Range Boilers for making domestic hot water:
In this article we define range boilers, and we explain the operation of range boilers used for making domestic hot water for washing and bathing. We provide photos and sketches as well as text to help identify the types of tanks found inside old buildings.
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A range boiler is an older type of domestic hot water heater which uses a separate hot water tank which is connected to a heating boiler as well as to domestic hot water piping in the home. Thanks to Carson Dunlop Associates, a Toronto Home Inspection Firm and Home Inspection Educator, for permission to use sketches shown in this article.
Below we describe some alternative ways to make hot water, either to replace or to supplement an existing hot water supply system. After knowing what the hot water problem really is, there are steps we can take to get more hot water or to increase hot water pressure.
Water circulates from inside the range boiler tank through a heat-exchanger coil that may be inside the heating boiler or it may be external, such as a Side Arm Coil. Heat inside of the physically separate heating boiler warms water that circulates, usually by gravity (or convection) between the range boiler and the heating boiler.
Modern indirect-fired water heaters use the same principle as the range boiler but add heat controls and a circulator pump, as we discuss in detail at Indirect-fired Water Heaters.
In our photo at page top you can see the old galvanized steel range boiler in the far corner of the basement. A newer (but still quite old) gas fired water heater has been installed in front of our old range boiler.
See WATER HEATERS for details about conventional direct-heated residential hot water systems.
You'll find at least four pipes connected to a range boiler tank, possibly five if the tank uses an overflow line in an attic instead of a pressure relief valve.
Don't do what we did early in our HVAC career: some of those many connections on the range boiler seemed to have no purpose so we eliminated and capped off a pipe that seemed unnecessary. It was a mistake. All four pipes which we describe here are needed:
In their earliest use range boilers were heated by a coal or wood stove as we show at far left.
In a later design range boilers may have included their own little gas or coal heater as we show in the sketch at left.
Later the same design was used in combination with a side arm coil to heat water in the range boiler tank using a coal or oil or gas fired heating boiler.
Range boilers can provide a large volume of hot water, depending on the tank size. But they have a slow recovery rate once the hot water from the range boiler tank has been consumed.
It would be unusual to find a range boiler installed as new equipment in a modern building.
Range boilers are vertical or horizontal hot water systems whose water is heated by circulating the water from within a water storage tank (the range boiler) through a heat exchanger which is inside or connected to the exterior of a heating boiler. The water in the hot water tank range boiler is heated by circulating its water through the heat exchanger which itself is heated by the water inside or from the heating boiler.
The sketch illustrates how a very early type of coal-fired water heater range boiler worked. As homeowners shifted fuels from coal to oil or gas and installed central heating boilers, often the range boiler water heater was adapted to work with these systems as well, as you can see in the photograph.
As with the indirect-fired boiler described next, range boiler water heating tanks are usually located close to the heating boiler and will have both cold and hot water lines leaving the tank to supply the building with domestic hot water and a loop of piping that runs between the bottom of the hot water tank and a nearby heating boiler.
Follow the pipes to see which pipes are performing which function. Our photo shows a silver steel range boiler hiding back in the corner behind the newer (though pretty old) gas fired water heater. (Notice also the efflorescence on the masonry block foundation, where the downspout has been spilling by the house foundation?)
The difference between RANGE BOILER WATER HEATER
INDIRECT WATER HEATERS is in the details. The heat exchanger that heats water in the range boiler is in or at the heating boiler. The water in an indirect fired water heater such as the SuperStorTM unit is heated by a finned copper coil located inside the hot water tank. The internal coil is in turn heated by circulating water inside the coil to and from the heating boiler. The range boiler is an old concept in use for about 100 years. Indirect fired water heaters are a modern system and are in current sales and use.
Because you might also encounter other smaller steel tanks connected to hot water heating boilers and found in building basements or attics see EXPANSION TANKS for a guide to these tanks that absorb pressure increases on hot water heating systems.
CONTACT us with comments about this attic tank.
Unless the range boiler is vented to an overflow pipe like the attic tank in our discussion below, range boiler tank should be protected by a pressure/temperature relief valve just as any pressurized tank. If none is installed your range boiler does not meet modern safety standards - it is unsafe, and a relief valve should be installed promptly.
See RELIEF VALVE, WATER HEATER for details.
My wife and I purchased our 1917 home in downtown Riverside, California in 1984. In a few more years this house will be 100 years old.
To celebrate its coming birthday, I have started working on a small book about the history of the house.
When we bought the house we were told we were only the third owners, and the women we bought the house from (in her nineties) had her daughter (in her seventies) sell it to us.
The daughter told us her parents lived in the house for over fifty years and that they had not really done much to the house over all those years.
This is an attic storage tank probably used for a solar water heater system. Details are at SOLAR WATER HEATER ANTIQUE - separate article
Take a look at and record the following information about an unidentified attic storage tank
It looks from the partial exposure as if the tank is in a location where people used to put expansion tanks on hot water heating boilers - instead of a relief valve, if pressure in the system got too high, water would push into the tank and if the tank got too full, water would flow out of a drain into an outdoor location, sometimes even a roof gutter or downspout.
But based on its piping connections shown at SOLAR WATER HEATER ANTIQUE - separate article this tank is something else. Usually an expansion tank has just one inlet pipe that feeds water from the hot water heating system, and for attic-located expansion tanks, an overflow drain line
Continue reading at INDIRECT FIRED WATER HEATERS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see ATTIC EXPANSION TANKS, HEATING used with some older hot water heating systems.
Or see IDENTIFY WATER TANK USE
Or see SOLAR WATER HEATER ANTIQUE
Or see WATER HEATERS - home
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(Nov 5, 2012) mat68046 said:
I suspect this both a hot water storage vessel from a range boiler and an indirect water heater-although the heat source in this case is from the flue that the tank seems to be encased with. By convection this tank may be heating static water before it is goes to domestic hot supply as a buffer for the boiler, to avoid cold start hot domestic. Definitely verify the potential asbestos hazard before disturbing that tank any more.
(Sept 27, 2014) Anonymous said:
I have a very old Range boiler. Maybe 20,s and what waere the common make ups of the actual metal of the tank. This seems to be galvanized as it has magnatized properties.
(Nov 12, 2014) james said:
I have I believe the old range tank boiler system over head tank in basement rafters. I am wondering if an indirect water heater can be added to increase the efficiency of this older design or system. For both domestic hot water and heating as well since they have their own recirculation pump. When the desire for heat comes from the thermostat instead of the boiler kicking on water from the indirect water heater is circulated until the temperature drops below a set point temperature.
Thus the furnace doesn't need to cycle on as often and therefore lower fuel or energy costs and consumption. I know probably not but if it is I know a lot of people that live in older colder climate homes that would also be interested. And this would be useful in any hydronic heating system oil, gas, or electric. The other good thing no added or minimal electric output in an older home slotted for rewiring from older wiring systems. And unhooking the electric water heater. The basic idea is like brewing a pot of coffee and pouring it into a Thermous jug for later use instead of leaving the coffee pot on all day.
typically you can add an indirect water heater - it acts as an additional heating zone. You might want to abandon the range boiler in that event.
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