@grantmethestrength OK, thanks, I don't use HA, I have written my own interface in MATLAB, if you know.

@tasos That is quite cool I had never come across that before.

Good day all.

Questions on heating using fan coils:

1.  can one use weather compensation with fan coils ? 

2. Do fan coils require higher water temperatures ?

3. Do fan coils operate with their own thermostats ?

4. Do they consume more energy therefore ?

Thanks

@tasos — @jamespa is our in house expert on fan coils, I will leave it to him to answer your questions.

Hi

Contrary to the outrageous claims made by @cathoderay Im not an expert on anything, just a regular guy with degree in physics from 40years ago and experience in engineering and local government.  All very relevant to this forum but nothing which classes me as an expert

I have one fancoil with an otherwise passive radiator system.  Answers below

Posted by: @tasos

↑

Good day all.

Questions on heating using fan coils:

1.  can one use weather compensation with fan coils ? 

2. Do fan coils require higher water temperatures ?

3. Do fan coils operate with their own thermostats ?

4. Do they consume more energy therefore ?

 

Thanks

1.  can one use weather compensation with fan coils ?   Yes, it works exactly the same

2. Do fan coils require higher water temperatures ? No.  Relative to a passive radiator of the same size radiator fancoils emit 50-200% more at any given flow temperature, so they can be run (for the same output) with a lower flow temperature than the same size passive radiator.  Put the other way round a fancoil will fit into a smaller space than a passive radiator with the same output.

3. Do fan coils operate with their own thermostats ?  Sometimes, but not always, depends on model

4. Do they consume more energy therefore ?  There is a small amount of energy consumed by the fan, but this is ~10W or less.  Otherwise they do exactly what radiators/UFH does, ie emit energy into the room in order to heat it, rather than 'consuming' it.   Most of the 10W consumed b y the fan will of course also end up in the room, albeit at a COP of <1 rather than >3.

Hope that helps

Fancoils can also be used for light cooling, ie cooling where the flow temperature is higher than the dew point.  If you arrange for a condensation drain (which many provide for) they can be used for below dew point cooling, but in that case the whole system must be designed for operation below dew point.

Posted by: @jamespa

↑

Contrary to the outrageous claims made by @cathoderay Im not an expert on anything, just a regular guy with degree in physics from 40years ago and experience in engineering and local government.  All very relevant to this forum but nothing which classes me as an expert

You are far too modest!

@jamespa Thanks for replying. Fan coil units in Greece are indeed used for cooling in the summer, with the appropriate hardware.

The main reason I asked the question is, that some people claim fan coil units have a limiter which does not allow water to flow if not greater than 40 or even 45 C. Are you aware of this ? And if yes, can it be altered through its interface ?

Thanks for your time.

Posted by: @tasos

↑

@jamespa Thanks for replying. Fan coil units in Greece are indeed used for cooling in the summer, with the appropriate hardware.

The main reason I asked the question is, that some people claim fan coil units have a limiter which does not allow water to flow if not greater than 40 or even 45 C. Are you aware of this ? And if yes, can it be altered through its interface ?

Thanks for your time.

Its certainly true that some have a limiter of some description.  Mine for example, a Mitsubishi Ilife2 slim, turns the fan off if the water temp <30C when in heating mode, or >20C when in cooling mode.  This is not adjustable.  It doesn't shut the water off though, and indeed has no valves.  Others that I briefly looked at seem to have similar features, or not - you need to check the specific one(s) you are proposing to buy!  

The limiter is actually a problem for me as my lowest FT is 27.  The 'fix' is the addition of a resistor in parallel with the thermistor, fooling the controller into thinking that its warmer than it is so that it switches on at 25.  I have made this removable though, because I don't want also to reduce the 20C limit in cooling mode, I will probably add a relay to switch it in and out automatically according to what mode its in, fortunately there is a signal conveniently available that I can use to trigger a relay.

@jamespa My god you've gone into great depth to make things work for you.

I wonder why this limit is not adjustable. Anyway, thanks again, I am not envisaging buying one, just to be able to advice people on a similar Greek facebook group.

@tasos In truth I wasn't expecting the limit to be a problem because I wasn't expecting to operate as low as 27.  But the first season showed I needed to towards the end of the season hence the 'fix'.  No idea why it isn't adjustable, I guess whoever did the controller didn't imagine such low temperature operation.  

As it happens you can also disable the limiter on this particular model by disconnecting the thermistor and power cycling it.  The controller then senses no thermistor and the fan runs continuously (but still adjusts its speed according to the measured room temperature).

Hi all, I need your help again, because of the lack of clarity of Midea'a manuals. Here is my question:

If one employs an external room thermostat (not the wired controller's), is the weather curve still in effect ? 

Posted by: @tasos

↑

Hi all, I need your help again, because of the lack of clarity of Midea'a manuals. Here is my question:

If one employs an external room thermostat (not the wired controller's), is the weather curve still in effect ? 

Im not a Midea expert but normally this is configurable one way or another.  The external thermostat basically acts as an on/off signal and the heat pump can be configured to ignore it or not.  Separately it can be configured to employ WC or not.  Thus you can normally have any combo of fixed/variable FT, external on/off switch (thermostat) or permanently on.

You will need a Midea expert to say where in the menus this is.