Instant Hot Water

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mcp6453 wrote:

I have had the Watts system, purchased from Costco, for about a year and am pleased with it. It saves me time and water by not having to run cold water doen the drain while waiting for hot water. By setting the timer to run only when I need it, the additional energy usage is trivial. The only drawback is some water hammer because of the sensor valve between the hot and cold lines.
The Watts system places the recirculating pump at the water heater and the sensor valve at the fixture at the end of the line. Other brands combine the pump and the sensor valve. One deciding factor is at which location an electrical outlet is available.
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Complex and innefficient. Best way to have "instant" hot water is to have a small water heater at the point of use which supplies hot water immediately on demand, untill the cold water has come through the pipes. You get HOT water right away, then the temperature drops a little bit if you use more than the capacity of the small heater as the cold bollus comes through, then back to hot.
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snipped-for-privacy@snyder.on.ca wrote:

Except the small heater will inevitably be electric, which cost significantly more to run than gas. Pumping a little cold water back to the heater costs next to nothing, and saves water over running the water.
Plus, the extra heater is one more to fail/replace regularly.
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mcp6453 wrote:

Another energy wasting idea from the fuel companies.
What you need is a small 6 gallon point of use tank under the sink. Gives you instant hot water and uses little energy. If you use enough hot water the hot water from the main tank reheats the point of use tank so it doesn't even need to heat the water.
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Van Chocstraw wrote:

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Van Chocstraw wrote:

Which introduces a big waste of energy all the time. The push button pump system wastes none. It only warms the pipes when you are going to use the hot water anyway.
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wrote:

Have you ever checked to see how much power is required to keep a well insulated 5 gallon water heater hot?????? Likely about as much as to run a circulating pump. And it's a lot easier to retrofit to an existing house. You can also put a SWITCH on it, or a TIMER so you only have hot water in reserve when you are likely to want it.
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snipped-for-privacy@snyder.on.ca wrote:

I seriously doubt that. A pump using less than an amp, running for 20 seconds a couple time a day will use very little power, compared to ANY tank water heater.
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wrote:

But most of the systems are NOT push-button on-demand circulators. And the non-push-button-on-demand systems not only draw constant power running the circulating pump, they also lose heat from the entire circulation loop constantly, meaning the water heater needs to run more.
They are definitely a convenience, but they most certainly are NOT an energy saver.
The push button type? Yes. But the complexity of the required plumbing for a retrofit is significant. The aditional small volume heater is a simple install, and NOT a huge energy waste. - and CAN be set up to run on a timer so you have hot water at , say, bath time.
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    Yes it works. There are several different ways of doing it. However how much if any energy that might be saved is questionable.
    I have seen versions that constently circulate the water and some that only circulate it when called on (meaning it still takes a little time).
    I have not bothered. I do have an instant hot water supply in my kitchen however. Convenient.
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I think pumping the tepid water into the cold water supply line means you won't have cold water, assuming the pump is in working order.
I like keeping the cold and hot water supply lines separate. When I was remodeling the bathroom, and had easy access to the lines, I added a return line from the far end of the hot water supply line back to the water heater, forming a supply loop. I put a check valve in the return line so when flow is high, the return line is disabled. I insulated the original supply line, and left the return line uninsulated. Through the magic of gravity (more reliable than a pump, and cheaper) there is a constant flow of hot water through the loop, so when we crack the faucet, we get instant hot water. There is no cost for electricity, and no pump to break. I do use a little more gas for the heater, as there is a heat loss from the return line, but that is welcome heat into the house during the cold months.
Installation is not hard if you can get access to the supply lines and a space for the return line. Operating costs are low, and the system will run until congress repeals the law of gravity.
mcp6453 wrote:

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mcp6453 wrote:

I think putting hot water into the cold pipe is not good. Just think, you get up at 3AM and want a drink of water. You get warm water or you then must run the cold to purge out the warm. I would prefer a real loop.
In my new house, everything seems to be connected with 3/4" PEX. The faucets are all lower flow than I'm used to. But, they have made up for the flow with better aerators. Anyway, my kitchen sink it right above the water heater (in the basement). Low flow, coupled with larger pipes and a kitchen faucet that has a pull out hose end, makes for a long wait for hot water. Also, the bathrooms take forever. Unfortunately, they are at opposite ends from the water heater. I was thinking of gravity loops, but I know they don't always work well. I might need 2 pumps to accomplish this ... or one, with some flow adjustments.
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I keep looking at the subject line and remembering the spoof ad for Instant Hot Water: Just add water and heat.
--
Christopher A. Young
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