Will your boiler replacement pay for itself?
Two weeks ago, Nate detailed the Worcester Housing Authority’s boiler upgrade and cogen installation. Today I’m going to share a second boiler replacement success story, and then discuss why we're seeing such great results from these upgrades. We’ve been asked not to disclose the building name or any specific characteristics for this project. Feel free to comment with a specific question, and I’ll try to answer the best I can.
This building is a low-rise apartment building that’s about 20 years old, with around 30 apartment units. It uses gas fuel for heat and hot water and is located in the northeast.
In January 2010, in terms of its gas usage, this building was performing 57% worse than similar buildings.
To reduce this number, the building owner targeted the building’s heating system, opting for a boiler replacement. (Note, the building has a separate gas hot water heater which was not changed.) After an energy audit, here’s what they added:
- 299,000 BTU Elite Heating Boiler (a modulating condensing boiler)
- circulator pumps
- combination fast fill backflow
- spiral vent air eliminator
- expansion tank
- isolator circulator flanges
- new electrical and gas piping
The total cost of the project was $18,500.
One year later, this building’s natural gas use has been reduced by 23% -- weather normalized -- and January gas bills were cut from $63.73 to $43.23. Over the course of the first heating season, the owner has saved $2095, which equates to a payback time of around ten years.
So, why are boiler upgrades so successful? And why isn't everyone running to their nearest boiler replacement shop?
- Not every boiler upgrade is actually this successful! We're detailing some of the best, most exciting examples of retrofits we're seeing. (If there’s interest, we can discuss cases where buildings did not see energy savings.)
- This said, one reason is that for many heating systems, the efficiency of the boiler is the most cricitcal component of the efficiency of the entire heating system. Other retrofits, like replacing a drafty window have an effect on heating demand, but savings are often less dramatic than those seen by installing more efficient equipment.
- Another idea is that during a boiler upgrade, you are likely to save roughly the difference in efficiencies between your old and new boiler, because you're able to convert more of your fuel to usable heat. If you're upgrading to a boiler that is 20% more efficient, you will likely reduce fuel use by about 20%, and this doesn't even include the value of better pumps or more effient controls.
- According to Energy Star, in comparison with furnace replacements "typically there are more opportunities to improve the efficiency of boiler systems due to their more complicated nature, as compared to furnaces." Not to say that furnace replacements can't also save you money.
Even with these incredible results, your boiler replacement might not pay for itself. Despite the 23% energy savings in this case study, the payback time was ten years! Payback time is affected by many variables including fuel costs, which can change over time, and the baseline equipment you are upgrading from. If the original boiler had been slightly more efficient or the cost of fuel was lower, payback time could have been extended beyond the life of the boiler.