Your Boiler Just Worked for Six Straight Months. Here's What It Went Through.

Somewhere around the first warm week of April, most MetroWest homeowners do the same thing: they nudge the thermostat down, hear the boiler go quiet for the first time since October, and stop thinking about it entirely until next fall.

We understand the impulse. But before you close the basement door on another heating season, we'd like to tell you what that boiler just did for you — because understanding what it went through is the best argument we know for giving it a little attention right now, while the weather is forgiving and we're not yet buried in emergency calls.

180

Days your boiler ran more or less continuously

10K+

Heating cycles fired in a typical New England season

Now

The best possible time to service it — before next season

🍂 A Season in the Life of Your Boiler

Most homeowners think of their boiler as a box in the basement that makes heat. What it actually is, is a precision mechanical system that fires thousands of times a season, manages water pressure and temperature continuously, circulates heated water through hundreds of feet of pipe, and does all of this reliably enough that you genuinely forget it exists. Until it doesn't.

Here's what it actually experienced from October through March:

🍂

October

First Fire of the Season

After sitting idle all summer, the boiler fired up for the first time — often to the smell of dust burning off the heat exchanger. Components that had been dormant for five months were asked to perform immediately. Seals, gaskets, and expansion tanks that contracted over the summer were suddenly pressurized again. Any weakness that developed over the off-season showed itself here — or waited quietly to show itself in January.

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November

The System Found Its Rhythm

As temperatures dropped steadily, the boiler began cycling regularly — firing, heating the system water to its set point, shutting off, and firing again. The circulator pumps — the workhorses that move hot water through your baseboard — began logging serious hours. Any air trapped in the system from the summer started making its way to the highest points, quietly robbing radiators of efficiency without anyone noticing.

❄️

December — January

Peak Demand — The Hard Months

This is when your boiler earned its keep. When the temperature outside dropped to single digits and stayed there for days, the boiler ran almost continuously — not cycling on and off, but just running. The heat exchanger cycled through thousands of thermal expansions and contractions. The burner ran at full capacity. The pressure relief valve held. The expansion tank absorbed the pressure swings. Every component was stressed at its design limits, day after day.

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February

Fatigue Sets In

By mid-February, your boiler had been running hard for four months. This is when we start getting calls about systems that were fine in December — a zone that's not heating as well as it was, a pressure gauge that's reading a little high, a noise that wasn't there before. February is when the accumulated wear of the season starts becoming visible. Small issues that were present in October have had all winter to develop into noticeable ones.

🌱

March

The Finish Line

The system staggered across the finish line of the New England heating season — the shoulder weeks where the boiler fires in the morning, sits idle in the afternoon, and fires again at night. Inconsistent demand is actually harder on a boiler than steady demand. And now, in early spring, it goes quiet. It will sit idle for five or six months. Whatever condition it's in right now is the condition it'll be in when you need it again in October.

🔧 What Wore Down Over the Winter

When we service a boiler in the spring, here's what we're actually looking at — the components that take the most punishment over a heating season:

💧 Expansion Tank

The expansion tank absorbs pressure changes every time the boiler fires. The internal bladder or diaphragm fatigues over time. A waterlogged expansion tank causes pressure relief valves to weep and erratic system pressure — one of the most common issues we find on spring inspections.

⚙️ Circulator Pumps

Your circulator pumps moved heated water through every foot of baseboard in your home, thousands of times this winter. Bearings wear. Seals age. A pump that's starting to fail often runs quietly enough that you don't notice until a zone stops heating — usually on the coldest day of the following year.

🔥 Burner & Heat Exchanger

The burner fired thousands of times this season. Carbon deposits build up, burner ports clog gradually, and combustion efficiency drops without any obvious sign. A burner that's running at 80% efficiency instead of 95% isn't broken — it's just quietly costing you money every month.

🎛️ Zone Valves & Thermostat Wiring

Zone valves open and close every time a thermostat calls for heat. After thousands of cycles, valve actuators can become sluggish or stick partially open — meaning one zone runs when it shouldn't, or doesn't fully open when it should. This shows up as uneven heating across floors.

Every fall we service boilers that haven't been touched since the previous spring — sometimes longer. Nine times out of ten they fire up fine. The tenth time, we find something that's been quietly developing all summer: a waterlogged expansion tank, a circulator bearing that's nearly gone, a heat exchanger crack that's been there since February. Spring is when we catch those. October is when they become emergencies.

🌡️ The Thing Nobody Talks About — Trapped Air

If any of your baseboard radiators were noticeably cooler this winter than the ones on other floors or in other rooms — the most likely culprit isn't a zone valve or a thermostat. It's air. Over the course of a heating season, air works its way into the system water and migrates to the highest points in the loop, sitting in the top of a baseboard unit and insulating it from the hot water flowing beneath it.

Bleeding your radiators in spring — releasing that trapped air through the small bleed valves at the end of each baseboard unit — takes about ten minutes and immediately improves the efficiency of the whole system. It also tells you something important: if a radiator needs bleeding every year, there's air getting into the system somewhere, which is worth understanding before next winter.

💡 How to Bleed a Baseboard Radiator

Use a flat-head screwdriver or radiator key on the small bleed valve at the end of the baseboard unit — usually behind a small cover. Turn it counterclockwise very slightly. You'll hear air hiss out. When water starts to drip steadily, close it back up. Have a rag ready. Check your boiler pressure gauge after bleeding all units — if it drops below 12 PSI, the system needs water added through the feed valve. If you're not comfortable doing this yourself, it takes us about fifteen minutes on a service visit.

🏠 The Window You Have Right Now

Here is the thing about spring boiler service that we want MetroWest homeowners to understand: right now is the best possible time to do it, and almost nobody does.

In October, every heating contractor in the area is booked. When a boiler fails in the first cold week of the season, the wait for service can stretch to days — during which your family is without heat. The homeowners who call us in March and April get our full attention, our best scheduling, and the satisfaction of knowing their system is ready before anyone else's.

If your boiler is more than ten years old, has had an eventful winter, or simply hasn't been serviced in a few years — spring is the time. Not because something is wrong, but because this is when we can look carefully, find anything that developed over the winter, and address it at a time that is convenient for everyone.

Spring Boiler Service — What We Check

• ☐Inspect and test the expansion tank — check pressure and bladder condition

• ☐Check circulator pump bearings and seals — listen for bearing noise, check for leaks

• ☐Inspect burner assembly — clean ports, check combustion, test ignition

• ☐Check heat exchanger for cracks or corrosion

• ☐Test pressure relief valve — confirm it opens and closes correctly

• ☐Inspect zone valves — confirm each zone opens fully and closes completely

• ☐Check system pressure and feed valve operation

• ☐Bleed all radiators and baseboard units

• ☐Inspect flue and venting for blockages or deterioration

• ☐Check all visible piping for signs of weeping or corrosion

• ☐Test thermostat calibration across all zones

✅ The Bottom Line

Your boiler ran faithfully for six months through one of the hardest winters New England can produce. It deserves twenty minutes of attention before it goes quiet for the summer. And you deserve to start next October knowing it's ready — rather than finding out in the first cold snap that it isn't.

⚠️ One More Thing

If your boiler is 15 years or older, a spring service visit is also a good time to have a frank conversation about its remaining useful life. Not because we want to sell you a new boiler — but because choosing when to replace it is far better than having it choose for you on a January night. We'll tell you honestly what we see and what we'd do if it were our house.

We serve Holliston and the surrounding MetroWest communities — Medfield, Medway, Millis, Sherborn, Hopkinton, Ashland, and beyond. Spring scheduling fills up faster than you'd expect. Give us a call while the calendar is open.

Ready to schedule your spring boiler service?

Lamont Plumbing & Heating · Holliston, MA · Serving MetroWest Boston

Book Online📞 508-429-6227