Commercial Boilers, ITT McDonnell & Miller Low-Water Cutoffs & B&G / Taco Hydronic Circulators
Complete boiler room mechanical trim, ASME safety relief valves, float and electronic probe low-water cutoffs, boiler water feeders, and wet-rotor / three-piece bearing-assembly circulators for New England facilities.
Keeping Massachusetts & New Hampshire Boiler Rooms Safe, Code-Compliant & Online
Under Massachusetts 522 CMR (Board of Boiler Rules) and ASME CSD-1, commercial steam and hot-water boilers require properly functioning primary and secondary low-water fuel cutoffs (LWCOs), ASME-stamped safety or safety-relief valves, and calibrated pressure/altitude gauges. A scaled-up float chamber on a McDonnell & Miller #67 or a seized bearing assembly on a Bell & Gossett Series 100 circulator can shut down an entire school or apartment complex in sub-freezing weather.
Frank P. McCartin Co., Inc. stocks genuine ITT McDonnell & Miller float and electronic probe cutoffs, replacement head mechanisms, bellows, and mercury-free snap switches, alongside Bell & Gossett, Taco, and Grundfos circulators, couplers, mechanical seals, and custom-threaded Schedule 40/80 black steel header piping up to 4" NPT.
Need Immediate Part Verification?
Bring your sample component or email a clear nameplate photo to our 149 Congress Street counter team for same-day pickup or regional truck delivery.
ITT McDonnell & Miller Low-Water Cutoff (LWCO) & Feeder Cross-Reference
Stocked at 149 Congress St—including complete units, replacement float heads, blowdown valves, and switch cartridges.
| McDonnell & Miller Model | Boiler Type | Max Pressure | Sensing Mechanism | Water Feeder Included? | Primary Replacement / Service Parts Stocked |
|---|---|---|---|---|---|
| Series 67 (67-2 / 67-G) | Low-Pressure Steam | 20 PSIG | Mechanical Float (Quick-Hookup Gauge Glass Mounting) | Optional (Pair with #101A or WF2-U-24) | Float Block (#67-12), #11M / #14M Snap Switch, Quick-Hookup Fittings & Blowdown Valve |
| Series 47-2 / 247-2 | Low-Pressure Steam (Up to 5,000 sq. ft. EDR) | 25 PSIG | Mechanical Float & Mechanical Make-Up Valve | Yes (Integral Mechanical Feeder) | Replacement Cartridge & Strainer Assembly (SA47-101-102), Float & Bellows Assembly |
| Series 63 / 63-M | Hot Water & Steam Boilers | 50 PSIG | Heavy-Duty Float in Cast-Iron Chamber (1" Equalizer) | No (Cutoff & Alarm Switch) | Head Assembly (63-HD), 121M Manual Reset Switch & High-Temp Head Gasket |
| Series 150S / 157S (150S-MD) | High-Pressure Steam & Hot Water | 150 PSIG | Monel Float & Packless Flexible Metal Bellows | Pump Controller + Low-Water Cutoff | Complete Head Mechanism (150S-HD / 150S-MD-HD), Micro-Switch Assembly & Gasket (SA150-14) |
| RB-122E / PSE-801 / PS-801 | Hot Water (RB-122E) / Steam (PSE-801) | 160 PSIG (Water) / 15 PSIG (Steam) | Solid-State Electronic Conductance Probe (3/4" NPT) | Optional Electronic Feeder | Replacement Self-Cleaning Probe Rods, 24VAC & 120VAC Control Modules (Auto or Manual Reset) |
Commercial Hydronic Circulator & Replacement Sub-Assembly Matrix
We stock complete pumps AND modular repair components (bearing assemblies, couplers, impellers, flanges, and seal kits).
| Manufacturer & Series | Construction Type | Flow / Head Range | Flange Size | Common Repair Parts on Our Shelf |
|---|---|---|---|---|
| Bell & Gossett Series 100 (106189) | 3-Piece Oil-Lubricated Cast Iron or Bronze | Up to 32 GPM / 10 ft Head | 3/4" to 1-1/2" (2-Bolt) | B&G Bearing Assembly (#118844), Spring Coupler (#118705), 1/12 HP Motor (#111034) & Motor Mount Rings |
| Bell & Gossett HV / PR / 2"–3" Inline | 3-Piece Oil-Lubricated Booster | Up to 140 GPM / 42 ft Head | 1" to 3" Flanged | Large Bearing Assembly (#189100 / #189105), Cast-Iron Coupler (#118723), Mechanical Seal Kit & Impeller |
| Bell & Gossett NRF / NBF & Series PL | Wet-Rotor Maintenance-Free / Dry-Motor | Up to 100 GPM / 58 ft Head | 3/4" to 2" Flanged | Complete drop-in cast-iron (heating) and lead-free bronze (domestic HW recirc) cartridges |
| Taco 007e / 0010 / 0011 / 0013 / 0014 | Wet-Rotor Replaceable Cartridge | Up to 70 GPM / 36 ft Head | 3/4" to 2" (Standard or Shut-Off Flange) | Taco Replaceable Rotor Cartridges, Flange Gasket O-Rings & Hy-Vent Automatic Air Vents (#400/#418) |
| Taco 110–138 & 1600 / 1900 Series | 3-Piece In-Line Commercial Circulator | Up to 350 GPM | 1" to 3" Flanged | Mechanical Seal Kits, Flexible Frame Couplers, Bearing Brackets & Resilient-Mount Motors |
Boiler Room Emergency & Preventive Maintenance Counter Checklist
- Check ASME Relief Valve tags: Never install a high-pressure hot-water relief valve (30–150 PSI) on a low-pressure steam boiler (which requires a mandatory 15 PSIG ASME Section IV 'V'-stamped steam safety valve!).
- For gauge glass replacements: Measure exact glass OD (5/8" vs. 3/4"), overall cut length in inches, and request fresh EPDM/Teflon gauge glass washers and brass friction rings.
- For 3-piece circulator repairs: Bring the stamped part number on the bearing assembly tag or motor plate so we can match shaft diameter (1/2" vs. 5/8") and impeller eye clearance.
- Need a custom steam header or Hartford Loop drop? Call (978) 454-7606—our pipe shop cuts and threads up to 4" Schedule 40 and Schedule 80 black steel pipe while you wait.
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Counter Q&A: Commercial Boilers, Low-Water Cutoffs & Circulators
How often should the float head or probe on a commercial boiler low-water cutoff be replaced?
Manufacturer guidelines from ITT McDonnell & Miller and CSD-1 best practices recommend disassembling and inspecting float chambers annually, replacing the low-water cutoff switch/head mechanism every 5 years (or 100,000 cycles), and replacing the complete LWCO unit every 10 years—or immediately if sediment prevents the burner from shutting down during a slow blowdown test.
Why does my Bell & Gossett Series 100 circulator keep snapping spring couplers?
Repeated coupler failure on a 3-piece B&G Series 100 or HV pump is almost always caused by sagging rubber motor mount rings (allowing the motor shaft to drop out of axial alignment with the bearing assembly shaft) or over-oiling the motor/bearing wicks, which softens the rubber motor mounts.
Do you stock replacement sight glass tubes and brass gauge cocks for commercial steam boilers?
Yes. We stock standard and high-pressure tubular borosilicate gauge glass (5/8" and 3/4" OD), red-line glass, brass guard rods, gauge glass gaskets, and Ernst / Conbraco bronze water gauge cocks with ball checks.
Request a Counter Quote or Cross-Reference: Commercial Boilers, Low-Water Cutoffs & Circulators
Routed directly to our 149 Congress Street, Lowell specialists. Eligible for COMMBUYS FAC124 (#201354) and MHEC G14 (#374) / G19 (#419) purchasing.