Tankless water heater

Poppy

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This past week my daughter, her kids, and I stayed with friends while we trekked to the World of Disney.
When we took showers, the temperature of the water fluctuated between scorching HOT to ground water temp cold, and back to scorching HOT, and back to cold. Strange. According to a google search, this is a known issue, sometimes with tankless water heaters.

My initial thought was to lower the temperature, so that as the unit fluctuated, there would not be an extreme difference in temps, which would make the fluctuations more tolerable. Troubleshooting guides suggested that there may be scaling contamination of one of the temperature thermistors, and cleaning of it may be the solution. The homeowner, and his Dad, tried flushing the system with vinegar to no avail.

They apparently store diagnostic codes within their electronic controller, and there is a method of pulling them. One of which is slow flow rate. I wanted someone to read instructions of how to pull codes while I attempted to do so, but was anxious to get started, and did so without a helper. When I opened the cover to the unit, the temperature setting controller fell out. It was set at 140F. I read that 140F is good for commercial settings, and kitchen sinks, but 120F is good for showers. I lowered the setting to 108F, which was too low, I set it at 115F, and it was just right.

Later that morning the Lady of the House came out of the shower with actual "tears of joy" in her eyes. The problem was solved. They had been living with that issue since they bought the house four years ago, thinking they would have to pay to replace the whole system.
 

bykfixer

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I have a friend who installs climate control systems and fixes plumbing. When he remodeled his house I asked if he was going mini-split and tankless. He said "no and no". He said fixing those things are making him rich.
 

KITROBASKIN

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Great job!
Suggest they maintain a regular schedule of mineral buildup reduction within the entire system. Don't some people install back flush valves to expedite that process?

Heat pumps are here to stay, for air cooling especially and we will see how heat pump water heaters will fare; pretty expensive now.

Thinking fixer's friend is dealing with older heat pumps. What I am reading on diysolarforum is, if installed correctly, high reliability and energy savings.

Being able to have point of use also lowers cost because extensive ductwork can cause significant inefficiencies that we always just accepted in the days of burning 'ancient life' fuel.

Not only are there the benefits of not having to cool the entire house when only bedrooms need it at night then everyone leaves for work in the morning, also redundancy can help when something fails, or grid power fails and reduced loads are needed.

Oops, this thread is about tankless water heaters. I avoid tankless because our water is hard and try to avoid systems that require that kind of regular maintenance.

By the way, there are clever people that use solar panels to cool their houses with heat pumps (some do not even have any batteries for that system), letting it rip during sunshine, then come home to a very cool environment, lessening those peak load electricity rate hikes.
 
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turbodog

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You get the old 'hot water sandwich' or 'cold water sandwich' at times. It's easier than you think to exceed their capabilities.

Gas piping & meters have to be increased usually. If electric (yes, they make whole house electric) you need some SERIOUS equipment on the supply side. Last one I used was 160A @ 240V, or more power than 2-3 houses condensed into one box on the wall.

And they don't store emergency drinking water like a tank unit does.
 

PhotonWrangler

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Later that morning the Lady of the House came out of the shower with actual "tears of joy" in her eyes. The problem was solved. They had been living with that issue since they bought the house four years ago, thinking they would have to pay to replace the whole system.
Congratulations! Nice job on saving them a huge repair bill.

It's interesting that a tankless system can oscillate like that, swinging between two extremes because it reaches the hot end of the extreme too quickly (or too far). It's acting like a closed-loop servo system where the gain is too high, causing it to continuously overshoot in each direction as it tries to find it's center point.
 
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TPA

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Tankless definitely isn't for hard water areas...like Florida. We have one in a construction trailer I sometimes work out of and Florida-temperature water + tankless heater = major burns if you're not quick enough to pull your hand away.

At my temporary condo, we have a Rheem heat pump water heater in the garage. Hot water + cooling the garage for free. Awesome so far. Never have run out of hot water with it, even with laundry and multiple showers going.
 

Poppy

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Tankless definitely isn't for hard water areas...like Florida. We have one in a construction trailer I sometimes work out of and Florida-temperature water + tankless heater = major burns if you're not quick enough to pull your hand away.
May I suggest that you get one of your construction plumbers adjust the temp setting on the tankless water heater? Get your safety man on it.
 

Got Lumens?

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I just recently read about CO2 heat pump systems that have been taking prevelances in the european countries over other refrigerants like R134 variations.
They are totally cool! They incorporate and use a hot water storage tank to provide your hot water, your heating, and cooling needs. Pretty cool, but cost >2X of current heat pumps installations. They also work down to -20 fahrenheit to provide heat unlike the +20 degree working temperatures of current heat pumps.
 

TPA

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My only issue with heat pumps, especially modern ones, is reliability. At least in the USA, there aren't options for quality residential / light commercial units, no matter how much you are willing to spend. They're all garbage. All of this talk of efficiency and environmentally-friendly goes out the window when you have to toss the whole system after 5-10 years.

I have a friend who Frankenstein'd his central HVAC. It's a homebrew water:water chiller, using reclaimed water on the hot side, and a chilled water loop inside the house going to fan-coil units around the house. Water flow is reversible if need be. Extremely quiet and efficient. I've been saying something like this is the future for some time.
 

RWT1405

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As usual, I'll be the outcast here.

I put a tankless water heater in my (then fiancées) house, when we were doing construction to add on a new Master suite, in 2018.

Her then current water heater was on its last leg, so I decided to go the tankless route, as we would have 3 full bathrooms after completion.

Multiple showers/baths a day (we have 5 living here), and my stepdaughters' "hours long" showers (or so it seems, LOL) and ALWAYS hot water available.

Every year I have it "flushed/cleaned" and can tell you that in the 5 years we have had it, not a single problem or regret.

Who knows what the future will bring, but so far, I am a fan and highly recommend them.
 

TPA

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What's the water like up in PA? It's absolutely terrible in Florida. Lime and calcium beyond belief here. and with the hurricane, tons of debris in the lines. I just had to clean the filters on our toilets because they were completely plugged with small bits of gravel and mud.
 

Galane

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I've often wondered why nobody takes a swamp cooler and modifies it with an air to air heat exchanger so the super moistened air isn't blown into the building?

Take a couple of Uchida 8.5" or Fiskars 6.5" paper crimpers, make a new frame to mount two of the roller pairs side by side on common shafts, run some very heavy gauge aluminum foil or very thin aluminum sheet metal through to make a bunch of air channel sheets. Stack up alternating crossed directions with flat sheets between to make a cross flow heat exchanger. The channels will be small so a lot of sheets would be needed. Compress the stack enough so there's no cross-leaking of air.

Blow the super damp air from the swamp cooler through one way so it goes back outside. Circulate interior air through the other way to transfer heat to the damp air via the aluminum.

Definitely need a way to catch condensation and dump it outside.

I'd prefer to use the Fiskars crimper since at least one of its rollers is metal. Both rollers on the Uchida are plastic. Fiskars makes a wavy crimper (more channel length in the same width) but both of its rollers are plastic.
 

TPA

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I've often wondered why nobody takes a swamp cooler and modifies it with an air to air heat exchanger so the super moistened air isn't blown into the building?

I live in a swamp and have my whole life, so my knowledge is very limited... but in my neck of the woods swamp coolers don't do anything meaningful. When the dewpoint's 80F at midnight, you're not going to be getting any appreciable cooling from that setup. More importantly, in my climate (Florida), dehumidifiers make more of an improvement of comfort than an aircon.
 

Poppy

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An air conditioner will also dehumidify. The trick is not to have one that is oversized, but rather sized correctly. It was explained to me that a properly sized unit will run more continually, than not. This way it will dehumidify and cool. If it is too largely sized, it will cool the room too quickly, that it doesn't have time to dehumidify it, and instead you'll have cool dampness.

A dehumidifier, will add heat into the room as it works, so there's that.
 

TPA

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Poppy, I'll disagree with you on that. I always oversize the condensing units in Florida. My condo came with a 2-ton system in it. I replaced it with a 3-ton condensing unit, 2-ton air handler. Indoor humidity always was ~41-45% with this setup. I do a few more modifications to my Florida systems than just that, but that's the first step.

78F/43%RH actually feels quite pleasant and uses less electricity to achieve than the typical 72F-75F most people here use.

When I go to hotels, I do carry a small space heater... aka. poor man's dehumidifier. Reheat is how you address humidity in hospitals and other large facilities. It works just as well scaled down too.
 

Poppy

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@TPA
I guess we'll have to agree to disagree on the definition of dehumidify. My definition would be that a dehumidifier actually removes water from the air.
Your's apparently defines it as reducing the relative humidity, by increasing the temperature, so that the warmer air has a greater capacity to hold more water.

My position is that a properly sized AC unit can reduce the humidity to 43% at 72F. Personally I'd be more comfortable at 72F than 78F. My daughter would prefer 70F or even 69F.

Of course with varying outside temps and varying humidity, one AC unit can not be perfect for all scenarios. For example when it is 74F with 99% humidity, my central AC will not run long enough to remove enough water, before it shuts off at the thermostat setting of 72F. It will leave the house cool and damp/ clammy. So on those odd days, I may run the heat and the AC at the same time. Energy Efficient? NO. But I pay the bills around here, and I want to be comfortable. Just label me spoiled.
 

Poppy

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I always oversize the condensing units in Florida. My condo came with a 2-ton system in it. I replaced it with a 3-ton condensing unit, 2-ton air handler. Indoor humidity always was ~41-45% with this setup
When my friend installed 2 AC units in my home office, he installed larger condensing units than what the evaporators called for. He said that with the larger condensers the system would run more efficiently. I suppose that would be true in Florida where the average temps are higher than in NJ. Or maybe he explained that the newer more efficient systems (at the time 1986) used larger condensers (heat exchanges) and smaller compressors.
 
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