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-   -   Strange pinging sound from heat pump normal ? (http://www.diychatroom.com/f17/strange-pinging-sound-heat-pump-normal-14988/)

Siffleu 01-01-2008 09:55 AM

Strange pinging sound from heat pump normal ?
 
since having a heat pump is new to me, I would like to know if I should call someone to check my heat pump because of a little pinging noise (like a popcorn into a can) that seem to came from the compressor on the exterior unit. I got it installed for about a month now. It's a Carrier 38QRF018 with a 40QNQ018. I had a look on the exterior unit and it's frosted. 25 F outdoor and indoor unit set to 66 F.

thanks

edit:had it stop for 15minutes, restart it, same sound came after few minutes... had it stop again 15min went to cooling mode, had the exterior coil defrosted a bit for 15minutes, stopped 30 minutes, turn back on heating and no more pinging sound but came back hours after...

jerryh3 01-01-2008 09:57 AM

It's probably the sound of the metal expanding and contracting.

Siffleu 01-01-2008 10:19 AM

no it's not
sound come from compressor...
here is the little story of what I might think the source of the problem...

when the unit has been start a month a go, about 10 ft of piping (5/8 and 3/8) wasn't covered by armaflex.

yesterday I've finalized all this and everything is now covered... could it be possible that the new insulation has changed something into the initial r410 charge ?

I mean, gas has been added because unit is made pre-charged for ~25ft of piping and I have 50ft. If we consider the temperature vs pressure chart, adding insulation to 10 ft of piping at the back of the indoor unit could change something or not ?

bigMikeB 01-01-2008 06:46 PM

Let the unit run and don't start and stop it when it's in the defrost mode. Does the compressor have a crankcase heater? And NO, insulation on the tubing won't effect the charge.

Siffleu 01-01-2008 08:38 PM

if I let it run, it won't heat a lot...

if adding insulation increase the temperature of the liquid/gas phase before the indoor unit, then probably there is a mess of where the liquid/gas come back to liquid/gas. I tell liquid gas because I don't really know in heating mode if it's gas first and switch to liquid after beeing into the indoor unit...


I don't really have the correct word to express my thinking but you probably understand what I try to describe as the possible reason of all this

because I run this for a month now without this new noise, but yesterday. I have installed the last 10 ft of armaflex on piping, and since this that, I have notice this sound from the compressor

so I think of a overcharge or a undercharge of r410 since the condition have changed with adding the insulation..

bigMikeB 01-01-2008 10:30 PM

Trust me piping insulation has no impact on the freon charge. If you have to start stop the unit to get it to work, you have other issues than armaflex. Who charged the unit? Was it charged in the a/c mode? In the heat mode you have hot gas going to the indoor coil to be condensed to liquid. Who wired the control wiring of the unit?

Siffleu 01-01-2008 11:08 PM

Quote:

Originally Posted by bigMikeB (Post 84671)
Trust me piping insulation has no impact on the freon charge. If you have to start stop the unit to get it to work, you have other issues than armaflex. Who charged the unit? Was it charged in the a/c mode? In the heat mode you have hot gas going to the indoor coil to be condensed to liquid. Who wired the control wiring of the unit?

the unit has been charged by a hvac tech who normaly don't really do carrier unit but he followed the temperature vs pressure chart

the wiring has been done by myself according to the wiring diagram inclued with the unit (electrical part, and thermostat wiring)

the unit was working fine for the last month. the suddenly ping sound(popcorn in a can) came the day after the insulation...

considering the sound come only ~45min after starting the unit in a cold start, this is why I tought it might be explained by the added insulation because now, gas come hotter in indoor unit now because at the back of the indoor unit was the garage's attic, also, a cold place

undone 01-02-2008 12:43 AM

Sounds familiar. I'm guessing scroll compressor (maybe not). Smaller capacity heat pumps opperate better with an apparent overcharge. For whatever reason the pressure/temperature chart is for reference--be certain all variables are considered. Next, get a sound blanket to cover the compressor--these help considerably.

bigMikeB 01-02-2008 11:19 PM

Did he charge it in the heating or cooling mode? Heat pumps need to be charged in cooling mode. Charging any heat pump is in no way brand specific. The charge is only relavent to the size of the unit and piping and temps. Superheat and sub cooling don't change with a manufacturers label.


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