If the option presents to separate your DHW load from your heating load it is an investment worthy of consideration. Frequently, the required MBH to meet the DHW demand of a building is only 25% or less than the boilers MBH rating. Thus, if you are firing at 100% a 5000MBH boiler just for DHW you are literally pouring money down the drain. On average, a 1000-1500MBH DHW system can meet the demand. This enables you to turn off the monster boiler 5 or 6 months per year and generate DHW using about 75% less energy....and the DHW boiler will likely not have to operate at 100% capacity. It's a worthwhile investment to consider.