Should an air handler \"howl\" ??

D.Carpentier

Hi guys,

Why would my air handler howl when its fan and circ pump are running ?

It doesnt howl when just the fan is running.

It doesnt howl in the summer, when i run the circ pump and fan in quasi-a/c mode (i use the a/h circ pump to push the liquid thru the slab trying to pick up some coolness back into the a/h.. seems to work but needs some tweaking)

It just seems to howl when things are hot.

The freq of the howl is probably around 1000 hz. (Im a telco guy, and im used to the 1000 hz test tone signal. lol)

Ive bled the circ pump in the a/h numerous times. There's a air bleed in the highest line connected to the a/h. And Ive tried pushing and pulling on most things in the box.

Did i just get a crummy a/h ???? (for $900 i sure hope not..)

Thanks for any advice..

Dave

Weezbo

hmmm....

try cleaning the fan ? if it is an oiler oil it. bearings like oil from time to time.dust and fuzz bunnies make a fan "Drag" and can burn out bearings and races.when the smoke is let outta them bad boys its way spendier than a few min of time cleaning stuff and 4 drops of oil.

don_25

Well then I guess one can rule out the fan.It sound more like the circ made be to big.

Hot water has lower density and lower viscosity.And it just
the opposite with cold water,That properly why you dont here it in the summer.

What size is the circ?

Mark Hunt

Just when it's hot


sounds like the coil may be expanding and restricting air flow.

What water temp is running to the coil?

Mark H

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Jerry Boulanger_2

It's possible

that what you are hearing is cavitation. If the pressure inside the coil is low and the water is hot, vapor bubbles can form - as they cool, or move into an area of higher pressure, they implode. You will hear the same noise coming from a low mass boiler at high temperatures if the flow is below spec or the system pressure is too low.

D.Carpentier

Thanks for the replies, guys..

Don. The air handler is an Enerzone unit with a Grundfos internal pump. Ill pull the lid off and check the model of the grundfos if visible.

Mark. The a/h is tapped off the boiler in parallel to the primary loop, so it gets full boiler temp (currently at 160-170 deg). As i was leafing thru my papers just now I noticed a warning for the Enerzone not to exceed 180 deg. Im running pretty close to the design limit, i suppose.

Jerry, also along the thermal idea.. would cavitation create a steady state buzz that may be vibrating something else in the cabinet and thusly the "howl" ?

In any case, Im going to drop the temp on the boiler down to 150 and see what happens.

Dave

Ken D.

Howl

Sounds to me like you are moving too much air at too high a velocity. Either the ducts, coil or registers are not sized properly. The reason for more noise in heat is that the hot air molecules are moving faster than cooler air making the hot air easier to move,thus moving more air. Is it possible to reduce the fan speed any more? Please let me know how you made out.

Rudy

Gotta go with Jerry on this one..

Simple test... while it's running interrupt power to the pump.....then fan. That should tell you if it's an air or circ. problem. I've heard low mass boilers "whine" and your AH might be doing the same

D.Carpentier_2

howling a/h (it gets better..)

Dropping the boiler temp primary loop (of which the a/h is tapped) down to 155 didnt make a difference.

What I stumbled across when I went to do the pump vs fan test...

TStat off, fan on manual, heated water: runs quiet.
TStat on, fan on auto, heated water: howls.
TStat on, fan on manual, heated water: runs quiet.
TStat on, fan on auto, cool water: runs quiet.

From the wiring diagram on the electrical cover plate, it appears that the manual fan switch powers (via a relay), the black wire going into the fan motor. But, the Tstat/pump relay powers the motor (relay) a red wire.

Ill assume this is a 2-speed motor ?

Sure does sound like a combination of the heat AND the fan speed.

Ill mess around more shortly.

(thanks for the replies)
Dave

Mark Hunt

I made an \"airhandler\" howl once


I dropped a furnace on his toe!

I couldn't resist!

Mark H

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