Does an oil furnace burner heat water constantly or only when someone uses the hot water?

Question

I've somehow gone through 75 gallons of oil in three weeks at our new condo (with no heat on and we were only living here for one of those three weeks) *and* I'm trying to figure whether or not we have a leak or we need to move because I can't afford to pay for all that oil every month, imagine how bad it would be if the heat were on? ;-)

Answer 1

It is set to keep the water at a pre-set temperature.  If not too many people, for instance, need to shower in the AM it could be set at a lower temperature so not so much cold water needs to be in your mix when you turn it on and set it to your liking.

Answer 2

Sounds like your neighbor on each side of you are getting free showers........ask them if they will furnish the soap and towels:) Sorry.......you've got a problem some place....have it looked into.

Answer 3

If your water is heated by the oil furnace, there should be a 'tank' with a burner under it. If so, then it does run as the water cools off-whether you are using the water or not. Double check and make sure that your water isn't heated by an electric water heater...not too many furnaces also heat hot water.

If your FURNACE isn't running to heat the condo, then it shouldn't be using fuel oil if your water is heated by electricity.

Are you sure you really used that much, or did you move in with either an almost empty tank or only a partial tank? If it is on a scheduled delivery basis, or they came to fill it once you moved it-you might not have used that much-they may have just topped off the tank to fill it up.

If you 'share' a common basement area with other condos and the furnaces and heaters aren't in 'locked' areas...there is also the chance that someone else has run their piping to your system to get hot water or fuel oil to their condo...

When you moved in, you could have asked all the utility suppliers (electric, water, oil, gas, etc.) what the previous owner/renter used while they were there for the last year...so you could tell right off what your monthly expense should be.

Answer 4

Dear Leela,

Typically, oil burners providing domestic hot water, as well as hot water for an hydronic heating system, maintain a small amount of domestic hot water, in their hefty cast iron cores.  Shortly, after you start a shower, or a load of wash, the oil-burner will start, in order to provide a continuous supply of hot water.  Such a system, is known as, an on demand system.

Using a small amount of water, e.g., washing your hands, ordinarily, does not activate the oil-burner.  However, the oil-burner does loose heat to its environment.  The regulatory mechanism, starting the oil burner when cold water is introduced, also starts the oil-burner, when it simply cools down.  Fuel consumption, due to ambient loss, should be minimal.

If a shower, takes about twenty-five gallons of water, and you are increasing the temperature of the water, about 50 degrees Fahrenheit, you would consume about 10,000 BTUs of energy.

A typical gallon of heating oil, contains about 150,000 BTUs of energy.  A really inefficient system, would be able to extract, at least two thirds of that energy.  Therefore, a gallon of fuel oil, should give you ten typical showers, or ten loads of laundry.

Since 75 gallons, are equal to 750 showers, I can think of three scenarios, regarding the missing oil, a measuring error, a leak, or theft.  If the measurement was made with a dipstick, I would consider a measuring error most likely.  A leak would make quite a mess, unless the leak was underground.  Is your tank, or any of the piping underground?  In regard to theft, is your tank accessible from the outside?  Home heating oil, will work in a diesel motor vehicle, with the appropriate additives.  Seventy-five gallons of diesel, is worth about $300.

Please, don't hesitate to ask any questions; you may have.

Larry

Answer 5

I'm guessing you have an oil-fired boiler (forced hot water heat, with an internal coil to heat your domestic hot water), not a furnace (forced warm air). 75 gallons in 3 weeks is ALOT of oil, especially when you weren't there for 2 of the 3. The boiler will cycle to maintain water temperature, whether you're using the hot water for sinks, showers, etc., or not... but 75 gallons is still way outta line. You may want to have the oil company's service man come look your lines over for you, to see if you're losing oil. But first, are you sure your tank's fill gauge is working properly?