Humidifier Troubleshooting

3 years ago

I have a neighbor who is a senior citizen on a limited budget and from time to time I try to help her with projects around her house. Her humidifier (Aprilaire) failed when the fan motor fell off, near as I can tell because the plastic cracked. Her HVAC guy wanted $500 to put in a new one, which may be a fair price because he's a professional with a truck, tools, overhead he's got to pay for.

So I find a new Aprilaire 700M humidifier for $240 delivered. I figure it's no big deal to replace the old one, I've installed them before and I don't even have to cut a hole in the duct. Other than a cramped space, the new one is installed and connected. Fire up the furnace, turn up the humidistat, and nada.

My understanding is that the old one worked before the fan failed but I'm not getting low voltage to the unit as measured by a digital multimeter. I can hear the old (I din't replace it) humidistat (which is located upstairs next to the thermostat) click as I adjust it but no voltage across the terminals there either. Furnace is working properly. So my next steps are:

Because Aprilaire was nice enough to include a 24 VAC transformer in the box, bypass the furnace entirely and supply unit directly. The should confirm that the humidifier is working properly. Assuming it does...
Jump the terminals on the humidistat, bypassing it.

After that, I'm not quite sure where to look. If it makes a difference the furnace is a newer Bryant high efficiency (direct vent) gas unit. I don't have model number.

Any suggestions would be appreciated.

Sort by:Oldest

Comments (6)

mike_home
3 years ago
last modified: 3 years ago
I took a look at the installation diagram for the Aprilaire 700M. Are you getting 24 V between the two brown wires? If not then you may need to add the transformer to be the power supply for the 24 V. The humidifier may be drawing too much current and dropping the voltage. This could potential cause the furnace control board to not operate or possibly damage it.
Elmer J Fudd
3 years ago
It's very nice of you to help out your neighbor. Keep the phone number of the guy with the truck and tools handy, you may need to use him.
Related Discussions
Humidifier solenoid works -- unless it's hooked up to the furnace
Q
Comments (8)
I misunderstood your original post. I thought your were testing with the furnace transformer. Are you reading 26.9V when the furnace is running and the humidifier is trying to run? If that is true then it doesn't seem to be a low voltage problem. Does your meter measure AC current? If it does then set the meter to current measurement and connect in series on one of the wires between the solenoid and the humidifier control. The current should go from zero to some value when you turn on the humidifier. If it does not, then you have an open circuit. The humidifier control board may need to be replaced.
...See More
humidifier cuts off furnace burner prematurely
Q
Comments (8)
https://www.heatair.org/ CAUSES OF SHORT-CYCLING Clogged Air FilterCLOGGED AIR FILTER This is one of the most frequent causes of trouble in an HVAC system. If the filter is heavily clogged with dust and debris, it may cause the furnace to shut off as a safety precaution. Fortunately, this is a basic problem to solve—just put in a clean filter. We recommend changing the HVAC system filter every 1 to 3 months depending on how often you run the heater and the strength of the filter. MALFUNCTIONING THERMOSTAT If the thermostat in your home is sending incorrect signals, it may be be the reason your heater keeps turning on and off. The thermostat might be reading temperatures incorrectly or have a bad connection to the heater’s control board. Technicians can recalibrate the thermostat or take care of other repairs so it operates the heater correctly. CORRODED FLAME SENSOR This applies to gas furnaces, which are the most common type of heating system. The flame sensor determines if the burners are on when the gas valve is open. The sensor will shut off the gas if it doesn’t sense flames—this prevents a buildup of unburned gas in the combustion chamber. Since the flame sensor is not able to detect fire when it’s covered in dirt or debris, it will continuously close the gas valve and cause the furnace to keep shutting off. OVERSIZED HEATER This is the most serious issue that will cause a furnace to keep shutting off is an improper installation. When a heater is too powerful for a home, it will heat up the living spaces so fast that the thermostat will shut the heater off prematurely. All you can do in this case is arrange for a new heating system installation—this time from a qualified professional who will make sure the heater is the right size.
...See More
Air in house very dry - Forced hot air furnace
Q
Comments (12)
Thank you rweigand - I will check and also try to get some photos of the setup. The filter was replaced just a few days ago. Do you reckon having humidity meters on each floor is a good idea? PS: We're in Massachusetts. The weather has been all over the place in recent days. Its rainy and 11C today and tomorrow, and then dry and 21C on Thursday! Hows that for xmas eve? Never thought I'd see that kind of temperature for xmas! mike_home - There is no doubt we have air leakage issues. We have drafty windows (and it is a very old house anyway) that will be replaced in the 2nd week of January and then insulation will be blown in to the external walls on 19-20th of January by a MassSave contractor. Should we wait it out to see what changes the windows and insulation will bring before blaming the HVAC system for all our humidity woes?
...See More
Strawberry Begonia (Saxifraga Stolonifera) help please.
Q
Comments (10)
Mybe this will help: Growing Strawberry Begonia Year-Round Photo credit: Stan Shebs Repot in spring every couple years or when the roots fill the pot. Put it in a hanging pot to show off its trailing plantlets. Use a pot with drainage holes to prevent soggy soil. Brown, crispy leaves? Dry-looking foliage can be caused by a few things: Direct sun can cause leaves to look faded or brown. Keep Saxifraga stolonifera out of strong summer sun. Crispy, shriveled leaves are often a sign that the air is too dry. Use a pebble tray or a room humidifier to raise the humidity around the plant. Don't mist this plant because the tiny hairs trap water and may cause the leaves to rot. Dry soil could also cause dry leaves. Aim to keep the soil lightly moist. Winter Care. Give this evergreen plant a dry, cool rest in winter. Keep it in a cool (50-55°F/10-13°C) place, and water sparingly, but don't allow the soil to dry out. It'll suffer in the dry air caused by central heating. Use a humidity tray or room humidifier, if necessary to raise the moisture in the air around it. Watch for an invasion of spider mites that are attracted to dry conditions." This plant is a hardy perennial rated to zone 6. I grow mine outside in a shady area that stays consistently moist (but not wet). If in an appropriate zone I'd suggest you move outdoors for best results.
...See More
Mini-Split Warehouse
3 years ago
What are some troubleshooting tips to fix my humidifier?

https://www.cooling-heating.net/

The first thing you should do if your humidifier stops working is to check the water level. When the water tank gets too low, or empty there is an automatic shut-off function in most humidifiers that will stop it from working. Simply fill it back up with some filtered water.

Replacement parts for your humidifier should be changed often, such as the filter. If these parts become clogged it will not only reduce your humidifiers efficiency, but also possibly damage the unit itself.
johnc777
Original Author
3 years ago
I got it working. As I said, I connected it directly to a 24VAC transformer and it ran just fine, so that eliminated the humidifier. Then I started tracing the wires. Two wires ran up to humidistat and connected directly to the humidifier. At first I thought it picked up power at the thermostat (which is mounted next to the humidistat). Nope. So I rewired it so that the humidifier picks up power off the "humidifier" terminal on the furnace board and it runs just fine.

It simply wasn't getting 24 VAC. The furnace is about 10 years old and to the best of my knowledge the humidifier was installed with the furnace and it's obvious from the condition of the pad that there was water in the unit. I just have no idea how it ran.
mike_home
3 years ago
Good work! I am glad to hear you were able to help your neighbor.
johnc777
Original Author
3 years ago
She a nice lady, who at 81 still mows her own yard. Her husband passed years ago and I know she's on a tight budget so I try to help when I can.

Humidifier Troubleshooting

Comments (6)

mike_home

Elmer J Fudd

Related Discussions

Mini-Split Warehouse

johnc777
Original Author

mike_home

johnc777
Original Author

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Humidifier Troubleshooting

Comments (6)

mike_home

Elmer J Fudd

Related Discussions

Mini-Split Warehouse

johnc777Original Author

mike_home

johnc777Original Author

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

johnc777
Original Author

johnc777
Original Author