The Texas Winterization Guide for Tankless Water Heaters

As Winter Storm Fern continues to barrel down on the East Coast, thousands of outdoor tankless water heaters are at risk in Texas. During a similar deep freeze in 2021, even the “freeze-protected” units succumbed to the cold when the power went out in the Lone Star State.

To help you out, here are practical tips for protecting your tankless unit, and what to do in case of a blackout. We’ve also curated a list of the most winter-resilient tankless water heaters, as well as essential accessories to ensure your hot water stays on even when the temperature drops.

How Freezing Weather Can Damage your Tankless Water Heater

Compared to conventional water tank heaters, tankless units do not store hot water. This leaves them at greater risk of freezing up in cold weather once the groundwater drops below zero.

• Water inside the unit can freeze, causing pipes to burst
• Outdoor heaters with insufficient insulation may not cope with subzero temperatures
• Power outages can render the built-in heaters useless (see remedy below)
• The pipes leading to the unit itself may not have proper insulation, causing burst plumbing

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What to Do In Case of a Power Outage

During a blackout, tankless heaters cannot function as they require electricity for ignition and operation, even for gas models. Here’s what you should immediately do.

1. Unplug the unit

Unplug the heater and turn off the circuit breaker. This will avoid electrical damage to the PC board when power returns, in case of a power surge.

2. Drain

This step is absolutely important in freezing conditions: drain the heater. This will remove any water present in the pipes that would otherwise freezing, causing the pipe to crack and eventually burst from the expanding frozen water.

To drain the tankless heater:

• Shut off the power / gas supply
• Turn off the water valve to the unit

• Locate the hot/cold service at the bottom. These are marked by red and blue handles.
• Remove the caps
• Take off any water inlet filters. Now would also be good time to clean them while the heater drains
• Allow the unit to drain completely
• Leave the service valves open until you can safely use the heater again after the extreme freezing conditions have passed.

3. Optional: Flush

If you have a hard water supply or the heater hasn’t been cleaned in over a year, consider a flush to remove built-up blockages.

• Connect a pump and hoses to the service valves
• Fill with white vinegar
• Allow to circulate for 1 hour to remove sediment
• Flush with clean room-temperature water

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Tankless Water Heaters Built for Winter

If you’re not confident your existing tankless unit can withstand severe winter, it might be time to invest long-term replacement for peace of mind. After all, the middle of a winter storm is the worst possible time to run out of hot water, whether it’s for that daily shower, hot coffee, or more essential tasks like washing dishes and doing laundry!

Level 1: Direct Outdoor Replacement

If you currently have an outdoor unit that was damaged or uses old technology, Rinnai is a good brand for water heater replacement. The Japanese manufacturer is renowned for its line of tankless hot water heaters, catering to both residential and commercial applications.

For outdoor heaters, Rinnai’s RE Series units are the gold standard for outdoor installations. These units are specifically designed for cold weather, with built-in freeze protection down to -4°F. They are also a direct swap for most existing outdoor setups in Texas.

Rinnai RE199e High Efficiency Non-Condensing, 9.8 GPM Tankless Hot Water Heater for Outdoor Installation

This non-condensing tankless water heater allows the flame to adjusts accordingly to heat more or less water depending on the amount of hot water called for. This model is specifically designed for outdoor installation and does not require venting.

It features 199,000 BTUs and hot water delivery with a flow rate that ranges from 0.13 – 9.8 GPM, enough to cover simultaneous use of 4 – 5 fixtures at one time. It offers maximum settings at 125°F with an option to increase to 140°F.

For smaller demand requirements, Rinnai also offers outdoor models with lower BTU capacities:

Model	Capacity	Best For	Product Link
Rinnai RE180e	180,000 BTUs	3-Bathroom Homes	Price: $1,319.00 Rinnai RE180e High Efficiency Non-Condensing, 8.5 GPM Tankless Hot Water Heater for Outdoor Installation ... View Product
Rinnai RE160e	160,000 BTUs	2-Bathroom Homes	Price: $1,095.00 Rinnai RE160e High Efficiency Non-Condensing, 6.6 GPM Tankless Hot Water Heater for Outdoor Installation ... View Product

Level 2: Indoor Conversion Units

Many Texans are moving their units inside to spare spaces like garages or utility rooms, to avoid the elements entirely and provide greater protection in freezing weather.

For indoor conversions, Rinnai’s SENSEI RX and CX series offer protection down to -22°F when installed indoors. These units come with an outdoor vent cap, giving you the highest level of internal protection available.

Additionally, while they are designed for indoor use, they can also be installed outdoors with the addition of Rinnai’s Versa-Vent, making them flexible.

Residential SENSEI RX Series

The RX Sensei+ Series are super high efficiency, Energy Star Qualified, tankless hot water heaters. It features condensing technology that provides freeze protection down to -22°F on the indoor units. An integrated check valve located between the turbo fan and the combustion chamber stops cold air from entering the venting system and backflow of exhaust in common vent applications.

Rinnai RX199iN Ultra Low NOx High Efficiency 11.0 GPM Sensei+ Condensing Tankless Hot Water Heater

This model delivers 199,000 BTUs with hot water delivery with a flow rate that ranges from 0.13 – 11.0 GPM, enough for a home with 3 – 4 bathrooms.

The dual venting option on the top of the unit allows for maximum installation flexibility – one concentric vent or two PVC/CPVC/PP pipes can be used for venting. With concentric venting, one pipe allows for fresh outside air in, while the other allows for exhaust to go out. Outdoor installation does not require venting.

For smaller households, the RX160iN provides 160,000 BTUs 2-3 bathrooms, while the RX180iN is capable of 180,000 BTUs for 3-4 bathrooms.

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Built-in recirculation pump:

Rinnai RXP160iN Ultra Low NOx High Efficiency 9.0 GPM Sensei+ Condensing Tankless Hot Water Heater with Built-in Pump

This 160,000 BTU unit features a built-in recirculation pump. By keeping the water moving through the heater, this makes it much harder to freeze compared to standing water.

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Commercial Grade Units

The CX series are designed for commercial use, built with heavier-duty components for higher demand and extreme durability.

Rinnai CXP160iN 9.0 GPM Sensei CXP Series Commercial Condensing Tankless Hot Water Heater with Built-in Pump

This super high efficiency, Commercial Energy Star Certified, tankless hot water heater features 160,000 BTUs and hot water delivery with a flow rate that ranges from 0.13 – 9.0 GPM. It comes with a built-in pump for hot water recirculation and maximum setting of 185°F with parameter adjustment.

For higher demand requirements, the CXP199iN model 199,000 BTUs and hot water delivery with a flow rate that ranges from 0.13 – 11.0 GPM.

Level 3: The Bradford White Advantage

Bradford White heaters are proudly made in the USA, and thus are held to the highest standards. For extreme weather, the brand’s Infiniti series uses specialized ceramic heaters to protect the internal heat exchanger and ensure efficient performance even in challenging climate conditions.

Bradford RTG-S-199-N1 Infiniti GS Series High Efficiency Condensing Tankless Hot Water Heater

When installed as a residential hot water heater, this versatile unit can be vented with PVC, CPVC, Polypropylene or Stainless Steel venting. Additionally, direct vent, unbalanced vent or outdoor vent cap is also supported. When installing in a commercial setting, common venting including PVC, CPVC, Polypropylene are permissible for up to 8 units. The GS series is Energy Star Qualified and Certified Green by the Green Restaurant Association.

This model features 199,000 BTUs and hot water delivery with a flow rate that ranges from 0.5 – 9.7 GPM, enough to service simultaneous use of 3 – 4 fixtures at one time.

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For freeze-prone areas, the RTG-R-199-N1 version includes a built-in pump. This is our top recommendation for freeze-prone areas because it keeps water moving through your pipes automatically.

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How to Protect your Tankless Heater in Winter

Even the best water heater needs power to run its internal heaters. If the Texas power grid fails, your unit is at risk, and with it your hot water supply in deep winter.

Here’s how save your unit in the event of a power outage:

✅ Drain down

If the power goes out and temps are below freezing, you must drain the unit. to prevent the water from freezing inside and causing the pipes to burst.

✅ Solenoid valves

A solenoid valve helps prevent heater damage by automating the draining process. Ask us about Rinnai’s auto-drain valves that empty the unit the second the power cuts.

Rinnai 104000285 Freeze Protection Drain Down Kit for Sensei

This drain down kit for Rinnai Sensei Tankless Water Heaters in the event of a power failure. When power goes out, the valves will shut off the cold water and drain your tankless water heater to help protect the heat exchanger, making the whole process convenient and worry-free.

This kit is specifically designed for Rinnai’s Sensei Series water heaters including RU160e, RU180e, RU199e, RUR160e and RUR199e models.

✅ Insulate your pipes

While high end tankless units may have built-in protection, the copper pipes leading do not. This represents a weak point in the system.

Use high-quality foam insulation and heat tape on all exposed plumbing to insulate them from freezing temps.

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Essential Winter Accessories for Tankless Heaters

Winter accessories are available for tankless water heaters that provide freeze protection as well as improved performance in colder regions.

Rinnai RXOVC Outdoor Vent Cap for Sensei+ RX Series Condensing Tankless Hot Water Heater

This Vent Cap allows you to install your Rinnai RX**iN Series tankless water heater outdoors. It covers the venting required in an indoor installation, allowing for a quick and easy outdoor installation.

Outdoor Tankless Water Heater Cover

This protective cover helps shield your outdoor unit from the elements. The outer layer is constructed from thickened Oxford cloth, with a plastic waterproof layer and a cotton inner layer. The silver color helps reflect intense sunlight.

Pipe Insulation Foam Tube 5/8 inch,- 6FT 5/8″ Foam Tubing for for Indoor Outdoor Plumbing Pipe

This insulating pipe sleeve uses material that is fire-resistant material, fire-retardant, and self-extinguishing, while being environmentally friendly and nontoxic. It has good bending flexibility, high cold and heat resistance, and low thermal conductivity.

Pipe Insulation Tape 2″ Wide X 32.8 Ft Foam and Foil Pipe Wrap Insulation Tape Self Adhesive

This outdoor pipe insulation wrap roll from Amazon is made of 0.2-inch thick rubber and plastic cotton. In addition to providing freeze protection for pipes, it offers waterproofing and fire resistance protection. The extended size makes it suitable for any diameter pipe such as 3/4,1 1/4,1/2 inch.

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Ready to Upgrade?

We realize how crucial it is to have hot water in freezing temperatures. All the units featured here are in stock and shipping fast to Texas. Don’t wait ’till your tankless heater conks out from the winter storm — secure your home’s hot water today.