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Is insulating your hot water pipes worth it?

Enter your pipe, your insulation and your energy price. Get the yearly saving, the payback time and a straight answer.

Heatuneed

Is insulating your hot water pipes worth it?

Prepared

Bare pipes leak heat every hour they are hot

An uninsulated hot water pipe in an unheated basement loses roughly 30 to 50 watts per metre, around the clock. This calculator estimates that loss, compares it against the same pipe with insulation, and tells you whether the insulation pays for itself.

Only the currency the figures are shown in changes. The prices stay exactly as you typed them, so set them to what you actually pay.

Start from a typical case

The pipe

m
Total length you would insulate, in metres.
°C
°C
Heat lost inside a heated room is not fully wasted in winter, so the saving is lower.

The insulation

$ / m
Material plus labour. Leave it and we suggest a typical price for the thickness you picked.

Operation & energy

Hours a day the pipe actually holds hot water, not how long you run the tap. Use 24 for a circulation loop whose pump runs continuously, or the hours it runs if it is on a timer. This tool assumes the pipe is kept hot: on a pipe that only warms up when a tap is opened, insulation mainly delays cooling instead of saving energy, so treat any figure here as a best case.
Days a year the circuit is in service: 365 for a domestic hot water loop, roughly 200 to 240 for a heating circuit that only runs in the cold season.
$ / kWh
How many kWh of heat you get per kWh of fuel or electricity bought.

Your inputs

Your result

Updated live as you change the inputs.

Insulate it — this pays back fast

The insulation pays for itself in well under three years, then keeps saving for decades.

Money saved per year —
Payback time —
Energy saved per year —
Insulation cost —
Net saving over 20 years —
CO2 avoided per year —
Surface temperature once insulated —

Heat loss per metre of pipe

Bare —
Insulated —
Heat loss cut by —

What the other thicknesses would do

Same pipe and use; only the insulation changes. In draw-off mode, each row also shows the water temperature at your typical gap and how long it stays above 40 °C.

Thickness Heat loss Saved / year Payback

Estimates based on steady-state cylindrical heat transfer with natural convection and radiation at the surface. Real installations vary with air movement, fittings, valves, supports and insulation quality.

Calculated with the free tool at heatuneed.com/pipe-insulation-calculator/

How the calculation works

The tool models the pipe as a cylinder losing heat by conduction through the insulation, then by convection and radiation from the outer surface.

1

Insulation resistance

The insulation shell resists heat with ln(D_outer / D_pipe) / (2 pi k), where k is the material conductivity. Doubling the thickness does not halve the loss - the returns taper off.

2

Surface film

The outer surface loses heat by natural convection and radiation. The tool solves for the surface temperature iteratively rather than assuming a fixed film coefficient.

3

Annual energy

Heat loss in watts is multiplied by your running hours, then divided by the efficiency or COP of your heat source to get the fuel or electricity you actually buy.

4

Payback

Installed cost divided by yearly money saved. Anything under about three years is an easy decision.

Common questions

A 15 metre uninsulated 22 mm loop at 60 °C in a 12 °C basement loses close to 50 W per metre, which is around 6,000 kWh of heat a year if it runs continuously. A 19 mm sleeve cuts that by roughly 80 percent. The material costs well under 150 and the saving is normally recovered in the first year.

For domestic hot water and heating pipes indoors, 13 to 25 mm covers most cases. Going thicker keeps helping but with diminishing returns, so the standard rule of matching insulation thickness to pipe diameter is a good default.

Less so in winter, because the escaped heat warms the room anyway. It still pays for domestic hot water loops that run all summer, and it keeps the water hotter at the tap.

Yes. An uninsulated valve or flange can lose as much heat as one to two metres of bare pipe, so leaving them out undoes a noticeable part of the saving.

It does, for a different reason: it prevents condensation and slows freezing. Those savings are not energy savings, so this calculator does not model them.

Want the same analysis for a whole room?

Heatuneed scans your rooms with LiDAR and calculates heat loss through walls, windows, doors and roofs the same way this tool handles pipes.

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