How to maximize the Efficiency of the Modulating/Condensing Boiler

1. Tighten up the structure to create an over-radiated system. Reducing heat loss while maintaining the same level of radiation will enable operation at lower water temperatures, thereby increasing home comfort. Temperature swings will disappear.
2. Do a heat loss on the building. A heat loss will properly size the boiler for maximum comfort and fuel savings.
3. Increase the delta-T of the system. Using a variable-speed pump will help achieve this. The cooler the water returning to the boiler, the more efficient it is. You cannot get carried away here, the normal delta-T with standard radiation is 20f-25f. See delta-T chart.
4. If feasible, add additional radiation to lower the operating water temperature.
5. Your greatest efficiency is a lower water temperature system and/or high-water volume systems. We need to run at near-condensing temperatures, which is about 126Â°F-130Â°F. When condensation in the boiler stops, we lose about 9% of the heat input that could otherwise be recovered from the flue gases.
6. Adjust the heating curve properly. Once the heat loss is complete, perform one at design outdoor temperature and another at approximately 50Â°F. Measure the radiation and plot the curve. See Instructions here.
7. Do not split the system into too many micro-zones. A micro zone is any zone smaller than the minimum output of the boiler. Mirozones can cause boiler short cycling, resulting in lower AFUE efficiency. If you already have these zones and do not want to change the zoning, maybe consider a buffer tank
8. Think about installing two smaller boilers instead of one big boiler. This will save significantly more than the upfront costs in the years to come and provides some comfort if one boiler fails.
9. Make sure all installed equipment is adjusted with a combustion analyzer if required. Some boilers today do this automatically.
10. Reduce the fan RPMs to reduce your boiler output to match the heat loss and or DHW, whichever is smaller. Typically, the DHW load is larger than the heating load in residential settings. Size the boiler to the heating load and upsize the DHW tank if used. This will increase the storage to make up the difference

Disclaimer: The information found on this website is for informational purposes only. All preventive maintenance, service, and installations should be reviewed on a per-job basis. Any work on your heating system should be performed only by qualified, experienced personnel. Comfort-Calc or its personnel accepts no responsibility for improper information, application, damage to property, or bodily injury from applied information found on this website, as it should be reviewed by a professional.