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  1. #1

    Problem reaching desired humidity (>40%)

    I'm struggling to keep humidity up in our house in Northern Virginia. New HVAC system has Thermostat control humidifier which controls humidifier, set to 45%, but I don't think I've seen it higher than 32 and its 27 right now. Outdoor temp currently 36, humidity 49%. My service company says the problem is that the thermostat only triggers the humidifier when the heat is on, not when the blower is on. Short of going back to a manual control, is there any work around?

    System spec:
    Thermostat: TZONE950 - Nexia Comfort Link II
    A/C: 4TTX5036 (XL15i)
    Indoor coil #4TXCC044BC3
    Furnace blower #TUH2C100A9V4

  2. #2
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    If it is a water panel type humidifier, the heat needs to be running for it to be effective.
    The controls may also be automatically limiting the indoor humidification, based on the outdoor temperature, to prevent condensation on your windows, etc..
    If more government is the answer, then it's a really stupid question.

  3. #3
    Join Date
    Aug 2010
    Location
    West Monroe, LA
    Posts
    1,529
    Quote Originally Posted by mark beiser View Post
    If it is a water panel type humidifier, the heat needs to be running for it to be effective.
    The controls may also be automatically limiting the indoor humidification, based on the outdoor temperature, to prevent condensation on your windows, etc..
    I agree with mark. If this the set up you have the heat needs to be running. Who and how did they size your heating system? If the system is oversized on the heating side then the unit will short cycle in turn not allow the unit to run long enough for the humidifier to work properly.

    I see by your model number you have a 100,000 btu furnace with (2) stage heating ablity. How big is your home? That seems to be a lot of heat but without looking at the home can't be certain it is sized propely? What has the installer said about the problem? Has he trying doing any adjustments to the system with air flow and or heating settings such as staging the heat? Please post back what if any adjustments have been done along with what the installer had to say about the problem.

  4. #4
    Quote Originally Posted by duckman06 View Post
    I agree with mark. If this the set up you have the heat needs to be running. Who and how did they size your heating system? If the system is oversized on the heating side then the unit will short cycle in turn not allow the unit to run long enough for the humidifier to work properly.
    I couldn't say anything about the sizing, but I first ventured into this forum asking about sizing question (3 contractors came out with quotes for similar systems, I went with company I felt most comfortable with)

    Quote Originally Posted by duckman06 View Post
    I see by your model number you have a 100,000 btu furnace with (2) stage heating ablity. How big is your home? That seems to be a lot of heat but without looking at the home can't be certain it is sized propely? What has the installer said about the problem? Has he trying doing any adjustments to the system with air flow and or heating settings such as staging the heat? Please post back what if any adjustments have been done along with what the installer had to say about the problem.
    Home is 3.6k sqft, three floors including basement. Top floor is on its own zone. Main floor has several two-story areas. Basement is rarely used, so I close vents (habit I picked up from my mother to save on energy). Should I open?

    Installer has been back a couple of times, but from what I can tell, has only worked on the thermostat. How can I check to see if my system is staging the heat? (Not real familiar with this)

  5. #5
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
    Posts
    1,654
    First of all, you'd have to tell us what kind of humidifier is on the system. It may be that it is one that is not necessarily dependent on heat to function, and they just have the stat programmed wrong. The other option, if you actually DO have more humidity need than heating need (due to the furnace just being oversized) is to either change the humidifier type to a non-heat-dependent type.

    The statement above about 'water panel humidifiers' needing heat is only partially correct. Yes, they do require heat to run to their capacity, but they will still add water to the air, even if just the circ fan is running. They will use more water, as more will end up going down the drain, but if you are talking about only trying to bring the air up to 30% humidity, there is still 70% there ready to pick up moisture as it passes over the pad. It's not efficient, as it forces the fan to run a lot more often, and you get a problem with 'cool' air blowing from the vents in this mode (it is effectively an undersized swamp cooler at this point) - but it DOES function. in fact, I run my own humidifier this way, as I get a lot of heat generation in my home from sources other than my furnace (server rack), so my furnace rarely runs, but I still need humidity for child health reasons.

  6. #6
    Thanks for your thoughts.

    Quote Originally Posted by CraziFuzzy View Post
    First of all, you'd have to tell us what kind of humidifier is on the system. It may be that it is one that is not necessarily dependent on heat to function, and they just have the stat programmed wrong. The other option, if you actually DO have more humidity need than heating need (due to the furnace just being oversized) is to either change the humidifier type to a non-heat-dependent type.
    AprilAire 700. Its gotta be ~15 years old, but in good enough shape that the HVAC guys just offered to reinstall it when they redid the furnace. I don't remember if I replaced the pad this year, but I definitely did last year.

    Quote Originally Posted by CraziFuzzy View Post
    The statement above about 'water panel humidifiers' needing heat is only partially correct. Yes, they do require heat to run to their capacity, but they will still add water to the air, even if just the circ fan is running. They will use more water, as more will end up going down the drain, but if you are talking about only trying to bring the air up to 30% humidity, there is still 70% there ready to pick up moisture as it passes over the pad. It's not efficient, as it forces the fan to run a lot more often, and you get a problem with 'cool' air blowing from the vents in this mode (it is effectively an undersized swamp cooler at this point) - but it DOES function. in fact, I run my own humidifier this way, as I get a lot of heat generation in my home from sources other than my furnace (server rack), so my furnace rarely runs, but I still need humidity for child health reasons.
    Like you, I'm worried about my young ones. Decrease in static would be major bonus as well.

    fwiw I've opened up vents in downstairs which will increase the time in heating cycle and hopefully raise humidity levels throughout house. Come to think of it, it might be cheaper to heat the basement with gas and let the heat rise to the upstairs bedrooms which rely on the electric heat pump. Hmm...

  7. #7
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,422
    You need to replace the pad each year. You'll get poor performance with an older pad still in it. Sounds like your furnace runs very short cycles so humidifier does not have a chance to keep up. Does your 3600 sq. ft. include the basement? You could have a "sail" type switch installed and run the fan on continous as mentioned by others. This will increase humidity output regardless of heat cycles. Just make sure and shut the humidifier off in summer so switch won't turn it on.

  8. #8
    Quote Originally Posted by wahoo View Post
    You need to replace the pad each year. You'll get poor performance with an older pad still in it. Sounds like your furnace runs very short cycles so humidifier does not have a chance to keep up. Does your 3600 sq. ft. include the basement? You could have a "sail" type switch installed and run the fan on continous as mentioned by others. This will increase humidity output regardless of heat cycles. Just make sure and shut the humidifier off in summer so switch won't turn it on.
    Ok, ordered a pad ($ with free shipping from Amazon seemed very reasonable)

    3.6k includes basement

    Is the "sail" switch something I need to ask my HVAC guys to install? Rough idea of equipment cost and labor time?
    Last edited by beenthere; 02-18-2013 at 03:23 PM. Reason: price

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,721
    Prices aren't allowed here, so you won't get any cost estimates from here.

    It should also be connected to the hot water line.

    Might want to see if you can seal up your house any better.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #10
    Quote Originally Posted by beenthere View Post
    Prices aren't allowed here, so you won't get any cost estimates from here.
    Yikes! Sorry, thought a labor estimate would be appropriate.

  11. #11
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,931
    Maybe your home is just leaking too much air for the humidifier to keep up. How are your heating cost?
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  12. #12
    Join Date
    Jul 2010
    Location
    wisconsin
    Posts
    270
    Quote Originally Posted by RLymburner View Post
    I couldn't say anything about the sizing, but I first ventured into this forum asking about sizing question (3 contractors came out with quotes for similar systems, I went with company I felt most comfortable with)



    Home is 3.6k sqft, three floors including basement. Top floor is on its own zone. Main floor has several two-story areas. Basement is rarely used, so I close vents (habit I picked up from my mother to save on energy). Should I open?

    Installer has been back a couple of times, but from what I can tell, has only worked on the thermostat. How can I check to see if my system is staging the heat? (Not real familiar with this)
    If it cant keep up, call the company back, and ask them to rectify the problem with a service tech, not an installer. If the tech cant make it work,ask the company for a steam humidifier, so it can humidify without a call for heat.

  13. #13
    Quote Originally Posted by tipsrfine View Post
    Maybe your home is just leaking too much air for the humidifier to keep up. How are your heating cost?
    Hard to say without a comparable baseline for neighborhood/area. Not sure how its helpful:

    Area: Mid-Atlantic
    Gas 2012 $67/month, peak $142 (02/12), low $24 (07/12)
    Gas 2011 $86/month, peak $207 (01/11), low $10 (08/12)
    Gas 2010 $112/month, peak $360 (01/10), low $22 (08/12)

    Electric 2012 $192/month, peak $268 (01/12), low $131 (05/12)
    Electric 2012 $211/month, peak $342 (01/11), low $93 (10/12)
    Electric 2011 $217/month, peak $290 (03/10), low $172 (10/12)

    Man ... I gotta talk to the wife about A/C costs!

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