Repair or Replace? A Stamford Homeowner's Guide to Old Furnaces and Boilers
Your furnace or boiler just quit, or a tech handed you a big repair quote, and now you're wondering if it's time for a new one. Here's how we'd think it through if it were our own house.
By the techs at Renew HVAC Stamford · Last reviewed [ADD DATE]
The short answer
Repair it if the system is still in the middle of its normal life and the repair is a small slice of what a new one costs.
Replace it if it's near the end of its life, the repair is big, or there's a safety problem like a cracked heat exchanger.
Everything in between is a judgment call. The rest of this guide helps you make it.
How long heating and cooling systems last
These are rough ranges, not expiration dates. A well-kept boiler can outlast them. A neglected furnace may not make it. It's not unusual to find old cast iron boilers around here still running fine.
How to tell how old yours is
Find the data plate. It's the metal or foil label on the side of the unit or inside the front panel. The serial number often includes the year it was made. Can't read it? Take a photo and have it handy when you call (203) 357-5857.
Warning signs your system is near the end
Furnaces
- Repairs every year, sometimes more than once
- Yellow or flickering burner flame instead of steady blue
- Rust, cracks, or soot around the burners
- Carbon monoxide alarm going off
- Gas bills creeping up with the same use
Boilers
- Water leaking from the boiler itself, not just a valve
- Rust or corrosion on the boiler sections
- Rumbling or banging that keeps getting worse
- Pressure that won't stay steady
- A steam boiler that needs water added all the time
AC and heat pumps
- Uses R-22 refrigerant, common in units from before 2010
- Refrigerant leaks that keep coming back
- Compressor trouble
- Can't keep up on hot days
- Loud or rattling outdoor unit
How to weigh repair cost against replacement cost
Two rules of thumb help. Neither one is perfect. Together they get you most of the way.
The 50 percent rule
If the repair costs half or more of what a new system costs, put that money toward the new system instead.
The 5,000 rule
Multiply the age of the system by the repair cost. Over 5,000 usually points to replacing. A 15 year old furnace with a $400 repair comes to 6,000, so lean toward replacing. An 8 year old furnace with the same repair comes to 3,200, so fix it.
What the rules miss
- Safety. A cracked heat exchanger or a cracked boiler section isn't a repair or replace question. It's a replace question.
- Fuel bills. Older furnaces and boilers usually burn more fuel than new ones for the same heat. If your bills are high, count that in.
- Switching fuels. Thinking about getting off oil? A big repair bill can be a good time to make the jump.
- Comfort. If half the house has never been comfortable, a repair won't change that. A new system sized for the house might.
Should I repair or replace? Calculator
Plug in three numbers. Get the repair quote from your tech, and ask them for a rough replacement price at the same time. A good contractor will give you both.
Fill in the boxes above.
Enter the age, the repair quote, and a rough replacement price. We'll tell you which way we'd lean and why.
Heat pump rebates in Connecticut
If you're replacing an old furnace or oil boiler, a heat pump may be worth a look. Connecticut has offered heat pump rebates through Energize Connecticut, and federal tax credits have changed recently. The amounts and rules change often, so we don't print numbers we can't stand behind.
Add current program names, amounts, who qualifies, and links here before publishing. Check Energize Connecticut, your electric utility, and current federal tax credit rules. Add the date you checked.
We can help you figure out which programs your job might qualify for. More on heat pump service.
Questions to ask before you decide
- 1How old is the system, exactly?
- 2What part failed, and why did it fail?
- 3Is anything else worn that will fail soon?
- 4Is there any safety problem?
- 5Roughly what would a replacement cost, and what size would it be?
- 6Would a heat pump or a different fuel make sense for this house?
When not to wait
If you smell gas, leave the house and call your gas company or 911 from outside. If a carbon monoxide alarm goes off, get everyone out and call 911. Don't try to fix or restart the system yourself.
Common questions
How long do furnaces last in Connecticut?
Most gas and oil furnaces last about 15 to 20 years. Yearly cleaning and filter changes help them reach the high end of that range.
Is it worth fixing a 20 year old boiler?
Often, if it's cast iron and the repair is a pump, valve, or control. Those boilers can run a long time. If the boiler itself is cracked or leaking, it's time to replace it.
Will a new furnace or boiler lower my bills?
Usually some, since newer equipment wastes less fuel. How much depends on how old yours is, your fuel, and how the house is insulated. Ask for an estimate based on your house, not a general claim.