Humidifier Question

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Old 12-26-07, 05:42 PM
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Humidifier Question

I have a bypass humidifier on my furnace and a bypass ductwork for my zoning system. On my humidifier there is a damper that you usually close in the summer. Are there concerns if I choose to leave the damper on the humidifier open all year?

Thanks,
Jerry
 
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Old 12-26-07, 06:11 PM
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No safety nor health concerns either, but keep in mind that a bypass does just that "bypasses". If you leave the damper open during the summer, some of the air will bypass the cooling coil, hence won't be conditioned. Not a good thing during the dog days of summer when you want that coil to be working at its best removing heat and moisture from your home.

And remember to shut the water off and do a good clean-up of the humidifier components at the end of the heating season.
 
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Old 12-26-07, 08:06 PM
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[QUOTE=pflor;1282938]No safety nor health concerns either, but keep in mind that a bypass does just that "bypasses". If you leave the damper open during the summer, some of the air will bypass the cooling coil, hence won't be conditioned.



Thanks for the return. I was surprised about your comment on the bypass air would not be conditioned. Here is where I am confused. The duct work going to the bypass humidifier leaves at the very top of my furnace where the evaporator coil is located and then returns through the humidifier to the cold air return. So, it appears to me the air is conditioned before it is bypassed. Your comments please.

Jerry
 
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Old 12-27-07, 03:40 PM
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My bad! I apologize for the confusion.
Sorry about the late reply. Kids are off school, I've been out with them most of today.

Indeed, air is at a higher pressure in the supply trunk and will move through the bypass pipe into the return (and not the other way around) since it connects the high pressure to the low pressure side.

It's still advisable to shut the damper closed because the bypass duct may sweat. Not a big deal, but it may be an inconvenience (besides possible rust over time)
 
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Old 12-27-07, 05:39 PM
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It should be shut in the summer, the cold air is blown back into the return, and may increase the chance of the coil freezing up on you.

There are a lot of them out there that don't get shut in the summer, and has no harm. But like P said, the pipe may sweat.
 
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Old 12-28-07, 12:29 PM
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Originally Posted by Jay11J View Post
It should be shut in the summer, the cold air is blown back into the return, and may increase the chance of the coil freezing up on you.

There are a lot of them out there that don't get shut in the summer, and has no harm. But like P said, the pipe may sweat.
Thanks to Jay and pflor for the clarification. My original post indicated I also have a bypass duct work for zoning. Should I have concerns on the coil freezing up from that?

Jerry
 
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Old 12-28-07, 02:47 PM
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I wouldn't worry too much, but if you do notice frost on your lines, or heavy sweat on the ductwork, then better get a bypass.
 
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Old 12-29-07, 07:17 AM
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Originally Posted by Jay11J View Post
I wouldn't worry too much, but if you do notice frost on your lines, or heavy sweat on the ductwork, then better get a bypass.
Thanks for the reply, but I need to ask what may be obvious. You said if I had frost, etc. to get a bypass. I do have a bypass and I was wondering if that bypass (for zoning) could cause my coil to frost up. It would seem the bypass air for the zoning would have the same effect on my coil as the air from my bypass humidifier.

Jerry
 
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Old 12-29-07, 09:47 AM
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Yes, if the air is cold and by passing into the system from the zone, can also cause the coil to frost, and have a higher chance of flooding the compressor.

What's the smallest duct size on your zone system? How big is the bypass duct?
 
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Old 12-29-07, 06:14 PM
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Originally Posted by Jay11J View Post
Yes, if the air is cold and by passing into the system from the zone, can also cause the coil to frost, and have a higher chance of flooding the compressor.

What's the smallest duct size on your zone system? How big is the bypass duct?
Jay -

Zone 1 (1st floor) is a rectangular duct work that is 36 X 8. It feeds into two branches that measure 12 X 8 and 24 X 8. These branches are where the zoning dampers are located, one in each branch.

Zone 2 (2nd floor) is a rectangular duct work that is 24 X 8. And it has a zoning damper.

The branches feed 19 registers, where the duct work going to the registers are about 6 or 8 round as best I can t ell.

The bypass damper is 10 round.

The AC is 3 ton.

New Info:
My furnace installation is new and I have had some whining noise in my duct work when Zone 1 is closed and Zone 2 is open. The HVAC contractor said the noise is coming from my motor due to excessive back pressure. He wants to change my bypass damper to 12 round. I am concerned about too much air being bypassed with a 12 damper. However, as you probably know, the bypass damper has its own barometric damper where you adjust its opening and control bypass air through it.

Jerry
 
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