[Mott Rettop]

Hi,

I have a new mini-split installed for the upstairs and when in heat mode it controls both heads at +6 above the setpoints.

In AC mode it controls temperature just fine. This problem only exists in heat mode :-(

The heat pump is a 3MXS24RMVJUA and one of the heads in 9K BTU and the other is 12K BTU

Daikin tried to blame it on the WiFi but that can be disconnected and the problem remains...

Here's a link to a guy with the same problem last year: (cant post links? - Search "Daiken Temperature Offset")

/hvac-talk.---/vbb/threads/2244114-Daikin-temperature-offset

This system(s) is sitting there reporting the correct room temperature and yet it controls at 6 degrees off the setpoint!

You couldn't design a system with a stupider failure mode!!!! Nice going Daikin!!

Thanks!

 

[VTP99]

Is there no offset adjustment ?

 

[rundawg]

I moved your thread to the "AOP Residential HVAC (Beenthere Zone)" forum as the other forum is for Commercial applications.

Please take note of this new location as the "Moved" icon in the other forum will only last a day.

 

[Mott Rettop]

No...according to the installers.

If there was it would only be for Heat mode (which seems odd!)

Thanks!

 

[Mott Rettop]

Hi,

is that why I only got 1 reply on a subject I would have thought would get dozens?

 

[rundawg]

Hi,

is that why I only got 1 reply on a subject I would have thought would get dozens?

You can never predict the number of replies to any thread, but with your thread now being in a forum more applicable to your situation (Residential and not Commercial), the number of responses should improve.

 

[FlyersFan]

A lot of mini split heads use some outdated logic for what Mitsubishi calls "heating height offset". They assume that where the head is located higher on the wall is going to be 3°C warmer than where people are so the logic subtracts that temperature from whatever the room thermistor is reading to try to make it warmer at person level. Combine that with the fact that on a multizone unit in heating the expansion valves don't close all the way when a system is satisfied and the indoor blower constantly runs to keep air moving over the return sensor, and you have yourself a perfect recipe for overheating the space. Can be turned off on most Mitsubishi units, not sure about manufacturers' equipment.

 

[Mott Rettop]

Yea...I would think that is pretty stupid, if air is moving in the room, that plan falls apart!

Anyway Daikin said it should be mounted at 6' and since this is a cape cod then it had to be about 4'. I can't see that making a difference of 6 degrees on the plus side though!

 

[pecmsg]

That # is just a guide. Find a spot where you're comfortable and leave it there!

 

[Mott Rettop]

Problem is I need it to work in Auto mode as it's in the Mother-in-law's area. I would never be able to explain all of the things she would need to do, whether in AC or Heat mode, if I just ran it with an offset.

 

[ksefan]

Does Daiken make a console model?

 

[pecmsg]

Problem is I need it to work in Auto mode as it's in the Mother-in-law's area. I would never be able to explain all of the things she would need to do, whether in AC or Heat mode, if I just ran it with an offset.

No mini split works well in AUTO between heating and cooling!

 

[Mott Rettop]

Both rooms it's servicing are facing the sun, they should both experience the same external perturbations.
(both setpoints are only degrees apart and stay set that way)

I'm an EE and for the life of me can't see why that would be a very hard to control situation ��

 

[pecmsg]

Both rooms it's servicing are facing the sun, they should both experience the same external perturbations.
(both setpoints are only degrees apart and stay set that way)

I'm an EE and for the life of me can't see why that would be a very hard to control situation ��

Complain to Daikin. We don't design or manufacture, just service and install!

Besides it's a lot easier to just accept it as that's the way it is!

 

[ksefan]

Did your contractor explain this to tech support?

 

[Mott Rettop]

Yea...they said they did. Now they put me on a waiting list for a Daikin "roving expert" to come out and look at it. (the installers have come out 4 times I should add, each time I explained the problem completely and no one seems to get it, as in the possible suggestions about why are really very poor)

I'm losing faith in humanity at this point...

 

[ksefan]

If the contractor did not know the unit was supposed to be installed at least 6 ft high, they should remove it and install a different unit.

 

[EugeneTheJeep]

Yea...I would think that is pretty stupid, if air is moving in the room, that plan falls apart!

Anyway Daikin said it should be mounted at 6' and since this is a cape cod then it had to be about 4'. I can't see that making a difference of 6 degrees on the plus side though!

4' is quite low, set the temp to a colder number.

 

[pecmsg]

Yea...I would think that is pretty stupid, if air is moving in the room, that plan falls apart!

Anyway Daikin said it should be mounted at 6' and since this is a cape cod then it had to be about 4'. I can't see that making a difference of 6 degrees on the plus side though!

Pretty Stupid for a manufacture to make all those silly recommendations for where and how they want their equipment installed all over the world. :gah:

 

[Mott Rettop]

I need auto mode to work!