Determining Your Temperature Rise
To determine your temperature rise, you need to figure out the temperature of the water coming into your home. And this is based on groundwater temperatures, which will vary considerably based on where you live in the U.S.
Take a look at this groundwater temperature map to get general idea of what temperatures you can expect depending on where you live. If you need real time temperature data, then consult this interactive map from the USGS site.
As you can see, the temperatures vary wildly by location.
Just take the temperature that you expect your incoming water to be based on the graph above. Then subtract that from how hot you want your water to be.
This is your temperature rise.
Once you have your temperature rise, you can look at the specification sheet of the tankless water heater you want to buy and see what the GPM is rated for based on that number.
What Size Water Storage Tank Would You Recommend
The size of the water storage tank you should choose depends on a variety of factors, such as the size of your home, the amount of water that will be used on a daily basis, and the water pressure in your home.
For example, a small family may be able to get away with a 1000-gallon tank, while a larger family may need a 2000- or 3000-gallon tank. You should also check to see if there are local regulations on the size of the tank.
The amount of water that will be used on a daily basis should also be taken into consideration. The higher the rate your household uses, the larger the storage tank you should get. Additionally, if your home has a low water pressure, you should consider getting a larger tank to provide the necessary pressure for your home.
It would also be a good idea to talk to a professional who can assess your specific needs and make an informed recommendation for the best size tank for your home.
A Tankless Water Heater Also Known As An On
A tankless water heater, which may be installed on the wall of your garage, utility room, or even outside your home, can provide hot water for your whole home, from taps and showers to soaking tubs, dishwashers, laundry, and other appliances.Tankless water heaters provide hot water on demand, which means that assuming you install a properly sized unit, you will be able to have hot water whenever you need it, in as many locations as you need it, for as long as you need it.Tankless water heaters are ideal for small to medium-sized households.In reality, these are two of the most significant advantages of tankless water heaters: they save space and money.There are two advantages to using solar hot water: 1) you dont have to waste energy continuously keeping a large volume of water hot, and 2) you can generate an unlimited flow of hot water, so you dont have to worry about running out of hot water during a long shower or filling a soaking tub completely.
HOW DOES A TANKLESS WATER HEATER WORK?
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What Size Tankless Water Heater Is Needed For A Family Of 4
By: Author Olin Wade
Choosing the size of tankless water heater needed for a family of 4 will depend on several factors, including the type of water heater being used, the amount of hot water demanded, the desired temperature of hot water, and incoming water temperature.
Tankless water heaters are typically measured in gallons-per-minute , and may range from. 5 GPM to 5. 0 GPM or more.
If you are utilizing a gas-fired tankless water heater, the amount of hot water needed can typically be calculated by figuring that each family member uses about 25 gallons per day for showers and water-related activities.
Therefore, a family of four would require about 100 gallons per day of hot water. It is also important to consider the temperature of incoming water and the temperature you desire for hot water because higher temperature water will require more BTUs of heat.
To give a more precise estimate, a professional plumber should be consulted. However, as a general rule, a tankless water heater rated between 3. 5 to 4. 5 GPM should provide enough hot water for a family of four, depending on frequency and duration of use.
A higher output of 5 GPM or more may be needed with higher temperature incoming water, or if numerous hot water fixtures are located in close proximity.
Is Lower Or Higher Gpm Better
The answer to this question depends on the particular situation and what you are trying to achieve. Generally speaking, in terms of measuring performance, a higher GPM is better in many cases.
GPM is a measure of how much fluid can be transported through a pipe, nozzle, or opening in a given amount of time. In some cases, a higher gpm indicates greater efficiency when trying to accomplish a certain task.
For example, if you are planning to use an irrigation system to water a large area, a higher GPM can mean higher efficiency. On the other hand, there are certain situations when a lower GPM can provide better results.
For example, in the case of fire hoses, a lower GPM allows for more precise control, which can be useful in containing a fire or minimizing the damage caused by a fire. Ultimately, it comes down to determining the specific needs of the situation and selecting the option that will provide the most efficient result.
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Determine Temperature Rise Needed
It is necessary to consider not just the volume of water that has to be moved, but also how much of that water needs to be heated. Another calculation is the temperature rise, which is the length of time it takes to raise the temperature of groundwater to the desirable hot temperature you want it to be. Typically, this temperature is approximately 120 degrees Fahrenheit, although this is simply a personal preference. Using a ground temperature map, you may quickly determine the typical groundwater temperature in your local area.
The map you choose to use when sizing a tankless hot water heater is entirely up to your personal taste and needs.
This is another another specification that will be used to determine the size of the water heater you require.
Water Heater Size Calculator: What Size Water Heater Do I Need
Adequately sizing a water heater is not all that easy. When choosing a water heater capacity for a family of 2, 3, 4, 5, or 6, there are two rather common mistakes most people make:
Both of these mistakes can be avoided if you know how to properly choose a water heater capacity for your hot water needs.
Heres the thing:
You only have one shot at sizing your water heater. You dont want to blow it and buy a unit thats either too big or too small.
Thats we will look into how to pick the right water heater size for your home. That includes factors that increase/decrease the water heater capacity requirements . We include the general rule of thumb for sizing any water heater .
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The Cons Of Choosing An Oversize Tankless Water Heater
- Additional Energy Use: If keeping your energy bills low is your primary reason for switching to a tankless design, then youll want to stick to a smaller size unit. Larger appliances heat at their rating level, no matter how many people require hot water at the same time.
- Higher Upfront Installation Cost: It makes sense that the larger the unit, the more expensive it is to purchase and install. This higher upfront cost might be over your project budget.
Gas Or Electric: Which Is Best
Both gas and electric tankless water heaters have their advantages, and if you’re lucky enough to be able to decide , you should definitely spend the time to research which is the best fit for your household.
Although, this topic is beyond the scope of this article, we highly recommend checking out our article: Gas vs. Electric Tankless Water Heater: Which is Best?
In the article we compare 9 factors head-to-head to help you make an informed decision.
As a general rule, you can expect that an electric tankless water heater will be easier to install, require less maintenance, and have a lower purchase price.
Where a gas tankless heater is capable of delivering a higher GPM, requires more maintenance, and is more expensive to install.
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Sizing A New Water Heater
A properly sized water heater will meet your household’s hot water needs while operating more efficiently. Therefore, before purchasing a water heater, make sure it’s the correct size.
Here you’ll find information about how to size these systems:
- Tankless or demand-type water heaters
- Solar water heating system
- Storage and heat pump water heaters.
For sizing combination water and space heating systems — including some heat pump systems, and tankless coil and indirect water heaters — consult a qualified contractor.
If you haven’t yet considered what type of water heater might be best for your home, learn more about selecting a new water heater.
So What Size Tankless Water Heater Is Equivalent To This 40 Gallon Unit
If you use 5GPM water, the 40 Gallon tank delivers hot water for 6 minutes before the temperature falls by 116F.
But a 5 GPM tankless water heater can limitlessly deliver hot water at 120F. However, a small 3 GPM tankless water heater can do the same with a low flow rate.
So, If your total water uses remains around 4 GPM, including bathroom, kitchen, and laundry, then a 5 GPM tankless water heater can replace a 40 Gallon unit.
Also, you can increment or decrement the size according to your flow rate calculation.
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Best Tankless Water Heater For 3 Bathrooms
In a three-bathroom house , youd normally want to take at least two showers at the same time. But dont forget about other appliances such as the washing machine and dishwasher, which may each consume up to 2 liters of hot water every minute. This amount of demand necessitates the use of something really strong. This is especially true when you require all three baths or showers at the same time. The peak demand is likely to be between 7 and 9 GPM at any one time. The Rinnai RL94iN a natural gas tankless water heater with a maximum flow rate of around 9.4 GPM and a reasonably affordable price makes it the ideal choice for a home with three bathrooms and extra household appliances.
Rinnai RL Series HE+ Tankless Hot Water Heater
The Rinnai RL Series HE+ Tankless Hot Water Heater has the following features:
- Natural gas or/and liquid propane as fuel
- Product Dimensions: 14 x 10 x 23 inches
- Maximum Flow Rate:9.4 GPM
- Product Dimensions: 14 x 10 x 23 inches Energy Star certified
Dont be deceived by the maximum flow rate figure on the label. Dont forget that this is the highest possible score for really hot environments. In actual life, it would be able to handle almost all you asked of it. That is between 7GPM and 9GPM, depending on how much the temperature has risen over time. Its also not the most energy-efficient model available.
Is 40 Gallon Water Heater Enough For A Family Of 4
40 gallon water heaters can generally provide enough hot water for a family of 4, assuming moderate water use. Depending on the size and layout of the home and the preferences of each family member, however, the specific needs of any given family may be slightly higher or lower.
Considerations such as the type of appliances in the home, the number of bathrooms and showers, and the type of water activities that require hot water can all influence the total amount of hot water necessary for a particular family.
Taking all of these factors into account, if moderate water use is expected for a family of 4, a 40 gallon water heater should generally be sufficient.
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Can You Take Two Showers At Once With Tankless Water Heater
No, you cannot technically take two showers at once with a tankless water heater. Tankless water heaters heat water on demand and only enough hot water for one shower at a time. As the water passes through the water heater, it heats to the set temperature, either through gas or electric, and then directly is send to the showerhead.
As such, it can only provide enough hot water for one shower at a time and attempting to have two showers running at the same time would significantly lower the temperature of the hot water being delivered by the heater for both showers.
Is A 40 Gallon Water Heater Enough For A 3 Bedroom House
No, a 40 gallon water heater is most likely not enough for a 3 bedroom house. It depends on the number of people living in the home and the amount of hot water those people need. A larger household that use a lot of hot water (e.
g. running dishwashers, washing machines, multiple showers, etc. ) would need a larger water heater to accommodate the increased hot water needs. Depending on the hot water usage, a 50 to 80 gallon water heater may be more suitable for a 3 bedroom house.
Additionally, households that use a lot of high-flow showers and other water-consuming appliances will require even larger water heaters. In order to determine the right size water heater for your home, consider these factors, as well as other factors such as local climate and building codes.
A qualified plumber or HVAC technician can help you identify the best size of water heater for your home.
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Wrap Up: Tankless Water Heaters
Adding a tankless unit to your home can be an excellent way to ensure everyone in the family gets the hot water when they need it most.
These appliances are much more energy efficient and can raise the overall value of your property, too.
While there are some cons, the overwhelming benefits of installing one highly outweigh the downsides. In short, if you have the budget for installing the right size for your needs, youll be very glad that you did.
See our tankless water heater servicespage for more info or to get a quote on installing one in your home.
So Cal Gas is currently providing rebates of $600 to $1,000 for certified Energy Star rated tankless water heaters. Check their rebates page for current availability.
More Tankless Water Heater Info
Tankless Water Heater Rebates: A Great Way To Save
Condensing tankless water heaters are so efficient, theyre certified by the federal Energy Star program, making them eligible for utility rebates across the country. These rebates are often enough to bridge the difference in price between the more expensive condensing units and the cheaper noncondensing ones. Then its basically a free or low-cost upgrade that will save money for the next 20 years or more. Richard Trethewey, TOH plumbing and heating expert
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Measure Your Cold Water Temperature
Using a thermometer, determine the temperature of your cold water.The first step is to determine the temperature of your water.Your tankless unit will heat this water to the temperature you specify, and it should be capable of sustaining that temperature at the maximum flow rate you specify.For example, 110 degrees Fahrenheit is widely considered to be the optimal temperature for kitchen sink hot water.Assuming a cold water flow of 50 degrees Fahrenheit, the tankless water heater must be able to raise the incoming water temperature by 60 degrees Fahrenheit while operating at maximum flow rate in order to maintain the kitchen water flowing at 110 degrees Fahrenheit.
Sizing Tank Water Heaters
In order to find the right size water heater, a plumber determines your households peak hour demand. The peak hour demand is the amount of hot water that is consumed in the peak hour of use, measured in gallons per hour .
To determine a households peak hour demand, plumbers consider the following factors:
- How many people are living in the house? Homes with one or two occupants typically require smaller capacity water heaters than large families.
- What hot water-consuming activities occur in the house? These include showers, baths, running the washing machine, using the dishwasher, washing by hand, etc.
- When do occupants prefer to do these activities? Do some shower in the morning and others at night, or is there a rush to catch a shower at a specific time before the hot water supply runs out?
- Do these activities take place simultaneously? Are occupants showering across different bathrooms at the same time, are washing machines running when dishwashers are?
- How do occupants prefer to perform these activities? Are long, hot showers common or are showers short with cooler water? Are tubs filled to the brim for baths or is a shallow water level used?
- What type of fixtures are in the home? Fixtures like jacuzzi tubs and spa showers require more hot water volume to deliver the experience users desire.
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