Replies

1. 
   DanH | Nov 21, 2008 07:30am | #1

   They're supposed to run a defrost cycle (run backwards) every so often to eliminate icing. If this is not happening it may be that the timer isn't working.

   The only function of economic forecasting is to make astrology look respectable. --John Kenneth Galbraith
1. 
   losh | Nov 21, 2008 10:41pm | #5

   I called the installation company for the annual maintenance routine and told them to have a look at the defrost cycle. I wonder how long this would have went on without me noticing? The Heat Pp worked fine cooling the house in the summertime.

2. 
   john7g | Nov 21, 2008 03:21pm | #2

   I know squat about HVAC but had one unit that a plug had come loose that prevented the defrost cycle from occurring (at least that was the story I was told).  Maybe pull the cover and look for loose plugs/connections?  HVAC guy also adjusted the intervall between the defrost cycles.  Kind of neat to see the cloud of steam lift off when it's working.

1. 
   JTC1 | Nov 21, 2008 03:35pm | #4

   I was working at an occupied home with 2 heat pumps.  House next door under construction.  I pull into driveway one morning and a guy from the next door crew comes running over to tell me about noise from one heat pump.

   Iced up to the point where the fan blades were hitting the ice pack.

   Knowing squat about heat pumps and considering this unit was only about 6 months old, I yanked out the electrical disconnect and called the installer.

   Installer came out in a few hours, opened up the panel and found one of his guys had never connected a wire controlling the defrost cycle.

   We thawed enough ice with a heat gun to eliminate fan contact with the ice and fired it up.  He had to trick the unit somehow to get it to go through the defrost cycle several times in a row. We checked unit #2 while unit #1 was defrosting - it was OK.

   Cool looking steam plume!

   Both units have worked fine ever since.

   Jim Never underestimate the value of a sharp pencil or good light.

2. 
   rasconc | Nov 22, 2008 09:23pm | #8

   When we first got our HP it scared the poop out of me when I saw that gigantic puff of steam for the first time.For those who have fought for it Freedom has a flavor the protected will never know.

1. 
   john7g | Nov 22, 2008 10:04pm | #9

   kinda the same

   Had no clue what I was doing. Staring at the ice cube in a drizzzle @ 32° thinking this can't be good.  Got my heat gun and chords and as I was kneeling down to start to thaw it out with the HG everything went white while I stood in a cloud of steam.  At least I got a laugh out of being wet & miserable.

3. 
   junkhound | Nov 21, 2008 03:22pm | #3

   Before we installed the WSHP (water source), and the conditions were ripe for coil icing, if I saw ice I'd hose down the unit and melt the ice before the defrost cycle started. Poor man's WSHP.

   Many HP's defrost cycle are on a timer, every 45min or so.  Better HP's have temp and icing detection circuits.  Your HP should defrost within 1 hour, you will see a big puff of steam when it occurs.

4. 
   Clewless1 | Nov 22, 2008 07:09am | #6

   what is Pp?

1. 
   losh | Nov 22, 2008 09:20pm | #7

   Sorry, it's short for pump. You might also see Vv, it is short for Valve. Lingo we use, not sure if it's used everywhere though.