Low amperage, lowest cost point of use electric water heater tank for low volume use?

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Melissa2007B

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Hi people,

I'm looking for a low amperage, lowest possible cost point-of-use electric water heater tank for low volume use.

We have a whole house humidifier here, the Aprilaire 360, and I've posted about the stacking problem that it causes, when using it from the water heater itself.

I was thinking in terms of an instant unit, but that costs more and uses more amps and simply isn't needed.

This humidifier may use 10 gallons a DAY, max!

So I'm thinking a small low amperage, low volume tank unit, and as low cost as possible?
 

Jadnashua

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WE went into this previously...just plumb it with cold water and don't worry about it! If you want, you might add a small storage tank that would let the incoming water warm to ambient prior to use to raise the temp maybe as much as 30-40 degrees, depending on where it is and what your incoming water temps are. So, it might run the humidifier a little longer...big deal, it will still raise the humidity.

There are lots of small tank-type WH out there, many just plug into 120vac, so no special wiring required, just cold coming in and hot going out. If it makes you feel better, install one of those. Lots of people get satisfactory results using cold tap water. I don't see why you can't as well.
 

Melissa2007B

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WE went into this previously...just plumb it with cold water and don't worry about it! If you want, you might add a small storage tank that would let the incoming water warm to ambient prior to use to raise the temp maybe as much as 30-40 degrees, depending on where it is and what your incoming water temps are. So, it might run the humidifier a little longer...big deal, it will still raise the humidity.

There are lots of small tank-type WH out there, many just plug into 120vac, so no special wiring required, just cold coming in and hot going out. If it makes you feel better, install one of those. Lots of people get satisfactory results using cold tap water. I don't see why you can't as well.

What state do you live in? Down south? When I lived in Miami originally, the tap water was around 65-75 degrees, I think. If the power was out, I could squeak by with a shower, though I prefer it above 87. But since 1980 I've lived in the Denver area. Our tap water is from snow melt and it can range from 35-45 degrees. NO WAY can I shower in that - I tried it once in the SUMMER and couldn't.

I tried your suggestion back when you made it before and the water was running through that Aprilaire 360 and down the drain, almost full time, and could barely humidify right. AND I think Aprilaire recommends only 140 degree water because that's the magic number for preventing bacteria and fungus in the hot water line. Being it's hot water, it can breed them otherwise.

http://www.treehugger.com/green-food/is-it-safe-to-turn-down-your-water-heater-temperature.html

We discovered, about a year ago, that Jennifer's tub at the far end of the house, was never able to get enough hot water. We never knew why, until I researched it and found out ( was it on this forum? ) about the stops they put in the hot water tub faucets, to prevent kiddies and elderly folks from getting scalded. So I took the faucet apart and adjusted the stops out, and now she gets plenty of hot water. But I found that article too, and it educated me to that.
 

Reach4

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We have a whole house humidifier here, the Aprilaire 360, and I've posted about the stacking problem that it causes, when using it from the water heater itself.
You could replace your 350 with an Aprilaire 500, 550, 600 or 700. Those can be used with cold or hot water. Since delivering hot to your humidifier is causing you problems, it may be worthwhile switching humidifiers. You would have to check the dimensions.

The 700 needs one hole. I have the 500, which is a "bypass" type. That means it uses a connection to both plenums.

There are other good humidifiers that can work with cold water.
 

Dana

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The bacteria issue is real enough, but so is mold/fungus spores.

Humidifiers are a well known source of poor indoor air quality problems. They are a "solution-problem".

Low indoor air humidity in winter is a symptom of high ventilation &/or infiltration rates. The better solution is to get serious about air-sealing the house, and ventilating at a more moderate rate. Most homes that meet the IRC 2015 code-max 3ACH/50 (3 air exchanges per hour @ 50 pascals pressure) experience winter dry-air problems only at substantial ventilation rates.

Many hot-air furnaces are set up to pull in a fixed amount of ventilation air whenever the air handler is running. When the heat load is high (cold outside), the ventilation rate goes up, over-drying the indoor air. Adjusting the ventilation intake for much lower ventilation in winter can solve a lot of dry-air issues in reasonably tight houses.

Keeping the indoor humidity TOO high in winter with a dehumidifier results in the exterior walls adsorbing large enough amounts of moisture over a winter to support mold, which delivers much higher indoor-air mold spore counts in the spring. In the extreme it can cause rot issues inside the walls. Keeping it under 40% RH @ 70F indoors is a must for wood-framed wood sheathing buildings in climates as cool a Denver, under 35% is even better. The dew point of 40%RH 70F air is about 45F, which means when the sheathing is 45F or colder (which is most of the winter in Denver) there is a vapor pressure drive from the interior of the house into the wall assemblies. At 30% RH @ 70F (the low end of the still-comfortable & healthy range for humans) it backs off to a dew point of 37F, a temperature only slighly above the January mean temperature for Denver, and thus a much healthier-safer humidity for the house.

daily_high_and_low_temperature_temperature_f.png


^^^Weatherspark.com's temperature normals for Denver^^^

Bottom line, if you can, lose the humidifier- it's not your friend, and if you use it, take care to keep the house under 40%RH.
 

Melissa2007B

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You could replace your 350 with an Aprilaire 500, 550, 600 or 700. Those can be used with cold or hot water. Since delivering hot to your humidifier is causing you problems, it may be worthwhile switching humidifiers. You would have to check the dimensions.

The 700 needs one hole. I have the 500, which is a "bypass" type. That means it uses a connection to both plenums.

There are other good humidifiers that can work with cold water.

We need a through-the-wall one, like the 360, because we used the humidifier all year, not just in the heating season, and you cant use it in cold ducts. ( our AC uses the heating ducts )

I don't know of any other through-the-wall whole house humidifiers on the marker, yet alone ones that use cold water, and it goes right back to the same problems mentioned above.
 

Reach4

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We need a through-the-wall one, like the 360, because we used the humidifier all year, not just in the heating season, and you cant use it in cold ducts. ( our AC uses the heating ducts )
My mistake. I had looked it up, but I did not properly comprehend.

How about a hot water recirculation system that is used to give instant hot water for a bathroom typically? That would eliminated the sandwich I would think.
 

Melissa2007B

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The bacteria issue is real enough, but so is mold/fungus spores.

Humidifiers are a well known source of poor indoor air quality problems. They are a "solution-problem".

Low indoor air humidity in winter is a symptom of high ventilation &/or infiltration rates. The better solution is to get serious about air-sealing the house, and ventilating at a more moderate rate. Most homes that meet the IRC 2015 code-max 3ACH/50 (3 air exchanges per hour @ 50 pascals pressure) experience winter dry-air problems only at substantial ventilation rates.

Not here. Denver is a semi-arid ( semi-desert ) climate. We've actually had the house so well sealed that they advise against sealing it more ( gotta have some fresh air ). We had an energy evaluation with an IR camera. They sealed and insulated the crawl space walls, sealed the crawl space vents, and sealed the entire main floor as much as they dared, they said. Our energy bills went down by about 1/3 after that.

Many hot-air furnaces are set up to pull in a fixed amount of ventilation air whenever the air handler is running. When the heat load is high (cold outside), the ventilation rate goes up, over-drying the indoor air. Adjusting the ventilation intake for much lower ventilation in winter can solve a lot of dry-air issues in reasonably tight houses.

Haven't heard of that. We have gas forced air heating, and I think it just ventilates the flame so it gets enough oxygen to burn.

Keeping the indoor humidity TOO high in winter with a dehumidifier results in the exterior walls adsorbing large enough amounts of moisture over a winter to support mold, which delivers much higher indoor-air mold spore counts in the spring. In the extreme it can cause rot issues inside the walls. Keeping it under 40% RH @ 70F indoors is a must for wood-framed wood sheathing buildings in climates as cool a Denver, under 35% is even better.

We don't like static, and it kills electronics. So we've found that the ideal humidity is about 47% and it prevents static. We never keep the heat over 65 in winter - 60 at night ( good sleepin'!) and we like the AC set no higher than 68 in the summer, because otherwise we have problems sleeping. We're cool weather folks. :)

The dew point of 40%RH 70F air is about 45F, which means when the sheathing is 45F or colder (which is most of the winter in Denver) there is a vapor pressure drive from the interior of the house into the wall assemblies. At 30% RH @ 70F (the low end of the still-comfortable & healthy range for humans) it backs off to a dew point of 37F, a temperature only slighly above the January mean temperature for Denver, and thus a much healthier-safer humidity for the house.

daily_high_and_low_temperature_temperature_f.png


^^^Weatherspark.com's temperature normals for Denver^^^

Bottom line, if you can, lose the humidifier- it's not your friend, and if you use it, take care to keep the house under 40%RH.

Jeez, without the humidifier, it plays havoc on our sinuses and skin. Cracked fingers, dried sinuses and infections. Have to think about that. And computers and other electronics are trashed by static.
 

Melissa2007B

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My mistake. I had looked it up, but I did not properly comprehend.

How about a hot water recirculation system that is used to give instant hot water for a bathroom typically? That would eliminated the sandwich I would think.

Checked it out long ago. Costs too much. And we have pex plumbing and have been told that it radiates heat, so it would lose an enormous amount of energy.
 

Jadnashua

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FWIW, PEX vs copper for radiation...copper will win hands down - much higher than pex. If it's an issue, insulation works equally as well with either.
 

Reach4

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Consider a small point-of-use or "Single Point Hand Washing" water heater. How about something like these: https://www.lowes.com/pd/AquaPower-...of-Use-Tankless-Electric-Water-Heater/4744353
http://www.homedepot.com/p/Bosch-2-5-gal-Electric-Point-of-Use-Water-Heater-ES-2-5/206428467


If you choose tankless, make sure the flow is enough to turn on the WH. http://www.aptankless.com/tech-data-aqm.html says it takes 0.21 GPM to activate. It is internally restricted to 0.32 GPM. That may reduce the flow of water to your pad, but I expect that would work OK for humidifier operation.
 
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Melissa2007B

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Consider a small point-of-use or "Single Point Hand Washing" water heater. How about something like these: https://www.lowes.com/pd/AquaPower-...of-Use-Tankless-Electric-Water-Heater/4744353
http://www.homedepot.com/p/Bosch-2-5-gal-Electric-Point-of-Use-Water-Heater-ES-2-5/206428467


If you choose tankless, make sure the flow is enough to turn on the WH. http://www.aptankless.com/tech-data-aqm.html says it takes 0.21 GPM to activate. It is internally restricted to 0.32 GPM. That may reduce the flow of water to your pad, but I expect that would work OK for humidifier operation.

The reason I was thinking of a small low amperage tank unit was because of the high current draw and expense of the "instant tankless" types. Tankless "instant" is considered "oh so cool" for bathrooms, showers etc, but seems like overkill for this ( especially what they cost for that feature ).

I don't know what's on the market, but was thinking of something that would only draw a few amps, could be set to 140 degrees and just provide that tiny amount that the Aprilaire needs, without taking it from the gas water heater.
 

Reach4

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The reason I was thinking of a small low amperage tank unit was because of the high current draw and expense of the "instant tankless" types. Tankless "instant" is considered "oh so cool" for bathrooms, showers etc, but seems like overkill for this ( especially what they cost for that feature ).
I show $159 for that first link. For that, and whatever WH you found, I think you should have a dedicated power circuit.
I don't know what's on the market, but was thinking of something that would only draw a few amps, could be set to 140 degrees and just provide that tiny amount that the Aprilaire needs, without taking it from the gas water heater.
I really don't understand that sandwich thing for a gas tank type WH.
 

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Not here. Denver is a semi-arid ( semi-desert ) climate. We've actually had the house so well sealed that they advise against sealing it more ( gotta have some fresh air ). We had an energy evaluation with an IR camera. They sealed and insulated the crawl space walls, sealed the crawl space vents, and sealed the entire main floor as much as they dared, they said. Our energy bills went down by about 1/3 after that.

That's actually bad advice. Random air leaks are not a great source of fresh air, since there is no way to guarantee the cleanliness of the path it takes, or where the ventilation is actually needed. Current code max air leakage of 3ACH/50 almost always requires mechanical ventilation, and with known paths and quantities it doesn't have to be anywhere near ASHRAE 62.2 ventilation rate 24/7 to have superb quality air. Keeping the house as leaky as it is saved the up front cost of mechanical ventilation systems, but imposes the cost of humidification & controls.

There are numerous existence proofs in the Front Range of tight houses with mechanical ventilation that don't need humidification systems to stay above 30% RH in winter.

Haven't heard of that. We have gas forced air heating, and I think it just ventilates the flame so it gets enough oxygen to burn,

We don't like static, and it kills electronics. So we've found that the ideal humidity is about 47% and it prevents static. We never keep the heat over 65 in winter - 60 at night ( good sleepin'!) and we like the AC set no higher than 68 in the summer, because otherwise we have problems sleeping. We're cool weather folks. :)

The ventilation intake on hot air furnaces is often in the form of make-up air duct to the outdoors tied into the system's return air ducting, usually 5-10' before the tie-in to the furnace. It may or may not have a vane/valve on it for adjusting it. Sometimes it's more sophisticated than that. That is to be distiguished from the ducted combustion air intakes on direct-vented sealed combustion condensing furnaces. Yours may or may not have any connection between the return ducts and the outdoors to worry about.

Even 30% RH is enough to prevent static- how are you measuring the RH?

A body of air that is 47%RH @ 65F has a dew point of 44F, about the same as air that is 40% RH @ 70F. That's at the very high end of where you want to be in terms of keeping the springtime mold-spore counts indoors under control. If you knocked it back to 40% RH@ 65F you'd have a dew point of 40F, which is quite a bit better for the house, based on your wintertime outdoor temperature averages.

Jeez, without the humidifier, it plays havoc on our sinuses and skin. Cracked fingers, dried sinuses and infections. Have to think about that. And computers and other electronics are trashed by static.

Again, air that dry is a symptom of over-ventilation.

All too often unbalanced or poorly implemented duct system designs, or leaking ducts create room-to-room and room-to-outdoors pressure differences, that drives air infiltration (the "great outdoors" is part of the pressure equalizing path in a leaky house), with air leakage an order of magnitude or more higher than what the calculated natural air exchange rates would be based on the blower door numbers.

Does every room with a supply register have an associated return located where it isn't restricted by a door? Every supply duct needs an appropriately sized return path to avoid excessive pressure differentials.

Are the ducts all inside conditioned space (rather than above the insulation in an attic)? Leaks in ducts that are outside the pressure boundary of the house create super-high air-handler driven air infiltration.

Are all duct joints & seams sealed with duct mastic?

Are all register boots caulked to the subfloor or ceiling/wall gypsum, to guarantee that all of the air is going to/coming from where it was designed to be, rather than through wall/ceiling/floor assemblies?

Are the air handler seams all taped with foil tape?

What were the actual ACH/50 numbers (or cfm/50) numbers when they did the blower door test?
 

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I show $159 for that first link. For that, and whatever WH you found, I think you should have a dedicated power circuit.

I really don't understand that sandwich thing for a gas tank type WH.

It was explained to me in this forum years ago. They called it "stacking effect" or just stacking.

The humidifier draws a tiny amount of hot water from the top of the water heater. This draws in the super cold water from our snow melt, at the bottom. The burner turns on. This keeps happening, and soon, water that was set to 140 starts coming out at 185, and it shortens the life of the water heater too. We had black stuff coming out in the hot water, until I turned it down enough to compensate for the stacking. We lost a water heater about 5 years ago, that was new when the house was built in 2005.
 

Jadnashua

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Normally, convection prevents severe water stacking, but if the conditions are just right, you can get significant layering effects. There have been reported cases of people being scalded when going swimming because of the stacking effect...the water can get extremely hot outdoors. Doesn't happen often. It's easier to do with variations in salinity because of their differences in density, but it can happen in purer water, too. That effect has been used to store thermal energy.

In mine, I just use the shutoff valve to throttle the inlet water to just over the amount that can get evaporated going across the pad, and I leave the (multi-speed) fan on constantly to provide some airflow and just let the humidistat cycle on/off to maintain my desired humidity level. It doesn't actually run all that often. If my fan was a normal, one or tw0-speed fan, the power consumption would be extreme, but it's actually a 16-speed, and when left on, will normally barely be running and does not draw much power. It helps to keep the temperatures more even, and, because it runs the air through the filter more often than it would just cycling on during a call for heat (or cooling), the filter is more effective.

While I've lived in areas where the humidity levels in the summer are often quite low, most of the places had evaporative coolers, so that added all of the humidity that you could want, and then some!

It seems that most of those small point-of-use WH that plug into a 120vac circuit draw about 1400-1500W, so would require a dedicated 15A or greater circuit. Often, the 120vac and 240vac elements can be the same size...if you were able to find a unit designed for 240vac and only plugged it into a 120vac circuit or swapped a 120vac element for a 240vac one, you'd halve the power, but double the recovery time (which would probably be fine for your application). That MIGHT allow it to share a circuit, if that circuit was not already heavily loaded.
 
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Reach4

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It was explained to me in this forum years ago. They called it "stacking effect" or just stacking.

The humidifier draws a tiny amount of hot water from the top of the water heater. This draws in the super cold water from our snow melt, at the bottom. The burner turns on. This keeps happening, and soon, water that was set to 140 starts coming out at 185, and it shortens the life of the water heater too. We had black stuff coming out in the hot water, until I turned it down enough to compensate for the stacking. We lost a water heater about 5 years ago, that was new when the house was built in 2005.
Have you just been leaving the humidifier off since you got the new WH? I wonder if the new WH might not have the same symptom. A lot of people have humidifiers hooked to the hot water and have not noticed such effects.

And the black... is that your own well? Do you get a "sulfur" smell?
It could have been from the lining on braided flex connectors. The corrugated copper or stainless steel would not have that potential problem.
 
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Cacher_Chick

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If you really want to go through with the experiment, it would not be too hard to plumb an instant hot water dispenser to your humidifier. If 160F water is ok, it would work fine, but if you have hard water, none of the point of use heaters are going to do well for very long.
 

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While I've lived in areas where the humidity levels in the summer are often quite low, most of the places had evaporative coolers, so that added all of the humidity that you could want, and then some!

Somehow I don't think sane people in Denver are running swamp coolers in January/February. :)

The notion that Denver's wintertime air is dramatically drier than in NY/NE region or somehow has different physics isn't well founded. If you're more than 100 miles from the maritime influence of the coast it's actually pretty comparable. This is Denver's dew point averages over the year, per Weatherspark's data sets:

dew_point_temperature_f.png

^^^Denver^^^

This is Albany NY's dew point averages:

dew_point_temperature_f.png

^^^Albany^^^

You can see that in summer Albany is quite a bit more humid than Denver, but the mid-winter outdoor air humidity is VERY much the same, average in the mid-teens F for outdoor dew point temperature.

What's true in upstate NY is true in CO: If you tighten up the house sufficiently and control the ventilation rates rather than letting random air leakage or air-handler driven pressure differentials drive infiltration stratospheric it is not difficult to maintain comfortable & healthy indoor humidity levels.

It's common in high performance homes in the northeastern region operate heat recovery ventilation systems under de-humidistat control in winter to keep the humidity from going too HIGH. In summer when the dew points go north of 55F it represents a latent cooling load- humidity that has to be removed to keep it in the 50% range or lower, and the ventilation systems then have to run on a duty cycle rather than humidity control, particularly when there isn't much of a sensible cooling load and the AC isn't running a very often.
 
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