All house humidifier

We added an all-house humidifier to our system. It has a control dial where we can set the desired humidity. The instruction says that the optimal humidity setting at this time for us should be 40%, but we can set it to whatever we want until we see condensation on the windows. There is a problem, however: the thermostat, located on the first floor, shows humidity level at around 40% +/- 1-2%. The second floor humidity level stays at around 25%. When I turn up the dial on the humidifier to anything higher than 40%, the fan starts running continuosly blowing cold air through the house (I guess with added moisture). How do we deal with this? I'd like the humidity level to be set at 50%-55%, but don't want to have cold air blowing when the pump is "resting". Thank you...

 

Why would you like 50-55% humidity? Molds like moisture, and 55% gets to close to them getting comfy.

 

I have never seen the RH in a conditioned space very that much. I use a sling psychometer, not digital.

I would use the same tool to measure both floors.

You can read the I/O manual and see what kind of logic the HP control uses for humidity to solve the cool air issue.

Mark

 

50-55% is way too high for a northern winter. 30 is a reasonable minimum, 40 just about ideal but may cause condensation.

We strive for 45% during summer.

A dehumidifier is often an expensive bandaid applied to a bad southern HVAC system or one in an extraordinarily leaky home. I wonder if a humidifier up north is similarly a bandaid for a loose house.

 

My extremely leaky house shows a sharp drop in humidity to around 20% in the winter. I am on the fence about installing a band aid.
Eric

 

My kids have asthma and they seem to be doing better with higher humidity, I have a plug-in humidifier in each of their rooms set for 50%. We've been in this house for 5 yrs, had a conventional heating system (gas furnace/AC), and had an all-house humidifier, that ran gallons of water down the drain, so we never used it. But in the winter, with the heater running a lot, it got so dry in the house, we would start getting cracks in drywall. So when we put in geothermal a few months ago we asked the installers, and they recommended this humidifier.
There is something else I discovered last night: we have our thermostat set for 62F at night, the setting for the humidifier is on 40%, but the fan kicked in at 1 am just blowing cold air through the house. So it's not the matter of setting humidity level higher: it seems that when the system detects the humidity level drop, the fan kicks in. I was told by the installer that the humidifier will run when the heat pump runs, but it obviously not the case here. Is it typical, or is it a wiring or some other problem? I had to turn off the humidifier altogether, because it seems stupid to have cold air pumped into the hopuse, and then have to warm it up again. In fact, our heating bill since we've installed geothermal is much higher than what we had with gas.

 

My extremely leaky house has RH @ about 33%,

 

You need to consider the fact that your kids have asthma since they are exposed to higher mold concentrations secondary to the high humidity. The high moisture might make them feel subjectively better, but the mold usually is the reason they have it ti begin with.

The NIH has published many studies showing a correlation between the presence of certain molds and the prevalence of asthma. In addition, the concentrations of those molds and the severity of asthma, as well as the number of emergency room visits because of asthma attacks, were directly correlated.

There is the possibility that either your unit is wired to the humidity sensor of the thermostat, this it acting as a humistat. Could be set to turn the fan on a certain humidity setpoint.

 

I am with Doc on this issue.

I would consider a whole house air cleaner, like the Dynamic air cleaner. I have had very good results with these units. I would run, not walk, and add UVC lights to the system too. I then would add a make up air system to bring "clean" to the return side of the unit. This will pressurize the home turning infiltration into ex-filtration.

I have done a good bit of IAQ work over the years. Let me know if I can be of additional help.

Mark

 

Thanks, Mark and Doc,

We do have an all-house cleaner. And one of the kids is allergic to pollen and ragweed, (not mold or dust), which causes asthma flare-ups, the other has a cough variant of asthma caused by common colds and postnasal drainage (the room humidifier helps her a lot when she has a cold and asthma flare-up). We have a good allergist/asthma doctor, who keeps track of the in-house enviroment.

Docjenser, you mentioned "There is the possibility that either your unit is wired to the humidity sensor of the thermostat, this it acting as a humistat. Could be set to turn the fan on a certain humidity setpoint". Is it something we can fix ourselves if this is the case, or do we need a professional to help? Our geothermal installers haven't been very responsive

 

Many things can trigger an asthma attack, like the release of a substance called histamine during an allergic reaction, or increased air flow (exercise) or cold air, but those things alone do not mean you have asthma. The underlying reason is always an inflammation of the airways which makes those airways overly sensitive. Without that underlying inflammation one cannot have asthma. That inflammation is comprised (among other things) of a relatively rare white blood cell called an eosinophil, which is called in by the immune system when such immune system is trying to defend itself against certain molds. The way this works is that those eosinophils attack the molds via the release of their toxic proteins, one of them called major basic protein (MBP) which kills the molds but also makes your airway hyper-reactive to histamine, exercise or cold air. It also causes the constriction of the smooth muscles in the airway, tightening your airways. At the end of the day, if you have MBP in the airway, you have asthma, and if you don't have it, you cannot have asthma. Common colds increase the number of eosinophils in your airways, thus the worsening of asthma symptoms during common colds. The trigger for the eosinophils to come in and the release of the MBP has been shown to be certain molds. Everything else, like the pollen allergy or the common cold, occurs secondary, and in itself does not cause asthma. Take it for what it is worth to you, but if you continue like you do your kids asthma will worsen, associated also with more nose and sinus problems. I would just be curious how your allergist tracks your in-house environment.

It does not help if you have all house cleaner, since that sits on the return side, however, your humidifier which put moisture and mold spores into your ductwork is on the supply side, blowing it right into your house.
Your thermostats: You mentioned that your thermostat reads the humidity. So it could be wired as a humistat. Get the installation manual for your thermostat an check if the humistat outputs are wired.

 

I'm certainly no expert, but my understanding is that indoor winter humidity levels should be much less than what you're trying to get your house up to. Optimal indoor humidity also varies with outside temperature. See the recommendations here:

Home Energy Resource MN: Humidity

As others have already stated, excessive humidity condenses inside your walls and will contribute to mold growth.

On our system, limits are built into the thermostat (it has an outside temp sensor) so that as the temperature drops, you can't set the humidity too high. It auto-adjusts as the temp drops outside. Our system will also run humidify only (no heat) when needed, but it does this on a very low blower speed. The colder air is noticible only if you happen to be right next to a duct. If your house is moderately leaky, your system will try to humidify it's tail off just to try to keep up with where you're setting it, and it's not surprising it's running the humidifier a lot when the heat isn't running. When we put our system in, we also had all the ductwork reconfigured and replaced at the time. Between the new clean ductwork and the HEPA air filter in the geo unit, our indoor air has never been cleaner. We don't have asthma issues, but we do have mold and dust allergies, and have noticed a major improvement in our house in the winter since installing the geo system a little over a year ago.

Also, FWIW, the major cause of low indoor humidity is air leakage. It might be worth doing an energy audiit / blower door test on your house and getting the air leakage down as much as possible, if you haven't already done this.

 

Thanks for the info on asthma and mold. I was born in a different country, and lived 28 yrs in a city where relative humidity very rarely dropped below 75%, 4-5 months we had snow on the ground with temp sometimes as low as -25F, and the rest of the year was quite rainy. In all my years there I did not meet 1 person suffering from asthma. My kids are doing just fine, in fact my daughter seems to be "growing out" of her asthma. And we don't have mold in the house. I appreciate your input, but I was just trying to figure out what our new geothermal system was doing, but somehow it turned into a medical discussion.

 

Thanks for the input. It sounds like your system is similar to ours, except I don't think we have an outside sensor. And the house isn't leaky - we have new doors/windows, insulated attic, air-tight fireplace doors, and even insulated electrical outlets on the outside walls. The HEPA filter works great, but the humidifier doesn't The blower gets pretty loud, and when it works just to humidify it blows enough colder air to feel it. So I'll need to try and figure out how to get the humidifier to work only when the heat is pumped. Even when it was set to 35%, it still was just blowing without the heat. By the way, I read here that some people leave the temp at night same as during the day with an idea that it takes too long for the pump to get to the right temp in the morning while using more energy to do so instead of just maintaining the same temp. How is your system set up? Our electric bill with geothermal was much higher than gas bill last yr, which doesn't seem right since we have a pretty mild winter this yr and haven't turned on AUX heat even once.

 

It sounds like you have a Honeywell True steam and it is wired to run whether you are heating or not.

 

The medical discussion came up because you mentioned that your kids have asthma, and what you are doing to your indoor air quality is actually conversely affecting them. The mold which is actually linked to asthma is more an indoor than an outdoor mold called Alternaria. 2 things have to come together for it to grow well: temperature (preferable around 85F-100F and moisture (above 60%). What do you think happens in your air duct? The supply air gets heated up to around 100F and gets humidified above 60%. You are correct, asthma in northern climates is less common, they are missing the temperature outside, and inside they heat, so heat and humidity rarely co-exist.. So I bet in the city you are coming from, they did not have airducts with humidifiers, and air conditioning. In addition, air tight house are prone to have increased indoor mold concentrations, since there is not much ventilation anymore. You think you do not have molds in your house, I assure you you do, you just cannot see it, the spores are 10 micrometer in diameter and pretty buoyant in the air. We thought that people with childhood asthma are able to outgrow it, but their immune system learned just to tolerate the mold antigens better, however she will flare up at common cold infections and when she gets in environments with higher spore counts. Again, take it for what it is worth for you personally, but postings here are also not just for you, but also for others to think about what they are doing. I understand you did not wanted to get into this, but what you are describing is a pattern we see over and over and over again, with the same outcome of inflammation in the airways manifesting as asthma.

 

Yes, that is exactly what we have. Is there a way to have it run differently?

 

Thank you!

 

If I bother to set mine back at night, it's only by a degree. When it gets down to close to 10 degrees outside, I don't set it back at all. We like it cool...67 or 68 degrees, and cooler when we sleep. I find it's easier to shut the supply off in our bedroom at night and close the bedroom door than set the geo back several degrees and make it work hard to bring the temp back up again.

As far as electric cost, I can't compare to natural gas as we don't have it where I live. I used to heat with wood and oil. I know I can't buy split wood for less than the geo costs us to run, and over oil it's a no-brainer. Here's a link to info on our system with our electric costs. I'm currently buying all as wind power for about .12 per kwh:

http://www.geoexchange.org/forum/ge...monials/4982-new-system-central-new-york.html

 

If you have kids with asthma who need more humidity in their bedrooms at night, I would discuss this with their pediatricians. Perhaps a room vaporizer would be more appropriate than over humidifying the entire house. When your windows fog in the winter (or summer) you are probably feeding the microorganisms that feed on your drywall glue, carpet padding, wallpaper glue, among other things. Check with the doc.

From Doctor Mom.