Boiler replacement in Saint Paul, MN

Not every old boiler needs to go. A sound cast iron boiler with a bad pump or control is worth fixing, and we'll say so. We look at a few things: the heat exchanger and sections for cracks or leaks, the condition of the flue passages, whether controls and parts are still available, how often it has needed service, and how it's piped. We also check the venting and chimney liner.

If the boiler has a cracked section, if it's leaking into the combustion chamber, or if a repair would cost a large share of a new boiler on a unit well past its normal life, replacement is usually the smarter money. We'll show you what we found and give you the numbers for both, so the decision is yours.

If your home has steam heat, the new boiler has to be a steam boiler. You can't drop a high-efficiency hot-water boiler onto a steam system. Steam boilers are sized by the total radiation in the house, so we measure every radiator rather than guessing from square footage. Oversizing a steam boiler is a common mistake that leads to short cycling, banging and wet steam.

Hot-water systems give you more options. A modern cast iron boiler is simple and durable. A high-efficiency condensing boiler, often wall hung, uses less gas and can modulate its flame to match the weather, but it needs a different vent and a condensate drain. Some homeowners also pair a new boiler with an indirect water heater so the boiler makes domestic hot water too. We'll walk through the tradeoffs.

• Cast iron steam boilers for one-pipe and two-pipe steam
• Cast iron hot-water boilers for simple, long life systems
• Condensing hot-water boilers with outdoor reset
• Combination boilers or indirect tanks for domestic hot water

On steam systems, the piping in the first few feet above the boiler decides whether you get dry steam or a wet, noisy mess. Manufacturers publish specific header heights, riser sizes and equalizer details for each boiler. When an installer reuses old piping or takes shortcuts, the new boiler can bang and surge from day one. We follow the manufacturer's piping drawing every time.

Hot-water systems need their own care. Condensing boilers often need primary and secondary piping or a hydraulic separator to keep flow right through the heat exchanger. We add new isolation valves, a properly sized expansion tank, air separator, fill valve and backflow device, so the next service visit is simple and the system holds pressure.

An old boiler often vents up a masonry chimney that also served a water heater. When the boiler goes, the chimney may be too large for the water heater alone, which can cause condensation and poor draft. We look at that during planning and may recommend a liner, a new vent path or a direct vent water heater.

Condensing boilers vent through plastic pipe out a side wall or the roof, which frees up the chimney but needs a good exit location away from windows and snow drifts. We also confirm the gas line can supply the new boiler's input. Any gas work is pressure tested before the boiler is fired.

Most boiler swaps take one to three days depending on the system. We drain the old boiler, disconnect it and remove it, which in an older basement can mean breaking it into sections to get it up narrow stairs. We set the new boiler, build the near-boiler piping, connect gas and venting, wire controls and fill the system.

Then we fire it, check combustion, set pressures or water levels and walk the house to confirm every radiator is heating. Steam boilers get skimmed to remove oil from new piping. We pull the city permit and schedule the inspection, and we show you how to operate and check your new boiler before we leave.