BOILERS ON DEMAND designs, builds and markets the ENHANCED CONVECTION, DIFFERENTIAL TEMPERATURE MANAGED, HYDRONIC HEATING APPLIANCE (US Patent 10,690,356 & Canada to follow). It is specifically configured to your application as an Integrated Hydronic (FHW) Heating & DHW Appliance. Position at your site and attach to your piping and utilities. Reduces time and cost, with guaranteed, superlative performance.

Mercier Engineering d-b-a BOILERS ON DEMAND is a fully bonded/insured and referred Weil-McLain Contractor. We are dedicated Weil-McLain-Taco-HTP-Only installers and servicemen, based on our 60 years plus of trade history experience.

Our collaboration with Taco Comfort Solutions® (America’s Premier Hydronics Manufacturer) has resulted in fully integrating their 00e Series VT2218 Delta-T Circulator-based Hydronic Distribution System into our design.

On-Site Services are provided as follows:

  1. We can fully install NH Oil Installations only. Gas (NG/LP) Systems install with a Licensed Technician (by others).
  2. Partial installation to the degree that site applicable Codes permit is provided at other locations.
  3. Where we deliver, installation instruction and assistance can be provided by arrangement.

Otherwise, we supply an appliance to Distributors, Dealers and Installers for their completion.

All Trade Distributor, Dealer and Jobber Licensing inquiries are welcomed.


For any and all services provided outside NH a signed “Save Harmless Agreement” is required.

The customer is responsible for obtaining and providing any applicable Licenses, Permits, both prior and post-installation. These include Installation, Inspection and Operation Permits with specific installation details (proximities, fire containment and/or attenuation, etc.).

Specific details and conditions must be provided prior to contracting service(s).

Author’s Note: Updated 10/17/2020. -pdm