Tricky Furnace + Humidifer Question.

[Bill]

We have low humidity problems in the house, so I purchased a whole house humidifer and had it installed professionally. Here's the problem....

It only works when the furnace is working, which makes sense. But there is about 1 minute delay from furnace on to the solenoid clicks on and it starts to humidify. My furnace is high efficeincy, and only seems to run for 2-3 minutes at a time, then shuts down. So I am really only getting 1-2 minutes of humidity, and it is not really helping the house.

To prove my threory, I shut the furnace off, and let the temp fall about 5 degrees. Then I put the furnace on. and ran for sometime. The humidifier ran that whole time, and the humidity levels increased by 2% more than it stopped ans went back to about 31%.

Any ideas on how I can get the humidifier to run more?

Thanks Bill

[Stormin Mormonn]

It sounds more like your furnace is over sized. But you won't want ot change the entire furnace for the humidifier.

The couple things that come to mind to me are to run the furnace in "fan on" and see if the humidifier runs.

second, your furnace guy might be able to adjust the fan limit switch so it has a larger swing between fan on, and fan off. That would give you a longer run time. depends if it's got a mechanical fan limit switch.

[m Ransley]

Im not a heating pro , But a furnace running 2 to 3 minutes may be bad for the furnace because it doesnt warm up to real operating temp . And you surely cant reach optimal efficiency. Furnaces should run mimimum , Im guessing 10 minutes. 20 is better. Reset your anticipator. Or you are possibly oversized. Call a different pro to look at your situation, On my furnace a 3 minute cycle might give 1 to 2 minutes of fire, the rest is start up ,and cool down, without fire. How many times does it run an hr and what is outside temp. Im at 28 today, I may run 15 min once or twice an hr.. I think you need a better Hvac person

[Ron]

With a high efficiency furnace, you probably have a setting for continuous fan. Give that a try.

[Joseph Meehan]

I sense a bigger problem.

How often does your furnace cycle? That is when it is cold out how often does it turn on? How much does the temperature change during a cycle?

I am suspecting that the thermostat is not properly adjusted (short cycling, which will waste energy) or the furnace is oversized.

[Stephen R]

Honeywell manufactures thermostats that have built in humidity control. I think that you have to have a pro install them, since they are of a higher complexity than a standard thermostat. Check out Honeywell.com, or any thermostat manufacturer for that matter.

Stephen R.

[Tony Hwang]

[m Ransley]

Try an experiment , let the house cool 4-5 degrees. Put a thermometer on a vent , read it after one minute then 2 figuring that is all the heat you get till cool down cycle , now leave it on till you are up 3-4 degrees , before cool down cycle begins. Your difference is what is lost in heating your duct work and furnace to full effeciency. Its 30 where I am now and my furnace runs 20 minutes with a 2 degree rise on low fire of a 2 stage unit and 2 minute cool down. Also as others said try fan ON I dont know if your humidifier is wired to work but you will see it working. The humidistat thermostats may only work on variable speed units. Humidistats should be calibrated every few years , not electronic ones. By wraping them in a moist towel for 1/2 hr and setting them to

94-96%. Most that I see are 5 - 20 % off . I have a new Taylor it is 21% low.

[Chris Hill]

Adjust the thermostat's swing. Better yet, hire somebody who knows what they're doing to make sure the thing is set optimally. I can't see how a high efficiency unit would be very efficient starting and stopping all the time.

[TURTLE]

this is Turtle.

Well First You have a over sized heating system for your home as you say you have a 2 or 3 minute run time for a 2 degree cycle. Correct this problem and you will get a hold lot more humitity put in your home. Call the fellow who installed it and have him set you gas pressure at the lowest level allowed by the manufactor of the furnace. this will add run time and help humitifier out on more run time.

Second Now if you can get enough of run time out of it. have him wire up a over ride switch for the blower and humitifier to run on it's own when you have a humitifing problem. The humitifier will not put as much water vapor in the air as normal heating run with the humitifier but it will increase the water vapor to a point of being useful.

Thrid The next furnace you have install get a hvac installer that knows what a Manual J is and have him size your furnace correctly. If the first and second thoughts don't work out. Your out of luck till you can buy you a new furnace , but don't worry for you short cycling the furnace like your doing it. you will need a new one in the near future.

TURTLE

[TURTLE]

This is Turtle.

Over fired or Over sized.

TURTLE

[HvacTech2]

Hi m, hope you are having a nice day

On 07-Dec-03 At About 03:08:06, m Ransley wrote to All Subject: Re: Tricky Furnace + Humidifer Question.

mR> 0007001 From: [e-mail] (m Ransley)

mR> difference is what is lost in heating your duct work and furnace mR> to full effeciency. Its 30 where I am now and my furnace runs 20 mR> minutes with a 2 degree rise on low fire of a 2 stage unit and 2 mR> minute cool down.

If this is true you need to call a tech as it should have much more of a rise when running.

-=> HvacTech2