Will I inherit a condensation problem changing hot water?

Jim Davis_3

A domestic hot water coil in a cast iron oil boiler has an efficiency of about 40%. That would make oil about $8.75 a gallon or $62.47 per 1,000,000 btu. Electric @.21 per kwh is 61.53 per 1,000,000 btu. Okay that one is close but what about the extra A/C load the oil boiler puts on the building radianting its excess heat??

In 90% of the states, electric rates are under .10 per kwh(.07 - .08 cents per kwh are more standard) and oil is close to $4.00 gallon. This would make an electric water heater 50% -60% cheaper.

Sopuzzled

Will I inherit a condensation problem changing hot water?

I have oil hot water and am thinking about changing to electric hot water in order to save on oil fuel during warmer months. I'd like to cap off the hot water coil in my oil-fired boiler and switch over to electric hot water in order to avoid firing my oil furnace from spring through fall. But, I have been warned that not firing the furnace over the summer months could result in rapid rusting of my oil boiler because of condensation build-up. Is that true? If so, what are my options to protect my boiler when I change over to electric hot water?

Tony_25

Condensation, Yes

Shutting down your oil fired bolier will have some problems. First any soot in the boiler get wet and most likely block off the flue passages. When you go to start the boiler in the fall,it may have no draft over the fire and smoke. The boiler has pressure in it and it might leak water from the gaskets. You could lower the high limit to around 100 degrees when not in use. This will keep the boiler warm and not cause many problems. Also instead of capping off the boiler coil you could connect into it and valve the coil off. In case you ever want to use to boiler coil again, or use both at the same time.

Derheatmeister

Condensation/ sudding may form if you leave a standing pilot going all summer long.

You may be better off installing a Indirect fired waterheater off of the Boiler, which will also exercise the boiler in the summer and possibly produce water at close to the boilers eff. the operational cost may be lower too.

Jim Davis_3

There are thousands of consumers with oil boilers that don't have domestic hot water coils and don't run them in the summer. A real big fuel waster in the summer. The only condensation problems you would have would be humidity sucking down the chimney in the summer because your house is too negative. If your boiler has soot, someone didn't set it properly. I do recommend having heating equipment serviced in the spring after heating season so that no residue is left inside all summer. Get your electric water heater and save some big bucks!!!

Robert O'Brien

Jim

"Get your electric water heater and save some big bucks!!!"
Doesn't that depend on electric rates and oil prices? On Long Island electricity is 21 cents/KwH and oil has dropped into the $3.50/gallon range. Electric DHW would be foolish here even accounting for eff. losses with the oil system.

"If your boiler has soot, someone didn't set it properly."
Older oil burners without valve on delay will produce some level of soot deposition regardless of adjustment.And unfortunately most burners in the field don't have valve on delay or motor off delay.




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Sopuzzled

You second the opinion of the contractor I spoke with

The concept of a hybrid hot water system where the electric hot water is valved into the direct hot water coil of the oil furnace is what one contractor I spoke with recommended. He said not only would this exercise the oil boiler over the summer but would also reduce the amount of electricty required by the water heater. In effect, the hot water would be fueled by both oil and electricity. And, the oil boiler would not need to fire nearly as often because the high efficiency of the electric hot water heater. BTW, it is the original Eureka Williams Oilmatic boiler that came with the house built in the mid 1950's. It beats the Energizer bunny for durability...thanks for the second opinion.

CC.Rob_7

SDHW?

How about solar instead of electric? Might that be an option?