8 Things Homeowners Should Consider Before Replacing an Outdated Water Heater
Planning a water heater replacement is one of the most important home improvements you can make, and most people do it wrong. They wait until the system fails and then buy whatever the plumber has available. To make a smarter choice and save money, you need to consider a few important details before making a purchase or calling in an installation service.
Look at Your Electrical Panel First
Before you start browsing listings and product specs, look in your switchboard and become familiar with the limits of the current setup. Your electrical capacity defines the limits within which you can choose a heater replacement. For example, if you want to switch from gas to electric or a hybrid heat pump, there is a good chance that your current panel cannot support the amperage required by the new system.
A heat pump water heater’s resistance element can require anywhere from 15 to 30 amps, so if your panel is already at its limit, you will need to budget for an upgrade. The same applies when switching from electric to gas – a licensed plumber will be able to advise you on the required pressure in the gas pipeline for a continuous flow system.
In short, make sure to evaluate the home’s existing energy infrastructure and the potential upgrade costs before choosing a heater model.
Calculate Peak Hour Demand
The most common mistake homeowners make when replacing a storage tank is selecting the same volume. While a 160-liter tank can indeed provide you with 160 liters of hot water, it does so over several hours. To calculate the peak hour demand, you need to determine how much hot water you and your household members use simultaneously.
The easiest way is to add up the flow rates of all the outlets and appliances that use hot water at the busiest time of the day. For example, if two people take a shower at 7 am, one runs the dishwasher with dishes from the previous day, and the washing machine is set to begin at 7:30 am, you will need to select a heater capable of sustaining the flow rate of at least three simultaneous outlets.
For continuous flow systems, the calculation is similar, although in this case, you will need to compare the total flow rate with the capacity of the selected model. As a reference point, one shower uses approximately 9-12 liters of water per minute. Two showers and a dishwasher will require a peak flow rate of at least 25 liters per minute – well beyond the capacity of most small tankless heaters.
Remember that undersized systems will fail to provide the required amount of hot water at busy times, while oversized heaters are usually too expensive and wasteful.
Compare the Physical Footprint of the System
When selecting a replacement for your storage tank, remember that continuous flow and heat pump systems are not as simple as their name suggests. Heat pumps, in particular, require additional space to the side and above the unit for the evaporator and exhaust fan. In addition, most manufacturers recommend at least a few cubic meters of free space around the unit for proper air circulation.
Some heat pump systems, however, are designed for installation in confined spaces. For example, some models come with special ducts that channel the cool air from the evaporator back into the room. As always, make sure to read the installation instructions carefully before purchasing the unit. The noise level is also an important characteristic to consider – heat pump compressors can be as loud as 40-50 dBA. This is about the same volume as a refrigerator, so it is not unreasonable to expect such a unit to be installed in a utility closet rather than next to a bedroom window.
Continuous flow systems, on the other hand, are compact and can be mounted on a wall, making them ideal for small spaces. However, gas units require a flue for exhaust gases, and electric heaters require an additional circuit in your switchboard. Neither is a deal-breaker, but both require additional considerations.
Compare Lifetime Costs, Not Just the Price
Most homeowners make one critical mistake when choosing a heater replacement – they try to stay within the limited budget for home improvements. A basic electric storage tank, for example, has a low purchase and installation cost. However, it also has a thermal efficiency of 100%, which means you will have to pay for the full amount of electricity the heater uses.
A heat pump hot water system, on the other hand, can have a coefficient of performance (COP) of 3-5. This means that for every unit of electricity the heater consumes, it produces 3-5 units of heat. In other words, a heat pump system can be 60-75% more energy-efficient than a standard electric resistance tank.
Domestic hot water typically accounts for 23% of the total energy consumption of the average home (Australian Government Department of Climate Change, Energy, the Environment and Water). By switching to a more energy-efficient system, you can reduce your energy bill by as much as two-thirds. At the same time, the higher purchase price of a heat pump will typically be recouped within 4-8 years, depending on the system and local electricity rates. Over the 15-year lifespan of the heater, the savings on energy bills will far exceed the difference in purchase prices.
Gas systems, meanwhile, are generally less efficient than heat pumps and electric resistance tanks. Most gas heaters installed before 2010 had an efficiency rating of no more than 60%, and even modern condensing units rarely exceed 85% thermal efficiency. In other words, a substantial amount of gas is wasted in older heaters, with heat loss through the chimney.
Research the Climate Where the Heater Will Be Installed
Heat pumps are powered by ambient air, which means that the efficiency of these systems is directly linked to the temperature of the room where the unit is installed. Ideally, the temperature should not drop below zero degrees Celsius, as lower temperatures reduce the efficiency of the heat pump.
Most modern systems are equipped to function in cold climates, but the lower the outside temperature, the higher the electrical consumption of the heater will be. In other words, while a heat pump will be able to maintain a steady supply of hot water in sub-zero temperatures, it will not be as energy-efficient as in warm and temperate climates.
If you are in a cold climate, research the temperature range in which the selected heater can operate and compare the COP at different temperatures. In particular, look for heaters that are rated to work at temperatures as low as -10 degrees Celsius or lower. The lower the operating temperature, the more powerful the heat pump is likely to be.
For all but the coldest regions, climate is unlikely to be a limiting factor for selecting a heat pump.
Look Into Compliance and Safety Regulations
Water heater installations are subject to local safety regulations, which can vary significantly from one region to another. However, most of them are similar in many ways. For example, most jurisdictions require tempering valves on storage tank heaters, while others may require you to apply for a building permit if you are replacing a gas system with an electric one.
Tempering valves are designed to reduce the water temperature at the outlet to prevent scalding. Hot water in storage tank systems is typically heated to 60 degrees Celsius or higher to prevent the growth of Legionella bacteria, but this temperature is dangerous for humans. A tempering valve allows you to reduce the temperature to 50 degrees Celsius or lower at the point of use.
While the installation of tempering valves is not always mandatory, it is a good idea to have one, especially if you have children or elderly family members. In many cases, the presence of a tempering valve is a requirement for obtaining a building permit.
Finally, make sure to choose a licensed installer who is familiar with local regulations and will complete all necessary paperwork, including permits and inspections, so that you are not surprised by additional costs when selling the house.
Review Maintenance Requirements
While all water heaters require some maintenance, storage tank systems typically need more of it. The most important procedure is anode rod replacement, which is required every 3-5 years. Anode rods protect the tank from corrosion by drawing the corrosive agents away from the steel walls of the tank. If anode rod replacement is neglected, the tank will corrode and fail prematurely.
Most continuous flow systems do not have anode rods, but they are subject to scaling, particularly in areas with hard water. In such cases, a yearly descaling procedure is required to remove the mineral deposits from the heat exchanger. Heat pumps, for their part, require maintenance of both the tank and the air filter on the evaporator.
These procedures are not particularly difficult, but they need to be scheduled regularly. In the end, a system that requires annual maintenance is preferable to a more efficient system that is completely neglected.
Research Incentives and Rebates
Many governments offer rebates and incentives for the purchase and installation of energy-efficient hot water systems. These programs exist to encourage homeowners to replace old gas and electric heaters with hybrid heat pump systems and solar hot water systems. In particular, you can receive a significant discount on the purchase of a heat pump if you apply for a rebate in your local jurisdiction.
The amount of the rebate varies from one region to another and depends on the type of the heater being installed. In some cases, rebates can be as high as 40% of the purchase price. Before choosing a system, therefore, it is a good idea to research the available rebates in your area and consult with your installer about your options. In many cases, these rebates can be applied directly to the purchase and installation of the heater.
Finally, make sure to ask your installer about the eligibility of the selected system and installation method. In particular, if you are replacing a gas heater with an electric system, you may be able to receive additional incentives for removing the old equipment. In the end, the choice of a water heater is a long-term investment, and a few extra days spent researching rebates and incentives can save you thousands of dollars.