Peerless Series MI Gas Boiler (Discontinued)
The Peerless Series MI cast-iron gas hot-water boiler (MI-03 to MI-09) is discontinued and listed by Peerless as Out of Circulation. GSHA Services, LTD still services and repairs existing Series MI boilers, and the current Peerless Series MI-e is the closest alternative if you are considering replacement.
Description
Discontinued Model. The Peerless Series MI gas boiler is no longer manufactured. Peerless (PB Heat, LLC) lists it as Out of Circulation. This page is kept for homeowners who already own a Series MI boiler. There is no purchase offer on this page.
This Peerless model has been discontinued, but GSHA Services continues to service and repair existing Peerless boilers. If your boiler needs repair, contact us to schedule service. If you’re considering replacement, explore the current option below.
GSHA Services, LTD installs, services and repairs Peerless boilers in McHenry County and Lake County, IL, the northern and western Chicago suburbs and southeastern Wisconsin. Call (224) 220-3660 or book online.
Schedule Boiler Repair See Current Alternative
About this model
The Peerless Series MI is a residential cast-iron gas boiler for hot-water (hydronic) heating only, offered for natural gas or LP gas in seven sizes, MI-03 through MI-09. A hot-water boiler circulates heated water through baseboard, radiators or radiant floor; a steam boiler boils the water and sends steam to radiators through larger pipes, and the two systems are not interchangeable. The Series MI is not rated for steam.
It is also a heating-only boiler, so it does not make domestic hot water on its own. A combi boiler heats the home and makes domestic hot water in one appliance, and a tankless water heater makes hot water only; the Series MI does neither of those jobs. A Series MI home gets its hot water from an indirect water heater fed by the boiler or from a separate water heater.
The Series MI is a non-condensing boiler. That means a cast-iron heat exchanger, a spark-pilot ignition, an integral draft diverter and natural-draft venting into a chimney, with published AFUE ratings of 82.0 to 82.2 percent. Cast-iron sections are long-lived and simple to service, which is why many of these boilers are still in use.
A condensing boiler, by comparison, uses a stainless steel or aluminum heat exchanger, vents through PVC or polypropylene pipe out a side wall, needs a condensate drain and reaches 90 percent AFUE or more. It saves fuel, but it depends on a workable sidewall vent route and a place to drain condensate, so it cannot always go where a chimney-vented boiler sat.
AFUE is the share of the fuel’s energy that becomes usable heat over a heating season. The input is the gas the boiler burns; the net I=B=R rating is the heat actually delivered to the radiators or baseboard after piping losses, and it is the number a heat-loss calculation should be matched against.
Original sizes and ratings
| Model | Input (BTU/h) | DOE heating capacity (MBH) | Net I=B=R water (MBH) | AFUE |
|---|---|---|---|---|
| MI-03 | 70,000 | 58 | 50 | 82.2% |
| MI-04 | 105,000 | 86 | 75 | 82.1% |
| MI-05 | 140,000 | 115 | 100 | 82.0% |
| MI-06 | 175,000 | 143 | 124 | 82.0% |
| MI-07 | 195,000 | 160 | 139 | 82.0% |
| MI-08 | 227,500 | 186 | 162 | 82.0% |
| MI-09 | 260,000 | 211 | 183 | 82.0% |
Source: Peerless (PB Heat, LLC) archived product data for the Series MI, peerlessboilers.com. No prices apply; this model is discontinued.
Specifications
| Boiler type | Residential cast-iron gas boiler; hot-water (hydronic) heating only; no built-in domestic hot water |
|---|---|
| Fuel | Natural gas or LP gas |
| Condensing | No (non-condensing, chimney-vented) |
| Heat exchanger | Cast iron sections |
| Ignition | Spark pilot |
| Venting | Natural-draft chimney venting with integral draft diverter; vent connector 5, 5, 6, 6, 7, 8 and 8 in. for MI-03 through MI-09 |
| Dimensions | Same jacket dimensions as the current Series MI-e: 26-5/8 or 29-5/8 in. deep, 12-1/2 to 32-3/4 in. wide, 31-3/8 in. high |
| Manufacturer status | Out of Circulation (discontinued) |
Source: Peerless (PB Heat, LLC) archived product data, peerlessboilers.com. Weight, vent material and the original standard-equipment list are not verified; see the manufacturer’s product data for your unit.
Peerless publishes a non-prorated limited lifetime warranty on the cast-iron sections of its residential water boilers, conditioned on registration, installation by a heating contractor and use in a one- or two-family dwelling; the factory warranty does not cover labor. The detailed terms that apply to a Series MI specifically are not verified here, so check your original paperwork or contact Peerless.
Repair and service for this model
A discontinued boiler does not automatically need to be replaced. GSHA Services, LTD services and repairs existing Peerless boilers, including the Series MI, and a cast-iron boiler that is sound and serviceable can keep running after the model leaves production.
Items commonly serviced on chimney-vented cast-iron boilers, depending on how the system was installed, include the ignition and pilot assembly, gas valve, safety and limit controls, circulator, relief valve, expansion tank and air-removal components, plus the yearly cleaning of the burners and heat exchanger passages. An annual tune-up matters on a chimney-vented boiler: it checks combustion, the draft and the safety switches, and it catches small problems before the heating season.
Repair of a hot-water boiler is diagnosed on site. Learn more about the brand on the Peerless boilers page or see the Boiler Installation hub. Check our service area for the cities we cover.
Replacement options
Current alternative
Peerless does not name a successor to the Series MI. The closest current alternative is the Peerless Series MI-e Gas Boiler: it is comparable because it is the same family of residential cast-iron, natural-draft, hot-water, spark-pilot boilers, offered in the same seven sizes (MI-e-03 to MI-e-09) with the same jacket dimensions and water content. What changed: Peerless lists the Series MI-e as compliant with the 2021 DOE efficiency standard, rated 84.3 to 84.6 percent AFUE compared with 82.0 to 82.2 percent for the Series MI, and its input range runs 70,000 to 280,000 BTU/h. Peerless also lists a Series MI-x.
The right replacement is not chosen by matching the old nameplate. It depends on whether the home has hot-water or steam heating, the fuel available, a heat-loss calculation of the house (many older boilers were oversized), the condition of the chimney or the possibility of sidewall venting, and the piping, gas line, electrical and clearance requirements of the new boiler. A free on-site estimate settles all of this.
A chimney liner is often needed when a new boiler goes on an older masonry chimney, and an indirect water heater can be added if the home wants boiler-made domestic hot water. If the home has several zones, each with its own thermostat, the zone valves or circulators are checked and reused or replaced as part of the estimate. Financing is available with approved credit; see our financing page.
Frequently asked questions
Is the Peerless Series MI boiler still made?
No. Peerless lists the Series MI as Out of Circulation, and it is no longer produced. The related MI85 and MIHII models are also out of circulation. The closest current Peerless boiler in this family is the Series MI-e.
Can my existing or discontinued Peerless boiler be repaired?
Yes. GSHA Services, LTD repairs existing Peerless boilers, including the discontinued Series MI. Parts availability for a specific repair is confirmed during the repair visit; if a part is no longer stocked, we will explain the options.
Do you install and repair Peerless boilers in my city?
Yes, if your home is in McHenry County or Lake County, IL, the northern or western Chicago suburbs or southeastern Wisconsin. Check our service area page for the cities and ZIP codes we cover.
What is the difference between a combi boiler and a heating-only boiler?
A combi boiler heats the home and makes domestic hot water in one appliance; a heating-only boiler such as the Series MI heats the home only, so hot water comes from an indirect water heater fed by the boiler or from a separate water heater. A tankless water heater makes hot water only and does not heat the home.
Is this boiler for steam or hot-water heating?
Hot-water (hydronic) heating only, in all seven sizes, MI-03 to MI-09. The Series MI is not rated for steam, and a steam system needs a boiler rated for steam.
What replaces the Peerless Series MI?
Peerless does not name a direct successor. The closest current alternative is the Peerless Series MI-e, a cast-iron natural-draft hot-water boiler in the same seven sizes with higher AFUE. Whether it is the right choice for your home depends on sizing, venting and the rest of the system, which a free on-site estimate confirms.
What does installation of a replacement include and what can change the price?
No price applies to the discontinued Series MI; a replacement such as the Series MI-e is priced after a free on-site estimate. GSHA’s standard Peerless cast-iron boiler installation includes setting and leveling the boiler, a new electrical disconnect with power and control wiring, connections to the existing supply and return piping, a new cast-iron circulator, a backflow preventer with autofill, an air separator, an expansion tank, new flue piping to the existing chimney, a commissioning water-treatment kit, a new hydronic thermostat, removal of the old boiler, a start-up and safety inspection and a one-year tune-up. Chimney or venting condition (a liner or a sidewall vent route), piping and zoning changes, circulators and zone valves, gas line capacity, electrical work, condensate drainage on a condensing boiler, permits and accessories change the price. A Series MI-e uses the same jacket dimensions and chimney-type venting, so it often fits the same space and chimney, but the chimney may need a liner and the piping, circulator, expansion tank and gas line are checked and updated as needed.
When does repair make more sense than replacement?
Repair usually makes sense when the boiler is sound, the fault is a single part such as an ignition control, gas valve, circulator or safety switch, and the cast-iron sections are not leaking. A discontinued model can keep running as long as it is safe and serviceable. Replacement makes more sense when a section or heat exchanger is cracked or leaking, repairs are recurring, parts become hard to find, or the boiler is old or badly oversized to the point that a heat-loss calculation shows a properly sized new boiler would serve the home better.
Need help with a Peerless Series MI boiler?
Book a repair visit, or ask for a free on-site estimate if you are weighing a replacement. Call (224) 220-3660.
Schedule Boiler Repair See Current Alternative Request a Boiler Installation Estimate
Additional information
| brand | Peerless |
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