Best big home humidifier setup. (steam versus evaporative, etc.)
We just bought a new (to us) house in Calgary, Alberta. Its a 2 story, built in 2007, 5,000 ft^2 finished, including the basement, 9 foot ceilings throughout. Hardwood everywhere on the main and upper floors. Finished in place floors, hard wood built ins, solid hardwood doors. Its appears to be a very well built home. Its probably pretty air tight.
Calgary is extremely dry in winter. Its dry when its cold out (-20F) and even dryer when the chinook winds roar through. Think 32F, 30 MPH winds, 10% relative humidity.
The house is deficient in humidity. The hardwood in the floors has shrunk slightly. We've been advised to do something about the humidity problem ASAP or risk long term damage to the floors.
The house has an on demand natural gas hot water heater and hot water storage tank feeding heat exchange coils in dual forced air heat exchange units, one for the main floor and one for upstairs. The basement has its own recirculation fan and ducting and in floor hot water heat coils.
The house also has dual AC.
The forced air heat exchangers are each equipped with Honeywell drum type evaporative humidifiers with simple local humidistats.
What should we install in this house to maintain the humidity at 30% or more through the worst conditions Calgary has ?
Thus far the best option seems to be dual AprilAire 800 steam humidifiers. I'm liking them over the GeneralAire steam unit because of the controller and the fact it starts up the fan to sample air humidity from time to time and its got an outside temperature sensor.
However, these units seem to draw a lot of electricity ! Is there any way to humidify this house with an evaporative humidifier or is there such thing as a natural gas steam humidifier ?
Would the AprilAire 700 be better than the typical drum style evaporative humidifiers ?
It seems to have a similar control to the 800 model, ie outside temp sensor.
I wouldn't base the humidifier choice on the controller - in most cases, you'd be better off replacing the main thermostat with one that controls humidity as well, so it is all controlled as a single system. For starters, you may NOT want the humdifier running unless the heater is also running, simply because you end up getting 'cool' air blowing out the vents when this is happening (it is essentially an evaporative cooler). Really, the only good way to coordinate this is with a singular controller for both temp and humidity. Most that support this also support an outside temp sensor, to prevent dew formation on the windows. Also, if you have the space around your air handlers, you might even get away with the cheaper AprilAire 600, as it does't have it's own fan, and just uses the main air handler's fan. I believe it is the same pad, so the same effectiveness as the 700.
Originally Posted by BigBear23
Is there a problem with the current honeywell humidifiers already in place? if it is just a control issue, I'd look at doing a thermostat/humidistat upgrade, and continue to run what you've got.
They appear to have insufficient capacity to keep the humidity up.
Originally Posted by CraziFuzzy
FWIW, we currently live in a similarly sized house. Probably 4500 ft^3 finished on 3 levels, 10 foot ceilings on main and upstairs, 8 foot in the basement. Its also in Calgary.
It has twin force air natural gas furnaces with the same Honeywell humidifiers as the new house. The current house also has a humidity problem in that the air is too dry in the winter. However, the current house doesn't have as much hardwood and its the manufactured hardwood which doesn't seem to be nearly as sensitive to humidity. I have taken to over riding the furnace control and leaving it on "fan" most of the winter so that the humidifiers are running constantly.
It seems to me its a real problem to keep the humidity up in large homes around Calgary and I've heard this from may other people as well.
I think my first course of action is to increase the capabilities of the humidifiers.
This response is going to cross over to your other post regarding fresh air change. If two of those honeywell drum humidifier aren't keeping up, then the house is very leaky. I'd say in this case, your first step would be to have a blower-door test done on the home, and find the major leak points, and tighten up the envelope. Of course, if you get it too tight, you will then have to look into the fresh air exchange, but it will be well worth it in the end. Either way, it seems both questions being asked are pointing to the same first step.
Originally Posted by BigBear23
That is a very interesting idea. The new house is getting a Zwave automation upgrade, including the thermostats. It probably wouldn't be too hard to integrate control of the humidifiers into the system.
Originally Posted by CraziFuzzy
That is a very good point. Now that you say that, we sometimes find the house to be cold when the thermostat is set to a reasonable temperature and then find it too warm at the same temp a while later.
For starters, you may NOT want the humdifier running unless the heater is also running, simply because you end up getting 'cool' air blowing out the vents when this is happening (it is essentially an evaporative cooler).
How would the cooling effect change if steam was injected into the air flow rather than evaporated water ? The air would be moist and warm or at least not cold ?
This is an incredible forum. This is the first that I have ever heard of that type of controller. Can you recommend a brand or model ?
Really, the only good way to coordinate this is with a singular controller for both temp and humidity. Most that support this also support an outside temp sensor, to prevent dew formation on the windows.
How effective would it be compared to a steam unit in terms of getting the humidity up ?
Also, if you have the space around your air handlers, you might even get away with the cheaper AprilAire 600, as it does't have it's own fan, and just uses the main air handler's fan. I believe it is the same pad, so the same effectiveness as the 700.
I've talked to 2 HVAC sales people in Calgary and both told me they are installing steam humidifiers left and right as the solution to home humidity problems around here. But I don't know if they are trying to sell me something or if its what I really need. The biggest turn off to me about the steam units is their operating cost for electricity. 10+ amps at 240VAC for 2 units is no small load ! Basically 5KW or 50 cents an hour when they are running. Could get expensive pretty quickly.
I think I'm going to install an AprilAire 700 in each of the heat exchangers for the "normal" humidifying load and back them up with an AprilAire 800 downstream in the duct as needed.
I'll run separate humistats on each. I'll have the 700s kick in first and only fire up the 800s if/when needed. Maybe have the 700s kick in at 40%rh and the 800s kick in at 30%rh. Something like that. I should then have more than enough capacity for all conditions.
It sounds like a lot of hardware, but it isn't going to take long to pay for the 700s (at $230 each) with the 800s costing 25 cents per hour each to run. They should pay for themselves in a single season (1000 hours). I can buy a AA700 and an AA800 for the price of a single General Air steam unit.
I like fan evaporative units over bypass units because their performance is independent of ducting pressure differentials.
I'm going to pipe hot water into the 700s to increase their effectiveness.
I would make sure your humidifiers are operating 24/7 before replace good equipment. You will need 3-4 lbs. per hour of moisture to humidifier 150 cfm of fresh air that infiltrates a 5,000 sqft. home. Get your current humidifiers operating agood as possible. Avoid electric humidifiers because of cost of operation and maintaince. Get more air flow through your humidifiers.
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
There is no way a seasoned or as you put it a journeyman hvac specialist can tell how tight your house is without a blower door test done to CFM50 standards..
I have seen foamed insulated houses that are supposed to be airtight to the point of needing ventilation added that were as leaky or more so as a conventional home.
TB is correct if you have humidity issues with two operating humidifiers then you have serious air leakage or your leaving a window or door open..
This leakage could be caused by ducts leaking outside the envelope, supply ducts in attics are a major problem if leaky as the air that is leaked outside must be replaced by that dry outdoor air that is outside..
Get a blower door test performed to CFM50 standards and find your problem.. Your bills may be reduced, your comfort will be increased and your humidity level issues will go away...
Look for a company that is BPI certified or comfort institute certified..
We ran a blower door test and did some infra red camera snooping yesterday.
The house has a leakage rate of 0.215 volumes at 50 Pascals. It has an equivalent open area of 172 square inches. Given the size of the house, this is considered very good.
Infra red testing showed everything to be really good with the exception of pot lights in the upper floor, a leak in the attic entrance area and a leak where the gas line enters the house. Tightening up these areas will further reduce the air leakage rate.
The tester strongly agreed that a house this big and this tight needs an active ventilation system.