4 ms·

The problem is the cool water in the pipes. A typical solution is recirculating the water so that it stays hot. (I have a gas tank heater and the faucets far

The problem is the cool water in the pipes. A typical solution is recirculating the water so that it stays hot. (I have a gas tank heater and the faucets far away take a bit to warm up, because of the water in the pipes)

analog31 5y ago
Are recirculating systems safe? Those have to be designed to prevent microbial build-up. I'm thinking of Legionnaire's disease.
- sgc 5y ago
  They are not closed loop, they just push some water from the hot water line back down the cold line, where it will wind up back in the water heater and be used. They are no more prone to disease than you existing system.
- eliaspro 5y ago
  We have a solar (parabolic vacuum pipes) water heater which provides 95% of our annual hot water needs, backed up by gas. The heat is stored in a layered and heavily insulated 300 liter tank. The water delivered to the tap isn't actually from the tank, but it's just fresh water heated instantly and on-demand through a heat exchanger which is part of the storage tank. No need to worry about stale hot water with such a system.
krrrh 5y ago
I had a friend who spent months measuring the power output of all his appliances and lights trying to figure out where half his electricity bill was going. He finally realized it was the hot water recirculator.
- gnicholas 5y ago
  We have an under-sink unit that has hot water ready 24/7. After hooking it up, I noticed it increased our monthly bill by about $15. I bought a used Wemo plug for $10 and set it to only be on for 3 hours in the morning and 3 hours at night. Now we have hot water at any of the times when we actually would want it, and we aren't wasting money/energy to keep hot water on tap 24/7.
  - fy20 5y ago
    You probably only need to run the pump for 1 or 2 minutes every hour. The water in the pipes will stay warm for a while, no need to run it constantly.
  - adrianN 5y ago
    Make sure to set the temperature really high if you don't run it continuously or you risk breeding Legionella.
    - gnicholas 5y ago
      Appreciate that; it's practically boiling.
- throw0101a 5y ago
  > He finally realized it was the hot water recirculator. The problem is using devices that are either timed or (even worse) just runs 24/7. Ideally you'd want one that runs on demand when triggered by a switch: hit the button, it runs for 30-60s while you undress, and then we you turn on (e.g.) the shower the water is already hot. The hot water supply for the shower should be the same as the sink, and so when you go to shave or brush your teeth, that's then already primed as well. Do a search for "Gary Klein", who has written a lot of designing good hot water systems over the years. * https://www.garykleinassociates.com/videos.html https://www.garykleinassociates.com/videos.html

analog31 5y ago

Are recirculating systems safe? Those have to be designed to prevent microbial build-up. I'm thinking of Legionnaire's disease.

sgc 5y ago
They are not closed loop, they just push some water from the hot water line back down the cold line, where it will wind up back in the water heater and be used. They are no more prone to disease than you existing system.
eliaspro 5y ago
We have a solar (parabolic vacuum pipes) water heater which provides 95% of our annual hot water needs, backed up by gas. The heat is stored in a layered and heavily insulated 300 liter tank. The water delivered to the tap isn't actually from the tank, but it's just fresh water heated instantly and on-demand through a heat exchanger which is part of the storage tank. No need to worry about stale hot water with such a system.

krrrh 5y ago

I had a friend who spent months measuring the power output of all his appliances and lights trying to figure out where half his electricity bill was going. He finally realized it was the hot water recirculator.

gnicholas 5y ago
We have an under-sink unit that has hot water ready 24/7. After hooking it up, I noticed it increased our monthly bill by about $15. I bought a used Wemo plug for $10 and set it to only be on for 3 hours in the morning and 3 hours at night. Now we have hot water at any of the times when we actually would want it, and we aren't wasting money/energy to keep hot water on tap 24/7.
- fy20 5y ago
  You probably only need to run the pump for 1 or 2 minutes every hour. The water in the pipes will stay warm for a while, no need to run it constantly.
- adrianN 5y ago
  Make sure to set the temperature really high if you don't run it continuously or you risk breeding Legionella.
  - gnicholas 5y ago
    Appreciate that; it's practically boiling.
throw0101a 5y ago
> He finally realized it was the hot water recirculator. The problem is using devices that are either timed or (even worse) just runs 24/7. Ideally you'd want one that runs on demand when triggered by a switch: hit the button, it runs for 30-60s while you undress, and then we you turn on (e.g.) the shower the water is already hot. The hot water supply for the shower should be the same as the sink, and so when you go to shave or brush your teeth, that's then already primed as well. Do a search for "Gary Klein", who has written a lot of designing good hot water systems over the years. * https://www.garykleinassociates.com/videos.html https://www.garykleinassociates.com/videos.html