Installed Insert this weekend, chiminey cap question

[orenn89]

I installed my hampton HI300 insert this weekend. Installation went very very smoothly thanks to the tips you guys had given me. I am very confident in the installation, got an air tight back off plate installed and about 2/3 a bail of roxul in the top and bottom of the chimney around the liner. Still have to finish up repainting the surround and installing it (bought stove used). I have 2 questions regarding the top of my chimney.
1) It said in the liner instructions that the top of the liner has to be 3 feet above the top of the highest point of the roof, im at about 2 feet, any cause for concern? What is the purpose of this requirement? Is this a saftey concern?
2) I cant figure out how to do my chiminey cap. Currently i have it cut of at the top plate and under the existing cap. I would like to leave it like that, thoughts? I have about 4 inches of clearance from the top of the liner to the top of the existing cap. When in install the cap that came with the kit, it has 5 inches. However if i use the cap that came with the kit i have to use another cap for the other flue that is for the furnace, and they are too close together and it dosent work. Plus i would rather keep the existing cap if possible as it keeps water off the entire top of the chimney. I see the following options.
A) leave it as is and see how it works. (my preferred and cleanest option)
B) custom fab up (i have a welder) a spacer to raise the existing cap up another 2 inches.

 

[bholler]

not gonna work like that you either need to get a taller multi flue cap or cut that old clay down flush to give you more space between the top of the liner and the bottom of the cap

 

[orenn89]

How tall does it need to be, I think i can fab up a spacer fairly easily.

 

[bholler]

6" min. But i have had issues at times with 6" so i try to get as much as possible. why not just take the clay down it is easy and will work just fine

 

[orenn89]

6" min. But i have had issues at times with 6" so i try to get as much as possible. why not just take the clay down it is easy and will work just fine

How do i cut it? Also concerned cause i already RTVed the top plate down and i think i would make a mess of it trying to get it off.
If i only need 6" i can fab up a spacer that will do that in less than 2 hours.

 

[bholler]

I usually just take them down with a hammer but an angle grinder will work fine. Either way it will take 10 mins and cost you nothing. Like i said 6" is min but more is always better

 

[orenn89]

I usually just take them down with a hammer but an angle grinder will work fine. Either way it will take 10 mins and cost you nothing. Like i said 6" is min but more is always better

I'll measure what that would get me for clearence later this week. I'll shoot for 8" of clearance. Any concern with only 2 ft above the roofline?

 

[bholler]

I'll measure what that would get me for clearence later this week. I'll shoot for 8" of clearance. Any concern with only 2 ft above the roofline?

It really should be higher but it probably wont be an issue