow]

Cool. That's what I thought. But just needed some input. Thanks for your response!!

 

[Lake Girl]

3" thimbles are made to accommodate 3" pellet venting ... all are double walled. If worried, measure the od on the venting and confirm it will fit in the thimble.

 

[Iburnslow]

Sorry in advance if this sounds like a whine, but, it's been awhile since I've engaged with a dealer over stove parts...so after getting your input, I had some business near the store I typically get pellets from. I stopped in to see if they had a thimble in stock. They didn't, but being a good dealer, directed me to another store a few miles away that's better stocked with parts...I figured I'd drop by. I've seen thimbles online for around $50, but for whatever reason, the delivery is about ten days?! Not sure if they are making them to order? Anyway, I go to the other dealer, tell him what I need and he rummages around in the stockroom and comes out with the thimble 'kit'...hmmm...looks a little overcomplicated than what I was expecting...over-engineered I mean...I'm thinking two pieces of crimped sheet metal with a tube, but this thing has a lot of tabs and pipe, and fit and finish looks high end...okay, if it's $60 or even $80, I'll pick it up so I can get the stove in over the weekend. I can understand a healthy markup to keep a local guy in business...so I ask what he's getting for the thimble.....wait for it................$220.00?!?!? Uhhh, come again?! Man, I'm sure enough people don't know a lot about stoves, don't have the time to educate themselves, or are just uncomfortable with the install, and simply pay the dealer the price they charge, but holy moley...In the age of the inter webs, it seems foolish to allow yourself to be fleeced, even if you do have the money to burn...that is ridiculous, and I'm a little surprised there are still dealers out there getting away with this...oh yeah, purchased a thimble on eBay when I got home for $39, free shipping, 5-8 day turnaround...

 

[Lake Girl]

The thimble on ebay ... are you getting the stainless steel outer cover place and inner wall plate? Cost will also be dependent on the manufacturer...

 

[Lake Girl]

This is the venting I use, Biovent manufactured in Minnesota. The thimble is only $38 but the wall plate is $46 and the outside flashing is $38.
http://www.woodmanspartsplus.com/Chimney/Chimney/D65645N1C500O-1.html?infield=Filter1:Bernard Dalsin