Frequently Asked Questions

Where can I locate the main water valve shut off?

Locating the main water valve is important for emergencies.  Shutting this valve will stop water supply to the entire house and it is usually located in the basement or outside of the house. Here are three ways to finding the valve:

  1. If you are in the basement the valve will be eye level or above.
  2. Make a mental straight line from the outside water meter to the exterior perimeter of the house (the shut off valve should be close to that point).
  3. Check the inspection report.

What do I do if I smell gas?

It is very important not to light any fire. Turn off all appliances – electrical and gas. Be sure to leave the house immediately and call your emergency response team and follow their directions.

How much money can I save by having my oil burning equipment serviced annually?

The amount the homeowner could save will vary on the geographical location, present condition of the heating equipment, the price of fuel, and other factors. For example, a homeowner burning 1300 gallons of oil a year in a very inefficient heating system could save about $450 in fuel costs at a price of $2.599 per gallon with proper servicing. This is a 13% savings in the total fuel bill as the efficiency of the oil burner is increased from 65% to 75%.

How much pollution reduction will result from proper maintenance of oil burning equipment?

In a recent study, it was found that by identifying and replacing non-tunable units, carbon monoxide (CO) was reduced by more than 65%, gaseous hydrocarbons (HC) were reduced by 87%, and filterable particulate was reduced by 17%. By tuning the remaining burners, in addition to replacing non-tunable units, the total reductions were as follows: smoke was reduced by 59%, CO was reduced by more than 81%, HC was reduced by 90%, and filterable particulate was reduced by 24%.

Why should I have my oil burning equipment serviced annually?

Many people don’t call for service until the heating equipment fails. Unless this occurs during normal working hours, the homeowner will usually have to pay for service at higher hourly rates. By having annual maintenance during the summer months, unexpected equipment failures are less likely to occur. Also, burner performance can deteriorate over time. Nozzles and oil filters should be replaced annually to promote proper burner performance.

Can I service the oil burning equipment myself?

It is recommended that a qualified oil burner service technician perform the work. When nozzles are changed, the excess air level normally needs to be adjusted. To do this properly, special instruments are used to measure the following:

  • Carbon dioxide(CO2)
  • Flue gas temperature in the stack
  • Smoke number
  • Stack draft

Most homeowners do not have access to the equipment needed to make these measurements and do not know how to use the equipment properly. Also, the service technician has a better understanding of how to diagnose problems that may be encountered and should be familiar with any safety codes or standards that apply to the heating equipment. The furnace owner should inspect air filters monthly during the heating season and change them as necessary. Air filters should be replaced at least twice during the heating season and more often in some cases. Dirty filters reduce furnace efficiency.

Should I have my furnace vacuumed periodically?

Yes. Soot serves as an insulator and significantly reduces the amount of heat transferred to the house. Therefore, when needed, vacuuming can save the homeowner in fuel costs. Depending on the smoke level, a furnace may need vacuuming yearly or as infrequent as once every 5 years. Ask the service technician for a furnace inspection to determine whether vacuuming is needed. If the burner is properly maintained by keeping the smoke number below No. 2, the furnace should not require vacuuming very often.

What should the values of CO2, net stack temperature, smoke number, and stack draft be?

A new oil burner with a properly matched furnace or boiler should operate with a minimum of 10% CO2 at a maximum smoke No. of 1.  The following table provides a general range for a typical (gun type) oil burner:


CO2 (%) 1196 Excellent Average Poor
Smoke Spot Number 012



5 or higher

Excellent Excellent Good

Average for un-tuned Burners



Net Stack Temp. (°F) 400-600600-700 Average for original equipment average for replacement burner
Stack Draft(A measure of inches of water on gauge) .04 to .06 Average for non-forced draft units. For forced units and other types, follow recommendation of manufacturer

How much combustion efficiency should I expect?

Efficiency of 80% or above is excellent. This means 80% of the heat received from the oil goes into the house while only 20% is lost to the atmosphere. A 75-79% efficiency is good, 70-74% is fair, and below 70% is poor. If the efficiency is below 70%, the burner should be readjusted. If an efficiency of 70% or better cannot be achieved, or if adjustment increases the smoke number significantly, the burner should be replaced. The savings in fuel cost will offset the cost of the burner over a period of time.

If my service technician does not measure CO2, smoke number, stack temperature, and draft, what should I do?

These measurements are essential for proper burner servicing. At Ranshaw, you have little to be concerned about because all of our technicians are capable and equipped to perform these tests with the latest burner testing equipment. In fact, all of our technicians have gone through extensive training and are certified by the National Oilheat Research Alliance (NORA).