Odd timer needed

Are you sure the humidifier is operating correctly and is sized correctly for the house? Assuming the humidistat is operating correctly, if it wants to run the humdifier for long periods of time, maybe the humidifier isn't working as efficiently as it should be. Or, maybe the humidistat isn't working right, and replacing it would help.

You can get a small electric circulator pump that connects to the hot water line and pumps water back to the water heater. This would probably even out the temperature in your water heater, and also give you hot water quicker at the faucet.

Or, you can get small water heaters that are designed to run a single hot water faucet, either tank-type (a few gallons) or instant. Maybe installing one of these to serve just the humidifer would help.

You could use a plain old light timer - the kind that lets you set an on or off for every hour of the day - in the 120 V supply to the humidifier. Set it for 1 hour on, 3 hours off, around the clock. This is easy to do (it doesn't need current sensing), but has the disadvantage that when the humidistat calls for humidity, the timer might be in its "off" cycle for a few more hours.

On the other hand, adding the timer is probably going to make the timer the dominant variable in the equation. If the humidistat calls for humidity for several hours, the timer will prevent the humidifer from ever satisfying the request, unless the humidity in the house goes up for some other reason. So the humidifer will just cycle on and off with the timer.

The timer also has to default to the "on" (contacts closed) state, so it can tell if the humidifier is drawing any current or not. It doesn't start the clock until it sees the humidifier drawing current, but the contacts have to be closed so the humidifier *can* draw current.

I don't know if you can get a timer that does this all on its own. I know you can get current sensing relays that close a set of contacts when they detect current in another wire; Aprilaire even makes one for enabling the humidifier with the furnace blower on furnaces that don't have separate humidifier terminals, and "general purpose" ones are available from Functional Devices

and probably others. Once you have the current-sensing relay, you'd have to add a timer to it, maybe using a time-day relay. Amperite and other vendors make these.

Again - if this is a widespread problem, I think Aprilaire would probably sell it as an add-on box, or as a feature on a high-end humidifer. So maybe adding a timer isn't the way this typically gets solved.

Standard disclaimers apply; I don't get money or other consideration from any companies mentioned.

Matt Roberds

Jane Galt wrote in news:XnsA1207A449750EJaneWhoIsJaneGaltnet@216.196.121.131:

Reasons not to have been covered by Matt Roberds

I have an alternative suggestion for you. The water heater presumably can be (or is) controlled by an external programmer so has a terminal for an electrical control signal, (If not, you need someone experienced to hack its thermostat circuit) so all you need is an auxillary thermostat right at the top of its tank that detects the over-temperature condition and cuts the control signal until it has dropped back to near normal working temperature.

Result: It 'stacks' till its lets say 15 degrees too hot, then stays off till its droppped back to within 5 degrees of your usual setting, and repeats indefinately.

However I suspect that local electrical heating for the humidifier feed would be cheaper to run long-term even if it is significantly more costly to set up.

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Is it really necessary to run hot water to the humidifier? I had a house with forced-air heat, and worked up in stages to a HUGE in-duct humidifier. It ran from the cold water tap, and worked fine. Is yours in the heating ducts or a separate unit that sits on the floor, with a fan, maybe? If in the ducts, the heat from the hot water heater seems totally unnecessary, the hot air will do the job.

Our current house has hydronic heat, which is really NICE, quiet, clean, etc. but doesn't allow you to attach a humidifier, as there are no ducts. I built a frankenstein monster with a pot heated by a heating element, and refilled by a float sensor and a solenoid valve. It works great, but the humidity is not blown around as well without the forced air.

Jon

Probably the most common type of water heater in single-family homes in the US is entirely self-contained, with no external programmer. There is a tank of somewhere between 30 to 60 gallons (110 to 220 liters), and either a gas burner or some electric heating elements. The heater tries to keep the entire volume of the tank at the set temperature.

The gas burner has a standing pilot; a thermocouple in the pilot flame shuts off the gas valve if the pilot goes out. (The gas valve usually has no other source of electricity.) The gas valve also has a thermostat in it, which opens the gas supply to the main burner when the water in the tank gets too cold, and shuts the gas off again when the water is hot enough. The thermostat is usually set by a knob on the side of the gas valve. This kind of water heater will still work even during a power failure.

Electric water heaters have a line (mains) voltage thermostat on the side of the tank that controls the heating elements. It is usually set by removing a cover from the side of the tank and turning a small knob with a screwdriver. Obviously, during a power failure, you are out of luck with one of these.

A variation on the gas heater is a "pilotless" heater, which does need line voltage (mains) to operate; when the thermostat calls for heat, a spark igniter comes on to light the main burner. Some of these also have an electric draft fan to make sure the exhaust gets outside. These save gas and emissions, but don't work during a power failure.

There are other things ("tankless" heaters that do tend to have either local or remote control panels that can be tapped into, combined water and space heating boilers, solar heating, etc), but from the original description, Jane has a tank-type gas water heater.

Matt Roberds

Yes.

No on both those things. We have the Aprilaire 360:

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It uses hot water at 140 degrees and blows it out over a pad. Humidifiers work over periods of time. This one puts out about 1/2 gallon per hour. Putting it out too fast might tend to cause condensing moisture.

Yes, a circulating loop around the house. But that requires adding plumbing and the pump, and this is a UBC modular house that was put on a regular foundation, but it still has plastic and insulation beneath it, so that would cost a LOT in labor.

Would love to, except for above.

More expense we cant afford...

Yeah but that sounds good actually. Let it run for half an hour and then 2 hours later for half an hour.

What it's doing now is running once or twice a day for 2-3 hours.

Yeah. In fact I can even use a plug in one, right at where the humidifier plugs into the AC in the laundry room. I suppose it will have to be an appliance timer, because of the motor, but no problems with that! And I'll get a mechanical one, so it doesn't need backup batteries or anything. It won't matter if the power goes off or daylight savings or any of that, because it simply limits the thing to half an hour of run time several times a day. Thanks Matt! Great suggestion!

I thought it would too, until I looked at the directions (online) for the Watts pump that Home Depot sells. For that one, the pump goes at the water heater. The "return" is provided by a valve that connects between the hot and cold water lines at a sink; apparently it lets water flow from the "hot" side to the "cold" side whenever somebody turns on a cold water tap. The idea is to avoid having to run a pipe back from the furthest faucet to the water heater. I have no idea how well this works in practice; I just know it exists.

Just make sure you let it run "enough". 0.5 hours out of every 2 would be 6 hours total, which matches what it is doing now. Otherwise, you will end up with lower average humidity in the house.

You might also check that the humidifer returns to the previous setting by itself after incoming power is lost. Just unplug it while it is running, wait several minutes, plug it back in, and see if it starts up again. (Mechanical appliance controls have no problem with this; some electronic ones always default to "off" after a power failure.)

Matt Roberds

you just need enough flow to stir the water in the tank, you don't need to circulate the water around the house

perhaps a thermostat set at a higher temperature than the heater thermostat mounted near the top of the tank that turns on a pump to stir the water when it detects the overhot water.

should work, but if the humidifier hs a cycle it should complete before it shuts down, fitting the timer will disrupt that. it it meant to dry the pad out before it shuts down?

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It appears that you can put the loop on a timer for the times you shower, but it could also send scalding water up through the cold line. How would you regulate it?

It's installed for over a week now, and seems to be working very well, thanks!

I actually bought one of the mechanical timers and set it to run for a half hour out of every 2.5 hours. So if the power goes off, it doesn't matter, it just starts up again and runs. There's no absolute time setting needed this way, it doesn't matter where the dial is. :-)

Hadn't thought about that, and thanks! Seems simple enough to just put a tiny pump in to circulate the water from the top of the tank to the bottom, constantly.

I don't know exactly how it works. It could be that the remote valve meters a small enough amount of hot water into the cold side that it doesn't raise the temperature of the cold side that much. The remote valve is supposed to go at the sink that is farthest from the water heater, so some of the "hot" water that it flows into the cold line won't be that hot by the time it gets there.

Right. I was thinking of the timer or control that is already built into the appliance itself (in this case, the humidifier). For instance, if you have an older dishwasher with an electromechanical timer, and the power goes out while it's halfway through the cycle, nothing really bad happens - the timer motor just stops where it is. When the power comes back, everything picks up where it left off - the wash or rinse might not be as effective if the water has cooled off, but it should go on and complete the cycle. A newer dishwasher, with electronic controls, will also stop when the power goes out, but when the power comes back, it may stay in "stop" mode, waiting for somebody to push the button again.

As long as your humidifier just starts back up again when the timer you added switches on, then everything is OK.

Matt Roberds

Yeah, it's great.

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Nice to hear your selected solution works for you. OTOH i expect 1/2 or

1/3 duty cycle will work as well as the present 1/6 duty cycle. You may need to buy some tabs or things though.

?-)