HT Series – Direct Vent

The HT Series provides maximum heat transfer to the ultimate in economical operations with a unique three-pass construction.

Its large water content ensures excellent tankless coil performance to meet the hot water demands of today’s lifestyle.

  • EFFICIENCY – A wet-base design, a horizontal tube, and a three-pass heat exchanger make this one of the most efficient boiler designs available.
  • HIGH WATER VOLUME AND STANDARD 5 GALLON DOMESTIC WATER COIL – An amazing 30 gallons of water in the wet section of the boiler, combined with the 5 GPM coil provides the customer with abundant domestic hot water.
  • FORCED DRAFT BURNER – eliminates chimney draft problems.
  • QUIET OPERATION – Due to the horizontal tube and wet-base, the HT is remarkably quiet. The “Uni-flow” path of combustion gases allows for smoother, quieter combustion than firebox, wet-leg designed boilers.
  • EASY CLEANING – the heat exchanger is easily accessible for cleaning. Available for sidewall direct vent applications. No power ventor required.
  • RATING – The 86.2% AFUE rating is among the highest Department of Energy (DOE) ratings.
  • ONE-PIECE BOILER CONSTRUCTION – ensures years of trouble-free service. There are no push nipples or “O” rings to leak.
  • MULTIPLE FIRING RATES – Each boiler is listed at three (3) different firing rates. All three nozzles are included with each unit. This allows for more accurate sizing to the heat loss, yet keeps the cost of the boiler lower. The firing rates range from .90 to 1.50 GPH within two (2) boiler shells. This feature reduces inventory costs with one model covering several firing rates.

  • A 5-GPM TANKLESS COIL – with a 30-gallon boiler water content assures abundant hot water.
  • WET BASE -THREE PASS DESIGN – Known in the industry as the most efficient and durable design. Water completely surrounds the combustion chamber, plus two sets of tubes to further transfer heat before venting from the rear of the boiler. The “uni-flow” path of the combustion gases allow for quieter combustion.
  • FORCED DRAFT BURNER – The forced draft burner eliminates chimney draft problems. The HT-Series is designed to work in spite of poor draft conditions. It also seals products of combustion from the living area, reducing potential “puff-back” problems.
  • ASME CONSTRUCTED  – Each boiler is constructed and hydrostatically tested in accordance with ASME Boiler Code.

Standard Features

ASME Code BoilerConvenience Box with Switch & Outlet
Flush Jacket007 or Equivalent Circulator (not mounted)
Ceramic Fiber Combustion ChamberBrass Boiler Drain
Altitude, Temperature & Pressure GaugeBuilt-in "Air Scoop"
ASME Relief ValveFactory Assembled, Wired & Packaged
5 GPM Tankless HeaterNational Board Stamped
GeniSys Control (Beckett)Aquasmart Control or Hydrolevel Control


Advanced three pass design traps more heat during longer, slower passage of combustion gases through the boiler heat exchanger. This design transfers the heat to your home instead of out the chimney. Note: Circulator not mounted for shipping.

All appliance designs are forced draft pressure fired for optimum performance. They are available with either Beckett, Carlin, or Riello oil burners

Blended SizesHT 90/100/110 EEHT 125 EE
Heat Capacity109,000121,000132,000151,000
Gross OutputN/AN/AN/AN/A
Net Out94,000105,000115,000131,000
Firing Rate0.901.001.101.25
BafflesFully BaffledFully BaffledFully BaffledFully Baffled
Water Content - Gallons30303028
Supply 1¼"1¼"1¼"1¼"
Returns (2)1¼"1¼"1¼"1¼"
Coil Capacity5 GPM5 GPM5 GPM5 GPM
AFUE - DOE Efficiency86.
Combustion EfficiencyN/AN/AN/AN/A
Overall EfficiencyN/AN/AN/AN/A
Burner ModelBecket AFG, Becket AFII, Becket NX, Carlin EZ-1, Riello BF5Becket AFG, Becket AFII, Becket NX, Carlin EZ-1, Riello BF5Becket AFG, Becket AFII, Becket NX, Carlin EZ-1, Riello BF5Becket AFG, Becket AFII Carlin EZ-1, Riello BF5
* Model 90/100/110 and 125 available in choice of chimney or direct vent with Beckett AFII, Beckett NX, Carlin EZ-1 and Riello BF5 Burners only.

Vent Kits

THERMO-VENT 175 Vent Kits
One per boiler required.
One wall opening required.
Part No.Shipping Weight (pounds)
TV-175 Combination Vent Kit - 10ft28107224
TV-175 Combination Vent Kit - 15ft28108230
TV-175 Combination Vent Kit - 20ft28109336
* Note: Vent Hood Packaged Separately from Tubing. (2-cartons) 4" tubing shipped inside of 5" tubing.

DIRECT VENTING KITS – 10ft., 15ft., 20ft. Includes:

1 – Sized Length of 5″ Stainless Steel Flexible Vent Tubing
1 – Stainless Steel Combination Air Intake Exhaust Vent Hood
1 – 5″ Stainless Steel Flex Tubing Connector
1 – 4″ Tee w/Vacuum Relief
1 – Sized Length of 4″ Aluminum Flexible Intake Tubing
Attaching Screws, Silicon Sealer, Instruction Sheet
Note: Connector Tubing standard NFPA 9″ Clearance to Combustible.

HT – Series Manual

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Boiler Warranty

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