My air con/heat pump in defrost mode... Leeds, UK.

[back2space]

Hey guys, some of you wont bother but took a video of my ac system in defrost mode this morning, temps -2C outside in Leeds when the video was taken.

The system is a LG Multi Split Inverter, compressor is soo quiet. Most the noise is the fan.

Some pics also of the coil before defrost started, it was covered in ice, the unit had been running for 50minutes before defrost, very efficient defrost took only a matter of minutes, one thing noticed is that normally the fan does run in defrost mode however this time because it was so cold the fan did not run at all and the steam can be seen coming off the coil. At one point I get closer to the unit you can hear the inverter winding down as defrost comes to an end & at 1:51 into the video you can hear the 4 way valve come into action however passing traffic drowns this noise out. You can see from the car how bad the ice was, we had freezing rain.

It will probably bore most of you this post but just thought it would be different rather than problem solving for a change. :)

http://www.youtube.com/watch?v=6JZvqFWpA7U

Plus we have nearlly resolved our probs with temperature monitoring inside, we are waiting for the installer to come back and install 2 remote sensors halfway up the wall to monitor temp better.

[multisync]

Must be me but I didn't see the outdoor isolator?

Multisync
London

[back2space]

Its right behind the unit mounted low down so that people do not see it, the garden is open and dont want someone coming up and theres a bright red/yellow button for people to tamper with.

[paul_h]

Must be me but I didn't see the outdoor isolator?

Multisync
LondonIf you expect every a/c to have an isolator, you won't like australia :mad:

[back2space]

As soon as the outside temp got to 2C there wasnt ice appearing on the coil like there was at -1. IN fact when it went into defrost again there was no ice on the outside of the coil????

[Brian_UK]

It's based on coil temperatures and running times I believe so amount of frost visible is not always the criteria.

Video ? 8/10, probably due to condensation on camera lens. ;)

[back2space]

HAHA, or have i lost 2 points because of the poor quality of my camera phone more like!!!!

[back2space]

Well looks like the weather in the uk about to take a turn, temps not been much above 1c all day already at Its the same situation today, were at 0C at night and we have snow on the ground and the indoor temp when I got in was 14C it is now 4hours later and we have just got up to 22C. Its struggling to get above 22.5C though and I think thats due to it being so cold outside. Should it be able to heat up any higher than this? When the central heating is on, the central heating will only manage to get the indoor temp upto about 21 after being on for the same ammount of time.

The reason we have the system installed is because we have no control over the central heating system so it comes on for 2hours in the morning, and 5-10 in the evening, outside of those times we have to use electric heaters which were costing a fortune on our coin meter. Since we have had this the house is nice and warm however just worried that if its managed to pull temp upto 22.5 it should be able to go higher and higher. Perhaps will just slowly climb. Just looked at temps again and were at 23.5 now with outside temp of -0.5C. Air off the unit is really toasty warm! :)

http://www.refrigeration-engineer.com/forums/images/VA_RE/misc/progress.gif

[Brian_UK]

It all goes back to how good the heat load calculations were.

The fact that you have 'hot' air being discharged is a good sign but, you know us;), what temperature is "toasty warm" ?

[back2space]

Just checked air off and its 34C when maintaining setpoint of 23C, when I put it upto 30C on the remote the air off then becomes 37C i assume would climb further if left for longer as its an inverter.

Does this seem about right, outside temp is -0.2C

One other question, would you say its better to leave the unit on overnight maintaining setpoint rather than have it work very hard tmrw to bring room upto 23C?

At the mo its happily coming in and out every 10mins or so for 10minutes at a time to maintain whereas if its bringing the room up from 14C it will be on constantly for about 4hours to get upto 22C when the setpoint is 23C. During this time the coil will freeze over becoming white outside which obviously decreases heat output?

Which would use less power? And what setpoint would you use if you was reducing it at night and whilst not in the house?

[back2space]

Just to point out also brian the units are oversized in cooling and heating also. We used to have a 2kw portable heater in here that would heat the room ok but would be pretty much constantly on. These are 3.5kw units we have now.

[Brian_UK]

I seem to remember that you had discussed the sizing of the units earlier/elsewhere, sorry.

It's hard to say sometimes about keeping equipment running overnight/constantly. Would you operate it at a night set back temperature or try to maintain the 22°C 'ish condition?

[back2space]

I guess I would operate it at a lower temp at night, as obviously if no heat at all the house is dropping to 13/14C. Very cold when your in the house during the day and the unit is working overtime to get it back upto 22C. So i was looking to perhaps set it at 18/19C at night then come day time time bang it back upto 22C? What do you reckon and do the air off temps seem ok? This unit is supposed to have 80% capacity still at -15C.

[Brian_UK]

Seems fair, you can but try.

Temperatures seem pretty good. (Logging off now, have a quiet night)

[back2space]

Cheers bud. Sleep well.

[back2space]

After leaving on all night with set point of 18C its used hardly any electric to keep the house at 18c. The unit is now happily running at 22C after taking just an hour to reach the 22c from 18c.

[Brian_UK]

There you go, just need to install that log-burner now for that authentic cozy glow.

[Karl Hofmann]

To be honest, on a reasonably well insulated home it would take a long time to drop from 22 to 18c... My night set back on my CH is 18 with a daytime setting of 21 and never comes on at night.. If I am working late, then I click on my living room heat pump and leave the door open and let the warm air rise in to the office at the top of the stairs.

The only real issue with my LG Artcool (Fixed speed) has been in times of freezing fog or snow, the frost does get a little too thick and won't shift fully in defrost forming an ice coat preventing air flow..

Must admit, that although it is against regs, I didn't want to have an outdoor isolator.... So I didn't fit one... The isolator inside is clearly labeled and the unit is on an RCD. It is my view that this is more than adequate for a domestic installation

[back2space]

My house is a very old victorian house converted into flats, we have a cellar downstairs that is half converted into a flat. The temperature drops very quick inside the house so the units are oversized to cope with the heat loss. The house has double glazing but theres no cavity wall insulation or anything in between the floors so it could drop to 17C in a couple of hours.

Weve had a couple of defrosts the last couple of days, the annoying thing is you can see that it needs to defrost cos the output is dropping and you look at the coil and its covered in ice. However it doesnt kick into defrost for about half an hour after that point. It gets so bad that the fan isnt even able to pull air through.

[Karl Hofmann]

Ha! When it comes to buildings, then I'm afraid that I'm a soulless sod.. If it cant be insulated, then knock it down and start again.

Every LG that I know will frost up till it is clogged solid before it goes in to defrost.. By comparison the Toshiba in my dining room defrosts well before it gets to that state... And it doesn't make clunky, whooshy buzzy noises like the LG.... And that is one of the best LG units that I have ever fitted..:D

[back2space]

i'll have you know karl my lg doesn't make those sort of noises lol. You can hear the valve reversing when its in defrost. Other than that its silent check out the vid compressor was running whole time.