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This collection of articles on oil hot water heat will answer most questions about oil-fired water heaters as well as many other building plumbing system inspection or defect topics. This page contains links to in-depth articles on inspecting, testing, and repairing problems residential hot water heaters of all types, including their parts, controls, and alternative sources for hot water as well as tips for improving hot water temperature, hot water pressure, and hot water quantity. Reproduction of this web page electronically at other websites is prohibited. Our photo at page top shows an oil fired hot water system with the main components easily available, and with evidence of an oil burner operating problem.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.t.

Inspection, Diagnostic, & Repair Guide to Electric Hot Water Heaters

But watch out: sometimes an electric water heater is installed as an additional or backup hot water source, so you'll also want to see if you have other hot water heating equipment installed, such as a Tankless Coil for Hot Water. In our photo below at left an oil-fired water heater and an indirect-fired water heater are installed in tandem.

Here are a few things to check on your oil-fired water heater:

Look for signs of improper oil burner operation: such as sooting, draft problems, or back-pressure burns around the oil burner or around the combustion chamber inspection port.

Soot blowing out of the barometric damper or flue pipe, soot and burn marks, oil leaks, stumbling, rumbling, noisy oil burners, odors, are examples of improper oil burner operation that need prompt service.

Our page top photo and our photo at left show examples of improper oil burner operation on an oil fired water heater: both systems show soot blow-out at the water heater's combustion chamber inspection port. Our photo at left also shows that the discharge tube is missing from the relief valve - a safety concern.

Often these soot marks are a symptom of excessive pressure or "back pressure" inside the combustion chamber.

This problem can be caused by an oil fired water heater that is way past due for cleaning (soot blocks the exhaust flue), by a blocked chimney, by improper draft regulator adjustment, or other defects.

See OIL BURNERS and OIL BURNER NOISE SMOKE ODORS

Check the hot water piping and control valves connected to the water heater for leaks, support, and for proper location of shutoff valves. An improperly installed shutoff valve on a water heater can be very dangerous, risking an explosion. Usually the "hot water tank shutoff valve" is installed only on the cold water pipe coming into the water tank. There should be no shutoff valve installed on the hot water line leaving the water tank.

Check for leaks at the water heater drain valve. Most water heater manufacturers recommend that their water tank be drained periodically. This process will help remove sludge and debris or mineral deposits that may have accumulated at the bottom of the water heater tank. Removing this debris can extend the life of the hot water tank, especially where electric and gas fired water heaters are involved. But since few people remember to open and drain the tank it may be that the drain valve does not open easily, or worse, it won't close.

• Tips On Draining the Oil-Fired Water Heater Tank: Don't try opening the hot water tank drain valve without first noting these warnings and tips:
  • The water heater heat source should be turned off and the water tank cooled down (or run hot water out through building fixtures) before attempting to drain the tank - there can be a serious scalding hazard otherwise
  • You can connect a garden hose to drain the water heater tank to a suitable destination
  • If it's a Sunday - you may have trouble obtaining spare parts or emergency plumbing service if a problem occurs
  • Be sure to have a spare garden hose cap to install over the end of the drain valve in case it drips and won't shut off completely
  • If you have trouble turning the water heater tank drain valve to open it - don't force it - if break off the valve stem you may have a leak that you cannot shut off except by turning off cold water supply to the water heater
  • After opening the heater drain valve, if you forgot to turn off the cold water supply coming into the water heater, you may find that water just shoots out of the drain forever - you'll need to turn off the cold water supply to the water heater.
  • You will probably need to open a nearby hot water tap to let air into the plumbing system and through it into the water heater tank so that water can drain out at the tank's bottom. We don't recommend opening the pressure/temperature relief valve for this purpose as you may find that the TP valve won't shut successfully afterwards.

Check for heating oil leaks and oil piping defects: see OIL TANK PIPING DEFECTS

If plastic water piping is installed, such as polybutylene water supply piping, it should be at least 18" from the water heater.

Vacuum relief valves are required at water heaters in some communities, to protect against collapse of the water storage tank and to prevent backup of hot water into the cold water piping should cold water pressure drop. Here is Carson Dunlop's sketch of a vacuum relief valve.

A Guide to Oil Fired Water Heater Controls & Operation

Check the Sacrificial Anode & Dip Tube of Your Oil Fired Water Heater Tank

Check the Oil-Fired Hot Water Tank Temperature and Pressure Safety Relief Valve

Please see Testing the Water Heater Temperature Pressure Relief Valve

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OIL FIRED WATER HEATERS
  DRAFT REGULATORS - barometric dampers
  OIL BURNERS
  OIL BURNER NOISE SMOKE ODORS
  OIL PIPING
  OIL TANKS

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

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