heat loss cost saving ...?

Question

using an insulation to the copper pipe with hot water inside i save X watts..
how much would this count in cost (US $)??
is there a way to know..

i want to check if i've saved money by installing this insulator..

Answer 1

The first method would be to compare you utility bills to see if there is a drastic change (or any) between last year at this time and the most recent bill with the insulation on.

For an exact calculation, you need the following:

The R value of the insulation
Length of pipe insulated
Temperature of the water inside the pipe

Then plug them into this equation:

Q=UA(Tinside - Toutside)
where Q is the amout of Btus
U is the thermal insulation (or lack there of) expressed as =1/R
Tinside = water temperature
Toutside = air temperature (average) where the pipe is installed
A = the surface area of the pipe

Once you get that for the insulation, do it once with out the insulation. For the second R value without the insulation, use a R-value of 0.5. The two different Q's you get will be the amount of Btu's you saved.

To convert that to $, you need to convert the Btu's (Q) to kW. Divide the Btu's by 3.412 to get watts. That will be the amount watts you saved at your hot water heater/boiler or whatever is heating the water (assuming it is electric). You then look at your electric bill to determine the cost $/W or $/kWh. Take the number you got for watts and convert to kilo Watts by dividing by 1000. Then multiply it by the cost off of you utility bill for $/kWh.

This is all for a one hour period. You need to calculate that for a month, day, or year (720, 24, 8765 hours respectively). You now have what your savings for this project was.

Answer 2

You'd have to know how much X watts cost you which is a function of the efficiency of your water heater, the cost of the energy supply to fuel the heater. You'd also need to figure out the temperature outside the pipe and the amount of heat lost.

In reality, when you're taking a shower, water is running constantly from the water heater to the shower head and you really don't care if it drops a few degrees. You only pay to heat the water in the heater and not the pipe. When you turn off the shower, the only heat that's lost is what's left in the pipe. I doubt that's it's worth the trouble and cost. I have seen cold water pipes with insulation but that's only to stop the condensation (sweating) that can happen in hot humid weather.