Water Heater Troubleshooting

Water heating troubleshooting information for pilot lights, oil-fired water heaters, indirect water heaters, on demand water heaters and more.

Why Does the Pilot Light on My Gas Fired Hot Water Heater Keeps Going Out?

A. A bad thermocouple, the thermocouple is a probe that sits inside the pilot light flame inside the gas water heaters, the other end of the coil attaches to the gas control valve in the front bottom of the water heater. The pilot flame generates Mila volts that hold a magnet that keeps the pilot lit, when the thermocouple fails it starts to send less and less power to the gas control valve, till it can no longer hold the magnet open,

B. A bad gas control valve, sometimes the control goes bad and even though the thermocouple is sending the correct amount of power, the valve still closes.

C. A draft, this is a hard one to figure out sometimes, any kind of draft can blow out the pilot. But this may be a warning of a larger problem. For example if you have a forced air furnace and the return air intake duct is too close to the water heater and there is no combustible air being brought in from the outside, (as per code) the furnace will pull air from the water heater flue pipe and blow carbon monoxide into the rest of your house when the water heater is making hot water. Other things that blow a pilot out are attic fans, central vacuums, opening a door and strong winds.

My pilot was out, I relit it and turned it back on, and I can hear water dripping onto the burners, what is causing this?

The tank is full of cold water the heat from the burners is causing condensation, this condensation is dripping on the burners, once all the water in the water heater is heated it will stop.

Oil-Fired Water Heaters

When it comes to recovery the oil fired water heater is the best of the best. Because it is oil fired it can heat a 30 gallon tank of water in no time at all, it works just like a boiler, The down side is, as with any oil fired unit, you have to have the heater cleaned and serviced every year, and you have to have the chimney cleaned every year also. Oil fired water heaters also have T&P relief valves, with the same temperature and pressure settings, but requires a relief valve with a higher BTU rating, a standard Watts 100XL will not be safe on this water heater.

How to troubleshoot an oil fired water heater, if you don't have hot water, make sure you did not run out of oil, then push the red or black button ONLY ONCE, if this does not help, call a professional, there is no other way.

Indirect Water Heaters

An indirect hot water heater is also known as a hot water maker. The hot water maker does not use any fuel to heat the hot water in the tank, the water is heated form a hot water boiler or a steam boiler, the hot water from the boiler circulates through the water maker by way of a backwards coil, (backwards because the boiler water runs through the coil) The coil is immersed in the water in the water maker tank, heating the water in the tank. This water heater also must have a T&P relief valve. The way it works is just like a heat zone in the house, an aquastat sends a signal to a zone valve of a separate circulator, the water from the boiler at about 180 degrees Fahrenheit, runs through the coil till the aquastat is satisfied, about 120 degrees Fahrenheit, Although many plumbers and heating companies use zone valves to control the water maker zone, most water maker manufacturers recommend the water maker zone be controlled by a circulator, because a zone valve can get stuck open, causing the water to become extremely hot and causing damage to the tank. The recovery of the water maker (assuming the boiler has sufficient capacity) is second only to the oil fired water heater. Other type water makers do not use a coil but use a tank within a tank setup, the inner tank holds the water that goes to the faucets and the outer tank is where the hot boiler water circulates.

Coils On Boilers

Boiler coils are coils of copper immersed in the boiler water, the hot water in the boiler transfers water to the water in the coil, there are many known problems with boiler coils.

1. The water coming out of the coil is very hot, a tempering or mixing valve is needed to cool the water down before it reaches your faucet, many so called plumbers do not use a mixing valve

2. You cannot fill a bathtub with hot water, it will cool off in 2 minutes, a water flow restrictor needs to be installed to slow the water going through the coil, and this also reduces water pressure on the hot side of the house plumbing.

3. Hard water will clog the coil restricting the flow to a drip. The harder the water the quicker the coil will clog, I have seen it happen in a week's time. Just slightly better then an electric hot water heater.

On Demand Water Heaters

The tankless water heater is also known as the on demand hot water heater. It's a coil filled with water that is heated instantly by gas or electricity, the flow of water triggers the water heater to fire. Endless hot water is really not the case. Tankless water heaters have similar limitations to standard water heaters.

This article is only meant to give you general information on water heaters. Consult with a local plumbing professional to insure you are making the smartest and safest decision.