I bought the AirKing rotating drum type humidifier from home depot and installed it on my furnace today, however, something I found it's very stupid by design. I set the % humidity to my desired percentage. However, the humidifier is on even the heat is not on, the drum keeps rotating all the time. It's waste of my electricity.
Is it possible to install a device that detects air flow, then turns it on?? is there such as device? Help... please..
This is Turtle.
Yes there is a switch for this. It is called a Sall switch. It sticks out in the duct and will lift up and turn on anything you want while the air is moving. then when it stops the sall switch will cut it off.
Now you can use a isolation relay to do the same thing. It's nothing to set up.
TURTLE
"TURTLE" wrote
(Turtle meant to say SAIL switch)
There is also a current sensing relay that is wrapped around the common wire of the fan.
I can tell you though: Even if than little 24 volt motor (on the humidifier) ran all day, it would probably use 1 ir 2 cents worth of electricity.....
That's nothing, compared to the huge waste of heating fuel.
Nick
I owned a humidifier with a relay switch as described here, but the problem was that the heater still didn't run long enough at one time to disburse enough humidity to make the humidifier worthwhile. Before engineering a clever on-off system, take some measurements of the average run time of your blower on an average cold day (very difficult to do), and decide if that's enough. At my house, running a hunidifier 30% of the time would be like not having one. Then I got a standlone humidifier in my bedroom where I really needed it, and that's another subject. It works best in a small area, so I have to keep the bedroom and bathroom doors closed.
-B
Newer furnaces (since 1985) have on their circuit control board provisions for humidifiers. But make sure the board humidifier terminals are for the voltage(s) of the drum humidifier. (Some are 115 volt, and most are 24volt controls.) Then the humidifier will only operate when the furnace is on. (Not all furnaces have this feature though.)
Humidifiers actually save fuel. The air temperature 'seems' warmer to humans (creature comfort) if the humidity is high. Thus lower setting on the thermostat. Also, air that is 50% RH can harbor more heat per cubic foot than air that is 30% RH for example.
Zypher repeats itself:
Nonono. Repeating this won't make it so :-) Evaporating the water takes far more energy than the lower thermostat setting saves.
The ASHRAE 55-2004 comfort standard says a 48x48x8' house with R20 walls and ceiling would be equally comfy at 69.4 F and 20% RH or 68 F and 50% RH. If it's very tight, with 0.5 air changes per hour, would humidification to
50% save energy?G = 48'x48'/R20 + 48x4x8/R20 = 192 Btu/h-F, so dropping the room temp from 69.4 to 68 F saves 1.4x192 = 269 Btu/h. At 69.4 F and 20% RH, Pd = 0.2e^(17.863-9621/(460+69.4)) = 0.1466 "Hg, approximately, with wd = 0.62198/(29.921/0.1466-1) = 0.003063. Air at 68 F and 50% RH has wh = 0.007347. With 0.5x48x48x8/60 = 154 cfm of air leakage, humidifying from wd to wh requires evaporating 154x60x0.075(wh-wd) = 2.96 pounds of water per hour, which requires about 1000x2.96 = 2960 Btu/h of energy, so the net "savings" is 2960-269 = -2691 Btu/h, or minus 64.6K Btu/day, costing about $1/day more with oil heat or $2 per day with electric heat.
People tend to forget that evaporating water takes heat energy, even if the "humidifier" uses little energy by itself, and that heat energy has to come from somewhere. And we often get into discussions about health and furniture, vs energy, and forget that caulking (vs humidification) can raise the indoor RH while SAVING vs wasting more heating fuel.
Nick
Nonono :-)
Nick
Hi Nick;
Here's a link for you to read up on [albeit consumer literature but it drives the point well.]
Hi Zypher,
The program in the ASHRAE 55-2004 comfort standard shows 69 F at 35% is equivalent to 69.8 at 19%.
Lennox sells furnaces and humidifiers, and their statement above ignores the heat energy needed to evaporate water, which is far more than the heat energy saved with a lower thermostat setting.
Nick
I just purchased a Honeywell 260A (?) which comes with a sail switch and
30 VA transformer. I didn't want the hassle of cutting another hole in the cold air return for the sail switch and running a 120VAC circuit to the furnace for the transformer. However, I also didn't want to blow the transformer on the furnace (Lennox G12, circa 1990).I finally got through to a tech person at an HVAC dealership and he told me that the transformers on furnaces are usually 40 VA, which is more than the one that comes with the Honeywell.
Make sure you take a voltmeter and check which low-voltage terminals supply 24VAC when the blower is running.
Of course, the humidifier would also run >Newer furnaces (since 1985) have on their circuit control board provisions
Perhaps when Nick leaves egghead academia for the real world, he'll travel and see the real world, instead of reading about it in books. I suggest a trip to Las Vegas when it's 100 and quite comfortable, followed by a trip to Georgia when it's 80 and feel's like hell. Then maybe he will rethink his ideas.
I've installed a few drum type humidifiers, and each have been actuated only when the fan for the furnace is running. Are you sure you installed it correctly? With many furnaces, you can run the fan continuously, in which case the humidifier may run continuously as well. Time to read your manuals.
Dave
It's surprising how little hvac installers know about physics and comfort. You'd think they'd be curious, beyond the everyday nuts and bolts, or feel some sense of responsibility.
We might try this in two steps:
If so, where are your calculations?
Nick
This is Turtle.
I don't have a Boat so I don't know how to sold.
TURTLE
This is Turtle.
How about putting it around the 115 volts going to the Fire Chamber vent fan motor of the gas furnace and would only run in heat mode.
TURTLE
No disagreements? No calculations? :-) Let's try again, from the top:
I suspect that winter humidification wastes vs saves heating energy, and the savings claim is an energy myth. People tend to forget that evaporating water takes heat energy, and that heat energy has to come from somewhere, even if something like a humidifier belt motor uses little energy by itself.
The heat saved by turning a thermostat down appears to be far less than the extra heat used to evaporate water, in all but extremely tight houses, eg submarines.
If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance, turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320 Btu/h.
Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh = 0.00617. Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.
With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275 Btu/h of heat energy.Humid air seems healthier and may prevent furniture cracking and static electricity, but serious air sealing seems like a better solution, with blower door testing. Houses have natural humidity sources. Andersen says an average family of 4 evaporates 2 gallons per day of water by breathing, cleaning, cooking, and so on. Unlike humidification, more air sealing can raise the RH while saving vs wasting heat energy.
Nick
Sure evaporating water wastes energy, but it is a matter of comfort, static electricity, cracked wood etc. Plants and sealing the house can do alot, but for most not enough.
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