Resolved Dometic Heat Pump - what's the loud grinding noise?

[Neal]

Neal, Sounds to me what you are hearing is the harmonics of the fan running and the compressor running at the same time. The sounds are somewhat close together and when the two sound waves cross they cancel each other out somewhat. Totally normal and totally a PITA.

Agreed. Used furnace last night. Done with the heat pump nonsense. Too loud right over the bed. Someday I may try turning zone 2 off and only use zone 1 and see how that heats the bedroom as the duct work seems to pass zone 1 through to zone 2.

 

[AbdRahim]

Since I don't like a lot of heat and appreciate less noise, at night, I run zone one on the heat pump and leave zone two off. If I really need more heat I will run a small electric heater in the living room only. I do use he heat pumps during the day sometimes, but the small electric heaters do a good job without the noise.

Hey if you think it is loud in a Newmar, try one of the other brands that has the A/C unit extend through the ceiling. It is like parking next to a busy runway.

 

[Gronk]

There is still a possibility of an unbalanced squirrel cage wheel contributing to the noise. Only way to tell is pull it apart and clean it since you are in there anyway.

 

[VTPete]

sound about like mine. Maybe louder but no context.
I have trouble finding a use for my heat pumps. Too loud and slow.

 

[osuallen]

Agreed. Used furnace last night. Done with the heat pump nonsense. Too loud right over the bed. Someday I may try turning zone 2 off and only use zone 1 and see how that heats the bedroom as the duct work seems to pass zone 1 through to zone 2.

Our bedroom unit is somewhat noisy on defrost. My solution is to set the bedroom a 2-3 degrees cooler than I want the night temperature to be and set the living room unit 1-2 degrees warmer than it would otherwise be for night. I can barely hear the front unit when in the bedroom and it has to get really cold for the back unit to kick on (down to pretty near needing to use the furnace).

 

[TJ&LadyDi]

Heated floors are nice and quiet! Just sayin’.

TJ

 

[Neal]

It seems this "grinding noise" which per above sounds like the defrost, only occurs with temps under about 47F outside. Currently it's 55 out and the heat pump is working well, no annoying noises. Only the bedroom (aft) unit has done this, the other zone has not.

 

[Neal]

Scratch that, it's doing it again. It's a harmonic vibration somewhere in the unit. I could probably go on the roof and push on things to find it but I'll pass on that for now.

 

[Neal]

I've continued to use the heat pump and for whatever reason "that noise" has stopped. For the longest time I preferred the furnace but the heat pump is what I've been using lately and prefer now. It seems to be more effective in heating than the furnace and without "that noise" it's actually less annoying. It's the same sound when using the air conditioner. Even down near 40 last night it worked well.

 

[Neal]

Back to this thread on the heinous grinding noise which is happening in 100 degree weather and trying to run A/C. I did another google and got good results showing freon line vibration. Today I got up on the roof while the A/C was running and sure enough I could see right away the cause. It's a cold line so I could touch it but I used my screwdriver initially and the noise stopped. I wasn't sure how to really resolve this so I had 15 inch cable ties and was able to get the tie through a piece of the casing and pull against the freon lines to keep them from vibrating. I can only imagine the freon line vibration would lead to eventual failure. The cause is probably the blower fan out of whack for some reason but for now we have peace and quiet again. So much so I can't even hear it running. Part of that is because I'm deaf from the high dB noise I've had to deal with all day long from this issue!!!

The freon tube is rapidly vibrating but I think the 30 frames per second video makes it look like its wobbling which it is not. It's a high rate vibration.