Questions for Installing chiminey liner

[xformer]

Been in the commercial svc. industry for 15 years, so this residential install is a little out of my scope, but i find myself with the task of replacing a boiler and hw heater next week. Removing an atmospheric 125k btu 80% boiler and putting in a 105k btu 81% with auto vent damper (5") (http://www.dunkirk.com/product_detail.asp?key=189&view=features )
and a standard 40Kbtu hw heater.
Chimney is brick and clay- 31.5 ft from top of boiler to cap. Chimney is inside except above roof. Location is western new york
Questions:
(1) Wholesaler says that I should use a 5.5" liner. If boiler flue diameter is 6" is it ok to REDUCE the size to 5.5" ?
(2) when connecting hw Heater flue- use a why fitting or a tee fitting
(3) Is the auto vent damper a factor when sizing liner,as it will not allow the residual heat to keep the liner warm?
(4) how long will the aluminium liner last. is the cost of stainless justified for this type of installation?
Thanks

[hearthman]

Xformer, welcome to the forum! Please read the site rules. We cannot discuss details such as you ask in the open public forum. Get your post count up then apply for Pro membership.

I think I can respond to a few of your questions though:

The liner must be sized according to the codes and listed instructions, which all state must be at least the size of the appliance collar.

Corrugated liners must be derated 20% plus another 20% if offset.

Must look up the common vent size in the fuel gas code charts to size the common vent (liner) but also the sizing charts for the vent connector and manifold.

If you can get an aluminum liner down intact, not torn apart or crushed, then it may last 1-20 years. I don't know of any aluminum liners with warranties longer than that and none of their warranties are transferrable. There are numerous stainless steel liners that carry lifetime warranties and several that are transferrable. You can stand on almost all stainless liners except one brand common to supply houses and a few cheap internet ripoffs.

Since you seem to be a little weak in the liner aspect, I heartily recommend you contact a chimney pro to assist you in this case. Meantime, get you post count up and meet us over in the Pro section!

HTH,

[xformer]

Thanks hearthman. you are def. the chimney guru of this site and I commended for your dedication. I understand the importance of the fuel gas codes and utilizing a chimney pro. I will def. look it up so its done right. I guess i was just looking for the quick answer from the guy thats done a thousand of them "exactly" (ha ha) the same. Can you tell me this? wye fitting or a tee fitting? ive seen many of both.
How many post do you need to get in the pro section??
Thanks and have a great day!

[hearthman]

go to the Pro section and you should see a sticky note on how to apply for Pro membership. Once a Pro, you can also apply for posting advice in the AOP section separately.

I'll pm you tonight on the Y/ T

[xformer]

Incorrectly stated that boiler flue diameter was 5". It is 6"