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Takes to long to get hot water

We have a 1930's era home which we bought this summer. We've noticed that it takes FOREVER to get hot water to any of the fixtures, even many of the basement fixtures closest to the heater. I hate wasting so much cold water. We have lots of pressure, even on the third floor of the house, and once the hot water comes it is scalding. I'm wondering if this is simply attributable to insulation and plumbing lengths, or if the water heater itself is in any way responsible? I'd like to stop wasting so much water but am not sure where to start. I don't even know which type of contractor this would come under (plumber? insulation? gc?). Any advice would be greatly appreciated.


Re: Takes to long to get hot water

The most likely culprit is exceptionally long pipe runs. Another possibility is oversized pipes. For example, a sink supplied by a 3/4" pipe will take twice as long to get hot water than one supplied by a 1/2" pipe (assuming there are no other fixtures between the water heater and the sink). It is necessary to have larger pipes to a point, to avoid pressure drop when multiple fixtures are in use. If the house has been remodeled, you could have pipes snaking all over the place. In the house I grew up in, the bathroom sink was back-to-back with the water heater on opposite sides of the wall, but the water had to go through twenty or thirty feet of pipe to get there.

The ideal solution is to install a loop system with a recirculating pump to always have hot water near the point of use. While this saves water, it wastes energy due to heat loss (even in well insulated pipes). It's quite possible that the energy costs will outweigh the water costs.

Another solution is to install a special "undersink" recirculation pump. These circulate the cool water from the hot lines back through the cold water lines. A thermostatic valve in the pump stops the flow of water when the hot water reaches it. The disadvantage is that you end up with some lukewarm water in the cold lines.

Since you say the pressure is great, it's unlikely that restricted lines are the problem. Insulation will provide some benefit in that there will be less heat loss while the water is being used, but when the water is sitting in the pipes it WILL cool off eventually; probably within half an hour the water will be cold again.

If the plumbing is galvanized steel, or heaven forbid 70's-era polybutylene, it might be a worthwhile investment to replace the plumbing.

Some more questions:

  • Is the heater gas or electric?
  • What type of plumbing do you have?
  • Is the water heater in heated space or an uninsulated area?
Re: Takes to long to get hot water

Took me a while to get back to a computer, but here is the additional info.

The heater is natural gas-fired. It is located in our poured concrete basement, technically uninsulated. However, it is located directly beside our gas-fired boiler (which I think gives off a good amount of heat now that it is cold enough that we have it running) and I've noticed that the whole basement is unexpectedly warm. I don't know if that is because of the boiler or because of the heat coming from all the water pipes. We don't know what the plumbing is, unfortunately, as all the old stuff is wrapped in what looks to be asbestos wrap (we haven't had the chance to investigate that yet and so are leaving well enough alone). Any exposed or newer piping is copper. We do not believe there is any polybutylene in the house.

I would not be at all surprised if there are overlong pipe runs in the house, as any modifications I've noted seem to be somewhat hodgepodge. I hadn't thought about oversized lines, but that may well be an issue, too. I guess the next step is to chase all the plumbing as best I can and determine line sizes and materials where possible? Is there a good reference for determining appropriate pipe sizes? Also, I wondered if installing a second water heater on an upper floor would be of benefit?


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