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| House hot water upgrade; endless *really hot* water! | |
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| Tweet Topic Started: Dec 2 2010, 04:18 PM (965 Views) | |
| Stately | Dec 2 2010, 04:18 PM Post #1 |
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Geo cheerleader
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Somewhat accidentally, I discovered a hot water configuration that works really well. I share it with and bore my local buddies, so thought I'd do the same for you guys: We've got a large, old, run-down house that had been used many years for boarding college students--named "Stately" because it's on State Street and probably used to be stately a long time ago. It's hot water was set up as a weird parallel 2-tank gas fired system. It worked ok, but not well. Then one tank went out (and the other was already on borrowed time). So, instead of just replacing the dead tank with another, I installed a tankless on-demand heater (think it was around $500 on sale). Results were underwhelming as it was factory set to 122F--pretty much lukewarm. Not good for baths, dishes, or laundry. They sell thermostats for these units to allow you to raise the water temp, but cost over $200! That's as much as a standard water heater would run you. And I already had the 2nd heater running and plumbed. So . . . Just put them in series with the on-demand pre-heating the water going into the standard heater set at the desired higher temp. Has worked like a charm--never run out of hot. Four morning baths within an hour, multiple washer warm/hot loads, and dishwasher (before it broke!)--no problem! And without the shock of cold water entering the standard heater, it's still working 15 years after the warrantee expired. A friend copied this scheme when he saw how well it worked. He had a hot tub installed and couldn't get enough hot water into it initially--no problem now! Know you all like the pix: Here's the funky old piping I ripped out--weird! ![]() On-demand unit, faceplate off: ![]() New piping--just flip 3 shutoffs to take either unit offline: ![]() Whole setup:
Edited by Stately, Dec 2 2010, 06:31 PM.
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| Car Nut | Dec 2 2010, 09:26 PM Post #2 |
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I have an electric tankless. No gas run out here. Rats. Run mine opposite of yours. I'm on a well so water is real cold coming in. Heat it in big tank to about 80-90 degrees & plumbed to tankless unit from there. That's all they use in Russia and other countries. Gas tankless jobs. No big hot water tank like us. |
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| Stately | Dec 2 2010, 10:47 PM Post #3 |
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Geo cheerleader
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Sucks not having gas! Been there before. A few reasons to put tankless first: - temperature max isn't high enough at factory setting - when flow increases past spec (which is pretty low), temperature goes down even more--even if the max temp were bumped up - it's designed to rapidly heat flowing water--therefore greater temperature differential is advantageous--tanks are designed to take time to heat The tank is like putting a battery in a trickle circuit--you want to place it as close to the load as possible. |
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| CityConnection | Dec 3 2010, 02:30 AM Post #4 |
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Sir, yes sir!
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You are not the first person with this idea... I just haven't got a tankless unit yet! lol Good to know it works in practice. The theory seemed pretty sound to me. Actually since I have a south facing house/roof/front yard I'm going to try my hand at a solar batch water heater that will be heat water then send it into the regular electric (ugh) tank water heater. Same idea in a way. I expect to reduce the cycle time of my tank heater by about 80%. That water heater is the biggest user of power at my house. It takes 4.5KW per element... and it's got 2 of them! After that I'm going to try a similar system for space heating (minus the electric water heater, of course). |
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| Stately | Dec 3 2010, 12:33 PM Post #5 |
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Geo cheerleader
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Yep, not really innovative--the idea of pre-heating water going into the tank goes back ages. Just wanted people to know it does work, really well. Did this install winter '04 and has been working untouched since. We get strong windstorms somewhat frequently (had two just last month), and subsequent power failures. The gas tank works w/o power, the tankless is electric controlled so does nothing w/o power, but lets water through unobstructed. So we still have (some) hot water when power's out. Would like to do solar pre-heat, but probably not worth it this far north. Plus, if the money were there I'd fix/replace our dishwasher that broke 2 years ago first. What I like best about the configuration is how quickly it can be reconfigured (3 ball shutoffs) into 1) tank only, 2) tankless only, or 3) both in series. |
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| Spock | Dec 5 2010, 09:49 AM Post #6 |
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Live Long and Prosper.
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A lot of folks down here in Florida use solar heating for their hot water. Works pretty well if you are 2 miles from the sun like we are. Believe it or not, it does get chilly here in the winter (40-60 degrees) which is cold enough to make a total solar hot water system a little bit useless. I took a shower in January at a friends house that has it installed. Not pleasant. |
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| bogs | Dec 5 2010, 12:58 PM Post #7 |
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Duct tape heals all wounds
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I envy your not pleasant showering conditions in 40-60 degree weather being described as chilly sitting here in new england (where it has yet to crack 35f today and the wind is howling)
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| Stately | Dec 5 2010, 01:44 PM Post #8 |
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Geo cheerleader
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All-in-all, I'd *much* rather it be too cold than too hot. Inside house hovers at 60 this time of year. That's fine, BUT *must* have hot water! |
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| superduty5.9 | Dec 5 2010, 03:06 PM Post #9 |
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Metro Defender
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I wanted to do a similar setup but solar. There is several youtube videos about this using all free or cheap parts. Even in Ohio on a sunny day in the winter it works great. It's just like anything else, time is a factor! |
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| Stately | Dec 6 2010, 03:13 AM Post #10 |
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Geo cheerleader
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Pre-heating by any means is where the gains are found. The standing hot water in the tank is actually pretty efficient these days--fiberglass lined tanks don't leak a lot of heat. And in my case it's in the basement, so any lost heat just heads upstairs to living quarters. Tanks in unheated garages can have additional fiberglass wrappers around the outside to further prevent heat leakage. |
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