Fujitsu Heat Pump

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gcorgnet

1078 posts

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#123318 3-Jul-2013 10:55

Hi,

Just got a Fujitsu Heat Pump installed and I am just wondering about one thing: It seems like the temperature of the air coming out of the unit (indoor) is directly related to the temperature I set on the remote. eg I set it to 20deg and after blowing hot air for a while, it started blowing tepid (at best) air at about the same rate. This actually felt a bit cold since the air was moving... Is this expected? If the inside temperature has reached its target, why not simply stop blowing air (or only blow minimal amount) and pick up later as temp drops?

Maybe it's something we are doing wrong or maybe this is just how it is supposed to work but if it is, I find it quite strange.

Any help, experience, etc appreciated!

Thanks,

Guillaume

ubergeeknz

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Vocus

#848629 3-Jul-2013 11:00

If you set fan speed to "auto" and mode to "heat" - it should do just that, usually.

Goosey

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#848670 3-Jul-2013 12:00

As per previous post, you need to set the fan speed to 'auto' and the make sure your using 'heat' mode. Do not use 'Auto'...always use 'heat' for heat, 'Cool' for cool. Dont bother with Dry or Auto.

If your using 'auto' the unit will always heat and cool to the temperature you select....wasting time, money and making your HP work harder than it has to. Dont get this confused with 'auto' fan.

Also, dont try to quickly heat the room when you first turn on the unit. Start out low fan speed and low heat for a few minutes.

Niel

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#848827 3-Jul-2013 15:41

To add to above, if in auto mode then the hysteresis is greater because the heat pump cannot smoothly switch between cooling and heating, much better to set it either to cooling or heating but not cycle.
EDIT: This does apply to inverter drive, not only on/off drive.

Ours was set to 23 degrees, but then we got the power bill... Dropping to 21 degrees made some difference and is fine for us. It comes on at 21 when the kids come home, then drops to 18 at 11:00. Works well for us. Also now that my reverse-heat-transfer system is installed, the bedrooms are more comfortable and no more condensation (note, there is no ventilation, this is only sucking stale air out of bedrooms and blowing it into the living space).

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Batman

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#848830 3-Jul-2013 15:46

your problem is the thermostat.

if you set say 21 degrees, it does not mean 21 degrees where you face is. it means 21 degrees where the thermostat lies.

so if the heat pump is sitting in a nook with low ceiling and smallish room, the thermostat (which is at the top of the heat pump or something like that) will reach 21 degrees very quick especially if the ceiling is well insulated at that particular vicinity.

set the temp higher until you get it right for that particular day. on a colder/warmer day/night the thermostat micro vicinity will reach 21 degrees at a different room temperature.

you'll never win!

good luck

gcorgnet

1078 posts

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#848834 3-Jul-2013 15:55

Thanks for input guys.
We'll monitor over the next few days and report back.

Cheers,

Guillaume

Stan

929 posts

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#848907 3-Jul-2013 19:24

Niel: To add to above, if in auto mode then the hysteresis is greater because the heat pump cannot smoothly switch between cooling and heating, much better to set it either to cooling or heating but not cycle.
EDIT: This does apply to inverter drive, not only on/off drive.

Ours was set to 23 degrees, but then we got the power bill... Dropping to 21 degrees made some difference and is fine for us. It comes on at 21 when the kids come home, then drops to 18 at 11:00. Works well for us. Also now that my reverse-heat-transfer system is installed, the bedrooms are more comfortable and no more condensation (note, there is no ventilation, this is only sucking stale air out of bedrooms and blowing it into the living space).

Bit off topic but the heat transfer system you did works off the principle of creating a vacuum in the bedrooms there by encouraging air to move in that direction? If so how well does it work? What fan are you using?

Niel

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#848975 3-Jul-2013 22:16

Stan: Bit off topic but the heat transfer system you did works off the principle of creating a vacuum in the bedrooms there by encouraging air to move in that direction? If so how well does it work? What fan are you using?

Yes, drag air through hallway where it looses less heat than through ducting. Ducting you can expect to loose a few degrees loss, insulated ducting is only about R0.8. Conventional heat transfer only works when you have a concentrated heat source like a fireplace, not a temperature regulated heat source.

I've got a 200mm centrifugal fan and well insulated ducting on TradeMe (search for Mingfans).

Currently the fan runs at full speed, only get noise on the outlet and only because the fan is too close to the outlet (and high speed causes turbulence).

Actually our aircon now works much better, at times we drop the setting further as the ventilation fan is creating better air flow in the living space.

Temperature in the bedrooms down a 10m corridor is 2 degrees less than the living space (measure with a thermocouple).

We have a Mitsubishi aircon, base model but 7kW. Highly recommended by an independant installer, he gets the same mark-up from all brands but Mitsubishi has the least problems and longest warranty.

The intention of what I did was to get better performance to the bedrooms, which turned out okay, but unexpectedly it improved performance in the living space. So yes, a but off topic, but a side effect was getting better aircon performance.

At work in one of the small labs we have a standard wall mount split aircon (Fujitsu?) which has the temperature sensor in the remote (there are slots on the top corner where the sensor is). It did not work well when someone left the remote on top of a heated cabinet... Interesting that our Mitsubishi remote also has a small hole at the back on one top corner, and the manual says you need to store it in it's wall mount cradle.

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Niel

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#848987 3-Jul-2013 22:41

I had a closer look at this, a user manual of a 10 year old Sanyo aircon says the remote has a temperature sensor and sends the measurement to the head unit every 5 minutes. If the remote is out of range, batteries flat, or lost then the head unit will switch to it's built-in sensor.

A current model DeLonghi Dein38 also says it has a temperature sensor in the remote.

Can't be bothered looking further this time of the night, think we have enough evidence that remotes have a temperature sensor built in and the head unit sensor is only used when the reading from the remote is not available.

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timmmay

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#848990 3-Jul-2013 22:46

Anyone know if the Fujitsu Nocria remote has a temperature sensor in it?