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Volume Indirect Water Heating for Residential & Commercial Applications

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The AquaStar Tankless Water Heater - Model 125BL can be used as an indirect water heater in conjunction with a storage tank for high volume situations. The Storage tank should be 30 gallons or larger. The standby losses that are associated typical gas water heaters are eliminated because there is no flue dumping the stored heat out of the storage tank. Recovery time can be over 4 times faster than a typical gas water heater due to the high recovery rate of the AquaStar. Efficiency is also maintained over time, which is not the case with a storage tank water heaters. The circulator is constantly flushing the heat exchanger in the AquaStar clean.

You can use a typical electric tank water heater for the storage tank - you disconnect the heating elements and use the lower aquastat to activate the circulator relay to turn the circulator so when the tank's aquastat calls for hot water - it activates the circulator that will pump water from the tank to the AquaStar 125BL tankless water heater and then back to the tank. You can use different size tanks to accommodate up to 5 bathrooms or more. Also - if you want to use this in an open loop heating system - you can heat your radiant floors with this also as show with the optional domestic hot water recirculating line.

Houseneeds, Inc sells all the components needed for this system.


Legend for the Indirect Application with an AquaStar 125BL High volume application and optional heating loop in an open-loop system Wow! all for less than $1200 complete!


Components for an Indirect Water Heating System
All the below components can be found on the Heating Supply Page or by clicking here.
This will take your to our main site - www.houseneeds.com where you will be able to see more info on this setup and see prices for the system.
You must use bronze parts for an all open loop systems.

  1. Taco 0011 Bronze Pump - $297.00
  2. Bronze 3/4 inch flange set - $29.75 or $41.27 for shut off flanges
  3. Bronze 3/4 inch flow check - $28.20
  4. Circulator Relay - $55.20


Please Note: You should obtain the electric hot water storage tank from a local source as the cost to ship one of these is generally more than the cost of tank it self.


Components for an Open Loop Heating System
All the needed components can be found on the Heating Supply Page or by clicking here

To use this system you must use an open loop heating system, but if you wish to have your heating system in a closed loop - you can use a heat exchanger for this. The heat exchanger will be feed from the storage tank and the back side of the heat exchanger will feed your hydronic or radiant heat system. This way - you can keep the potable water and heating system separate. We sell a flat plate heat exchanger for this system. Click on the "Contact Us" button on the top of this page or most other pages to inquire about this system.

If you intend to run a closed loop heating circuit off a 125 BL Indirect Water Heating System you need a heat exchanger. Below is the link to the Flat Plate Heat Exchanger page.
(please note to get back to this page hit the back button on your browser)
Flat Plate Heat Exchanger


HouseNeeds, Inc.
Post Office Box 525, Warren, Vermont 05674
802-583-2726