G77

We keep getting static shocks and I have dry itchy skin - I understand this is due to the humidity in our house (or lack of). I have located the humidistat - should I be turning this so that it has a higher % reading on it?

How long does it take to make a difference?

I have a weather station which says the indoor relative humidity is currently 25%....

johnh009

Any indoor humidity level below 30% is too dry. Around 45% to 50% is ideal. Check that your humidifier is working. Be careful, too much humidity may result in mould.

G77

How do you check it is working?

I turned it up earlier and I can now hear it operating, water is running into it and it makes a hair dryer type noise - I'd not noticed it doing this before I changed the setting on the humidistat. I've now got it set to 40%

I set it to this about 4 hrs ago and the RH on the weather station still says 25%...

johnh009

Be patient, the cold has come quite suddenly so it has some catching up to do. Water is fed into the air stream circulating through the furnace. When you see condensation on your windows you will know it is working and you may even wish to crank it back slightly.

Not easy to gauge exactly but as the outside temperature rises your indoor recommended relative humidity should increase.

G77

Cheers, will see if it's any different tomorrow..

MB-Realtor

Have you cleaned and sterilized your humidifier this year, I see so many that have a new alien race growing in them that I often recommend them to be disconnected.

G77

I did wonder about that - we've only been here just under 4 months, it looks like it is from at least the 80's.... There didn't appear to be an obvious way to open it and I didn't like to mess with it in case it pissed out water.... I guess I could ask the landlord, he's pretty helpful...

johnh009

Just to make life more interesting, there is now rain forecast for the end of the week.

G77

Still at 25%, so I guess I need to try and get the sucker open and see if there's something living inside....

bpc123

It sounds like your humidifier hasn't been maintained, so it isn't functioning. There are several different type of furnace based humidifiers (tray, drum, drip, spray), and all of them need to be maintained on an ongoing basis or else they won't work.

Firstly, if you have a tray humidifier (identified as a metal box attached on the duct above your furnace, with a simple tray inside that holds water) then it is 100% useless.

If you have a drum humidifier (identified by a drum shaped evaporator pad that will rotate in a tray of water when the furnace comes on), then check the humidifier pad to be sure it is working. If it feels like a wet sponge (wet and pliable) then it is in good shape. If it is hardened with calcium and lime, then it needs to to be replaced. Generally, unless you add de-scaling tablets to the water tray every 1-2 weeks, the evaporator pad will be toast within a month during the winter when the furnace is cycling constantly. They operate by air flow entering the middle of the drum pad and flowing through the pad. The humidified air then is returned to the heating duct for distribution. If the pad is hardened with minerals, there is no air flow, and no humidification.

A drip humidifier has a flat, articulated metal screen that water cascades down from the top when operating. The air flow through the screen picks up humidity and returns it to the system for distribution. This is a far better device than a drum or tray humidifier, but it still needs to be descaled periodically. They will usually have a drain hose coming out the bottom and leading to the floor drain in the furnace room, so this can help identify the humidifier type, as well.

A spray humidifier does just what it sounds like. It sprays a mist to create humidification. The problem with these is that unless centrally softened water is being used in the house, the spray tip will clog up with scale and instead of a mist will simply dribble water eventually and have no humidification effect.

One final type is a rotating disk style humidifier (only one brand uses this technology) and it is very effective and low maintenance. It has greater surface area for evaporation, and doesn't clog like a drum humidifier.

The best recommendation, since it doesn't seem to you your own house, is to buy a large, portable floor humidifier (2-4 gallon capacity). These use an evaporator pad which will probably need to be replaced half way through the winter, but they are extremely effective in regulating humidity. In a dry house, it will easily raise the humidity by 20% within a 24 hour period. I recommend the large capacity because otherwise the tank might be drained within a few hours, and once the pad becomes dry, it will begin to harden from calcium and lime deposits. Buying water conditioning tablets (specifically for humidifiers) will help to extend the life of the evaporator pad, and you might get a full season of use. You can also manually descale it every couple of weeks, using a product like CLR or something similar.

Finally, humidity should generally be kept between 30-40% (higher in summer, lower in winter to prevent condensation). If you get a cold snap (-20 or lower) you might want to lower your humidity temporarily to below 30% to prevent ice buildup on your windows, until it warms up. Once you get below 30%, though, you can expect a lot of static electricity on sheets, clothing, cats, etc.

G77

From your description, sounds like it's a tray humidifier - the model is a Honeywell Aprilaire Model 550 (http://www.aprilaire.com/themes/aa/e...50_600_700.pdf).

Does a portable humidifier cover a whole house? Where do you have to place it to be effective?

Nice 1st post btw

Steve_P

From your linked PDF I would say yours is the more efficient drip humidifier.

bpc123

A large portable humidifier should cover an entire house quite easily. If the house is over 1,500 sq. ft., then run the fan on the furnace to continuously circulate air in the house for the first day or two (there should be a switch with a 'Fan' position on the house thermostat). This will equalize the humidity throughout the house. After that, the normal cycling of the furnace should be enough to keep humidity even.

bpc123

That's a drip humidifier, which is a good thing. I would guess that the pad needs replacing, though. One of the advantages of the drip, besides what I mentioned in my previous post, is that they stay quite clean (limited bacterial growth) because there is no pooled water. They will build up calcium deposits, however, and will need annual replacement (or you can take out the pad and descale it with a product like CLR). The disadvantage is that they waste a lot of water compared to other types of humidifiers because it flows down the pad and out the drain tube.

The reason it is difficult to bring humidity up in a house with low humidity, with a furnace mount system, is that they only operate when the furnace is in a heat cycle (they don't work when it's just the fan running). You would need to have the heat constantly running for a day or more to raise the humidity by an appreciable level, once it has dropped too far. Once the humidity is up, a drip humidifier can usually maintain the level, depending on how dry the climate is where you are. That's why you need to get a portable floor unit. Nothing can bring up the humidity as quickly as one of those, and do it independently of needing the furnace to blast heat.

G77

Could be right there Steve, it certainly has a drain hose coming out of the bottom of it...

From the PDF, looks a bit complicated to dismantle - the personal injury bit was disconcerting Will wait and have a word with my landlord, he's dropping off an xmas present for us this week