The Department of Indirect System Combines Closed & Open Direct Systems explains how they work and why you should use them.
When it comes to water heating in commercial applications, most of the time, you will see what we call a standard tank-type water heater setup in the boiler room.The classic tank-type water heater setup consists of one or multiple commercial water heaters, in standard or high-efficiency variations, heating and storing the domestic hot water for your building.
It is still the most common setup, but there are other options for getting hot water to your faucets.Another type of commercial water heating setup that has gained popularity is a combination system, which combines an indirect tank with a heating boiler to provide domestic hot water for a building in addition to the heat.
It is helpful to have some basic knowledge about boilers to understand how this system works.The hot water produced by boilers can be used for various purposes, like space heating, but they can't store it.The hydronic heating boilers used only for space heating don't need a place to store hot water because it's sent out into the system to heat the building instead.In a building with a closed-loop system, water is heated by a boiler to a point just below boiling and flows in a constant loop from the boiler, to the pipes, into the radiators and back to it.
A combination system is when a boiler is used for both hydronic heating and water heating.A heating system has two main components.
It's important that you have a heating boiler if you're considering an indirect water heater for your domestic hot water.An indirect water heater is like a sidecar on a motorcycle, it piggybacks off the power of the primary appliance to get a secondary bonus function.
Although they don't have their own controls, indirect water heaters are more than just storage tanks.An indirect water heater has a cold-water inlet and is filled with fresh water from the municipal water system.The indirect heater is connected to the boiler through a closed-loop water pipe.A pipe runs from the boiler into the indirect tank, where it connects with a heat exchanger coil that is basically a metal pipe twisted around like a corkscrew inside the tank.A closed loop is created when the other end of the coil connects to another pipe.See the diagram.
In these types of combinations systems, the water that is heated by the boiler to heat a building and the hot water coming out of the faucet or dishwasher are not the same, and those two different streams of water never come in contact with one another.The primary and secondary loops of non-potable water are continually heated by the boiler.The primary loop of water is used for heat in the house, but the secondary loop is also used to heat the water stored inside the indirect tank.The boiler and connected piping are the common element.
The water in this secondary loop is heated by the boiler to near boiling and then runs into the indirect tank and through the coiled corkscrew-like heat exchanger pipe inside the tank.The water within the coil loops back to the boiler to be reheated after being transferred from the coiled pipe.The coil design maximizes the heat transfer to ensure the water held in the indirect tank gets hot enough to provide plenty of domestic hot water for sinks, dishwashers, and faucets.The term "hot water heater" is redundant in the case of the indirect tank.An indirect tank is a hot water heating device.
The practicality of a combination system depends on your current system, but the advantages of an indirect water heater system mostly come down to energy efficiency, cost, and a space-saving footprint.Adding an indirect water heater to a boiler was similar to adding a sidecar to the motorcycle to gain additional functions.To explain why indirect water heaters are still a niche fit in today's market, we need to take that further.A sidecar is useless if you don't have a motorcycle.If you don't have a hydronic heating boiler, an indirect water heater has nothing to connect to for its heat source, making it pointless to consider.
Adding a sidecar to your existing vehicle may be an option if you have a motorcycle.If your building is already set up with a boiler for hydronic heat, then adding an indirect water heater to establish a combination system may be a cost-effective and efficient option for your water heating.Just having an existing boiler for hydronic heat doesn't mean it's right for you.
Not all hydronic boilers are worth using for multiple purposes.If you retrofit an older, standard-efficiency boiler, you can reduce the lifespan of your boiler by making it work all year to provide hot water, and this doesn't usually provide any benefits over a standard boiler.
When you are shopping for a new higher efficiency hydronic boiler, it is the best time to look into a combination system.If you are starting with a clean slate and are installing a new boiler system, an indirect tank may be an inexpensive addition that will save you money in the long run.
Adding an indirect water heating system to an existing setup requires more than just piping and pumps.A combination system can last a long time if you make the initial investment.Boilers are designed for long-term operation, so you are already getting a lot of life out of that piece of equipment.The indirect water heater tanks tend to last longer than the gas-fired water heaters.Here is why...
A standard atmospheric tank-type water heater pulls in air from the environment to generate a flame that burns the fuel.There are multiple exhaust flues inside the water heater.Baffles in the flue pipes slow the hot air down as it travels upward, heating the water surrounding those pipes and out the top flue through the chimney.When enough hot water is used in the building, the water heater tank is refilled with fresh cold water from outside to be heated up for the next round.This process causes the standard tank to constantly expand and contract, putting stress on the welded joints.The welded seams break open when the high heat exchanges degrade the water heater tank.
When very hot water from the boiler travels through the coiled pipe in the indirect tank, it transfers heat to the cooler water held within the Indirect tank.The hot boiler water travels through a coiled pipe rather slowly, but the water inside the indirect tank is very hot.The temperature differential, or (delta) T, is a lot less when cold water is added to an indirect tank.Less stress on the tank is a result of the thermal expansion being less drastic.This process makes indirect water heaters more efficient.It's important to review all of your options to make the best choice for your building and needs.
An indirect tank is a great space-saving option if you have limited space in your boiler room.It is possible to get away with a smaller indirect tank for hot water than you would need if you were to use a typical water heater because the high BTU input of the boiler makes up for a lack of storage.
When working in conjunction with the newer, high efficiency modulating boiler models, it is important to clarify that indirect water heaters do tend to be most beneficial.These high-efficiency boilers can provide both heat and hot water, and still save you money on your energy bill, because they achieve efficiency ratings between 90-99%.The modulating aspect of these boilers is a huge factor in getting the most out of a combination system.Modulating boilers have the ability to provide differing levels of burner firings, so they can determine if they need to fire a full flame or low flame.During warm weather, the boiler can stay on low if you don't use it for heat.
If you plan to update an existing boiler system to include an indirect water heater, there are additional considerations such as wear on the boiler, as well as the efficiency of the boilers.Whether it is worth choosing indirect over a standard water heater is dependent on boiler efficiency.An inefficient boiler can be used for multiple functions.
When boilers are only used for hydronic heating, they are off during the warmer months of the year.Adding an indirect heater for domestic water use would lead to the boiler working year-round, as well as the associated costs.The boiler can't tell the difference between needing to fire for heat or the hot water, so it fires the same amount either way.The lifespan of the boiler could be shortened because it is being used more frequently.
The domestic hot water always takes precedence over the hydronic heat in a combination system.If tenants are showering or using domestic water at the same time, the building heat still takes priority.If another polar vortex hits, the boiler may need to provide heating over the showers, dishwashers, etc.If half the building is getting ready for work and taking showers, what if the systems are set up to ignore the domestic needs for longer than 30 minutes?
When your boiler goes down, your entire system is down like when you choose one big water heater over several smaller units.Your entire building will lose both hot water and heat in one shot if you rely on one boiler for hydronic heating and water heating.Before choosing a water heating system, it is important to plan and assess your needs.
The quality of the water used in your system is another consideration.It is important to make sure your boiler and indirect water heater tank are using softened water.If you want your boiler and water heaters to live a long, healthy life, you need a water softener.Natural minerals in hard water are left behind when the water is heated.The hotter the water gets, the more debris gets left behind to build up inside your equipment and pipes.Did we mention that boilers make hot water?
The most expensive part of a boiler is the heat exchanger tubes, and they cause a ripple effect that can eventually block the tubes.There are pockets in between the deposits where water can get stuck and pop out.This can cause the boiler to bounce up and down.This will eventually result in a leak from the heat exchanger that will cause a stop to all heating capability and end up as a giant puddle on the floor of your boiler room.By the time noticeable symptoms appear, the damage is difficult to reverse.Since hard water can lead to the catastrophic failure of your equipment, prevention is a worthy investment to preserve your boiler and indirect water heating system for as long as possible.
If you are at the beginning stages of a commercial water heating setup, you may be faced with the decision between a standard tank-type water heater or a combination system that uses a boiler and an indirect tank.A combination system is a great option for heating your commercial water and space.You can save money by increasing the efficiency of your water heating operations if you add an indirect water heater tank to your hydronic heating system.
There are many benefits to the boiler and indirect water heater tank system, but it may not be an ideal fit for your business.It is important to understand the basics of boilers and water heating before making a change.A water heating system technician can help you decide which set up is best for your application.
Do you not know where to start?If you want to make the best decisions about your commercial heating and domestic water setup, review our information.Reliable Water Services has trained professionals.We can help you choose the best water heating system.
The system we have is the old one.We have 9 units.The upstairs gets very warm.Is it possible to turn off the heat in one unit?
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