Whole House Humidity

[Jim Frye]

Well it's really getting cold here and our heating system can't get the humidity much above 30%. The house is 1.900 sq. ft. on a single floor. 95% efficient gas furnace with a Honeywell HE360 powered humidifier on the warm air plenum fed by hot water. The humidifier should be good for 4,500 sq. ft. and has a new media pad installed. The windows are Pella triple glazed and there is 18" of insulation in the attic. The home qualified as Energy Star efficient when built seven years ago. I have run the system with the humidifier always on when the furnace runs, but at 20 degrees outdoor temperature and 71 degrees indoor thermostat setting, the humidity still won't go above 32 percent. Any Ideas what is amiss?
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[capncarl]

Before you do any destructive investigation check your house humidity with a different hygrometer. How hard is your water?

[Jim Frye]

Before you do any destructive investigation check your house humidity with a different hygrometer. How hard is your water?

There are four different units in the house, and they all agree, so we know pretty well what we have. City water is relatively soft. The media pad doesn't have much build up at the end off the heating season. The humidifier runs when the furnace blower runs, but it doesn't run often enough due to the tightness of the house. If it's 20 degrees outside, it can take an hour for the indoor temp. to fall enough to trigger a call for heat. I've tried running the blower motor full time, but SWMBO says if feels it's blowing cold air (room temp.).

[capncarl]

Does the humidifier evaporate water using heating system? Or is it independent of it?

[dbhost]

For what it's worth, it's all in perspective. I am sitting here in coastal Texas wondering why on earth anyone would WANT to add humidity to their home. Seems completely alien to me.

[Jim Frye]

That big coffee table I made a couple of years ago recently split the back panel from the sudden dryness. It didn't split at a glue line and the panel has reinforcement ribs across the grain of the back at the top and bottom. The wood is finished on all sides, but the sudden dryness was too much for the maple.

[LCHIEN]

I'm in the same town as Dave (DBHost) - here we battle humidity in the 90% range most of the year.
In the summer when the AC runs you can be draining gallons off your AC evaporator an hour. In some parts of the house you can actually hear the water running down the drain lines to the sewer, when the compressor is running.
They say that having too large a compressor unit causes it to run too small a percentage of the time and you don't get enough humidity out of the air.

So maybe your problem is related in the inverse way.
If the heat is only running a few minutes an hour then your humidifier is not running enough to add significant humidity to the house.
Can you run the humidifier on a separate control with the fan circulating air being on a higher percentage of time than the heat? Perhaps at a lower fan speed so it doesn't get drafty.

If you are only heating for 5 minutes an hour then you are only humidifying 5 minutes an hour with your present setup and apparently that is not enough.

[mpc]

Loring's idea is a good one. Many furnaces have two or more speeds on their fans... selecting the lower speed may make the fan run longer, helping the humidifier. The furnace in my first house could be set to run at one of two speeds when the furnace was on, plus a setting that just ran the fan constantly. An electrician might be able to connect a speed controller to the "always run the fan" switch position so the fan runs at a slow speed - fast enough to help the humidifier but slow enough to not make wind currents inside the house. Or the electrician might be able to add a keep-alive timer to the fan: when the furnace calls for the fan, the fan runs... when the furnace shuts off the new controller keeps the fan running for some specific amount of time. Very much like the gizmos used to control shop vacs or smaller dust collectors: vac turns ON when the tool is turned ON, then keep the vac running for a few seconds after the tool is turned OFF. This will push slightly warmer air (picking up heat in the ductwork) rather than simply room temperature air.

My current house has a fairly modern furnace + air conditioner (one of the last US built Carrier branded systems) with a Honeywell smart thermostat. The thermostat includes humidity control capability so it can run the fan at one of several speeds to work with a humidifier. If I had a humidifier. Being too dry is generally not a big problem in SoCal, a little too much humidity is more common so the Honeywell thermostat cycles the air conditioner at low speeds to de-humidify as needed.

mpc

[Jim Frye]

I tend to agree that the furnace doesn't run enough to allow the humidifier to do an adequate job when it gets really cold outside. I ran the furnace blower on full time rather than automatic with heat call from the thermostat and it did raise the humidity, but SWMBO can't take the "cold" air blowing from the registers.The Trane XP95 furnace (builder install) doesn't have a multispeed blower. It just has a soft start feature to make the outrush less obnoxious at cycle start.

[capncarl]

How does your humidifier work…. (Not just by selecting “on” on the thermostat) saying you have a media pad suggest it acts like a swamp cooler where water runs through a mesh screen with air blowing through it and carrying moisture into the house or is it a flat pan located in the duct with media in it that heated air blowers over it?

has this been an ongoing problem or have you been able to raise the humidity to a much higher rate than it is now?

[capncarl]

I feel for you, our humidity in south Ga. Is high like south Texas. When the rh drops down in the 60s I start itching like crazy. A front blew through earlier this week and temps drop from mid 70s to 30 and the rh dropped to 51. Instead of installing that dang monster of a garden tub my wife just had to have I wish we had installed a dip tank full of moisturizing lotion…. I’d hit it 3 times a day! I’m about to itch to death!

[Jim Frye]

The humidifier has its own sensors in the heat run and the cold air return along with an adjustable RH control. The unit itself runs when the furnace blower runs so it is working with warm air. It runs unless the actual RH is higher than what the control is set for or you can also set it to be on regardless of RH. The unit pulls air out of the warm air plenum above the burners and then blows the air back into the warm air plenum through the expanded metal mesh wick pad that is wetted by hot water from the adjacent hot water heater. It's not quite a steam injection humidifier, but better than running cold water through the pad. The excess water from the media pad drains out the bottom of the unit with condensate from the furnace, so it won't stay wet and grow mold. So it's easy to see if the humidifier is working. You can also feel/hear the humidifier fan running. I think I'm going to have our HVAC dealer/service come out and get an expert's diagnosis. I also might try a warm air room humidifier that can be moved from room to room as needed, like the bedroom at night.

[dbhost]

I'm in the same town as Dave (DBHost) - here we battle humidity in the 90% range most of the year.
In the summer when the AC runs you can be draining gallons off your AC evaporator an hour. In some parts of the house you can actually hear the water running down the drain lines to the sewer, when the compressor is running.
They say that having too large a compressor unit causes it to run too small a percentage of the time and you don't get enough humidity out of the air.

So maybe your problem is related in the inverse way.
If the heat is only running a few minutes an hour then your humidifier is not running enough to add significant humidity to the house.
Can you run the humidifier on a separate control with the fan circulating air being on a higher percentage of time than the heat? Perhaps at a lower fan speed so it doesn't get drafty.

If you are only heating for 5 minutes an hour then you are only humidifying 5 minutes an hour with your present setup and apparently that is not enough.

That might be spot on. I know about the AC / moisture removal. You might just be spot on with heating / humidification.

I think I would consider using small humidifiers if I was in that situation, like a Vicks vaporizer. They are inexpensive, and readily available.

[cwsmith]

We're in this old 1887-built house, fairly insulated, but the windows are old and we have storm windows. The furnace is forced hot air with the typical plenum-located exchanger and A/C unit outside. It is probably 30 years old. Right now it is 10-degrees outside, quite windy, and the temperature on the first floor is about 70 degrees with a degree or two variation depending which room you are in. The second floor is 67 and the basement 66. Humidity is 34 % here in the basement where I have my work area/office. We have had only two or three zero degree nights in the past few weeks. Personally speaking, I saw a lot more sub-zero nights a few decades ago.

My wife cooks every night and of course there's the showers and laundry, so we produce adequate moisture I think. I don't have a problem living with 34% humidity and I've noticed nothing drying or cracking. The library or any of rhe kitchen remodel work as shown any signs of shrinking, cracking, or other movement.

Summers in these last few years are quite uncomfortble with far to many days in the mid-to -high 90's and here in NY's southern tier it is alway humid. We run the central air from about 11:00 in the morning until maybe 7:00 pm, and on occasion will maybe turn it on of an hour or two in the late evening. Generally we keep the temperature below 80. Bottom line are comfortable living temperature si between 70 and 75.

This coming spring we're considering replacing the heating/cooling system with something more modern. Mostly for reliability and efficiency, because the present system is just old.

CWS

[capncarl]

Jim, what you describes sounds like a bypass system. They usually have doors, flappers or baffles or whatever the mfg wants to call them. They may not be opening, or are only partially opening.. can you access the box to see if they are opening?

in your lack of humidity it may be necessary to run your fan in Auto and make sure the humidifier is on and it’s doors open fo allow air flow thru the media…… regardless what the head of the house says! I’d won’t take but a few hours and she will be use to the constant flow of air. Do you have ceiling fans, are they on? Ceiling fans will help keep the air stired up so you don’t notice the blower constantly running. We recently turned our hvac fan to auto to keep the Remi-Halo (think UV device in the duct) running full time while I get thru Covid.

[Jim Frye]

It is most certainly not a bypass system. No doors or baffles, and it has no connection to the return air ducting as bypass systems do. I have had the unit apart many times fooling around with different media types and cleaning it every year at the end of the heating season. The unit has a fan that pulls warm air from the plenum on the sides of the unit and then blows it back through the media pad into the warm air plenum for distribution. AUTO setting on our Honeywell thermostat means the furnace blower fan only runs when the thermostat calls for heat(cooling). To get the fan and the humidifier to run constantly, the thermostat fan control is set to ON.

[capncarl]

Right..Auto means auto, as needed, brain fart on my part! As a test, heater off, close doors to bedrooms, bathrooms etc and boil a large pot of water without the stove vent running and see if it raises the RH on your thermostat in the kitchen area.

[Jim Frye]

SWMBO remembered that we had an old cool air humidifier in the basement. Cranked it up after dinner tonight and the house humidity is on the rise, but it has gotten a bit warmer outside today. Time will tell.

Update: The tabletop humidifier has the humidity up to 42% running just when we are up. Of course the outside temp.has risen to 47 degrees, so an imperfect test.

[capncarl]

What about an update on your humidifier problem.

[Jim Frye]

SWMBO remembered we had an old cool air humidifier from when the kids were small, so we dug it out and started running it during the day in the area between the kitchen and living room. I also discovered that the media housing frame in the whole house humidifier had somehow gotten out of level, so the pad wasn't getting evenly wetted. Those two things combined got the house humidity above 42%, even when the outside temperatures were sub freezing. We just run the room humidifier when we need to now.

[Jim Frye]

After four days of running the 19 year old cold air humidifier that produces droplets of moisture into the room along with a lot of dust, even though we are using filtered water; we picked up an ultrasonic nebulizer type machine to boost the humidity in the home. This one is really quiet and produces a much finer mist and it also uses UV and ionization to purify the interior of the machine and the mist. We'll see how well it performs for a few days. We are getting a huge temp. drop, so the new machine will get a challenge.