Insulator for return air sensor

[back2space]

Having a couple of probs with a return air sensor on our LG wall mount.

Its installed in a very cold room with cold outside walls.

The original placement of the sensor is against the coil, which controls well if only one unit is in operation.

Due to it being a multi split if any other unit is turned on then hot gas is circulating the entire system even on units that are thermo off, this then raises the temp inside the unit so the unit doesnt come on when the room temp has dropped.

Turn the other units off so that the wall unit drops at the same rate the room temp drops and we end this problem.

Obviously need to use the other units so decided to point the sensor out through the filter and into the air, this means the unit now comes on when the room temp drops but comes on too early, or it overshoots the set temp, the only reason I can think for this is because it is sensing the draught coming down the wall.

The unit might be on for half an hour raising room temp but then cycle off and then 5 minutes later it starts another cycle, this I believe is because the cold wall is making the sensor temp drop very quickly.

There isnt a remote sensor available for this model so have to keep it at the unit, is there anything that can be wrapped around the sensor some sort of insulation so that it is insulated from the draughts but will still read the room temp but not get as cold as quick.

Eg the room temp might not even have dropped 0.1 degree before it thinks it needs to heat the room back up.

What can you use?

Thank you.

[momo]

The wonders of LG: on heating some wall splits will run a 2-3minutes cycle to test the air temp... blowing a draught of (cold) air across the room for 15 secs! Evidently they have tried different solutions to the return air measuring problem. Once out of guarantee cut and extend the sensors wires about a foot - but no more since RF (Mobile phone crap etc) will probably cause problems - to where you find a better reading. At present a lump of "blu-tack" or kids plasticine should slow down the response of the probe. P.S. I admire you insitence at trying to solve a manufacturers faults publicly! It is educative for all !! Mind you I would rather not have you as a customer !!!!

[back2space]

The wonders of LG: on heating some wall splits will run a 2-3minutes cycle to test the air temp... blowing a draught of (cold) air across the room for 15 secs! Evidently they have tried different solutions to the return air measuring problem. Once out of guarantee cut and extend the sensors wires about a foot - but no more since RF (Mobile phone crap etc) will probably cause problems - to where you find a better reading. At present a lump of "blu-tack" or kids plasticine should slow down the response of the probe. P.S. I admire you insitence at trying to solve a manufacturers faults publicly! It is educative for all !! Mind you I would rather not have you as a customer !!!!

HAHA I know a few people have said that but ive had that much let down with engineers who have messed things up in the first place I think its not all LG;s fault but this sort of thing is.

We had to put remote sensors in on the floor units as they dont even do the 15second fan thing they just sense temp inside the unit so room temp dropped quicker than inside the unit!

This time its other way round!

There is a rubber sheath that is around the wire of the sensor, I have managed to pull this further down the wire to cover the end of the sensor... will this do the same as a blob of blue tac.

Once the sensor has been extended where would you place it? At the moment it is sticking out of the unit about 1 cm, and away from the wall, I imagine it would be worse if it was mounted on the wall.

[back2space]

OK so this rubber sheath thing has stopped the unit coming on so much and allowed the room temp to drop a bit more before it constantly cycling off and back on again.

However... whilst the room temp was maintained at 17C all night, if I set it to 20C, the room temp will reach 22C and it will still be blowing hot air, its obviously still detecting that cold wall!

Most annoying as evenings the unit is set to 20/21C but is unnessesarily runnng over set point.

[Brian_UK]

I know that it isn't pretty but have you tried putting a sheet of something like cardboard above the unit to deflect the falling cold air away from the sensor area.

If it makes a difference then it might give us another angle to try.

The idea of using Blu-Tak makes me think of fridge sensors which are placed inside dummy product blocks to simulate the cooling effect better.

The trouble is with insulating the sensor in this fashion is the it may well slow down the restart time but it will also delay the switch on time.

To be honest I think that you are trying to get the results of a close control air conditioning system when you only have a comfort cooling unit.

[back2space]

I know that it isn't pretty but have you tried putting a sheet of something like cardboard above the unit to deflect the falling cold air away from the sensor area.

If it makes a difference then it might give us another angle to try.

The idea of using Blu-Tak makes me think of fridge sensors which are placed inside dummy product blocks to simulate the cooling effect better.

The trouble is with insulating the sensor in this fashion is the it may well slow down the restart time but it will also delay the switch on time.

To be honest I think that you are trying to get the results of a close control air conditioning system when you only have a comfort cooling unit.

Hi Brian

Thanks for your reply... I have tried having the sensor poking out the top of the unit but its then affected by heat rising out the top of the coil when the unit reaches thermo off and the other rooms are thermo on (oil return thing meaning refrigerant circulating all the time).

I have tried a different place so it is very close to the plastic of the unit so hopefully this will mean it isnt feeling air cooling down so quickly. I have also had it on the grilled just above where the air exits the unit so that it would hopefully mix with the room air but where the plastic casing got warm it just gave it false readings.

Its probably installed on the worst wall possibly due to it being a very cold outside wall, with no insulation and the wall itself actually can get condensation on it if drying washing in that room.... it really gets that cold!

the cardboard thing could be an option but I dont think my tennant would be impressed.

The unit was put in so as not using fan heaters which cost a fortune and can cause fires etc. THe outdoor unit had the capacity so it seemed daft to.

The close control I can see what you mean but really I just want it to do as it is supposed to without sensing the wall temp.

My lounge unit used to do similar but installing the remote sensor on a warmer internal wall resolved the issue as it wasnt feeling the external wall temp.

I think I need to get the sensor extended onto an internal wall so it isnt feeling the cold draft!

Thanks for your replies so far everyone, I hope you dont think " oh there he goes again" when I post, I find the forums really informative, I enjoy spending time here and have learnt a lot on how systems operate from various people such as thermatech and Nike123.

Thank you everyone.

[Brian_UK]

One thought, having done it on a larger scale before and this is dependant on finding the right bits.

Finding a small enough and quiet enough fan to fit under the plastic so that room air is drawn continually over the sensor.

[back2space]

One thought, having done it on a larger scale before and this is dependant on finding the right bits.

Finding a small enough and quiet enough fan to fit under the plastic so that room air is drawn continually over the sensor.

Thats something else I have considered lol, but the space inside the unit is soooo tight it dont close properly with the sensor poking through!