I just had a 100k Boiler installed when I converted from oil to gas. The original quote was for a 125K Boiler. After the install he wanted the same amount as the quote, I said it should have been a little cheaper since he put in a smaller boiler. Does this sound right?
And why would he tell me I needed a 125k but then put in a 100k?
WIthout a heat load analysis, what sized boiler you need is pure speculation. Older systems were often oversized. A correctly sized boiler will save money and be more comfortable and may last longer since it would likely have fewer starts. Without knowing your requirements, whether you got what you needed is impossible to state. To really save on fuel, a modulating, condensing boiler has the potential to get up to 98%. A typical boiler is in the order of 80% on the newer ones. How it is installed and the effectiveness of the controls can boost that up. The worst thing is to have an oversized one since it would only need to run for a short time. Ideally, when heat is needed, it could run continuously and match the load.
Most of the cost is in the labor, the difference between the cost of a 100 vs 125K BTU is fairly small.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013