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  1. #101
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    A friend and former mag clued me in that mine probably has a thermocouple. Still Greek to me but I'll start there..

    https://en.m.wikipedia.org/wiki/Thermocouple

  2. #102
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    Does your WH have a pilot light--if so the thermocouple can generate enough electricity to operate it. I guess some do, although neither of the ones I'm famiiiar with do. This is how a lot of furnaces used to work and tank water heaters still work. Apparently some tankless have a little generator that makes electricity when you open the faucet and water starts flowing through it. News to me. Mine still doesn't work with the power off.

  3. #103
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    Yup pilot light. I've never looked into how water heaters worked because the one time I had to replace one it was because the tank rusted out, not because the burner stopped working. Guess I will see if I can replace my thermocouple to get another year out of it. Might be out of here soon would be silly to spend a bunch on a new heater.

  4. #104
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    Quote Originally Posted by Rideski View Post
    Yup pilot light. I've never looked into how water heaters worked because the one time I had to replace one it was because the tank rusted out, not because the burner stopped working. Guess I will see if I can replace my thermocouple to get another year out of it. Might be out of here soon would be silly to spend a bunch on a new heater.
    I missed the pilot light in your first post. Sorry.
    As I understand it the thermocouple is supposed to sense if the pilot light goes out and shut off the flow of gas. I would have thought that if a bad thermocouple wasn't sensing heat the gas to the pilot light would have shut off. But I've already proven I don't know shit about water heaters. Just for giggles, have you tried turning off the gas and then relighting the pilot? I mean, rebooting works for computers. Why not for water heaters.

  5. #105
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    No worries. I was going to try a reset of some sort.
    Working way too much and I've just been showering at the gf's for a couple days.
    Bad timing but I'll have some time soon.
    I watched some vids of ripping a thermocouple out if a traditional WH. Didn't look easy, but not harder than a car radiator.

  6. #106
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    Quote Originally Posted by Rideski View Post
    No worries. I was going to try a reset of some sort.
    Working way too much and I've just been showering at the gf's for a couple days.
    Bad timing but I'll have some time soon.
    I watched some vids of ripping a thermocouple out if a traditional WH. Didn't look easy, but not harder than a car radiator.
    What's so bad about showering at the GF's? With the GF of course. (We added a bathroom and a shower with two heads. But way too late in life.)

  7. #107
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    How about this? Heat pump water heaters. Seems the math works out pretty darn well:
    https://cleantechnica.com/2022/04/08...-panels-costs-

    Sent from my Pixel 3 using TGR Forums mobile app

  8. #108
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    Quote Originally Posted by old goat View Post
    What's so bad about showering at the GF's? With the GF of course. )
    sounds ok as long as your wife doesnt mind
    Lee Lau - xxx-er is the laziest Asian canuck I know

  9. #109
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    Quote Originally Posted by Rideski View Post
    No worries. I was going to try a reset of some sort.
    Working way too much and I've just been showering at the gf's for a couple days.
    Bad timing but I'll have some time soon.
    I watched some vids of ripping a thermocouple out if a traditional WH. Didn't look easy, but not harder than a car radiator.
    I'm late to this thread, and didn't read all the previous posts. My WH just shit the bed, I pulled the burner assembly out and buffed the carbon scoring off of the thermocouple and it's good as new. Skip the sand paper and go straight to the dremel. Then make sure you reset the tiny invisible little fuse that is (probably) coming off of the power supply from the controller to the tank. This is a slightly temporary fix, as the thermocoupler will gather carbon scoring faster now that it's been cleaned, but it can get you up and running until you can grab a new burner assembly. I'd replace the whole thing, not just the thermocoupler. Generally you can buy them as one unit.

  10. #110
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    Thanks, that is rather encouraging since this is an older discontinued model and I wasn't sure I would be able to buy a new thermocouple even though they are cheap and seems to fit a variety of machines.
    Didn't get up there to look at it yet, working my guts out.

  11. #111
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    Jan 2005
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    I’m launching a kickstarter for a crypto mining server integrated with a tankless water heater. Teenage daughters + long showers = profit.
    Know of a pair of Fischer Ranger 107Ti 189s (new or used) for sale? PM me.

  12. #112
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    Anyone replace 2 water heaters with one tankless? I have two 50gal gas tanks that are 22 years old. Working fine but probably just a matter of time before I end up with a shitshow in my basement. One is on a recirculation system, the other one is not. My hunch is that the labor cost alone here will make it not worth it, but curious if anyone has gone down this road.

  13. #113
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    We replaced 2 50 gallon electric tank heaters with one gas tankless. This is in a house that gets a lot of overnight company, especially in ski season. 2 or 3 people can take showers at the same time and people can take showers one after another after another without running out of hot water. It's a 199K BTU unit, with very cold intake water temp, and showerheads are 2gpm. We set the temp at 130 so we can mix in a fair amount of cold--I've never thought seriously about that; it probably makes no difference what temp you set as far as the number of showers and appliances that can work at once.

  14. #114
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    Quote Originally Posted by old goat View Post
    We replaced 2 50 gallon electric tank heaters with one gas tankless. This is in a house that gets a lot of overnight company, especially in ski season. 2 or 3 people can take showers at the same time and people can take showers one after another after another without running out of hot water. It's a 199K BTU unit, with very cold intake water temp, and showerheads are 2gpm. We set the temp at 130 so we can mix in a fair amount of cold--I've never thought seriously about that; it probably makes no difference what temp you set as far as the number of showers and appliances that can work at once.
    Thanks! How many years would you say to break even?

  15. #115
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    Quote Originally Posted by ColMan View Post
    Thanks! How many years would you say to break even?
    More than I have left.
    I have to admit I haven't done the math--comparing the electric bill before the switch with the gas bill after. And there are so many variables--weather, occupancy, the new tank being farther from the kitchen I'm not sure a comparison in an individual case would be meaningful. I go back to what my architect friend said--about the energy savings being small. We were going to have to replace the two 50 gal electrics soon anyway so the total cost of installing two electrics vs one tankless might have been similar--which would make the tankless more cost effective than if we were comparing to replacing with one tank water heater.

  16. #116
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    Quote Originally Posted by old goat View Post
    We set the temp at 130 so we can mix in a fair amount of cold--I've never thought seriously about that; it probably makes no difference what temp you set as far as the number of showers and appliances that can work at once.
    I had to think about this, but I think you could get better performance from a slightly lower output temp if the limiting factor is total watts to the heater. It should run slightly more efficiently (i.e. more total heat transfer to the water at max power) if the hot water has a little higher flow rate (aka a little lower final temp). But there's a limit where pressure drop through the heater takes over as the limiting factor, too, so maybe not.

    I had a thermodynamics professor who was adamant about this but explained his position purely based on change in entropy. Suffice to say he reached the same conclusion but didn't really convince me until I was today old. I'd lay out his reasoning, but I kinda doubt anyone else cares, either. RIP, Dr. M.

  17. #117
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    So…I just figured something out with our Rennai tankless. We did a whole bunch of work on our cistern etc. which messed with the temp at the faucet, so I turned the temperature up, and it actually resulted in colder water because to get it hotter it constricts the flow.
    Since we had low flow anyway it kind of screwed things up. I reduced the temperature from 140 to 125 and we actually have hotter showers now.
    Well maybe I'm the faggot America
    I'm not a part of a redneck agenda

  18. #118
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    Quote Originally Posted by jono View Post
    I had to think about this, but I think you could get better performance from a slightly lower output temp if the limiting factor is total watts to the heater. It should run slightly more efficiently (i.e. more total heat transfer to the water at max power) if the hot water has a little higher flow rate (aka a little lower final temp). But there's a limit where pressure drop through the heater takes over as the limiting factor, too, so maybe not.

    I had a thermodynamics professor who was adamant about this but explained his position purely based on change in entropy. Suffice to say he reached the same conclusion but didn't really convince me until I was today old. I'd lay out his reasoning, but I kinda doubt anyone else cares, either. RIP, Dr. M.
    So Dr. M. has reached a state of entropy.
    I took thermodynamics. Physical chemistry lite. A couple of my friends had their prospective medical careers torpedoed by P Chem, but then who wants a doctor without the common sense to not take P chem. I don't feel like not taking P chem hurt me in any way--my showers are hot, my jacuzzi is right at the sweet spot, and the water from my bidet toilet seat soothes and relaxes without burning. What more can a man ask for?

  19. #119
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    Lower utility bills?

    I feel like Dr M would argue for that. We had a different name for him, though. Now I'm wondering if our name for him was in any way related to the giant chip on his shoulder about P chem? (It was definitely about the chip, I just don't know if Pchem had anything to do with it.) He would have stamped his feet a few times over that--like everything else, really.

  20. #120
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    One of the highlights of my college career was watching a friend of mine who had flunked pchem sic his german shepherd on the prof as he biked across campus. The dog didn't bite him or knock him off the bike, just barked as the prof tried to kick it away until my friend called the dog off

  21. #121
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    Quote Originally Posted by old goat View Post
    One of the highlights of my college career was watching a friend of mine who had flunked pchem sic his german shepherd on the prof as he biked across campus. The dog didn't bite him or knock him off the bike, just barked as the prof tried to kick it away until my friend called the dog off
    That's beautiful. I knew a lot of people that would envy it, but I don't think any of us ever got such an opportunity. I recall a water balloon launcher, a well-placed racquetball and verbal rebellion--once with actual effect, even. But the dog sounds altogether better.

  22. #122
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    Quote Originally Posted by old goat View Post
    So Dr. M. has reached a state of entropy.
    I took thermodynamics. Physical chemistry lite. A couple of my friends had their prospective medical careers torpedoed by P Chem, but then who wants a doctor without the common sense to not take P chem. I don't feel like not taking P chem hurt me in any way--my showers are hot, my jacuzzi is right at the sweet spot, and the water from my bidet toilet seat soothes and relaxes without burning. What more can a man ask for?
    I love P Chem.

    My favorite nerd class.

  23. #123
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    The math of tankless water heaters

    H psi = E psi.

    Had to take one fill year of P chem in college. That is all I remember from those classes. Never used P chem once so far in my 25 year career as a chem E.
    Last edited by Sluff; 06-25-2022 at 12:52 PM.

  24. #124
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    Quote Originally Posted by Sluff View Post
    H psi = E psi.

    Had to take one fill year of P chem in college. That is all I remember from those classes. Never used P chem once so far in my 25 year career as a chem E.
    How about at home, when discussing how to set the thermostat with your wife? Does it help you win the argument? (I think not.)

  25. #125
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    Nov 2005
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    Definitely not. That's what EMEC is for.

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