3" exhaust pipe... More effiecient than 4" exhaust pipe?

When I was looking at a stove to buy a pellet stove (and where to locate it in my house), I knew the EVL would be close to 15, so I asked the store owner if I should go with 4" pipe. He said, "you don't want to move to 4" unless you have to because of a loss of efficiency." I noticed that he only sold 3" pipe on the shelves of his store, so I have been wondering if what he said was true or convenient for his business.

Hmmm, I'd be careful with a vent thats going to be at 15 EVL. This thread should help you.

http://www.hearth.com/econtent/index.php/forums/viewthread/65949/

unless I am mistaking breckwell says that after 11 feet you must be 4" pipe

Bad burns aren't efficient at all.

At a fixed diameter of flue as the EVL increases the temperature in the stove before and at the combustion blower will rise, after a while it will cause the combustion blower to overheat and stall.

Increasing the size of the flue aids the combustion blower in getting rid of the flue gases.

You likely will be able to peacefully co-exist with the EVL at 15 and maybe even a bit over, however you will have to be certain you correctly and regularly clean the stove, and have a proper incoming air supply, and nothing in the house that interferes with the air supply.

ETA: As always the manual will speak to the matter. I use a back of the eyelid calculation and when it reaches 15 the red flag goes up.

According to the manual for his stove 15 is the maximum on 3".

is there a max average for 4" pipe?

30 is somewhat considered to be the maximum for 4" pipe. However the cross sectional area of the 4" vs 3" says that it would be more prudent to consider 26 feet as the maximum.

On any particular stove it all depends upon the capabilities of blower.

Do not use averages except as a possible red flag.

If one were to put krooser's under development fully firing stove cleaning system on to the venting there would be no limit ;-).

what is a krooser?

Well, you aren't the first to ask that question. I think I'll defer to Jay for an answer.

Heck... even I can't answer this one!

ok,whats a krooser jay-takeman

This is too funny..... :lol:

Hmmmm...well, let's see.....he only sells (has) 3", and he doesn't have any 4" pipe at all. He wants to sell you some pipe.

Do I have to say anymore?

We have some very funny members here!

Its not a krooser, Krooser is a member here(one of the funny ones). Its a leaf blower. Thats what krooser has tought us to clean our stoves with.

Here is a picture of his latest modified leaf blower: http://www.hearth.com/econtent/index.php/forums/viewreply/735997/

According to my owners manual............

1 vertical foot = .5 foot so say 15 vertical feet would be 7.5 ft.

thats just according to my manual, yours may be different.

Your only counting the pipe. Add just one 90º or tee and your now at 12.5 EVL. Add everything in the vent setup to get the total EVL. Most of the pipe brands have manuals on how to calculate the total EVL.

true, i was only refering to vertical run...not counting tees or elbows.
is that fairly common among stoves and pipes of different brands......that 1 vertical ft =.5 ?

Yes, Some others below.

1 horizontal ft is 1
45º is 2.5
90º is 5

Don't forget to add the cap too! There is also a rule for 90º's and tees. No more than 2 to be in the vent system. Thats because 2 would be 10 EVL right from the get go.

For three inch pipe yes it is a fairly common thing. I've seen some stove companies use three different methods.

I'm using 3"SS flex for about 22ft without any issue's, only problem i had was last yr had a blockage caused by i have a slight bend up the flue, leafblower trick fixed that quick, before that used about 6' of 3"SS flex using a block off plate so it was using a 8x11" flue