coal/wood burning stove

We have a Hotblast - 1537G in our basement with the stovepipe extended outside which is setup beside a chimney brick base due to the base having holes in the chimney. The issue is that we are experiencing problems with bad creosote build up even though we are burning fires in the excess of 425 degrees which should be out of the creosote building area...we are burning seasoned wood, we have a temp gage on the pipe inside the basement which tells us what is creosote building, what is burn zone and what is fire zone and we try to keep it in the burn zone, yet it still seeps on the stove pipe outside of the house. The only thing we can think of is that the pipe which extends from in the basement to the outside is built in between the chimney base and causing a draft which is causing the pipe to cool down and causing the build up...how can we fix this or does anyone have any suggestions on how to remedy because we have almost had one house fire due to the creosote seepage on the pipe on the outside bursting into flames...note my grandmother has almost the exact same setup minus the pipe passing through the chimney flow, which is why i think the chimney pass is the issue! can anyone help please?

Not sure I understand the chimney setup. Is the chimney pipe running up through an existing chimney that isn't sealed so outside air is cooling the pipe? What kind of wood are you burning? You're right about the chimney needing to be hotter to limit creosote accumulation so anything you can do to stop the "draft" cooling the chimney would help.
Can you post photos so we can see how your chimney is setup?

Definately sounds like it's cooling too fast into the pipe, is the pipe double wall? insulated? or just single wall? Or just get your other chimney fixed.
Is your wood seasoned good? Dry for at least a year or so?

Post a pic or two and we can give you some comments on what to do or look for.