The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →You cannot calculate a defensible EcoDrain payback period from the challenge figures alone. Those figures are enough to estimate theoretical heat recovered—about 17,514 Btu per day, or 6.39 million Btu per year under the stated assumptions—but they do not include the installed equipment and labor cost or the household’s actual utility savings. The correct calculation is installed system cost ÷ annual bill savings. Until both values are known, any exact number of years would be invented.
What the EcoDrain challenge is actually asking
Tim Carter’s Ask the Builder challenge asks, “Okay, so let’s see if you know how to calculate what the payback period is on the EcoDrain product.” The useful way to answer is to separate three different quantities:
As an Amazon Associate I earn from qualifying purchases.
- Heat available in the drain water: a thermal calculation based on gallons, temperature difference and exchanger effectiveness.
- Energy that the water-heating system avoids buying: lower than the recovered heat when heater and distribution losses are considered.
- Dollar savings and payback: the avoided energy cost compared with the complete installed price.
Confusing the first quantity with the third is the most common error. A heat exchanger can recover a substantial amount of heat while producing a long payback if installation is expensive, showers are infrequent, water is already inexpensive, or the exchanger is poorly matched to the plumbing.
Free tools Windows power users keep installed
One-click scans. No signup required.
The challenge’s assumptions, kept in context
The following numbers come from the calculation challenge. They are exercise assumptions, not a guarantee of performance for a particular home or a measured rating for every EcoDrain model. The challenge explicitly treats the 80 percent transfer figure as an assumption and says the actual exchanger loss is unknown.
#1 Best Overall
- Valued Carpenter Pencil Set: You will get 2 pcs solid carpenter pencils with 26 piece 2.8 mm refills, 1 replaceable sharpener, 1 plastic storage box.The complete carpenter pencils combination allows you to finish your work faster and more easily
- Deep Hole Marker Pencil: The deep-hole construction pencils adopts 45mm elongated tip design, which is more convenient to mark in the small hole or in other tight areas that other carpenter markers cannot reach
- Carpenter Pencils with Sharpener: The sharpener is screwed into the top of the work pencil, which won't get lost either. Built-in pencil sharpener that keep the lead with pointed and smooth to Improves line of sight in fine work
- Stronger Solid Lead: This work pencil is matched with a 2.8 mm thick lead , which is much thicker and stronger during the drawing process of construction work, it will not break or damage easily
- Marks on Various Surfaces: 3 colors solid construction pencil can marks on various surfaces,such as metal, plastic, wood, paper etc. Ideals for woodworkers, contractors, craftsmen, builders, merchants and masons
| Input | Challenge value | How to interpret it |
|---|---|---|
| Shower flow | 2.5 gallons per minute | Stated as a modern shower-head flow |
| Showers per day | Three | Household-use assumption |
| Duration | 10 minutes each | Creates 30 shower minutes per day |
| Cold-water inlet | 55°F | Temperature entering the heat-recovery calculation |
| Water-heater output | 110°F | Challenge input; not necessarily the storage-tank setting |
| Drain water entering exchanger | 90°F | Warm effluent temperature at the exchanger inlet |
| Assumed transfer | 80% | An assumption, not a cited measured model rating |
| Electricity prices | $0.10/kWh and $0.20/kWh | Two illustrative rate scenarios |
| Natural gas price | $14.25 per thousand cubic feet | Illustrative fuel price in the challenge |
Real results vary with incoming-water temperature, shower flow, shower duration, number of occupants, drain geometry, exchanger orientation, water-heater efficiency, fuel price and whether hot drain water and incoming cold water flow at the same time.
Step 1: Calculate the daily shower volume
Flow multiplied by minutes and showers gives the daily volume:
2.5 gallons/minute × 10 minutes × 3 showers = 75 gallons per day.
This is the volume of shower water passing through the drain each day in the exercise. It is not the amount of water stored in the heater, and it does not establish that all 75 gallons will produce useful recovery. A shower drain-water exchanger needs simultaneous or closely overlapping flow on its warm and cold sides to transfer heat effectively.
Step 2: Estimate theoretical heat recovered
For a first-pass estimate, use the standard water heat-capacity approximation of 8.34 Btu per gallon per °F:
Recovered heat = gallons × 8.34 Btu/(gallon·°F) × temperature difference × transfer fraction.
Rank #2
- Ergonomically Designed: Work in tight areas with a compact design that gets into tough spots
- Both tools are designed to fit into difficult to reach spaces
- Complete a wide range of applications with a high-performance motor that delivers up to 300 UWO, and an impact driver delivering up to 1,400 in-lbs of torque
- Both the DEWALT impact driver and drill driver feature integrated LED work lights with a convenient 20-second delay, ensuring enhanced visibility in dimly lit or challenging work areas
- One-Handed Loading - Keep one hand free with a 1/4 in. hex chuck that accepts 1 in. bit tips
The challenge’s drain-to-inlet difference is 90°F − 55°F = 35°F. Substituting its assumptions:
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
75 × 8.34 × 35 × 0.80 = approximately 17,514 Btu per day.
Annualized over 365 days, the idealized result is approximately 6.39 million Btu per year. The 8.34 value is a calculation constant used for the estimate; it is not presented as a product test result. This figure describes heat transferred to incoming water under the assumed conditions. It does not say that a utility bill will fall by 6.39 million Btu worth of money.
Why recovered Btu is not the same as bill savings
Water-heater efficiency changes the purchased energy
If a heater is 80 percent efficient, supplying 6.39 million useful Btu may require roughly 7.99 million Btu of input energy before other losses. A high-efficiency gas appliance, heat-pump water heater and electric resistance heater convert purchased energy differently, so the same recovered heat can have different monetary value. Standby losses, mixing valves, recirculation and distribution losses also affect the result.
Fuel prices must be put in compatible units
Electricity is billed in kilowatt-hours, while gas is commonly billed in therms or cubic feet. One kilowatt-hour is 3,412 Btu, and one therm is 100,000 Btu. Convert the recovered useful heat to the input energy your heater would otherwise consume, then multiply by the applicable tariff. The challenge’s $0.10/kWh, $0.20/kWh and $14.25 per thousand cubic feet are scenarios, not a universal rate.
Flow timing and plumbing determine how much heat is usable
EcoDrain describes a drain-water heat exchanger: warm shower effluent transfers heat through separate passages to incoming fresh water. If the cold side is not flowing while hot water goes down the drain, some available heat may leave unused. Pipe length, slope, exchanger inclination, insulation, mineral scale and the distance to the water heater all influence delivered temperature.
Rank #3
- 【Great Compatibility】This Katerk 1/4 inch hex shank bit holder is specifically designed for 1/4 inch hex shank drill bits. It's compatible with most 1/4 fast hex handles, hex sockets, various electric screwdrivers, and handheld screwdrivers. The bit holder makes it a valuable addition for any handyman.
- 【Secure and Safe】Built with a secure backup nut design, each drill bit holder securely locks onto your bits, ensuring they stay firmly in place. Additionally, our bit holder incorporates a high-quality steel ball rolling design that holds up to several kilograms of weight, ensuring your various drill bits don't fall off.
- 【Easy One-Handed Operation】The bit holder for impact driver allows you to change bits single-handedly, simplifying your workflow. Its multi-color design further allows for quick identification of the drill bit you need.
- 【Compact and Convenient】Thanks to its compact size, this 1/4 inch bit holder is easy to carry around. The bit holder allows for easy attachment to various tools, making this a convenient addition to your construction accessories. The Katerk bit holder is cast from high-quality alloy material, promising a long product lifespan. Despite its rugged strength, the bit holder remains lightweight, making it portable.
- 【Cool Christmas Gift For Men Stocking Stuffers】 This screwdriver bit holder, driver bit holder, impact bit holder, can be given as a gift to your loved one, especially for anyone involved in construction or electrical work. It's a must-have for stocking stuffers for men and women, tools gifts for dad, tech gadgets for men, gifts for dad, gifts for him, gifts for husband, gifts for boyfriend, cool gadgets for men, and cool gifts for dad.
Water and sewer charges are a separate question
The challenge focuses on energy. A drain exchanger does not reduce the gallons used by a shower, so it normally does not reduce volumetric water or sewer charges. Any financial model should identify which portion of the bill is actually affected.
The manufacturer’s effectiveness definition
EcoDrain’s FAQ defines effectiveness as:
(preheated outlet temperature − cold-water temperature) ÷ (drain-water temperature entering the heat exchanger − cold-water temperature).
It also describes heat transfer with Q = m Cp dT, where mass flow, water heat capacity and temperature change all matter. These definitions explain why a single percentage cannot be moved from one installation to another without preserving flow and temperature conditions. The challenge’s 80 percent input is a convenient assumption for arithmetic; it is not the same as a measured rating for a named model under a specified test protocol.
Recommended Free Tools
Step 3: Convert heat recovery into annual bill savings
Use a measured or carefully estimated temperature rise on the cold side whenever possible. A practical worksheet has these steps:
- Measure use: record actual shower flow, minutes per shower and showers per day for a representative month.
- Measure temperatures: record cold-water temperature and drain-water temperature at the exchanger, rather than relying on the challenge’s 55°F and 90°F assumptions.
- Determine recovered heat: calculate mass flow × heat capacity × useful temperature rise. If using an effectiveness value, document its test conditions.
- Apply heater efficiency: divide useful recovered heat by the heater’s seasonal efficiency or coefficient of performance, as appropriate for the equipment.
- Convert units: express avoided input energy in kWh, therms or the unit on the utility bill.
- Use the marginal rate: multiply by the energy price that applies to the avoided consumption, including time-of-use periods if relevant.
- Annualize cautiously: account for occupancy, seasonal inlet temperatures, vacations and changes in shower behavior.
For a rough electric illustration only, treating the full 6.39 million Btu as useful electricity would equal about 1,873 kWh (6,390,000 ÷ 3,412). At $0.10/kWh that is about $187 per year, and at $0.20/kWh about $374 per year, before heater efficiency, timing and installation effects. Those figures are arithmetic illustrations from the challenge assumptions, not a household forecast. A resistance heater would require a different treatment than a heat-pump system, and gas savings require conversion to the gas appliance’s input energy and billing units.
Step 4: Calculate simple payback correctly
The formula is:
Simple payback (years) = total installed cost ÷ annual bill savings.
Rank #4
- Long Nib and Deep Hole Marker: Our mechanical carpenter pencil with 45mm nib is designed for easy marking of deep holes or narrow areas. These construction pencils are the great choice for woodworking tools, construction tools, carpenter tools, contractor tools, wood carpentry tools and architect tools
- Extra Refills in 2 Colors for Versatile Marking: The construction mechanical pencil comes with 12 extra 2.8mm refills, including 6 red and 6 black refills. The black refill is suitable for light surfaces, while the red wax is perfect for dark surfaces. Our carpenter mechanical pencil makes sure that you'll have an ample supply for extended use
- Built-in Sharpener: Our construction pencil comes with a built-in sharpener to ensure the mechanical pencil tip is always sharp and ready for use. Never buy an extra pencil sharpener again. A great tool for any woodworker pencil, contractor pencils. The refill can easily be extended or retracted with a simple click of the pencils mechanical, allowing you to work more efficiently and accurately
- Portable Clip Design: Our deep hole construction pencil features a portable clip design, easy to carry and attach to your pocket or tool box, so that you can keep the carpenter pencils mechanical close at hand, making it a convenient tool to have on the go. Great gifts choice for carpenters
- Stronger Pencil Lead: The black refills are made of lead, sturdy and smooth. The red refills are made of wax, clear and light. These marking pencils are much thicker and stronger than normal pencils during the marking process of construction work, suitable for various surfaces, such as glasses, metal, boards, floors, walls, furniture, etc. The written marks can be easily wiped with a wet paper towel when needed
“Total installed cost” should include the exchanger, valves and fittings, pipe changes, access work, permits, labor, insulation and any required restoration. “Annual bill savings” should use the household-specific calculation above, not the 17,514 Btu/day figure by itself.
| Installed cost | Annual savings | Simple payback |
|---|---|---|
| $2,000 | $200/year | 10 years |
| $2,000 | $400/year | 5 years |
| $4,000 | $200/year | 20 years |
| $4,000 | $400/year | 10 years |
This table is a sensitivity example, not an EcoDrain price list or a prediction. The challenge supplies no installed cost, so it cannot yield a definitive payback period. Financing interest, maintenance, exchanger cleaning, discount rates, future utility prices and replacement timing would make a life-cycle analysis differ from simple payback.
Choosing a configuration before pricing the job
EcoDrain says model selection depends on the drain layout and the water streams connected to it. Confirm the following with a qualified plumber before estimating cost:
| Model or arrangement | Intended fit described by EcoDrain | Critical check |
|---|---|---|
| V1000 | Vertical drain stacks | There must be accessible vertical stack space and code-compliant connections. |
| B1000 | Horizontal main-drain-line applications | Verify that the local jurisdiction recognizes the horizontal installation and that slope and access are adequate. |
| A1000 | Grey-water-only use; shorter for comparable performance | EcoDrain says it is not recommended for mixed-water drain lines. |
The exchanger may be connected to water feeding the heater, the cold side of a shower valve, or both when the plumbing permits. Each arrangement changes the amount of preheated water reaching the shower and the amount reaching the heater, so the connection plan belongs in the savings model.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which household uses are a good match?
Showers are the strongest residential case
Showers provide a relatively long period in which warm drain water and incoming cold water can flow together. Homes with several daily showers, high flow, cold incoming water and an accessible stack generally have more recoverable heat than homes with occasional short showers.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minutePC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Baths, dishwashers and laundry need different expectations
EcoDrain notes that bath water is often filled and only drains after it has cooled. Residential dishwashers and washing machines commonly separate their fill and drain cycles as well. That timing makes them less suitable for the same direct, simultaneous recovery pattern as a shower. A commercial process with synchronized hot discharge and cold-water demand can be a different use case.
Best Value
- Milwaukee Ink all Fine Point Marker, Black, 4 Per Pack
- 4 per pack Features Clog Resistant Marker Tip Writes through Dusty, Wet and Oily Surfaces Durable Marker Tip for Writing on Concrete, OSB and Rough Surfaces
- Clog resistant tip writes on dusty, wet and oily surfaces and is optimized for rough surfaces such as OSB, cinderblock and concrete
- Hard hat clip- attaches for easy access
- Quick dry time with reduced smearing and marking
Manufacturer-described application categories
EcoDrain lists residential showers, multifamily buildings, commercial settings and institutional hot-water uses as application areas. Those categories show where the equipment may be considered; they are not proof that every building in a category will achieve a particular saving.
What independent testing can—and cannot—tell you
EcoDrain’s resource page links an A1000 performance report prepared by the Food Service Technology Center for PG&E. The report covers three commercial high-temperature rack conveyor-dishwasher examples, not residential showers.
| Test example | Estimated annual gas saved | Estimated annual cost saved |
|---|---|---|
| Commercial conveyor dishwasher example 1 | 758 therms/year | $758/year at the report’s $1/therm basis |
| Commercial conveyor dishwasher example 2 | 418 therms/year | $418/year at the report’s $1/therm basis |
| Commercial conveyor dishwasher example 3 | 772 therms/year | $772/year at the report’s $1/therm basis |
The report describes moderate cost-savings potential of $418–$772 per year for that tested commercial context. It says outcomes depend on dishwasher type, use pattern, incoming cold-water temperature, distance to the primary water heater and exchanger inclination. Those figures must not be transferred to a house or treated as a residential payback.
Availability, code and installation checks
EcoDrain’s current FAQ says product sales are on hold. It describes vertical products and custom commercial exchangers as having been available previously, while horizontal A1000/B1000 availability was planned as jurisdictions recognized horizontal solutions. Check current availability directly before designing around a model; do not assume an old catalog or test report means a unit can be ordered today.
- Confirm the exact model and connection arrangement can be supplied in your jurisdiction.
- Ask the plumbing authority or installer about drain-line, venting, cleanout and backflow requirements.
- Verify whether the installation qualifies for a local code pathway, utility incentive or tax treatment; none is established by the challenge figures.
- Get a written quote separating equipment, labor, access work, permits and restoration.
- Request expected outlet temperatures or effectiveness under conditions comparable to your flow and inlet temperature.
A worksheet you can use without overstating the answer
Put the following values in a spreadsheet and keep the units visible:
- Daily gallons = flow rate × minutes per shower × showers per day.
- Useful temperature rise = measured preheated outlet temperature − measured cold-water temperature.
- Daily recovered heat = daily gallons × 8.34 × useful temperature rise.
- Annual recovered heat = daily recovered heat × actual operating days per year.
- Annual avoided purchased energy = annual recovered heat ÷ water-heater efficiency (or the appropriate heat-pump performance measure).
- Annual bill savings = avoided purchased energy × marginal utility rate.
- Payback = installed project cost ÷ annual bill savings.
Run low, expected and high cases for inlet temperature, occupancy, exchanger effectiveness, utility price and installed cost. Present the result as a range when those inputs are uncertain. If annual savings are zero or negative in a case, payback is not achieved in that case; do not force a year value into the spreadsheet.
The practical answer to “what is the EcoDrain payback?”
Using the challenge assumptions, the transparent thermal estimate is about 17,514 Btu per day and 6.39 million Btu per year. That is the starting point, not the answer. A real payback requires a site-specific annual bill-savings estimate and a verified, fully installed price. Because the challenge provides neither installed cost nor household-specific savings, no universal EcoDrain payback period can be stated responsibly. Check current sales status, model fit, local code and the installer’s measured assumptions before treating the calculation as a purchase decision.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
