What is outdoor reset?

Outdoor reset is a control strategy that lets your boiler modulate its output water temperature based on the outdoor temperature. The idea is simple once you see it. The colder it gets outside, the more heat your home loses, so the boiler needs to send hotter water to keep up. The milder it is out, the cooler the water can be while still keeping you comfortable. Outdoor reset matches the boiler’s water temperature to what the weather actually calls for, automatically, all day long. A small sensor mounted outside tells the boiler what is going on, and the boiler adjusts itself.

Why does running low and slow matter?

A boiler is most efficient when it runs low and slow inside its ideal operating range. If we can keep the boiler running in that sweet spot for as much of the day as possible, it is far more efficient, and the home is far more comfortable at the same time. The two go hand in hand here, which is not always the case in this trade.

Compare that to a boiler without outdoor reset. It tends to blast out 180-degree water no matter what it is doing outside, potentially overheating the radiators and overheating the home, then shutting off, then blasting again. That on-off, hot-then-cold pattern is inefficient, and it is less comfortable to live in, you feel the temperature swing. Outdoor reset smooths all of that out by giving the radiators the right water temperature for the conditions instead of slamming them with 180-degree water on a mild day when they do not need it.

How much does outdoor reset save?

This is the part that gets me fired up. Outdoor reset can equate to about a 15% efficiency bump on the system. That is real money back in the homeowner’s pocket every single heating season, for the entire life of the boiler.

And here is the kicker, the part that really gets me. It is something included for free from most manufacturers. The control is right there in the box when the boiler shows up. All it takes is the installer running the wire and putting in the outdoor sensor. That is it. No expensive add-on, no special equipment, just a little bit of labor.

So why do most installers skip it?

Honestly, because it is one extra step, and a lot of contractors take the easy way out. They do not run the wire. They do not mount the sensor. They leave a free 15% efficiency gain sitting in the box and walk away, and the homeowner never even knows it was an option.

In our eyes, that would be stealing from the customer. The manufacturer handed you a way to make the homeowner’s system run better and cheaper, at no added equipment cost, and you skipped it to save fifteen minutes of labor? That is exactly the kind of corner we flat out refuse to cut. We incorporate outdoor reset into our boiler installs because it is simply the right thing to do, and because we want your system running as efficiently as it possibly can for as long as you own it.

What outdoor reset gives you

• About a 15% efficiency improvement on the boiler, season after season.
• A more comfortable, more even heat instead of overheating swings.
• A boiler running in its ideal range, which is easier on the equipment over time.
• No extra equipment cost, the control comes free from most manufacturers.

If you are putting in a new boiler, ask whether outdoor reset is being installed. If the answer is no, ask why, and listen carefully to the reason. For the full picture on a smart boiler purchase, see our guide on how to pick a boiler.