Same thing all over again
So here we are, it's two years later and it appears that the sliding orifice (aka Flowrater) in this heat pump has jammed once again after a long summer without use. In heating mode, there is plenty of heat in the refrigerant supply to the AHU, the line out is cold and there is very little heat output in the air coming out. I can only assume the small amount of heat output is due to a lack of refrigerant flow.
I haven't jumpered to test cooling but I seem to remember these exact symptoms last time.
Assuming that it is the same waxy crap causing the issue:
-Does anyone have any ideas what could be the source of the waxy crap?
-One of the previous posters commented that a dirty coil could result in high ref temps. Is there a known upper temperature limit for POE oil or any other R410A additive that I need to beware of once back in operation?
-Any success on freeing up the slider without sucking down the system and pulling it all apart?
Last edited by timevacuum; 10-04-2012 at 04:35 PM.
I should have followed up on my previous reply two years ago, so sorry about the delay.
I mentioned the dirty coils because high head pressure and high compressor discharge temperatures go hand in glove. When refrigerant oil becomes too hot, it begins to break down and form carbon deposits. A film of this carbonized oil tends to show up in metering devices, because this is the location in the refrigeration circuit that has the most narrow paasage. Everywhere else the carbon partiicles tend to stay in suspension, but precipitate out in the metering device. Just this past summer I saw this first hand in a Trane Voyager rooftop unit with a metering manifold and a double row condenser coil. An unbelievable amount of dirt had built up between the two rows of coil, causing high head pressure. Double row coils can easily be missed by even well meaning techs who clean coils yearly. If you don't split them apart, they don't get clean enough. Not nearly. Micro-channel coils also need careful attention to stay clean.
The last time your system was serviced, was a new liquid line drier installed?
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.
Leaking A coil Found
-two year or two hours, either way I'm thankful for your response!
In answer to your question, it took some convincing to get them to change the drier/filter last time. It was tough as I was caught between "trust your tech" who says it isn't required / not something they normally do and me insisting on the good advice I have seen on this site.
I have changed techs away from the local factory authorized to another with good recommendations. Not that the other guy had any bad recommendations. However, one good sign is that after I told him the tale, one of the first questions was "Did they change the drier filter?" He looked at the system today and it appears that it may not be the orifice after all. He found oil in the drip pan and a very small leak in the A coil at one of the end turns. I guess we have been breathing POE oil for a while. Yikes! He will be back next week to fix it and I suppose I have just experienced the Goodman difference.
While the system is sucked down, we'll have a look at the orifice to see if it has any issues. I don't think that a clogged orifice would increase pressure in the A coil enough to cause weak points to pop, would they?
Last questions. I checked after the tech left and the coil is still under warranty.
-Does Amana/Goodman replace the whole coil if there is a small leak?
-Are new coils any better than the ones built in 2006 (year installed) design wise? problem wise?
-Any advice? Should I a)repair coil by new tech. b)install new coil with old factory authorized tech c)install new coil with new tech (Will Amanda/Goodman allow him to do it if not "factory authorized"?)
Have him leak check the coil. If it is leaking have it replaced.
Originally Posted by timevacuum
Where is the manual? What does it say?
Have the new tech replace the coil. Goodman/Amana doesn't care what company replaces it.
The tech found a tiny leak with his sniffer on the first visit.
will the replacement evaporator likely be an aluminum coiled unit?
I will search but if there is a debate somewhere on Goodman copper vs aluminum, a link would be nice especially if discussing Gooman in particular. What are your thoughts?
I would try and get the newer all aluminum coils!
Yes, you want aluminum. I have had lots of leaky copper Goodman coils. So far aluminum seems ok.