Thermal Expansion Tank Installation in Denver, CO
Water expands when it heats. In an open system it pushes back toward the street. In a closed system, which is most Denver homes with a pressure reducing valve or a check valve, it has nowhere to go and pressure spikes every heating cycle.
- Required by code on closed systems
- Tank pre-charge matched to your actual house pressure
- Mounted and supported so it does not stress the pipe
Get A Free Quote
We reply fast. Same day when possible.
What it is
Thermal expansion tank A thermal expansion tank is a small tank installed on a water heater's cold supply line that absorbs the extra volume created when heated water expands, preventing a dangerous pressure spike in a closed plumbing system.
Many Denver-area water systems use a check valve or pressure reducing valve that creates a closed system, and in that setup a missing expansion tank can cause pressure spikes that stress pipes, valves, and the water heater itself.
A dripping relief valve is usually an expansion problem
If the temperature and pressure relief valve on your water heater weeps after a hot shower, the system is almost certainly closed with no expansion control. People replace the relief valve and the drip comes right back, because the relief valve was doing its job.
- Protects the water heater tank and the relief valve
- Stops pressure spikes that fatigue supply lines
- Extends fixture and valve life
- Small, inexpensive, and required by code
You need an expansion tank if
- The water heater relief valve drips after heating cycles
- Pressure reads normal cold and high after a shower
- You have a pressure reducing valve or a meter check valve
- Toilet fill valves fail unusually often
- You just installed a new water heater on a closed system
What a correct install looks like
- Confirming the system is closed, with a gauge test cold and hot
- Tank sized to water heater capacity and system pressure
- Pre-charge set with a tire gauge to match incoming static pressure
- Mounted on the cold supply above the heater, properly supported
- Union or valve so the tank can be serviced later
- Post-install pressure check through a full heating cycle
What to expect and how the work gets done
- 1
Test
Read pressure cold, then again after the heater runs, to confirm expansion.
- 2
Size and pre-charge
Match tank volume to the heater and set the air charge to house pressure.
- 3
Install
Tee into the cold line above the heater with real support, not hanging on the pipe.
- 4
Verify
Run a heating cycle and confirm the relief valve stays dry.
Credentials, reviews, and company proof
- Colorado Master PlumberFixture and appliance work is permitted and code-compliant, not handyman work.
- Plumbing Contractor license 2110Licensed to pull permits and pass inspection on gas, water, and drain work.
- Serving Denver since 2006Two decades of Front Range water chemistry, altitude, and inspection practice.
Ready when you are
Tell us what is happening and your Denver neighborhood. We will route it fast.
Expansion tank cost factors
This is one of the least expensive protective upgrades in the house.
Need help right now? 24/7 emergency plumbing service. Planning a larger repair? See financing options.
- Tank size, which follows water heater capacity
- Access and clearance above the water heater
- Adding a support bracket where the pipe cannot carry the weight
- Adding a service valve and union
- Whether it is installed alongside a water heater or PRV replacement
Frequently asked questions
Licenses, credentials, and company proof
- Colorado Master PlumberLicense MP-18927
- Colorado State Plumbing ContractorLicense 2110
- Family Owned & OperatedServing Denver since 2006, 20 years
- Better Business BureauAccredited Business, A+ rating
- Angie's List Super Service Award2012 through 2017
- Serving Denver since 2006Residential and commercial properties across the metro
More plumbing help from Afford-A-Rooter
- Backflow Preventer TestingCertified backflow testing in Denver for irrigation and commercial assemblies. Repairs, rebuilds, and the report filed for you.View page
- Hose Bib and Outdoor SpigotOutdoor spigot leaking into the basement? We replace Denver hose bibs with frost-free sillcocks, pitched to drain. Call (720) 296-7972.View page
- Water Main Shutoff ValveMain shutoff will not close? We replace seized gate valves with full-port ball valves in Denver homes. Call (720) 296-7972.View page
- Gas Line InstallationGas line installation in Denver for ranges, dryers, fire pits, and tankless heaters. Load calculated, permitted, and pressure tested.View page
- Bathroom Remodel PlumbingMoving a toilet, tub, or shower drain in Denver? We handle remodel rough-in, venting, and finish plumbing with permits. Call (720) 296-7972.View page
- Kitchen Remodel PlumbingKitchen remodel plumbing in Denver. Island sink venting, gas range lines, pot fillers, and dishwasher hookups done to code.View page
Stop the relief valve drip at the source
Free pressure test and expansion tank quote.