Converting hot water from electric to oil


Old 02-25-13, 09:04 AM
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Converting hot water from electric to oil

Two-part question,

Do I need to replace my boiler to do this, or can an existing boiler be made to heat water too?

same question for hot water tank.

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Old 02-25-13, 09:15 AM
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If I understand correctly...

Yes, your existing boiler could be made to heat domestic water.

I won't say 'NO' that you can't convert an electric water heater to use an external heat source, but it is something that is only generally done by 'experimenters' by attaching heat exchanger 'gadgets' to the outside of the tank in order to transfer the heat to the water...

Yes, it could theoretically be done, but not without some engineering and 'tweaking'...

Besides, how old is the electric now? It may already be time for a replacement.

Look into ( Google it ) "Indirect Water Heater" for more info.
Old 02-25-13, 09:21 AM
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Thanks for the info! I'll look into it.
Old 02-25-13, 02:08 PM
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Let me re-phrase to see if I understand your question. You currently have an electric boiler and an electric water heater. You want to use fuel oil instead of electricity to heat your home and your domestic water. Is that correct?

If I am correct you will need a new boiler, there is no way to convert the electric boiler to a fuel-fired boiler. You will also need a new water heater but there are a few choices in that regard that I will address later. Oil is pretty much the "also ran" when it comes to residential heating. It is rarely used if natural gas is available and often propane gas is preferred over oil when the natural gas is unavailable. Oil fired boilers are the most complicated and consequently the most expensive when compared to either gas (natural or propane) or electric. An oil-fired boiler WILL require yearly servicing whereas gas-fired can often be serviced on an every other year schedule. Electric, as you know, requires almost no preventive servicing.

Oil requires that you have a tank to hold the oil and that tank may be as little as 50 gallons to as much as 450 gallons (or more) depending on local regulations. Some housing developments prohibit oil tanks so that would eliminate that choice of fuel. Tanks are installed in garages, sheds, outdoors and in basements. Environmental regulations will often (usually) require a secondary containment that will prevent any leaks from ending up on the ground. Homeowner's insurance companies may refuse to write policies on oil installations or may have additional premiums assessed for oil fuel. Oil tanks are sometimes buried (in the past most were buried) but this is seldom done in residential service these days for fear of contamination from leaks. If a buried tank is necessary your local regulations could require both secondary containment (essentially a double wall tank) AND continuous leak monitoring equipment. This could be quite expensive.

For water heating you can either buy an oil-fired water heater or you can use what is called an "indirect" water heater that heats the domestic water from the boiler. Do NOT let anyone talk you into using a "tankless coil" inside the boiler as it is the most inefficient method of producing hot water with the except for an open kettle on a wood-burning kitchen range. If you go with a separate oil-burning water heater that is yet another oil burner that will require yearly maintenance.

With both the new boiler and the oil-burning water heater you will need a chimney. Yo CANNOT exhaust an oil-burning appliance into the same flue as a fireplace so if you do not have a separate flue or a separate chimney then you either need to install one, designed for oil-burning applications, or you will have a limited number of boilers and water heaters from which to choose that can exhaust through a side wall by use of an induced draft blower. If you do not have a side wall near to where the boiler and water heater are to be installed then you may not even have the option of going with oil fuel.

To be brutal, I don't know ANYONE that has an oil-fired heating system that wouldn't prefer to have gas. With all the capital costs of changing to oil from electric the payback period will usually be quite long unless your electric costs are absolutely sky high. Even though your electric bills may appear high factoring in the capital costs, including the interest on any loans necessary for the fuel conversion, may show you that you won't save a dime for ten years or more.

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