Is Williamson Still in Business?

Yes. Williamson-Thermoflo still sells the OWB, OWT and OSB oil boilers, plus gas boilers, oil furnaces and indirect water heaters.

Who Makes Williamson Boilers?

Williamson-Thermoflo, a division of WM Technologies, LLC, which is part of SPX Technologies along with Weil-McLain.

What's the Difference Between the Williamson OWB and OWT?

The OWT has a tankless coil for domestic hot water and the OWB doesn't. Otherwise they share the same sizes and ratings.

Can a Williamson Oil Boiler Burn Bioheat?

Yes. Williamson lists Carlin and Beckett burner options for #2 oil up to B100, while Riello setups are for #2 oil only.

Can You Get Parts for an Old Williamson Boiler?

Usually, yes. We stock the common burner and boiler parts, and we'll tell you up front if a part for an older model is hard to find.

Williamson Boiler Repair and Replacement

Williamson Boilers

About Williamson Boilers

We install, repair and service Williamson boilers, including older units and the current OWB, OWT and OSB, and we stock the common parts. Repairs come with an honest repair or replace call, and estimates on new boilers are free.

Williamson and Thermoflo are two older heating names that now sell as one brand, Williamson-Thermoflo, out of Menomonee Falls, Wisconsin. It's a division of WM Technologies, LLC, and sits in the hydronics group of SPX Technologies along with Weil-McLain and Patterson-Kelley.

The same boiler models are sold under both the Williamson and Thermoflo names. Besides boilers, the company makes oil furnaces (PMP, PLB, CLB and CHB), GL indirect water heaters, and gas boilers like the GWC condensing boiler, GWA and GSA. Products are sold through distributors, and service is done by heating contractors and oil dealers. Compare other makers on our boiler brands we service page.

Get a Free Quote Today Call (631) 779-3196

Licensed Techs Williamson boiler repair on Long Island

Model Lineup

Williamson Boiler Models We Install and Service

Williamson's three oil boilers share the same cast iron section design. Ratings come from Williamson-Thermoflo's product pages.

Model	Type	Key Ratings	Good For
OWB Series 3	Oil, hot water, no tankless coil	86% to 87% AFUE; 75 to 185 MBH net; sizes 3 to 6	Homes with an indirect or separate water heater
OWT Series 3	Oil, hot water with tankless coil	86% to 87% AFUE; coil rated 3.00 to 4.25 GPM	Replacing an oil boiler that also makes your hot water
OSB Series 3	Oil, steam, cast iron	85% AFUE; 358 to 658 sq ft of steam	Older homes with steam radiators
GWA, GWI, GWC, GSA, FreeStyle	Gas boilers	Varies by model	Homes on natural gas

Long Island Homes

Williamson Boilers for Long Island Homes

The OWB and OWT are built for a standard chimney. Each comes with a rear flue outlet and a barometric damper, and a top flue kit is available if your old boiler vented out the top. Sizes 3 and 4 need at least an 8 by 8 inch or 6 inch round chimney, 15 feet tall.

The four "-T-S3-D" versions of the OWB and OWT are rated 87% AFUE and meet ENERGY STAR when you add the optional vent damper kit. For bioheat, Williamson lists Carlin and Beckett burner setups for #2 oil up to B100, while Riello setups are for #2 oil only.

The OWB and OWT controls include a temperature limit, a low water cutoff function and thermal pre-purge. The OSB uses a probe-type low water cutoff built for steam.

Warranty

Williamson Boiler Warranty

The OWB and OWT residential warranty covers the heat exchanger for 20 years from installation. Years 1 to 10 cost you nothing; from year 11 to year 20 you pay a share of list price that rises from 5% to 50%. In year 1, a failed heat exchanger gets you a whole new boiler (less the burner). Other parts are covered for 1 year.

You don't have to register to activate the warranty, but keep your proof of purchase and installation date. A heating contractor files the claim. Labor isn't covered, and burners carry their own maker's warranty. We couldn't confirm OSB steam boiler warranty terms, so ask us before you buy.

On top of the manufacturer's coverage, Domino backs every installation with a 1-year labor warranty.

Compare Brands

Williamson vs Weil-McLain Oil Boilers

Weil-McLain is Williamson's sister brand under SPX, and the published numbers match closely. Size for size, the OWT and Weil-McLain's WTGO list the same input and heating capacity, and both are rated 86% to 87% AFUE. The OSB and Weil-McLain's SGO steam boilers are both rated 85% AFUE, and both start at 358 square feet of steam in size 3.

The differences are range, venting and coverage. Weil-McLain goes up to size 9 and ships with rear and top flue outlets; Williamson stops at size 6 and needs a kit for top venting. Weil-McLain gives 2 years on parts and 20 years on the heat exchanger with no proration, while Williamson gives 1 year on parts and prorates after year 10.

Repair & Service

Williamson Boiler Repair and Service

Here are the Williamson boiler problems we see most, with the likely cause.

Burner won't light: the oil solenoid valve stuck closed, a clogged nozzle or a failed solid-state ignitor.
Delayed start and a puff of smoke: a dirty nozzle or electrodes out of position.
Boiler shuts off with low water: a leak in the system or a failing fill valve tripping the low water cutoff.
Little hot water from an OWT: scale buildup in the tankless coil.
OSB steam boiler cycles too often: a dirty sight glass, a clogged pigtail or the pressure control set wrong.

Good to Know

Williamson Boiler Tune-Up and Parts

We stock the common parts, including nozzles, oil filters, ignitors, solenoid valves, circulators and relief valves. Williamson boilers have a swing-away burner door, a top access cleanout cover and plug-in wiring, so a yearly cleaning is quick. Book it with our boiler repair on Long Island team.

Installation

Williamson Boiler Installation and Replacement

The price depends on size, hot water or steam, coil or indirect tank, chimney work and piping changes. Call for a quote; the estimate is free, and you can ask about financing.

We check the old boiler and tell you if a repair is still worth it.
We calculate your home's heat loss and pick an OWB, OWT or OSB size to match.
We inspect the chimney and decide on rear or top venting.
We set the boiler, connect the zones and add an indirect tank if you choose the OWB.
We start it up, run a combustion test and walk you through the controls.

Williamson Boiler Repair and Replacement on Long Island