Hot Water System: Everything You Need to Know

It is more important than ever to ensure that our hot water systems are as efficient, environmentally friendly, and reliable as possible. Here we’ll look at the main types of hot water systems, along with tips on how to choose one and improve its efficiency.

What is a hot water system?

Hot water systems are a crucial part of any residential or commercial building's heating system. They heat water to a desired temperature and distribute it to various areas in the building where it is needed.

A hot water system typically consists of a water heater, a boiler, and a distribution network that carries the hot water to the various points of use.

The water heater or boiler is the heart of the system. It contains a burner or electric element that heats the water.

As the water is heated, it expands and rises to the top of the tank, displacing cooler water. When the hot water is needed, it flows from the tank through the distribution network to the point of use.

Tankless water heaters: the pros and cons

Tankless water heaters are a type of water heater that does not have a storage tank. These heaters provide hot water on demand, typically for a single faucet or showerhead. They are also known as point-of-use heaters because they heat water only when it is needed, reducing the amount of wasted energy associated with storing hot water in a tank.

Tankless or on-demand water heaters have surged in popularity in recent years. But are they the right choice for your home? Let’s examine the pros and cons.

Pros

• Endless hot water- Tankless heaters provide a continuous, unlimited hot water supply on demand. No more cold showers when the tank runs dry!
• Space savings- Compact, wall-mounted design frees up floor space.
• Efficiency- No standby losses from constantly reheating a tank. Energy savings of around 20%.
• Longevity- Tankless systems tend to have a lifespan of 20 years or longer.
• Safety- No combustion chamber reduces risks associated with standard models.

Cons

• Higher upfront cost- The initial purchase price is 2 - 3 times higher than tank systems.
• Flow limitations- Most tankless heaters can’t supply enough hot water for simultaneous uses like shower and laundry.
• Cold water sandwich effect- Hot water takes a few seconds to reach distant faucets.
• Gas line upgrades- Large gas models may require pipe and meter upgrades.
• Permitting and installation- Often requires permits and professional installation.

The pros of endless hot water and potential energy savings make tankless worth considering. But carefully weigh the cons before taking the plunge.

Heat pump water heaters: a closer look

Heat pump water heaters deserve special attention, as they are one of the most promising emerging technologies in residential hot water. Let’s take a closer look at how these super-efficient systems work.

Extracting heat from the air

Heat pump water heaters operate on a simple principle: they extract latent heat from ambient air and transfer it to water. It’s the same fundamental process a refrigerator or air conditioner uses, just in reverse.

An electrically powered compressor and evaporator coil draw warmth from the surrounding air. This heat is then pumped to a condenser heat exchanger immersed in the storage tank, which warms the water.

Two types: air-sourced and geothermal

There are two main types of heat pump water heaters:

• Air-sourced: The standard version pulls heat from outdoor air. Efficiency drops in freezing climates.
• Geothermal: These units tap into subsurface heat by circulating water or refrigerant through underground pipes. Geothermal models provide superior performance in cold weather.

Significant energy savings

Because they utilize heat from the environment, heat pump water heaters typically consume about 50% less power than electric resistance storage tank models. This translates into meaningful savings on utility bills.

They can be up to 300% more energy efficient in ideal conditions than conventional electric tank systems. Even in frigid northern winters, heat pump systems retain a performance edge.

Smooth integration with solar PV

Heat pump water heaters pair perfectly with home solar photovoltaic (PV) systems. Some solar installers are now offering combined PV and heat pump packages.

With time-of-use controls, the heat pump can be set to operate using your home’s solar power generation during daylight hours. This maximizes the self-consumption of free renewable electricity. Any excess solar power is fed back to the grid.

Solar hot water systems

Solar hot water system represents an elegant and reliable renewable energy solution perfected over decades. While not as trendy as new “smart” systems, solar thermal deserves consideration, especially in sunnier southern climates.

How do solar hot water systems work?

Solar collectors mounted on the roof gather heat from the sun’s rays. The solar energy heats either water or a heat-transfer fluid like glycol flowing through the panels. This hot fluid circulates through a coil or heat exchanger within the water storage tank, warming the household water supply.

Two primary system configurations

• Active systems utilize an electric pump to circulate fluid between roof collectors and the insulated storage tank.
• Passive systems rely on natural thermosiphon-ing, where gravity and convection currents move water through the closed loop.

Reliable technology

Modern solar water heaters are a mature technology benefiting from decades of product iterations and improvements. Glazed flat plate and evacuated tube collectors offer excellent efficiency and withstand extreme weather conditions.

With minimal moving parts and simple maintenance, passive systems, in particular, can provide 20+ years of nearly trouble-free operation.

Payback period

Upfront costs are higher than conventional water heating systems. However, with available federal tax credits and rebates, a solar thermal system can pay for itself in energy savings within 3 to 7 years. ROI is even faster in states with robust incentive programs.

Ideal as a supplementary system

Even in cooler climates, solar water heating can supply up to 85% of hot water needs during sunny summers. Many hot water systems use a conventional heater as a backup for cloudy spells. This hybrid approach provides the best of both worlds.

Hybrid hot water systems

Hybrid systems take the benefits of smart water heating to the next level. These units combine multiple technologies—usually a heat pump with a secondary electric heating element. The heat pump mainly handles water heating, tapping into ambient air, or geothermal energy. When hot water demand spikes, the electric part boosts capacity.

Hybrid hot water system delivers the best of both worlds:

• Energy efficiency - Heat pumps can reduce water heating bills by 50% or more.
• Reliability - Electric elements provide backup and peace of mind.
• Environmentally friendly - Dramatically lower carbon emissions compared to conventional water heaters.

Currently, the upfront cost of a hybrid hot water system is higher than standard models. However, with energy prices destined to climb in the years ahead, the long-term savings may justify the investment for some homeowners. Costs should also decline as hybrids become mainstream.

How do I choose a hot water system?

If it’s time to purchase a new hot water system, do your homework to select the optimal model. Key factors to consider include:

Energy source

• Electric- Convenient but may have high operating costs depending on local energy rates.
• Gas- Often more affordable to run than electric, but not available everywhere.
• Solar- Harness-free and renewable energy, but requires adequate roof space.

Efficiency rating

• Look for systems with a high Energy Star score to maximize savings.

Household size & usage

• Storage tanks should be sized based on the number of bedrooms/occupants
• On-demand better suits smaller households with sporadic draw

Climate

• In colder regions, choose cold-climate-rated heat pumps
• Solar thermal works best in sunnier southern locales

Available space

• Make sure to accommodate tank, collector, or heat pump unit requirements.

Budget

• Balance upfront costs against long-term energy savings.
• Take advantage of rebates and incentives.

You can zero in on the ideal hot water solution for your home and family by weighing these key variables.

New hot water system planning

If you’re building a new home, you have the advantage of a clean slate when planning your hot water system. Keep these tips in mind:

• Size the system based on home size, number of baths, and occupancy. Don’t oversize.
• Locate the water heater central to primary hot water uses.
• For solar thermal, orient roof space to maximize exposure.
• With heat pumps, ensure adequate exterior ventilation.
• Allow room for hybrid system secondary electric elements.
• Plan for zoned hot water distribution to each area.
• Separate plumbing for hot and cold lines reduces heat migration.
• Insulate all hot water pipes, especially in unheated spaces.
• Install recirculation pumps only if runs exceed 50 feet.
• Include valved hot water line connections for future solar thermal.

By planning, you can optimize hot water usage in your new home from day one.

10 Tips to improve your hot water system efficiency

Looking to maximize efficiency from your existing system? Here are handy tips and tricks for squeezing every drop of savings from your gas, electric, solar, or tankless water heater:

1. Set the thermostat to 120°F- This provides sufficient hot water for showers and other uses for most homes.
2. Insulate exposed hot water pipes- Reduces standby heat loss over pipe runs.
3. Install heat traps- Inexpensive valves reduce convection loop heat losses.
4. Lower the setting while away- Turn the thermostat down to 90°F during vacations.
5. Drain and flush annually- Sediment buildup degrades heat transfer over time.
6. Let it shine!- If solar thermal, sweep away snow and trim vegetation-blocking panels.
7. Use less water- Low-flow fixtures and shorter showers reduce waste.
8. Upgrade showerheads- New low-flow models provide tremendous pressure using less hot water.
9. Run full loads- Hold off on partial loads to maximize washer and dishwasher cycles.
10. Air dry dishes- Skip the dishwasher-heated drying cycle and air dry instead.

With a few tailored tweaks, you can optimize your hot water system. Over time, these small measures add up to significant savings!

How to set the temperature of a hot water system?

One of the simplest ways to optimize hot water system efficiency is ensuring your heater thermostat is set enough. Follow these tips:

• Start at 120°F. This provides sufficient hot water for most needs.
• Lower 5°F per week to find the lowest acceptable temperature.
• Keep it 120-125°F for the average household with a dishwasher.
• With the tankless model, 125-130°F should work fine.
• Raise the setting to 5°F if you need longer or hotter showers.
• Never exceed 130°F due to increased scalding dangers.
• Install thermostatic or anti-scald valves at points of use if required.

Lowering your temperature setting reduces waste while still meeting your hot water needs. Give it a try! Dialing in your ideal temperature takes trial and error but optimizes efficiency.

Upgrades for existing hot water systems

Do you still need to get ready to replace your current system? Not a problem. A few easy DIY upgrades can still make a noticeable difference in performance and efficiency:

• Insulate pipes- Wrap inlet and outlet pipes in insulation to prevent standby heat loss.
• Install heat traps- These one-way valves reduce the thermosiphon effect, which wastes hot water.
• Check insulation- Inspect tank insulation and wrap any exposed areas to maximize heat retention.
• A lower temperature setting- 120°F is usually adequate for residential use rather than 140°F.
• Drain sediment- Annually flush out residue that builds up internally over time.
• Water heater blanket- An insulated blanket can reduce standby losses by 25% to 45%. Make sure to get the proper size and follow product instructions.
• Pipe insulation- Insulating hot water pipes with foam sleeves or fiberglass wraps reduces heat loss over the distribution run.
• Heat traps- These inexpensive, one-way valves are installed on the cold water inlet and hot water outlet lines to prevent gravity circulation losses.

With a few upgrades, you can squeeze more life out of your existing system while reducing energy waste at the same time.

5 Signs it’s time to replace your hot water system

With regular maintenance, the typical hot water system lifespan is 10-15 years. But there are telling clues your system may be nearing the end of its useful life:

1. Rusty water- Rust-colored or dirty water indicates internal tank corrosion and sediment buildup. Time to replace!
2. Declining efficiency- Frequent reheating and skyrocketing energy bills point to a failing unit.
3. Old age- Most systems should be replaced after 10-15 years as a precaution.
4. Leaks- Weeping, drips, or puddles signal looming outright tank failure.
5. Odd noises- Knocking, rumbling, or hissing could indicate serious trouble.

Catching problems early allows you to replace the system on your terms instead of emergency failure at the worst possible moment.

Conclusion

Overall, no matter which hot water system you choose, there are important factors to consider. Such as fuel source, efficiency, and size, etc. With careful planning and selection, your next hot water system can provide years of reliable hydraulic comfort while conserving resources and reducing environmental impact.