Amtrol BoilerMate WHS-40Z 40-Gallon Indirect Water Heater
Amtrol BoilerMate WHS-40Z 40-Gallon Indirect Water Heater Review
The Amtrol BoilerMate WHS-40Z is a 40-gallon indirect water heater — a storage tank heated by an external hydronic boiler rather than integral combustion or electric elements. Common in homes with hydronic space-heating systems where the boiler can also provide DHW.
Specs: 40 gallons stored, stainless steel internal coil heat exchanger, polyurethane foam insulation. Compatible with most US residential boilers (oil, gas, propane). 7-year tank warranty.
The 40-gallon capacity is the standard residential indirect size. Boiler-driven heat transfer: hot boiler water (typically 160-180°F) circulates through the internal coil, heating domestic water in the surrounding tank.
Advantages versus standalone water heaters in hydronic-equipped homes:
- No separate burner or electric element to fail
- Higher effective efficiency when paired with modern condensing boiler
- Longer service life (no combustion components in DHW tank)
About $1,300 unit, $2,200-$2,900 installed depending on boiler integration complexity. Right buyer: home with existing hydronic boiler wanting indirect DHW solution.