No hot water? Start here
A quick look before you call
How widespread is it?
Check a second hot tap in another room. One cold fixture points away from the heater; every tap cold points toward it.
Cold, or just not hot?
Stone cold and lukewarm usually have different causes. Note which, and whether it came on suddenly or faded over days.
What else stopped?
If the radiators or baseboards went cold at the same moment, the boiler that makes your hot water may be the common factor.
Anything on the floor?
Glance around the base of the heater for water. Look without touching.
Smell gas? Leave the building first, then call the gas utility and emergency services from outside.
Carbon monoxide alarm going off? Leave the home and call emergency services once outside.
What diagnosis means here
Diagnosis is the part of the visit where the technician works out why there is no hot water, before anyone replaces anything. It sounds obvious, but it is where a lot of money gets wasted: parts swapped on a hunch, or a sound tank replaced because of a fault in a control. A good diagnosis checks the heat source, the controls, the water supply to the heater and, where the boiler makes the hot water, the link between the two.
Common causes by type of system
Gas and propane tanks
The burner is not firing: a failed ignition component, a fault in the gas control, a problem with the flame sensing or venting safety devices, or a fuel supply issue such as an empty propane tank. None of these are things to troubleshoot yourself.
Electric tanks
A failed element or thermostat, or a safety cutoff that has tripped for a reason the technician needs to find. Sediment around the lower element is a common contributor in well-water homes.
Oil-fired water heaters
Burner problems, fuel delivery issues or a control lockout. Oil-fired tanks have more components in the burner than gas units, so the cause can take a little longer to pin down.
Tankless units
An error condition on the unit, a flow problem, scale build-up in the heat exchanger, or a fuel or venting fault. See tankless repair.
Indirect tanks and tankless coils
When the boiler makes the hot water, cold taps can come from the tank's control or sensor, the pump or zone valve that sends boiler water to the tank, or the boiler itself. The local installers work on the hot water side. If the boiler has failed, they will say so, and boiler repair is outside this service.
What Connecticut adds to the picture
Wells. Sediment and mineral scale from a private well make heaters work harder and can bring on failures in elements, burners and sensors. If the house is on a well, the technician will look at the bottom of the tank as part of the diagnosis, not just the part that stopped.
Cold inlet water. Lukewarm complaints spike in winter. Sometimes nothing has failed at all: a heater that was marginal in autumn simply cannot recover fast enough when the incoming water is at its coldest. That is a sizing conversation rather than a repair, covered on our running out of hot water page.
The boiler in summer. Where a tankless coil makes the hot water, the boiler has to keep running through the summer. If someone switched it off for the season, the hot water goes with it.
What to leave alone
- Relighting a pilot or resetting a gas control
- Resetting burners or controls on an oil-fired heater or boiler
- Opening electrical covers or touching wiring on an electric tank
- The temperature and pressure relief valve and its pipe
- The flue pipe or any venting
Repeated resets can hide the reason something shut down, and some shutdowns happen for safety reasons. Let the technician see the heater as it is.
Explain what you are seeing and get the right tech out.
How the diagnosis visit works
The technician asks what happened and when, then checks the heater from the supply side through to the controls and heat source. On boiler-fed systems they check the controls and pump that call for hot water. On a well home they will look at sediment and the condition of the tank. Once they know the cause, they explain it, say whether it is worth repairing, and give you the price for the fix before carrying it out.
What affects the cost
- What turns out to be wrong, from a single sensor or element to a failed tank
- The type of system, with boiler-fed and oil-fired setups involving more components to check
- Parts availability for the brand and age of the heater
- When the visit happens, with out-of-hours calls costing more
You hear the cost of the fix before it is carried out.
How long it takes
Many causes are found within the visit, and simple fixes can often be done straight away. Intermittent problems, or faults that sit between a boiler and an indirect tank, can take longer to confirm. Once the heater is running again, allow time for a full tank to heat, longer in winter.
No hot water questions
Why do I have no hot water but the heating still works?
If your hot water comes from a separate tank, the heating and the hot water are independent, so the fault is in the water heater. If the boiler makes your hot water through an indirect tank, the problem may be the tank's control, sensor or the pump that feeds it. The technician checks both sides of that link.
Why do I have no heat and no hot water at the same time?
That usually points to the boiler, especially in oil-heated homes where the boiler also makes the hot water. Boiler repair is outside what we arrange. Tell us what you are seeing and we will be straightforward about whether this is something the local installers can help with.
The pilot on our gas heater is out. What should I do?
Leave it for the technician; we do not give relighting or pilot instructions. A pilot or burner that has gone out may have shut down for a reason, and it needs to be looked at by a technician. If you smell gas, leave the building and call the gas utility and emergency services from outside.
The water is lukewarm, not cold. Is that the same problem?
Not usually. Lukewarm water often means the heater is partly working: one element out on an electric tank, a burner not firing fully, heavy sediment, or a broken dip tube mixing cold water into the hot. In winter, cold inlet water can also make an undersized heater seem to be failing.
Our hot water stopped when we turned the boiler off for the summer. Why?
If your hot water comes from a tankless coil inside the boiler, or from an indirect tank heated by it, the boiler has to keep running to make hot water, even in July. Turning it off turns off the hot water too. The technician can explain your setup and the options if you would rather the boiler rested in summer.
We are on a well. Could that be why the heater stopped?
It can contribute. Sediment settles on the bottom of the tank, where it can bury an electric element or make a gas burner work harder, and minerals can coat sensors. The immediate fault still needs fixing, but mentioning the well helps the technician look at the underlying cause too.
Is diagnosis a separate charge?
How the visit is priced is explained before the technician starts, and the cost of any repair is given before it is carried out. There are no hidden fees added afterwards.
What should I tell you when I call?
Your town, when the hot water stopped, whether it is every tap, the fuel, what kind of system makes the hot water if you know, whether the heating also stopped, and whether the house is on a private well or public water.
Could it be a problem with just one tap?
Yes. If only one fixture runs cold, the heater may be fine and the issue is in that tap's valve or mixing cartridge. That is outside our water-heater-only service, so check a second tap before calling.