Boiler Sizing Question - Burnham V8

Ken_15

The SuperStore has a 1" coil and 1" inlet and outlet. You need to make sure you have the horse that will pull the cart. If you cannot keep up with the hot water demand then you also cannot keep up with the heating. However, if you are in a warmer area and don't get too many subzero days, you could probably get by with the V73. Do you have any large demand for hot water, large tubs, etc? You may want to consider a Mega Store tank instead. It has a 3/4" set up and slightly different needs.

DaveGateway

Burnham V8 Sizing?

I have a 2300 sq ft home in New Hampshire with a calculated heat loss of ~75,000 BTU. I am considering a new Burnham V8 series oil fired boiler coupled with a Superstor Ultra 45 indirect. I have had various quotes, some recommending the V83 and others recommending the V84, both fired at ~1GPH (.85 nozzle at 140PSI). Both configurations would net about 110,000 BTU when fired at ~1GPH. The AFUE rating of the V83 fired at it's high end is 82.6% and the AFUE rating of the V84 fired at it's low end is 86.1%. The SSU-45 indirect calls for 144,000 BTU to meet it's published "continous" rating, but I have been told that this is not really a concern.

What are the pros and cons of using the V83 at it's high end capacity versus using the V84 at it's low end capacity? Should additional capacity be provided to assure good indirect performance and if so would this cause other issues with heating performance?