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Comment by zeristor | Hacker News Reader

The plumber recommended not using hot water from the boiler, since it takes so long for the hot water to start coming through it wasn’t worth it.

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I have a hot water recirculator for this. The price I pay is that instead of waiting for hot water at the kitchen sink I've to wait for cold water, as the hot water is recirculated through the cold water pipes.

I have seen a return loop on the hot side, but not returning through the cold side. Do you have more info on this? (I do wonder if recirculating hot through a pipe next to a cold pipe would result in heating the cold)

The thing consists of a) a pump that goes on the output of the water heater, and b) wax-based valves that go between the hot and the cold under each sink where you want hot water without having to wait a long time. The valves turn on when the water on the hot side cools, and they close when it gets hot. The pump stops when the valves and hot faucets are all closed, and it has a timer for scheduling hours of operation. I believe it's this:

  https://aurorixs.shop/product/watts-500800-instant-water-recirculating-pump-system-with-built-in-timer

So you’re always pumping hot water through your pipes? Does that not end up wasting quite a bit of energy? I guess in winter it’s not a big problem since you’re heating your house anyway, but presumably in summer it is just adding unwanted heat?

In the winter, as you note, it's not much of a waste, and it helps keep the pipes from freezing.

In the summer... this is central Texas, so the sun helps keep the water in the pipes hot, so I imagine that the pump is on less often than in the winter. I've not checked though. My gas bills are not out of the ordinary, so I think it's not a ridiculous waste.

4 day old post but these can have timers so they only run for one time window such as when you wake up.

That sounds like a great way to get Legionnaire's, unless I'm missing something.

actually its quite the opposite. because the hot water is constantly recirculating its hard for the bacteria to grow. Kind of like why they say never drink from stagnant water but water that is flowing is safer (not neccessarily safe to be clear)

I think all apartment buildings have recirculators so somehow it works.

I've been doing it for 15 years. No legionella here.

I have to ask, showers?

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