well guys, I just got a price on a 10,000 e, Im alittle nervous to be even thinking of this,but I believe im under sized, today I put my 5000mf forsale just to see if there is any bites,if there is I think I may bite the bullet, my house is approx. 4500 sq feet plus dhw and I think im working it too hard especially in the cold months, as you've prob seen my only complaint is when all the zones come on at once, my boiler temp drops from the quantity of cold water headn out to the boiler, not too mention I am going thru a ple of wood and maybe ill even cut that down abit, my concern is that the 10,000 may be too big and give me other issues like idling too long or something...now ill just wait and see if I can sell the 5000.ill keep yas posted....however chime in if ya want about your 10.000 experinces...it even looks to big,lolol