No Hot Water in Denver? 5 Steps to Take Before You Call
Before anybody calls about no hot water in Denver, there are five things worth checking, and a couple of them exist because this city asks a gas appliance to burn fuel a mile above sea level. Two of the five take a minute and settle the question without a visit.
Work down the list in order. If the answer is not in it, you will at least be able to describe the failure precisely, and that shortens everything that follows.
Five Checks to Make When There Is No Hot Water at All
- Find out which kind of heater you have before you touch it. A gas tank has a burner compartment at the bottom, a gas line and a flue going up. An electric tank has conduit into the side and two access panels. Everything below splits at that fork.
- On an electric tank, go to the panel. A double pole breaker that has tripped is the single most common cause of a house going cold overnight. Reset it once. If it trips again, stop and leave it off.
- On an electric tank the small red button above the upper thermostat is a record, not a repair. It drops the circuit when the water at the top runs past where the control wanted it, so the number worth having is how many times somebody has already pushed it. Twice in a week is a thermostat that has stopped controlling, or an element shorted to the shell, and neither one is fixed by pushing it a third time.
- On a gas tank, look through the sight glass at the base and check whether the pilot or the igniter is lit. If it is out, follow the relight sequence printed on the label, and watch whether it holds for a full ten minutes after the knob is released.
- Check that gas is reaching the house at all. If the range and the furnace are working, gas is fine and the problem is at the heater. If nothing gas fired is running, the issue is upstream of the tank entirely.
Nothing on that list involves opening the tank, draining it or adjusting a gas valve. If the pilot will not hold, or the breaker keeps tripping, those are the two symptoms that mean stop and call rather than keep trying.
What a Mile of Elevation Does to a Gas Water Heater
Air at 5,280 feet holds roughly a sixth less oxygen per cubic foot than air at sea level. A gas burner does not know that. It meters fuel through a fixed orifice and relies on the surrounding air to supply the rest of the reaction, so the same burner that ran clean at low elevation runs fuel rich up here.
Manufacturers deal with it two ways. Some certify a unit across an altitude band and publish a derated input for the upper end, meaning the appliance is expected to produce less heat here than the number on the box. Others sell a high altitude conversion kit, which is a different orifice sized for thinner air. Either way the appliance has to be set up for the elevation it is installed at, and the city's building department expects that to be part of a permitted installation.
What goes wrong when it is not set up correctly is consistent. A rich flame burns yellow and lazy instead of blue, it deposits soot on the burner and the flue baffle, and it upsets the thermocouple or flame sensor enough that the pilot drops out for no apparent reason. Recovery slows down, so a 50 gallon tank behaves like a smaller one. Soot on the baffle insulates the flue and pushes efficiency down further.
There is a second squeeze on the same air supply. Modern tanks draw combustion air through a flame arrestor screen at the base, and that screen collects lint, dust and pet hair. A partly blocked screen starves a burner that was already working with less oxygen than it was designed around, and the result looks exactly like a failing gas valve. Vacuuming the screen is a maintenance item here more than it is at sea level, and a finished basement with a tight mechanical closet makes it matter more, because the room itself has to be able to supply the air.
Electric Tank, Gas Tank: Two Different No Hot Water Stories
The failures do not overlap much, which is useful when you are trying to describe the problem over the phone.
- an electric tank that went cold all at once has usually lost a breaker, tripped the high limit switch or burned out the upper element. Cold all at once is the tell.
- an electric tank with a dead lower element goes lukewarm rather than cold, and the hot water runs out fast because only the top of the tank is being heated.
- a gas tank that goes cold has usually lost its flame: pilot out, thermocouple weak, igniter failed or the gas valve done. The relight either holds or it does not, and that answer is diagnostic on its own.
- a gas tank that makes hot water but not enough of it is a combustion or a sediment problem rather than a control problem, and that is where the altitude setup and the burner condition come back into it.
One symptom belongs to neither list. If the hot water is fine at one fixture and poor at another, the tank is doing its job and a mixing valve, a cartridge or a partly closed stop at that fixture is the actual fault.
Why the Relief Valve Drips in a House With a Pressure Reducing Valve
Denver Water moves municipal water across a service area that climbs several hundred feet from the low ground near the river to the high neighborhoods, and it runs a lot of separate pressure zones to manage that. Plenty of houses sit in a zone high enough that a pressure reducing valve is fitted at the service entrance.
That valve does its job and creates a side effect. It stops water flowing backward, which turns the house into a closed system, and water expands when it is heated. With nowhere to go, the pressure climbs every time the burner or the element fires, and the temperature and pressure relief valve on the side of the tank vents the excess. Homeowners read that as a failing tank. It is usually a missing or waterlogged expansion tank, which is a small pressure vessel that gives the extra volume somewhere to sit.
Worth knowing because the fix is inexpensive and the alternative is a relief valve cycling for years, which is how a good tank ends up rusting from the outside at the fitting.
What Turns a No Hot Water Call Into a Replacement
Most no hot water calls are a part. A few are not, and the difference is usually visible before anyone quotes anything.
Water on the floor coming from the shell rather than from a fitting is the end of the conversation. A steel tank that has rusted through cannot be patched, and once the glass lining fails the leak only grows. Rust in the hot water itself, a tank that has been rumbling for a year, and an anode rod that has been consumed down to the wire all point the same direction. Age matters too, and a tank past 10 to 12 years with a fresh failure is rarely worth a second part.
The honest version is that a control, a thermocouple, an element or a thermostat is a repair, and a compromised tank is not. Ask which one you are looking at and ask to see it.
Frequently Asked Questions About a Denver Water Heater That Went Cold
The pilot will not stay lit on a tank that ran fine for years. What changed?
Three things drift slowly and then cross a line: the thermocouple weakens, the flame arrestor screen at the base loads up with dust, and the burner sooties if it was never set up right for this elevation. Any of them lets the flame get lazy enough that the safety circuit shuts the gas off. Vacuum the screen if you can reach it, then have the flame looked at rather than relighting it repeatedly.
We brought the heater up from a lower elevation. Is it the wrong unit for Denver?
Possibly, and it is worth checking the rating plate. Look for an altitude range or a note about a high altitude orifice. If the unit is rated only to a couple of thousand feet, it needs a conversion kit or it needs replacing, and running it as it is means a rich flame, soot and nuisance shutdowns rather than a dramatic failure.
The thermostat says 120 and the shower still runs cool. Where is the heat going?
Check the mixing valve at the tank if there is one, then the shower cartridge. A broken dip tube is the other classic: cold water entering at the top instead of the bottom mixes straight into the outlet, so the tank reads hot and the shower does not. That one gets misdiagnosed as a heater on its way out more than anything else on this page.
What decides whether this is a part, a flush or a new tank?
What the tank looks like when somebody opens the compartment and reads the plate. Sediment answers to a flush, and how much sediment there is depends on the supply: Denver Water's snowmelt runs soft, generally under 6 grains per gallon, while wells drawing on the Denver Basin aquifer south of the metro are considerably harder on a tank. Cost varies with the part, the age of the unit and whether access is straightforward. Roto-Rooter provides on-site estimates before any work begins.
There is a small tank strapped above the heater and it feels warm. Is that a problem?
That is the thermal expansion tank, and warm is normal because it holds the same water. What is not normal is a wet fitting or a tank that sounds solid when you tap it, which means the internal bladder has failed and it has filled with water. A waterlogged expansion tank stops absorbing anything, and the relief valve starts dripping again.
Does a water heater need to be strapped to the wall in Denver?
Seismic strapping is a requirement in earthquake country and is not the concern here. What inspectors on the Front Range do look at is combustion air for the burner, correct venting, a drain pan with somewhere for the water to go when the tank is above finished space, and the altitude setup on a gas unit. Ask about those four rather than about straps.
Schedule a Denver Water Heater Repair Once the Checks Come Up Empty
A cold house full of people is a same day problem, and a pilot that will not hold is not a thing to keep relighting. Roto-Rooter runs 24/7, 365 days a year, is fully licensed and insured, and has been working on hot water since 1935. Schedule online and describe which of the five checks failed; if the rating plate carries an altitude range, read that out too, because it settles whether the tank was ever the right appliance for this elevation. If there is water on the floor as well as no heat, Denver emergency plumbing is the faster route, and Denver plumbing covers the rest.