Tankless Water Heater
Expert Tankless Water Heater Installation & Service in Seattle, King & Pierce Counties
Endless hot water and lower energy bills sound great, but only if the system is installed and maintained correctly. Tankless water heaters (also known as on-demand water heaters) are complex, high-efficiency appliances. Because they heat water instantly as it passes through a highly engineered heat exchanger, they require precise gas line sizing, correct venting, and routine descaling to survive the Pacific Northwest’s specific water conditions.
Grindstone Guys specializes in tankless water heater installation, repair, and preventative maintenance across Seattle, King County, and Pierce County. We ensure your system is properly sized for your household so you never run out of hot water mid-shower again.
Why Upgrade to a Tankless Water Heater?
If you are tired of scheduling showers around the dishwasher or paying to heat 50 gallons of water while you are asleep, a tankless system is the modern solution.
Endless Hot Water
It heats water on demand. As long as you have a fuel supply and water flow, you will not run out of hot water.Massive Space Savings
A traditional tank takes up 16+ square feet of floor space. A tankless unit is roughly the size of a carry-on suitcase and mounts directly to your wall.Energy Efficiency
You only pay to heat water when you actually turn on a hot water tap, eliminating the “standby heat loss” of keeping a giant tank hot 24/7.Longer Lifespan
While standard tanks last 8 to 12 years before rusting out, a properly maintained tankless unit can easily last 15 to 20+ years because it doesn’t store corrosive water.
Our Tankless Installation Process
Installing a tankless water heater is not a simple swap. It requires a complete plumbing and gas retrofit. We handle the entire process from sizing to municipal permitting.
- Flow Rate Sizing
We calculate your household’s peak Gallons Per Minute (GPM) demand—like running two showers and a washing machine simultaneously—to ensure we install a unit powerful enough for your lifestyle. - Gas Line Upgrades
Tankless units require a massive burst of fuel to heat water instantly. We often need to upgrade your existing gas line from 1/2-inch to 3/4-inch to provide the required BTUs. - Venting and Air Intake
We install specific concentric PVC or stainless steel venting to safely exhaust combustion gases outside your home. - Final Testing & Calibration
We calibrate the digital temperature controls and test the flow rate across all fixtures before signing off on the King or Pierce County permit.
The Importance of Routine Descaling Maintenance
Because tankless units flash-heat water to high temperatures instantly, the natural minerals in your water (calcium and magnesium) separate and stick to the narrow copper tubes inside the heat exchanger.
Over time, this scale buildup restricts water flow, forces the unit to burn more gas, and will eventually crack the heat exchanger—a catastrophic failure that voids the manufacturer’s warranty.
Our Annual Flush Service
Grindstone Guys provides professional tankless maintenance. We connect a specialized pump to your unit’s isolation valves and circulate a food-grade descaling solution through the heat exchanger for 45-60 minutes, dissolving the mineral buildup and restoring the unit to peak efficiency.
Use Our interactive sizing calculator to estimate the GPM (Gallons Per Minute) demand your new tankless water heater will need to handle during peak morning hours:
Peak Hot Water Demand Calculator
Select the fixtures your family might run at the exact same time during peak morning hours.
Why Choose Grindstone Guys for Tankless Services?
Tankless technology requires specialized training. An improperly installed unit will suffer from “cold water sandwiches” (bursts of cold water during a shower) or frequent error codes. Grindstone Guys brings licensed, manufacturer-trained technicians to every job. We install high-quality isolation valves on every unit to make future maintenance easy, and we pull all necessary municipal permits to guarantee your system is safe and up to code.
Frequently Asked Questions
How much does it cost to install a tankless water heater?
The initial cost is higher than a standard tank because it requires retrofitting your gas lines, upgrading the exhaust venting, and installing the unit itself. While prices vary based on your home's current layout, the long-term energy savings and doubled lifespan typically offset the upfront investment. We provide a firm, upfront quote after a home assessment.
How often do I need to flush or descale my tankless water heater?
In the Seattle, King, and Pierce County areas, we recommend a professional descaling flush once a year. If you have a whole-home water softener installed, you may be able to stretch that to every two years, but annual maintenance is the best way to protect your warranty.
What is a "cold water sandwich"?
This happens when you turn the hot water off and then back on a few seconds later. A small pocket of unheated water passes through the unit before the burner re-ignites, resulting in a brief blast of cold water in the shower. Modern, high-end tankless units have internal recirculation pumps or small buffer tanks that eliminate this issue entirely. We can help you select a model with this feature.
Can I install an electric tankless water heater instead of gas?
While electric tankless units exist, they draw a massive amount of electrical current—often requiring two or three dedicated 40-amp breakers just for the water heater. In most Washington homes, upgrading the electrical panel to handle this load is prohibitively expensive. We strongly recommend natural gas or propane tankless units for whole-home applications.
Do tankless water heaters work during a power outage?
No. Even though they use natural gas to heat the water, they require electricity to power the digital control board, sensors, and the electronic ignition. If you lose power during a winter storm, the unit will not fire. However, we can install a small battery backup system specifically for the tankless unit to keep your hot water running during an outage.
Do I have to wait for the hot water to reach my shower?
Yes, a standard tankless unit still takes time to push the cold water sitting in your pipes out of the way, just like a tank heater does. If you want instant hot water the second you turn the tap, we can install a tankless unit with a built-in recirculation pump that keeps a loop of hot water constantly primed throughout your house.