Not sure what the problem is with so many of the stove dealers. But they definitely don't seem to realize that a lot of people are wanting to be able to turn off the central heat (or turn the thermostat down to an emergency threshold like 60F) and heat the house with the stove/insert. They must visualize and fear a clueless homeowner who will leave his stat set at 70 in a cold room and have the stove fired up in another and come in complaining that the house is too hot.
I have to question if you actually tell the dealer, I want to be able to heat this house into the 70's and with only the stove/insert, would he still be undersizing. Maybe so, in which case, you just can't rely on them other than to write your requirements in the contract -- stove will be able to heat entire house to an average temp of 70F when temps outside are as low as 5F, if not, stove is exchangeable for only the difference in retail price (X) for the larger model (which will be installed at no addl cost).
So when the dealer balks at putting such a clause into the contract, you can tell him that in that case, you'll pick the size stove you think is right, his opinion has no value if he is not willing to back it up.
I have to question if you actually tell the dealer, I want to be able to heat this house into the 70's and with only the stove/insert, would he still be undersizing. Maybe so, in which case, you just can't rely on them other than to write your requirements in the contract -- stove will be able to heat entire house to an average temp of 70F when temps outside are as low as 5F, if not, stove is exchangeable for only the difference in retail price (X) for the larger model (which will be installed at no addl cost).
So when the dealer balks at putting such a clause into the contract, you can tell him that in that case, you'll pick the size stove you think is right, his opinion has no value if he is not willing to back it up.