explore documents

Mod Con Double Stack VWH Supply Boiler

The Mod Con Double Stack Volume Water Heater

The Mod Con Double Stack VWH features an intelligent design that delivers domestic hot water up to 98% thermal efficiency. The high-grade modulating gas burner operates at an incredible 10 to 1 turndown ratio (for most models) to meet variable water heating needs. Quality construction, a small footprint and convenient features make the Mod Con Double Stack VWH ideal for most commerical water heating applications.

view brochure

Free Consultation!

for more information and product savings, select an option below

A Low Mass VWH with a High Efficiency

Interior of the Mod Con Double Stack Boiler

The Mod Con Double Stack VWH is up to 98% thermal efficient with a 10 to 1 turndown. Up to 98% of the gas consumed by the Mod Con boiler is converted into heat, compared to a mid-efficiency system where up to 40% of the heat can be lost through the chimney.

The modulating burner combustion system and two independent boilers work together as one unit and is able to operate at a true 10:1 turndown ration, saving fuel and providing comfort levels efficiently and evenly.

The Perfect Fit


The Mod Con Double Stack VWH comes in two model sizes: 1 million and 1.7 million BTU. It features a built-in cascading capability allowing up to four boilers to be linked together. Cascading provides increased turndown ratios, built in redundancy and a total heating capacity of up to 6.8 million BTU!

view specifications

Model Btuh/Input Range Gross Output BTU/hr Btuh/Input Range Thermal Efficiency
Mod Con 1000 VWH 100,000-1,000,000 940,000 100,000-1,000,000 97%
Mod Con 1700 VWH 170,000-1,700,005 1,600,000 170,000-1,700,005 98%

Becoming Green

Not only does the Mod Con DS save energy and money, it is also eco-friendly. The Mod Con DS Boiler has ultra-low NOx emissions providing additional environmental savings due to its combustion control system, which minimizes levels of nitrogen oxide. If NOx levels are not reduced, oxidants can build up in the atmosphere and have harmful effects on human health. The Mod Con is an eco-friendly choice, protecting the environment while saving your energy and money.

An Easy Installation

The Mod Con DS VWH is equipped with concentric venting and requires only one exhaust connection through the wall or roof for exhaust vent piping. It has complete flexibility with the ability to vent up to 150 ft.

The lower exhaust temperatures due to high efficiencies allows for the use of PVC or other plastic venting materials which saves on installation cost and time.

The Mod Con DS VWH has indirect water heater integration. With the addition of a storage tank, the VWH can be converted into a hot water heater to provide ample heating and hot water to save you space and money!

view installation manuals
The Mod Con with an Indirect

High Heating with High Quality

The Mod Con Double Stack VWH is manufactured with 316L stainless steel to provide excellent heat transfer properties and increased corrosion resistance. The heat exchanger is made without the use of gaskets with superior welding technology. It is also ASME approved and is 150 PSI relief rated.

Advanced Assurance

The Mod Con DS VWH is backed by a limited 5 year warranty, right out of the box! No registration is required.

view warranty

Fast Connection, Anywhere


Download HTP’s FREE Mobile App. Perfect for when you need guidance on the job. You’ll be able to access installation manuals, parts and installation drawings, brochures, troubleshooting videos and more.

download the app

Get help buying

Have a question?
Chat Now


Read what others have to say
about our products?

Rebate center

Find available rebates
nearest you.

Warranty claim

Submit your claim,
its as easy as 1, 2, 3.

Stay Connected

App-Icon - HTP
Facebook - HTP YouTube - HTP Twitter - HTP Instagram - HTP LinkedIn - HTP

© Copyright Ariston Thermo USA LLC parent company of HTP | 272 Duchaine Boulevard | New Bedford, MA 02745 | 800-323-9651 Careers | Sitemap