Thermo Pride OL5 Furnaces

Thermo Pride OL5 Furnace Overview

The Thermo Pride OL5 is an oil-fired furnace with an efficiency of up to 86% AFUE. It features a lowboy design for use in basement installations with height restrictions. The OL5 comes with a PSC blower motor which can be upgraded to an ECM motor that operates at lower speeds for increased efficiency. It features a heat exchanger constructed of 13 gauge copper-coated steel, which helps prevent corrosion, and designed in an octagonal shape for improved heat transfer. The unit's interlocking steel cabinet has a powder coat finish and rounded corners for improved structural strength and appearance.

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Consumer Reviews of Thermo Pride OL5


  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
  • #1 of 3 Thermo Pride Furnace
  • 80% of customers recommended

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Thermo Pride OL5 Furnace Reviews

"44 years and still running fine"

5.0 rating
Very Satisfied

This furnace was installed in 1973 in a home built in 1940 replacing the original boiler. We bought the home in 1992 and have it serviced every 2 years. Our oil tech calls it the Cadillac of furnaces and we believe it. Transfer of warranty to us on the heat exchange chamber which is still original equipment from 1973. Can’t say enough about it. Wish more products were built as well as this is. Have upgraded the blower to a direct drive, more quite and can adjust the flow of air. 5 stars!

Rochester, NH

"Got mine in 1970"

5.0 rating
Very Satisfied

The blower motor belt just broke on mine, I have to find a place to get one. But for 45 years and still going (I did have to replace the caulking), I think it did pretty good.

Johnstown, PA

"Thermo Pride OL5-85 (fuel oil burner)"

5.0 rating
Very Satisfied

My Thermo Pride oil furnace was installed new in 1993. I service the burner myself on an annual basis. In twenty-three years of service, the oil burner has failed twice. On the first occasion, I found that the unit had run out of fuel oil. On the second occasion, I found that crap had made it’s way through external the fuel filter and had clogged the filter in the nozzle (I cleaned the nozzle using 2+2 brake cleaner then blew compressed air thru the nozzle). After replacing the external fuel filter and bleeding the air from the burner, it fired up and operated perfectly. Over the years, this burner has proven to be very stingy with fuel oil. My 550 gallon fuel oil tank needs a re-fill every three years.

New Jersey

"ThermoPride Forced Warm Air Furnace: Fine quality in outdated technology"

1.0 rating
Very Unsatisfied

The Thermo Pride OL5-85RB furnace was installed in this antique farm house in September, 1996. At that time, it was a largely state-of-the art, warm air, oil-fired furnace of a type commonly found throughout New England. At the time of installation it achieved an 85% burning efficiency. The furnace consists of a large, steel cabinet in one end of which is a nearly four foot high, cast iron tank-like device which is the burning chamber. In the bottom of this “tower” like thing is set an oil “gun” burner (Carlin brand) which shoots an oil stream into the chamber and ignites it. The resulting air from the combustion of oil is then blown through 8″ and 10″ galvanized steel conduits to outlets located in rooms on the first floor of this house. When the furnace was first installed (by a previous owner of this house), the heat needs of the house were augmented by a wood stove which exhausted smoke through an exterior chimney. At the time of our occupancy, the chimney and wood stove were removed, and we found the Thermo Pride furnace to be more than adequate for our heating needs in that late spring as we began to repaint the interior of the house. However, several other issues with the heating system were discovered. First of all, some of the warm air ductwork was loose or had actually separated from registers in the most remote areas of the house. These areas were in crawl spaces and repair of the ductwork was difficult. Furthermore, this ductwork was in unheated areas and not insulated. The resulting heat loss in deep winter would have made the otherwise good heating efficiency of the Thermo Pride furnace irrelevant as only by driving the furnace hard on those long, very cold winter nights could real warmth be maintained throughout the house. Warm air in circulated by a very large fan system driven by a powerful electric motor. Considering the house is approximately fifty feet long, this fan must be very powerful and the resulting electrical consumption plus the oil needed to provide heat indicated a very expensive heating system at the time we moved into this house. What was a highly efficient and quite expensive furnace and heating system in 1996 was obviously totally obsolete less than twenty years later. Immediately I began a complete heating system retrofit. The Thermo Pride furnace was shut down once the existing supply of fuel oil was depleted. I installed three Toyotomi computerized wall furnaces in different locations in the house. These small wall furnaces develop 20,000, and 8000 BTU’s specifically, burning either kerosene or ultra-low sulfur diesel fuel, and are fed from a single, 275 gallon exterior mounted fuel tank, through a single, electric distribution pump. Now in the fourth year, the system works well, the house is warm in the coldest periods and the fuel consumption through the year is approximately one quarter what the old furnace consumed. I have also added a considerable amount of insulation, particularly beneath the first floor, and blocked off all the old warm air registers. The fuel burned by the Thermo Pride is still the lowest cost, highest BTU fuel available for heating, and if the Thermo Pride furnace was located in a modern house with a full, insulated basement that was not as spread out as this house is, it probably would still provide excellent heat and relatively manageable fuel use and value. But for this house its time has passed and I cannot rate it highly in this particular application.

Morrill, Maine

"Great Unit!"

5.0 rating
Very Satisfied

I have just removed the Thermo Pride unit after 22 years of service with no service calls other than annual service. It still would be there heating my home but I converted to gas.


Other OL5 Reviews

Based on comments from online HVAC forums, the OL5 is a very good furnace. A post on from a homeowner asking if Thermo Pride makes the best oil furnace found every responder saying yes, with the OL5 mentioned a couple of times.

OL5 Warranty

Product registration is required within 90 days of installation for maximum warranty coverage. The warranty for the Thermo Pride OL5 furnace is comprised of the following:

  • Limited lifetime warranty on the heat exchanger
  • 10-year limited warranty on parts

Labor costs are not covered under the warranty, but an additional 10-year labor warranty is available.

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