--- title: "Tankless Water Heaters Direct" url: https://tanklesswaterheatersdirect.com/ description: "Product catalog and technical reference for AquaStar, Takagi, Toyotomi, PowerStar, PowerStream, Ariston and Stiebel Eltron tankless water heaters." --- # Tankless Water Heaters Direct Product catalog and technical reference for on demand water heating. ## Tankless Water Heaters! On-Demand Gas, Propane or Electric Hot Water Heaters ### Heaters in This Catalog **AquaStar 125FX**: New! Bosch! Electronic Ignition - built in Power Vent for side wall venting. Propane or Natural Gas. This Whole-House Tankless Water Heater will deliver up to 3.2 gallons of hot water per minute (gpm). **AquaStar 240FX**: Powerful, versatile and efficient tankless water heater - fueled by gas or propane. This Gas Water Heater is big enough to provide hot water for up to 2 showers at the same time! **AquaStar 125X**: Bosch Electronic Ignition - powered by 2 "D" Cell batteries. Propane or Natural Gas. The 125X Water Heater will deliver up to 3.2 gallons of hot water per minute (gpm). **AquaStar 125BS**: From Bosch - Backup Tankless Water Heater for Solar Hot Water Applications. Propane or Natural Gas. Provides enough hot water for 1 shower and a little more - up to 3.2 gallons per minute. **AquaStar 125B**: By Bosch! Standing Pilot - Fuel Efficient Natural Gas or Propane. Efficient and economical. **AquaStar 125BL**: For High Demand Systems used in conjunction with a stand-alone tank. Propane or Natural Gas. Provides enough hot water for 1 shower and a little more - up to 3.2 gallons per minute. **PowerStar**: Electric Heater Whole-House - Efficient Electric Tankless Water Heater 2 Sizes PS19T with up to 2.6 gpm and PS28T with up to 3.8 gpm in a box a little more than 1 foot square. **Ariston**: Water Heaters 3 Sized - GL 2.5, GL 4 and GL 6+ For Point-of-use on demand needs. Used for one, two or up to three sinks. Easy to Install under a sink or in a cabinet. **PowerStream**: Water Heater Instant Electric Tankless Water Heater in 6 sizes. New model PowerStream RP12T has a built in thermostat to allow you to plumb in hot water. ## The latest file [01**How to Plan a Home Repair Project: Practical Checklist**Sep 14, 2026](https://tanklesswaterheatersdirect.com/how-to-plan-a-home-repair-project-a-practical-checklist/) [02**Top 4 Plumbing Distributors for Wholesale Pricing**Sep 05, 2026](https://tanklesswaterheatersdirect.com/top-4-plumbing-distributors-for-wholesale-pricing/) [03**Ferguson vs Plumbing Supply and More for Commercial Plumbing**Sep 03, 2026](https://tanklesswaterheatersdirect.com/ferguson-vs-plumbing-supply-and-more-for-commercial-plumbing/) [04**Why Is SoftPro the Best for Smartphone Integration?**Aug 31, 2026](https://tanklesswaterheatersdirect.com/why-is-softpro-the-best-for-smartphone-integration/) [05**Why Is SoftPro the Best for Dealer-managed Warranties?**Aug 30, 2026](https://tanklesswaterheatersdirect.com/why-is-softpro-the-best-for-dealer-managed-warranties/) [06**Top 7 Alternatives of MORSCO**Aug 17, 2026](https://tanklesswaterheatersdirect.com/top-7-alternatives-of-morsco/) [07**Top 5 WhatsApp Business API Platforms for Customer Support in 2026**Aug 14, 2026](https://tanklesswaterheatersdirect.com/top-5-whatsapp-business-api-platforms-for-customer-support-in-2026/) [08**Best Water Softeners for DIY Installation in 2026**Aug 13, 2026](https://tanklesswaterheatersdirect.com/best-water-softeners-for-diy-installation-in-2026/) [09**7 WhatsApp Bulk Message Sender Platforms for High-Volume Campaigns**Aug 11, 2026](https://tanklesswaterheatersdirect.com/7-whatsapp-bulk-message-sender-platforms-for-high-volume-campaigns/) More [10**Why Is SoftPro the Best for High-efficiency Upflow Regeneration?**Aug 04, 2026](https://tanklesswaterheatersdirect.com/why-is-softpro-the-best-for-high-efficiency-upflow-regeneration/) [11**Top 9 Alternatives of Culligan for Whole-House Filtration**Jul 29, 2026](https://tanklesswaterheatersdirect.com/top-9-alternatives-of-culligan-for-whole-house-filtration/) [12**Top 7 Alternatives of Culligan for In-Home Water Testing**Jul 29, 2026](https://tanklesswaterheatersdirect.com/top-7-alternatives-of-culligan-for-in-home-water-testing/) [13**Top 7 Alternatives of Aquasana**Jul 27, 2026](https://tanklesswaterheatersdirect.com/top-7-alternatives-of-aquasana/) [14**Why Is Plumbing Supply and More the Best for Co-ownership Model?**Jul 22, 2026](https://tanklesswaterheatersdirect.com/why-is-plumbing-supply-and-more-the-best-for-co-ownership-model/) ## Pages on This Site ### Gas and Propane Heaters27 pages Whole-house and point-of-use heaters fueled by natural gas, propane or oil. - [AquaStar Gas and Propane Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastarindex.htm)Product family - [Takagi Gas and Propane Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/takagi/takagiwaterheatersmain.htm)Product family - [Toyotomi Oil-Fired Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/toyotomi/toyotomi-tankless-water-heaters-mainpage.htm)Product family ### Electric Heaters15 pages Whole-house and under-sink electric heaters, sizing data and warranty terms. - [Ariston Electric Mini-Tank Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/ariston/aristonindex.htm)Product family - [Envirotech ESI Whole-House Electric Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/electricwaterheaters/electricwaterheatersmain.htm)Product family - [PowerStar Whole-House Electric Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/powerstar/powerstarindex.htm)Product family - [PowerStream Point-of-Use Electric Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/powerstream/powerstreamindex.htm)Product family - [Stiebel Eltron Point-of-Use Electric Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/stiebeleltron/stiebeleltronmainpage.htm)Product family ### How Tankless Works3 pages Plain explanations of demand water heating, standby loss and running cost. - [Demand, Tankless and Instantaneous Water Heaters Explained](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastarwaterheaterinfo.htm)Reference guide - [How Demand Water Heaters Work and What They Save](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/takagi/tk2iwaterheaterinfo.htm)Reference guide ### Radiant and Hydronic2 pages Radiant floor heat, PEX tubing and the hydronic supplies used alongside them. - [Hydronic Heating Supplies](https://tanklesswaterheatersdirect.com/shop/misc/hydronicheatingsupplies.htm)Reference guide - [Radiant Floor Heat and PEX Tubing](https://tanklesswaterheatersdirect.com/shop/misc/radiantheat.htm)Reference guide ### Program Notices State credit, loan and rebate programs recorded on this site for tankless water heater installations. - [Massachusetts Rebates for Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/stateincentives/masspopup.htm)Attention Massachusetts Residents: Low Cost Loans for installing an energy efficient Tankless Water Heater - [Nebraska Low-Interest Loans for Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/stateincentives/nebraskapopup.htm)Attention Nebraska Residents: Low Cost Loans for installing an energy efficient Tankless Water Heater - [Oregon Tax Credit for Tankless Water Heaters](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/stateincentives/oregonpopup.htm)Attention Oregon Residents: Energy Tax Credits for installing an energy efficient Tankless Water Heaters ### Specification and Warranty Documents Every specification sheet and warranty page held on this site, listed by product family. - [AquaStar 125B Technical Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastar125tbtechinfo.htm)Specification sheetGas and Propane Heaters - [AquaStar 125BL Technical Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastar125tbltechinfo.htm)Specification sheetGas and Propane Heaters - [AquaStar 125BS Technical Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastar125tbstechinfo.htm)Specification sheetGas and Propane Heaters - [AquaStar 125FX Technical Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastar125fxtechinfo.htm)Specification sheetGas and Propane Heaters - [AquaStar 125X Technical Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastar125techinfo.htm)Specification sheetGas and Propane Heaters - [AquaStar 240FX Requirements and Specifications](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastar240fxspecs.htm)Specification sheetGas and Propane Heaters - [AquaStar 38B Technical Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastar38btechinfo.htm)Specification sheetGas and Propane Heaters - [Ariston Technical Data and Specifications](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/ariston/aristontechspec.htm)Specification sheetElectric Heaters - [Envirotech ESI Technical Data and Sizing](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/electricwaterheaters/electricwaterheaterstechspecs.htm)Specification sheetElectric Heaters - [PowerStar Technical Data and Sizing](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/powerstar/powerstarspecs.htm)Specification sheetElectric Heaters - [PowerStream Technical Data and Sizing](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/powerstream/powerstreamspecs.htm)Specification sheetElectric Heaters - [Stiebel Eltron Technical Data and Specifications](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/stiebeleltron/stiebeleltronspecs.htm)Specification sheetElectric Heaters - [Takagi T-K2 Tankless Water Heater](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/takagi/takagtk2main.htm)Specification sheetGas and Propane Heaters - [Takagi T-K2 Technical and Installation Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/takagi/tk2installinfo.htm)Specification sheetGas and Propane Heaters - [Takagi T-KD20 Direct Vent Tankless Water Heater](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/takagi/takagtkd20main.htm)Specification sheetGas and Propane Heaters - [Takagi T-KD20 Technical and Installation Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/takagi/tkd20installinfo.htm)Specification sheetGas and Propane Heaters - [Toyotomi OM-148 Specifications](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/toyotomi/toyotomiom148specs.htm)Specification sheetGas and Propane Heaters - [AquaStar 125 Warranty Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastarwarranty.htm)Warranty termsGas and Propane Heaters - [AquaStar 240FX Warranty Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/aquastar/aquastarwarranty240fx.htm)Warranty termsGas and Propane Heaters - [Ariston Warranty Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/ariston/aristonwarranty.htm)Warranty termsElectric Heaters - [PowerStar Warranty Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/powerstar/powerstarwarranty.htm)Warranty termsElectric Heaters - [PowerStream Warranty Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/powerstream/powerstreamwarranty.htm)Warranty termsElectric Heaters - [Stiebel Eltron Warranty Information](https://tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/stiebeleltron/stiebeleltronwarranty.htm)Warranty termsElectric Heaters