Lowest cost way to circulate water within water heater tank?

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Jadnashua

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Mine is probably 15+ years old, but is similar to the model 500. It is an AprilAire unit. It works just fine on the cold supply. You might end up using slightly more water if you use cold, but I think the major reason to use warm water is that it might not cool the exhaust stream quite as much. The extra heat from the hot water supplied does not really make that much difference on how much evaporates, but helps a little by not cooling the air from the evaporation process as much. Just like sweating cools you, evaporating the water from the pad will cool the air. How much is evaporated is MUCH more dependent on how hot the air is and its relative humidity level than the inlet water temperature. I've not had any issues. Rather than having issues with stratification in the WH, and then going to the expense and hassle of adding a pump and control circuits, I'd just swap it to cold. BTW, it calls for a MAXIMUM of 140-degree water, not that it must be that hot. Most WH are not set that high. I look at it this way...the thing doesn't usually run all that long, and doesn't use a lot of volume. The water in the pipes will have a chance to warm up to the ambient air temperature, and depending on where you run it from, it might actually be hot based on what it is running next to, so running dedicated hot water to it is IMHO, a waste. Now, I've not tried both ways, but mine does run successfully and keeps the humidity where I want it while feeding it cold and not impacting the hot air output. My supply line does run part way against the outlet ducting, so probably absorbs some heat from it, but I doubt it is truly hot from the cold supply. If it ran constantly and never reached the desired humidity levels, I'd reconsider, but it works fine as installed. Your results may differ. If the supplied water was near boiling, or was a steam based system, it would be a different story since the on-board heater may not be big enough to raise the temp from what could be near freezing, but an evaporative, bypass system, I don't see it. Cold water evaporates, too, and the hot air moving through has a great affinity for absorbing it. Just walk outside with one hand wet and one dry in the winter, see which one gets colder. That happens because one is evaporating. It's also pulling heat from your hand, but the outlet of the furnace is hot enough so you'd probably never notice.
 

Melissa2007B

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Depends on where we live, I suppose. In Miami, the water temp is in the 60's ( they don't need this anyway ) but here in Denver, the water is from snow melt and can be 40 degrees. You could waste a LOT of water that way. By the way, we even put a regulator on the output to the humidifier originally, so I'm not even sure how hot we were originally making it.

I'm just concerned that the black water may have been bad for us to shower with.
 

Jadnashua

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I live in NH where I've measured my incoming cold water at 33-degrees after a cold snap. No problems.

A bypass humidifier (I think, the type you have), runs hot air through the wet screen back into the return duct. The fact that it might cool off that air a little bit more when using cold verses hot is mostly irrelevant. The evaporation rate is more a function of the air movement than the water temperature. It's not like you're boiling it, which some humidifiers do.
 

Melissa2007B

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I live in NH where I've measured my incoming cold water at 33-degrees after a cold snap. No problems.

A bypass humidifier (I think, the type you have), runs hot air through the wet screen back into the return duct. The fact that it might cool off that air a little bit more when using cold verses hot is mostly irrelevant. The evaporation rate is more a function of the air movement than the water temperature. It's not like you're boiling it, which some humidifiers do.

No, ours is just mounted in the wall and takes air from the laundry room and blows it through the humidifier and out into the back living room.
 

Jadnashua

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Is that an approved installation? That type is generally installed on the outlet duct, with the bypass going into the return duct. As currently installed, it's acting more like an evaporative cooler, which does add moisture into the air, but is primarily designed as a cooler.
 

Jadnashua

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Mine is an older version of this one

https://www.aprilaire.com/whole-house-products/whole-house-products/humidifier/model-400

By using warm water with yours, the outgoing air will be warmer and not create as much of a cool breeze, so from a comfort level, hot water is required. From an actual performance issue, it would work with cold water coming in. Rather than adding pumps, controls, etc., I'd probably just install one similar to what I have then the problem goes away. Lots cheaper, too, at least if you can install it yourself.
 
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Melissa2007B

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Your is the in-duct type though, and only works when the heating is on. We use ours in the summer too, when it gets too dry, and the heat/AC needn't be on at the time, to use it. In fact an in-duct type would make a mess if it was on during the AC.
 

Jadnashua

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There are millions of humidifiers out there that do not use hot water.
 

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Why not turn the hot water heater down so the water temperature is around 120 degrees? It may solve the overheating problem and whether it does or not it will not cost anything to try.
 

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Alternatively, if you installed a tempering valve on the hot water line feeding the fixtures in the home, but had the humidifier connection upstream of the tempering valve, you could leave the water heater turned up without any issues.

A house that is properly insulated and air sealed will have plenty of humidity produced by cooking, showering, and other common happenings within a home. Ideal indoor humidity is 40%, and scales lower as the outside temperature drops.
I have an Aprilaire Humidifier, and I never turn it on because the house never falls below 35% humidity except during long periods of extreme cold outdoor temperature.
 

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Why not turn the hot water heater down so the water temperature is around 120 degrees? It may solve the overheating problem and whether it does or not it will not cost anything to try.

I did, last week. No more black water, but the shower at the far end of the house takes forever to get hot water and it's not that hot.
 

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Alternatively, if you installed a tempering valve on the hot water line feeding the fixtures in the home, but had the humidifier connection upstream of the tempering valve, you could leave the water heater turned up without any issues.

Not sure what you mean but it doesn't sound right.

A house that is properly insulated and air sealed will have plenty of humidity produced by cooking, showering, and other common happenings within a home. Ideal indoor humidity is 40%, and scales lower as the outside temperature drops.
I have an Aprilaire Humidifier, and I never turn it on because the house never falls below 35% humidity except during long periods of extreme cold outdoor temperature.

The house is as well insulated as it can be, for our low income. We had an energy company seal it and it's good. But you apparently don't know Colorado. As someone said to me years ago, you have to shower for the first 5 minutes to get your skin wet. :)
 

Jadnashua

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Rather than pumping things in the tank to eliminate the rather uncommon stratification you seem to be having...plus the fact you have a problem getting hot water to your far-away shower, a hot water recirculation system would solve both problems. Lots of companies make them. That would give you nearly instant hot water at your shower. Where I live, you are required to have a tempering valve on the outlet of your water heater to prevent the outlet from exceeding a safe temp...generally, that is considered to be 120-degrees, but the tank itself could be set higher. That would prevent super heated water from getting into your supply lines because of the operation of that valve.

Look at the humidifier supply this way...millions of stand-alone ones out there with an on-board water tank that work fine. Some are big enough to deal with a whole house. The fact yours is mounted through the wall is somewhat irrelevant with its own water supply so you don't have to refill the jug. Those do not have hot water feeding them, and they work fine. If you had room for a small tank, you could feed that in-line with the humidifier so, with the low volume needed by the humidifier, it would warm up to room temperature, and only use cold water to it. Then, you'd be exactly in the same situation as all of those other humidifiers out there with a jug to supply the water, except on yours, you wouldn't need to refill it.
 

Melissa2007B

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Rather than pumping things in the tank to eliminate the rather uncommon stratification you seem to be having...plus the fact you have a problem getting hot water to your far-away shower, a hot water recirculation system would solve both problems. Lots of companies make them. That would give you nearly instant hot water at your shower.

We had an energy company come back over last week, to see if the house is still sealed OK. One of the bedrooms seems colder. And I asked him about those. He said that EVEN of we insulated the hot water lines ( not practical because there's insulation and plastic sheeting up under the house - it's a UBC modular on a foundation and came that way ), it would use enormous amounts of energy, keeping that hot water circulating. He said that PEX is an especially good radiator and bad insulator.

Where I live, you are required to have a tempering valve on the outlet of your water heater to prevent the outlet from exceeding a safe temp...generally, that is considered to be 120-degrees, but the tank itself could be set higher. That would prevent super heated water from getting into your supply lines because of the operation of that valve.

Oh I see. Like the mixing valve that we use to feed the humidifier.

Look at the humidifier supply this way...millions of stand-alone ones out there with an on-board water tank that work fine. Some are big enough to deal with a whole house. The fact yours is mounted through the wall is somewhat irrelevant with its own water supply so you don't have to refill the jug. Those do not have hot water feeding them, and they work fine. If you had room for a small tank, you could feed that in-line with the humidifier so, with the low volume needed by the humidifier, it would warm up to room temperature, and only use cold water to it. Then, you'd be exactly in the same situation as all of those other humidifiers out there with a jug to supply the water, except on yours, you wouldn't need to refill it.

But you need to realize how the Aprilaire one works. It runs water over a pad and what doesn't evaporate goes down a drain next to the washing machine. So if the water is good and hot, maybe 95% of it evaporates. If it's cooler, more goes down the drain instead. That's why Aprilaire specifies it up to 140.

With those other humidifiers, like the table top type, the water sits in them and builds up junk that has to be cleaned all the time. With the Aprilaire, the flow keeps that from happening.
 

Jadnashua

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My furnace, by-pass unit works exactly the same way...water goes in the top, flows through the pad, and any that doesn't evaporate, goes down the drain. It works fine with cold water coming in. Having some left over is a benefit, as the minerals get concentrated as the water evaporates. It can help to be able to throttle the inlet volume to minimize any wastage.

FWIW, PEX radiates lots less heat than copper piping! It's not a big expense to crawl underneath and insulate as much of the piping as you can. It will help. There are lots of ways to activate hot water recirculation systems: manually before you need it, from a motion sensor when you enter say the bathroom, via a push-button, on a timer so it only runs when typically needed, or continuously. One study showed that using one on a timer so it was only running while typically using hot water, actually saved money when you added up the costs of the wasted cold water down the drain waiting, the cost of waste water (sewerage costs), not counting the convenience of having hot water when you want it without significant waits.
 
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Melissa2007B

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FWIW, PEX radiates lots less heat than copper piping! It's not a big expense to crawl underneath and insulate as much of the piping as you can. It will help.

Like I mentioned though, the house is a UBC modular on a foundation ( 4' crawl space ), and there's insulation under the floor, with plastic sheeting covering it. We're concerned that if we break into that, it could cost us energy.

There are lots of ways to activate hot water recirculation systems: manually before you need it, from a motion sensor when you enter say the bathroom, via a push-button, on a timer so it only runs when typically needed, or continuously. One study showed that using one on a timer so it was only running while typically using hot water, actually saved money when you added up the costs of the wasted cold water down the drain waiting, the cost of waste water (sewerage costs), not counting the convenience of having hot water when you want it without significant waits.

That's interesting.

Well I think closed cell foam is a pretty good insulator, though the energy guy told me it wasn't, and that puzzles me.
 
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