The bath reheating function, which reheats bathwater that has cooled down, is one of the most popular amenities in rental properties. While it can be effective in reducing vacancies, the cost of retrofitting it to existing properties is a key concern.
This article provides a comprehensive overview of the cost estimates, benefits, drawbacks, and key considerations for retrofitting a bath reheating function in rental properties. We also share tips for keeping costs down and how to choose a reliable contractor, so if you are considering this renovation, read on to the end.
How Does the Bath Reheating Function Work? Explaining the Types of Circulation Systems
The bath reheating function works by drawing cooled bathwater through pipes to the water heater, reheating it, and returning it to the tub. Before considering the installation, it is important to understand the different types of circulation systems available.
Natural Circulation (Two-Hole Type)
This type has two holes in the bathtub — upper and lower. Cold water is drawn in through the lower hole, and heated water is discharged through the upper hole. It utilizes the natural principle that warm water rises and cold water sinks. However, the upper portion of the tub tends to overheat and scale builds up easily, so this type is becoming less common.
Pump Circulation (One-Hole Type)
Although the bathtub has only one hole, there are two internal pipes — one for intake and one for discharge. Water is forcibly circulated, resulting in a more even temperature, making this the current standard.
Difference Between Auto and Full-Auto Functions
The auto function automatically handles filling, reheating, and keeping the bath warm, while the full-auto function adds automatic top-up and pipe cleaning. The price difference between the two is roughly ¥10,000–¥50,000, so choose based on your budget and tenant needs.
What Are the Benefits of Retrofitting a Bath Reheating Function?
Installing a bath reheating function not only improves convenience for tenants but also helps property owners reduce vacancies and potentially increase rent. Let's look at the main benefits.
Bathe Whenever You Want
In households with multiple occupants, bath times vary depending on when people return home. With a reheating function, cooled water can be warmed up again quickly, allowing everyone to bathe comfortably without worrying about timing.
Saves on Water and Gas Bills
Reheating lukewarm water uses less gas and water than draining and refilling the tub entirely. The savings are especially significant in properties that use propane gas.
Automatic Filling Reduces Hassle
Simply close the drain and press a button to fill the tub to the set temperature and volume automatically. Tenants no longer need to monitor the tub to prevent overflow, improving their quality of daily life.
Does Not Take Up Bathroom Space
Since the water heater for the reheating function is installed outdoors, it does not take up any space inside the bathroom. Unlike portable bath reheaters, there is no worry about space being taken up — another key advantage.
What Are the Drawbacks of Retrofitting a Bath Reheating Function?
Despite its many benefits, there are drawbacks to be aware of before installation.
Retrofitting Costs Can Be High
The cost of retrofitting a bath reheating function typically ranges from ¥200,000 to ¥600,000. When installing in all units, the total cost can be substantial, so carefully evaluate the cost-effectiveness.
Regular Pipe Maintenance Is Required
Scale and bacteria tend to accumulate in the pipes, so cleaning the boiler approximately once a month is recommended. Tenants must also be informed of this requirement.
Certain Bath Additives Cannot Be Used
Acidic, sulfur-based, and bath salt additives can corrode the pipes and metal components. Be sure to advise tenants to avoid using these products.
Reheating Alone Does Not Guarantee Higher Occupancy
Properties with a reheating function tend to command higher rents, which may not align with all tenant needs and could have the opposite effect. Make sure to thoroughly understand your target demographic before deciding to install.
Which Types of Tenants Appreciate the Bath Reheating Function?
To maximize the impact of a bath reheating function, it is important to match it with the right type of tenant.
- Couples with different bath schedules: Both can enjoy a warm bath even with a time gap
- Families of three or more: Everyone can bathe at a comfortable temperature
- Tenants who enjoy long baths: The keep-warm function maintains the ideal temperature
- Those who bathe twice or more a day: No need to refill the tub, significantly cutting water costs
Cost Comparison: Reheating vs. Refilling vs. Topping Up
Comparing the costs of different methods of warming bathwater shows that reheating offers the best cost performance.
| Method | Gas Cost (Estimate) | Water Cost (Estimate) |
|---|---|---|
| Reheating | Approx. ¥159 | ¥0 |
| Full Refill | Approx. ¥169 | Approx. ¥48 |
| Topping Up | Approx. ¥160 | Approx. ¥12–¥24 |
※Calculated based on 2022 Tokyo propane gas price estimates. Note that for properties using an Eco Cute heat pump water heater, topping up is more efficient.
Types and Cost Estimates for Retrofitting Bath Reheating in Rental Properties
The scope and cost of retrofitting work vary depending on the condition of the property. Here are three common scenarios.
Scenario 1: Water Heater Replacement Only
If the existing pipes and holes can be reused, simply replacing the water heater with a reheating-compatible model may be sufficient.
- Estimated cost: ¥200,000–¥400,000
- Duration: Half a day to one day
Scenario 2: Pipe Work + Water Heater Replacement
This applies when drilling holes in the bathtub or exterior wall (core drilling) and installing new pipes are required.
- Estimated cost: ¥300,000–¥600,000
- Duration: Approximately one day
Scenario 3: Full Unit Bath Replacement
When replacing the bathtub alone is not feasible, the entire unit bath may need to be replaced.
- Estimated cost: ¥800,000–¥1,000,000
- Duration: 5–7 days
Request a preliminary inspection from a specialist to confirm the most appropriate work scope and cost for your specific property.
Key Considerations for Retrofitting Bath Reheating
Here are the important points to keep in mind when proceeding with the installation work.
Retrofitting May Not Be Possible for Some Properties
Constraints on the water heater installation location or pipe routing may make retrofitting impossible. In such cases, consider using a portable bath reheater or a full bathroom renovation.
Prior Notice to Tenants Is Essential
Drilling and pipe work generate significant noise and vibration. Notify tenants of the work schedule and details in advance, and instruct contractors to avoid working in the early morning or late evening.
5 Key Points for Choosing a Reliable Contractor
Choosing the right contractor is critical to the success of the work. Be sure to check the following points.
- Compare multiple contractors: Always obtain multiple quotes and compare costs, work details, and warranties
- Verify qualified personnel: Gas pipe and electrical wiring work require certified professionals
- Quality of communication: Check whether the representative responds promptly and thoroughly to questions
- Warranty and after-sales support: Confirm the system for handling issues after the work is completed
- Clarity of the quote: Ensure the quote specifies the model name, capacity, and scope of work rather than just listing a lump sum
Portable Bath Reheaters Are an Option for Those Looking to Cut Costs
If the cost of a full installation is not feasible, portable bath reheaters can be introduced without any construction work.
- Keep-warm type: Maintains water temperature for a set period. Ideal for single-occupancy properties
- Heating type: Reheats cooled water. Recommended for family-oriented properties
For safety, choose products equipped with leak-prevention and dry-heating-prevention features.
Frequently Asked Questions (FAQ)
Q. How much does it cost to retrofit a bath reheating function?
Replacing the water heater only costs ¥200,000–¥400,000. Including pipe work brings the cost to ¥300,000–¥600,000, and a full unit bath replacement ranges from ¥800,000 to ¥1,000,000.
Q. Can a bath reheating function be retrofitted in a rental property?
Retrofitting is possible in most rental properties, but constraints on the water heater placement or pipe routing may make it unfeasible in some cases. Please arrange for an on-site inspection by a specialist beforehand.
Q. Which is more cost-effective — reheating or topping up?
For gas water heaters, reheating is more cost-effective in terms of both gas and water costs. However, for properties using an Eco Cute heat pump water heater, topping up is more efficient.
Q. How much can rent be increased by adding a bath reheating function?
This varies depending on the area and property conditions, but properties with a bath reheating function tend to be priced approximately ¥5,000–¥10,000 per month higher than those without.
Q. What is a portable bath reheater?
It is a device that can be placed directly in the bathtub without any installation work to keep water warm or reheat it. Available in keep-warm and heating types, it is a cost-effective alternative.
