1

I have a storage water heater in the bathroom which feeds several taps around the flat. The rather long (indoors) runs of pipe to these taps are exposed and not insulated (other than being painted). This lets the water in those pipes them cools down over time, making it necessary to let the tap run for 1-2 minutes to get hot water.

I'd now like to add insulation to these winding some form of tape or sleeve.

What tape would be recommended for this? PTFE, PU?

Our what kind of sleeves? Rubber, PU?

As the pipes are currently painted, would that have a positive or negative impact? Would there be risk of unwanted condensation forming under the insulation? Should I scrape the paint off, or just leave it be?

Improve this question

2 Answers 2

Reset to default
1

As you mention that the pipes are currently painted, I assume that means that they are in full view. If that is the case, consider that for insulation to be effective, it needs to have a certain thickness. The insulation will add about 2 inches to your pipe diameter.

You can best insulate your pipes with sleeves that are sold for the purpose of pipe insulation.

The paint on the pipes has neither a positive nor a negative impact on the insulation. As the pipes are typically hotter than the surrounding air and never significantly colder, there is no risk of condensation. If there was any risk, you would have seen it already on the non-insulated pipes. (This is a big difference between insulating pipes and insulating a house. The common knowledge for one does not automatically apply to the other.)

Improve this answer
0

Condensation forms on pipes, or surfaces, that are below the dew point temperature.

So a cold pipe compared to atmosphere will get condensation forming on it, same as you breathing on a cold mirror - does condensation form on a cold mirror when having a shower...

As for insulation, it will help reduce the RATE of heat loss but the hot water will eventually cool down especially when stationary. Remember a thermos keeps the content hot or cold but they Rach ambient eventually.

Two possible solutions:

  1. make the hot water pipe a loop back to the tank with a small pump to circulate the water - done often in big buildings to reduce the waste from waiting for hot.

  2. add an electrical tape heating element to keep the pipe and water hot - make sure the insulation is rated for the contact temperature.

Both require the insulation.

Improve this answer
5
  • But I don't see how dew point is a concern here. These are interior pipes. At worst, the OP can simply wrap whatever pipe is accessible with foam pipe insulation (example: homedepot.com/p/…).
    – Huesmann
    Commented Jun 1 at 13:32
  • @Huesmann the cold water pipe feeding the toilet cistern in my parents house drips condensation because the water coming in from outside is cold. A good example of the dew point re condensation... If not check a psychrometric chart.
    – Solar Mike
    Commented Jun 1 at 13:50
  • But we're talking about hot water pipes here. The only way those pipes would have cold water in them is if the tank runs out of hot water entirely.
    – Huesmann
    Commented Jun 2 at 12:34
  • @Huesmann so I explained how condensation tends to form - do you think the Op has misunderstood the situation and hot water pipes won't get condensation?
    – Solar Mike
    Commented Jun 2 at 13:00
  • 1
    Unless his tank is severely undersized, no, I don't think hot water pipes will get condensation. Lacking undersizing, the pipes will never be lower than ambient (interior) temperature. However, a simple test can be done by wrapping toilet paper around the pipes at various locations. Wait a year, come back to see if there's any telltale marks of condensation on the TP.
    – Huesmann
    Commented Jun 3 at 12:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.