Heating Equipment

Greenhouse heating is very demanding. In our cold winter one year of greenhouse heating is approximately 3 to 5 years of service of normal commercial use. So if pays both in time and mind set to have a system that is very reliable.

Gas Fired Unit Heaters

Since 1992 we have supplied and or installed Reznor unit heaters in all our commercial greenhouse projects, when called for. Over these years we have found these units operate with very little trouble and have provided dependable heating function. They are a very good and wise choice for a workhorse staple for heating.  The Series UD were introduced in 2008, which replaced the FE and BE series that had reliably serviced the industry for the previous 15 years. The series UD feature many new and valued standard features. These include titanium stabilized aluminized steel heat exchanger, multi-try direct spark ignition, power vent interior cabinet mount of all wiring, control devices and gas valve ( less visible hardware – which is ideal for greenhouse use ), 2 and 4 point suspension points, 115/1/60 supply voltage, fan relay, full fan guard and 83% thermal efficiency.

The most popular models for greenhouse use are models UDAP, UDAS, UDBP, UDBS.  Models UDAP and UDAS are low static propeller fan models and the UDBP and UDBS are high static blower fan models. UDAS and UDBS also feature separated combustion feature. Of these the model UDAP is the most popular. Far less popular in greenhouse applications Model SHE a high 90% thermal efficiency, condensing series is also available. All models are GSA and ULC approved.

We carry and stock UD models with exception of the SHE series (series SHE by special order only) and in the following popular sizes.

Reznor UDAP

Reznor UDAS

Reznor UDBP

Reznor UDBS

For additional technical data, assistance, sizing and or selection contact our office.

Hot Water Heating Boilers

Low Temperature Instantaneous Hot Water Boilers

During the past several years Instantaneous Low Temperature ( 140 deg. F supply ) has gained wide use for under the bench heating and irrigation water preheat applications. Due to the compact design of these units they can be simply wall or rack hung in a mechanical service room or area or on a wall or column in the greenhouse area. The use of these units also for very affordable under and in the bench heating systems.

Super Hot model HSE High-Efficiency Condensing Boilers

HSE125 and HSE145 are the wall hung condensing boilers that do more for less. As among the most versatile heating appliances on the market, it combines domestic hot water and central heating in a single compact unit. HSE is the Heating, Smart, Efficient solution. The HSE uses proven condensing technology with a unique double high efficiency heat exchanger performing at up to 95% AFUE. As an ENERGY STAR® appliance, it is eligible for most government and utility rebates. Reliability, high efficiency, economical design and a 10 year heat exchanger warranty are just a few of the reasons why it is the smart choice for builders and home owners alike. Available in two sizes HSE-125 with 28,000 to 124,000 BTU input and HSE-145 with 33,000 to 145,000 BTU input in natural gas or propane versions.

  • Features
    The unique double high efficiency heat exchanger uses copper waterways in an aluminum block for maximum heat transfer. The sophisticated controller with outdoor air sensor constantly monitors environmental changes and modulates according to specific heating and domestic water demands. With proven technology and up to 95% AFUE, you can take comfort in the warmth, and environmental and cost savings with one of the most advanced heating appliances available.
  • Unlimited Applications
    Two fully modulating condensing models for residential and light commercial applications: central heating, hot water, or both – with integrated irrigation water preheat and priority for indirect tanks, all in a low profile, wall-hung boiler.
  • Environmentally Friendly
    The smart HSE design does more with fewer parts and operates at up to 95% efficiency with near 0 standby losses and a 5:1 turndown ratio. A state-of-the-art production facility reduces overall environmental impact making it the green choice for heating.
  • Dependable Performance
    A proven, double high efficiency heat exchanger has fewer moving parts offering long lasting service. Dual all-copper waterways protect the heat exchanger from internal corrosion and are glycol compatible.
  • Easy Installation
    Trouble-free installation with simple piping and DHW kits, integrated hot water, 85 ft CPVC, SS, and PP venting options and a user-friendly controller, reduce setup time and costs.
  • Double High Efficiency Heat Exchanger
    A multi-pass heat exchanger with dual copper waterways allow all heating to be done in a single, compact and cost effective unit. No need for diverter valve, pump, hot water plate exchanger, or air pressure switch.
  • Reduced Maintenance
    The minimalist design with convenient access to internal components and few moving parts reduces maintenance costs and offers ease of service – all backed by a 10 year heat exchanger warranty.

High Temperature Hydronic Boilers

In the late 1980’s we were quick to understand the benefits of small to medium  large modular boiler systems were as compared to the large horsepower Fire tube boiler systems. Since this time we have used and recommended Superhot Commercial Gas Boilers as manufactured by Allied Engineering. The principal advantage gained by using smaller modular boilers is the ability of redundancy ( safety and backup ), and the ability to provide incremental small packets of staged firing as to allow accurate trending of the actual heating loads required. This provides for system and energy optimization and greatly reduced fuel/energy costs.

The Series AAA is most popular and a steadfast workhorse of the Super Hot line up.  They are available in modular sizes ranging from 480,000 to 3,000,000 BTU inputs.

  • 85% Combustion Efficiency
  • 2012 DOE & NRCAN Compliant
  • Commercial, Industrial, Institutional
  • Natural Gas or Propane

The AAA Series Commercial Gas Boiler is the latest evolution of Allied Engineering’s long history designing and building high quality heating products. More than 65 years of experience designing and building high quality hydronic heating equipment and providing outstanding customer service have made Allied Engineering and Super Hot leading names in commercial and industrial heating applications. Super Hot AAA Series boilers are the dependable, long lasting, efficient and economical choice.

This latest generation of our commercial boilers is 2012-DOE / NRCAN compliant and features improved efficiency with increased heat exchanger fin, an optimized burner, and improved insulation performance.

To the left, a true Two-Pass Heat Exchanger Supply and Return can be connected to either side. Heat Exchanger is supplied fully welded.

To the right, a Burner Draw Assembly with high Stainless Steel Burners.


Stainless Steel Atmospheric Burners

High grade, heat resistant stainless steel ensures years of trouble free service, exceptional performance and improved fuel efficiency with virtually no combustion noise.

Double Pass Steel Heat Exchanger

A unique double pass steel fin-tube heat exchanger offers increased heat transfer surface area through a continuous spiral-welded fins which has been extended in the latest generation. Steel top and bottom headers and riser completes the double pass design providing a sturdy, light weight heat exchanger that resists thermal shock. Large 2”OD ASME boiler tube waterways resist plugging and minimizes pressure drop, reducing circulator capacity requirements. The heat exchanger requires no field assembly and has no gaskets or push nipples. No other heat exchanger offers the strength, rigidity, low cost, and environmentally friendly construction.

  • Systems Integration
    A 2-stage BC-1 controller comes standard on all sizes and optional direct digital control contacts and outdoor sensors are available.
  • Rapid Response
    AAA Series design ensures rapid response to calls for heat, especially important for critical operations, indirect fired hot water heaters and tankless coils.
  • Quality Construction
    AAA Series boilers are constructed to ASME section IV standards with a maximum working pressure of 160 psi (1100 kpa) and a maximum operating temperature of 240°F (115°C). Each is tested to 240 psi and certified by a third party inspector.
  • Ease of Installation and Operation
    Fully assembled AAA boilers are the smart choice for swift, user friendly installation and easy, convenient maintenance. Direct digital control terminal contacts are available for integration into most modern building management systems. The AAA Series boiler’s modular design allows for easy dismantling and reassembly to transport through narrow doorways and passages.

  • Intermittent Electronic Ignition
  • Single Stage Gas Valve
  • Two Stage Gas Valve
  • Redundant Gas Valve
  • Temperature/Pressure Gauge
  • On/Off Switch with Indicator Light
  • Operating Aquastat
  • High Limit
  • 30 psi A.S.M.E. Pressure Relief Valve
  • 24 Volt Transformer and Fuse
  • Draft Hood
  • Control Panel Enclosure

  • Low Water Cut Off
  • Flow Switch
  • Flame Supervision
  • Indoor/Outdoor Control
  • Auto/Manual Switch
  • Alarm Feature
  • Full Modulation Gas Valve
  • Direct Digital Control Terminal Contacts
  • Combination Seismic Restraint/Lifting Lugs
  • Higher Pressure A.S.M.E Relief Valves
  • High/Low Gas Pressure Switches
  • Propane


Super Hot AAA boilers are constructed from the highest quality materials and built to the highest quality standards to exacting ASME standards. Allied Engineering is authorized by ASME to use the U stamp for pressure vessels and H stamp for heating boilers and is audited by their inspectors.


Manufactured under the highest standards for material and workmanship, the proven design is covered under a 10 year heat exchanger and one year parts and controls warranty. See printed warranty for details.


Allied Engineering uses an environmentally friendly heat exchanger design that is designed for longevity and 85% efficiency. Most components are recyclable after their long, trouble free life.

For additional technical data, assistance, sizing and or selection and design layout for any hot water boiler system please contact our office.

In addition to the primary hot water boiler we carry a wide selection of Grund-foss heating circulators and pumps, Techmar multistage indoor/outdoor boiler controls, Honeywell/Pen and Carrier control devices.

For additional technical data, assistance, sizing and or selection contact our office.