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Domestic Water Heater Question
#21
Well-done

You should size it for the total GPM / temp rise it would be called to produce if all fixtures were in use. Is that overkill? maybe and as you said it may never happen but it *could* happen. They'll be that time you need more hot water with no way to get it. If cost is an issue, demand heater, gas line upgrade (which you may have to do figuring both systems running at the same time) it might be worth it to just stick with a tank system. You could use a timer to keep it off at night. I have a timer on mine but previous home owner removed the pins. I'm sure I could order them since the timer is a common intermatic but just haven't gotten one of these yet:

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#22
One little glitch that can and often does happen with demand water heaters is what they call a 'cold water sandwich'. That's when you have previously used hot water and then quit for a while and then returned for some more. The water will run hot for a while from residual in the pipes and then go cold until the heater kicks on then go hot again. The combustion air fan is required to run a certain number of seconds to clear the chamber of any possible gas fumes prior to energizing the ignition and then the gas valve, hence the delay of hot water delivery.

Dude
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#23
(02-22-2016, 10:22 PM)AlanE Wrote: You should size it for the total GPM / temp rise it would be called to produce if all fixtures were in use. Is that overkill? maybe and as you said it may never happen but it *could* happen.

Right. I'm thinking that if that turns out to be the case, I'll add a third tankless unit, as I can easily split the kitchen from the bathroom. I could even add a fourth for the laundry room, but I think THAT would be overkill. Wink

The water coming in to the house is not very cold as I live in a very moderate climate. In the summer time it's possible to grab a quick shower and never turn on the hot water, as it gets heated just running through the pipes in the attic. But that is a really quick shower for a very over-heated person who's been outside sweating. The last thing you want in that situation is a hot shower.

Quote:If cost is an issue, demand heater, gas line upgrade (which you may have to do figuring both systems running at the same time) it might be worth it to just stick with a tank system.

That's what I said 8 years ago when I replaced the last tank. Hopefully the gas line is adequate. It's a 1" line coming into the house, but then quickly reduces to 3/4" at the first branch. The heaters I'm installing have 1/2" inlets. I'll run a 3/4" inch line to the next one, just in case I ever have to upgrade to a larger heater.

Quote:You could use a timer to keep it off at night. I have a timer on mine but previous home owner removed the pins. I'm sure I could order them since the timer is a common intermatic but just haven't gotten one of these yet:

I do have a timer and it's set to come on only at times when we're home. I had to install a relay because once the pump got a few years old it started burning out the digital timers I was using. It has an on-board analog timer but it can't be programmed differently for different days.

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#24
4? Tim would be proud.

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Using FlashAir W-03 SD card in machine. Access through wifi with FlashPAP or Sleep Master utilities.

I wanted to learn Binary so I enrolled in Binary 101. I seemed to have missed the first four courses. Big Grinnie

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#25
We've been living with gas-fired tankless water heaters for over a year now. One is at the south end of the house feeding the guest bath, and the other is at the north end feeding the master bath, kitchen, and laundry room. We added an electric tankless heater to the laundry room about a year ago because it was so far from the water heater that there was never any hot water delivered to our new washing machine.

The cold water sandwich at the sinks and showers is something I hoped I could adapt to, but after a year of trying I finally gave up and installed a small 2.5 gallon electric heater downstream of the gas tankless heater that feeds the kitchen and master bath. It makes washing the dishes, taking a shower, and the use of the bathroom sink upon waking in the morning much easier. The cold water sandwich means that once I get the hot water running I don't want to turn it off, so I end up wasting a lot of water.
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#26
Constant hot water requires a low volume pump to circulate water through the system, and a backflow valve to keep things moving one direction...there is a small matter of a return line. If you're the impatient type, it avoids multiple heating sources. That is how it is done in most hotels. I favor a Grundfos 2 GPM pump in-line to do the job.
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#27
Hot water circulation systems are great for saving water and for the convenience of not having to wait for hot water. But they do consume a lot of energy. You have to keep the water in the system hot. This is the reason I went with tankless heaters close to the point of usage. The cold water sandwich is inconvenient and wastes water in some cases but not in others. It depends on your use pattern. This is why I went with the small tank heater downstream from one of the three tankless heaters; it wastes a bit of energy and saves a bit of water, but it's far more convenient. It's not needed nearly as much in the other two cases because of their use pattern.
Sleepster
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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