@derek-m - that left hand number unfortunately doesn't show the left hand end of the weather curve (it would be helpful if it did, or even more helpful what the current LWT set from the weather curve is). I think it is either a random number, which just by chance on this occasion happens to show one end of the weather curve, or more likely it is the LWT if running in fixed LWT mode ie no weather curve, and it just gets stuck there, even when in weather comp mode. I'm pretty sure it is on the front page because that's where you set the LWT in fixed LWT mode. The little tear drop is part of the clue, it means 'water flow desired temp' according to the manual. The other clue is my wired controller also currently has 40, when the left end of the weather curve is 55@-4, and the current actual LWT is 48, which is about where it should be. Last week, before the controller went mad yesterday, I think it showed 25. The 40 is meaningless, another Midea smoke and mirrors number.
Midea 14kW (for now...) ASHP heating both building and DHW
@cathoderay thanks for your reply. This is what I’m a bit confused about. I am able to change the number on the left front screen (currently at 40), and adjust up and down- So assume this would indicate I am not in weather compensation? The only time I have not been able to change it and I have had the message asking if I want to come out of weather temp set mode, is when I have selectede a weather compensation curve from the preset temp screen- see attached!
Hi Curly,
The text on the screen is rather misleading, but I suspect that 'ZONE 1 H-MODE HIGH TEMP' is to be used if you have radiators. Whereas 'ZONE 2 H-MODE LOW TEMP' is for when your system has UFH.
Exactly how the system operates, whether it is set to one or the other, or even both, is unclear. If your system is operating then it may be best to leave it on the present setting at the moment, further tests can be carried out later if you still have sufficient enthusiasm. 🙄
out of interest, do you know what the zones and low/ high temp modes relate to?
The zones I am pretty sure are for zoned installations, ie where you have different setting for different zones (which I don't, so I just use zone 1). The high/low temp modes have baffled me too, I wonder whether they are to accommodate rads (high) and UFH (low) mode? It's Midea, its idiosyncratic!
finally, should I I need to adjust the curve, what’s the best method to do this? Ie. A degree at a time, higher number or lower temp number?
I make smallish adjustments, usually only one end at a time, and wait hours if not days to see the effect. The actual adjustment depends on what is not as it should be, eg if the house is cool at mild ambients, I might move the warmer ambient right hand end of the curve up say 5 degrees. Setting weather comp curves is an activity that makes watching the paint dry seem positively exciting.
You may find that setting the warmer (right-hand) end of the curve to a LWT of 25C at an outside temperature of 20C, gives a reasonably accurate value at that end, so that it only becomes necessary to make adjustments at the cold end.
@cathoderay thank you… I’ll look forward to watching pump dry then 🤣
Final question (for now!)- I have noticed on the app the ‘TBH’ is this to boost the temp for the DHW in low ambient temperatures or have I misunderstood? It seems to use quite a lot of electricity so just wondering!
Hi Curly,
As I think that many Midea owner's have discovered, the manual can be very confusing at times. Having once more delved into the delights of 'Midea speak', this is my interpretation.
It is possible that there could be two heaters installed on your system, one being termed a 'booster heater', whilst the other is referred to as a 'backup heater'.
The following text on page 4 of the comprehensive manual supplied by Batalto, would indicate an electric heater external to the heat pump, which can provide additional energy for central heating when the heat pump is struggling or malfunctioning.
The heating capacity of heat pumps decreases with ambient temperature dropping. M thermal Mono can be equipped with a backup electric heater to provide additional heating capacity for use during extremely cold weather when the heat pump capacity is insufficient. The backup electric heater also serves as a backup in case of heat pump malfunction and for antifreeze protection of the outside water piping in winter.
This 'backup heater' is shown as item 'P' in figure 3-4.3 on page 77 of the above manual.
Figure 3-4.3 also shows the 'booster heater' as item 'M', which would normally be called the immersion heater in the hot water cylinder. The 'legend' for figure 1-5.1 on page 9, also confirms that the immersion heater is referred to as 'Domestic hot water tank booster heater (TBH)'.
So far everything is crystal clear, there is the possibility of two electric heaters being installed, one the 'booster heater' (TBH), being installed in the hot water cylinder, and the second 'backup heater' located external to the heat pump.
Table 3-5.1 on page 80 causes a little confusion, when abbreviation 'IBH' appears, without adequate explanation, but the same table mentions 'TBH', so it is obvious that they are not the same beast.
Clarification appears on page 91, when the abbreviation 'IBH' and 'backup electric heater' are used in the same sentence as shown below.
dT1_IBH_ON sets the temperature difference between the heat pump’s leaving water set temperature (T1S) and the heat pump’s leaving water temperature (T1) above which the backup electric heater heating element(s) are on. When T1S - T1 ≥ dT1_IBH_ON the backup electric heater is on (on models where the backup electric heater has a simple on/off control function).
The following can therefore be deduced:-
TBH = Electric Booster Heater = Immersion Heater in Hot Water Cylinder.
IBH = Electric Backup Heater, which may or may not be installed.
The installer should have set the DIP Switches detailed in Table 3-5.1, as required by the equipment installed, but if anyone is concerned they should confirm that the DIP Switches have been correctly set.
The Midea manuals, wired controller and app really are a masterclass in obfuscation, and @derek-m, you are a master in finding meaning in word salads.
I've usually taken TBH to mean Tank Backup Heater, but have never been sure where it is physically, if it is fitted, which it usually isn't (see below). IBH - well, at least it's not ABH or GBH. One supposes IBH could even be Immersion Backup Heater (but it isn't, the I stands for Internal). But the key thing is these heaters are, at least in my installation, and I think most UK installations, phantom heaters that aren't physically present, or more accurately in the case of the TBH, aren't connected to the wired controller. Midea controllers are very happy turning things on that either don't exist, or turning on things they are not connected to, and then making up some data to go along with the phantoms. Perhaps Midea want us to live in interesting times.
My installation, and by implication most Headroom Heat Pump installation-recipe based installations, do not have the Midea wired controller connected to the bog standard immersion heater on the tank. That is controlled from a totally separate basic timer, intended to run the Legionella cycle (I have it permanently off, but it could be extremely useful if the heat pump packs up, so I have left it in place).
Further confirmation of what TBH and IBH comes from yet another manual. This is from a table describing the connections on a PCB on M-thermal Mono ATW Heat Pumps ie the ones we have:
The IBH is internal (to the main heat pump box), the TBH is in the tank. But the key thing is, on my installation (and other UK installations by implication as above) they either don't exist (the IBH) or they are not connected in any way to the Midea side of the installation (the TBH).
Midea 14kW (for now...) ASHP heating both building and DHW
Arrgghh! More confusion! More interesting times! From page 54 in the other manual mentioned and linked to in my last post:
During HEAT MODE test running, the default target outlet water temperature is 35°C. The IBH (internal backup heater) will turn on after the compressor runs for 10 min. After the IBH runs for 3 minutes, the IBH will turn off, the heat pump will operate until the water temperature increase to a certain value or the next command is received.
and
During DHW MODE test running, the default target temperature of the domestic water is 55°C. The TBH (tank boost heater) will turn on after the compressor runs for 10min. The TBH will turn off 3 minutes later, the heat pump will operate until the water temperature increase to a certain value or the next command is received.
These paragraphs describe a test run, and confirm the IBH (if present) is to do with HEAT MODE, and the TBH (if present, and now called the Tank Boost Heater) is to do with DHW MODE. But they leave open and ambiguous the question of where they sit physically, if they are fitted.
It's a long time ago, but I think it was my installer who told me to ignore the TBH icon (and so the usage when I got the app much more recently), as it was turning on a non-existent heater.
Midea 14kW (for now...) ASHP heating both building and DHW
The Midea manuals, wired controller and app really are a masterclass in obfuscation, and @derek-m, you are a master in finding meaning in word salads.
I've usually taken TBH to mean Tank Backup Heater, but have never been sure where it is physically, if it is fitted, which it usually isn't (see below). IBH - well, at least it's not ABH or GBH. One supposes IBH could even be Immersion Backup Heater (but it isn't, the I stands for Internal). But the key thing is these heaters are, at least in my installation, and I think most UK installations, phantom heaters that aren't physically present, or more accurately in the case of the TBH, aren't connected to the wired controller. Midea controllers are very happy turning things on that either don't exist, or turning on things they are not connected to, and then making up some data to go along with the phantoms. Perhaps Midea want us to live in interesting times.
My installation, and by implication most Headroom Heat Pump installation-recipe based installations, do not have the Midea wired controller connected to the bog standard immersion heater on the tank. That is controlled from a totally separate basic timer, intended to run the Legionella cycle (I have it permanently off, but it could be extremely useful if the heat pump packs up, so I have left it in place).
Further confirmation of what TBH and IBH comes from yet another manual. This is from a table describing the connections on a PCB on M-thermal Mono ATW Heat Pumps ie the ones we have:
The IBH is internal (to the main heat pump box), the TBH is in the tank. But the key thing is, on my installation (and other UK installations by implication as above) they either don't exist (the IBH) or they are not connected in any way to the Midea side of the installation (the TBH).
I suppose that it depends how you interpret the meaning of 'Internal', does it mean internal to the heat pump unit, or does it mean it is internal to your home? Figure 3-4.3 would indicate that it is internal to your home.
You are correct that both the TBH and the IBH cannot be wired directly to the Midea controller, but would need to be via suitable contactors, as detailed in figure 2-4.3 on page 28.
Figure 3-4.3 would indicate that it is internal to your home
IDH: not only that, but internal to your DHW tank, ie an Immersion heater. I am even more convinced they want us to live in interesting times.
I was a bit sloppy there, as installed, nothing gets connected to the wired controller except its wire going to the outside box, which is where the connections if present are made on the PCBs.
I suppose when it is warmer and I next have the outside box open I could check and see if anything is physically connected to (wired into) the CN22 (see image in last post) 'port' on the 'hydraulic/hydronic' PCB.
Midea 14kW (for now...) ASHP heating both building and DHW
Your installer probably told you to ignore the TBH icon because they had not installed the required contactor, so therefore the Midea controller could not control the power supply to the immersion heater (TBH) in your hot water cylinder.
I think you mentioned your installer had fitted a timer to switch your immersion heater on and off.
I think you mentioned your installer had fitted a timer to switch your immersion heater on and off.
Yes, I think this is very probably the standard Freedom based installation. See here from their installation manual (the edition I am pretty sure my installer used):
The same manual also has a a photo of the PCB connections, showing nothing attached to CN22:
Midea 14kW (for now...) ASHP heating both building and DHW
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