what is FTC?

are you using ECOdan mixers and room thermostats for the underfloor heating too?

If not, don’t expect anything near optimal performance…

Posted by: @alec-morrow

what is FTC?

 

are you using ECOdan mixers and room thermostats for the underfloor heating too?

 

If not, don’t expect anything near optimal performance…

FTC is the Mitsubishi Flow Temperature Controller. 

It is the standard Mitsubishi controller for heat pumps. It has been upgraded lots of times over the years. Consumers use it to control weather compensation, heat pump schedules etc. 

@alec-morrow

FTC is the Mitsubishi Flow Temperature Controller

The ASHP was retrofitted so the UFH uses controller and stats from Uponor as originally fitted approx 15 years ago

stats from uponoor and their mixing valve will be the issue

broadly speaking mixing simple on off signals which are the uponoor  stats, with controls that vary flow temp won’t work effectively.

heat pumps are one industry where we definitely need to adopt German or Swedish practices.. they use compensation controllers on electronic mixing valves to optimise efficiency comfort and reliability 

@peterr,

I don't see how what you're doing will work.  Auto-adaptation uses outside temperature and room temperature to try and work out the best way to run the ASHP.  If you set the FTC controller high so that it's always calling for heat then it will keep increasing the flow temp until it reaches its set room temp. If your ufh stats are set at the proper target room temp, lower than the FTC one, then it never will and you are going to end up with a high temp ufh system, which is what it sounds like you have. 

If you want to use the FTC and auto adaptation then turn your ufh stats up high so they are always calling and let the FTC control the flow and room temps.  I don't think this will support multiple zones though. 

I'm very interested in this as it's what I'm going to try next.  I have two zones, both radiators and I was planning on turning them both right up and letting FTC/auto adaptation control things. 

BTW you can get a remote room temperature sensor for the FTC off ebay for about £15. 

This is some info on Auto Adaptation

You might be better off with weather compensation

@kev-m 

Thanks for that information, it confirms what I thought was happening.

I'm not going to write off Room Adaptation just yet, but may have to revert to Weather Compensation while I investigate if a wireless controller can take over from the FTC, in which case we can set the UFH stats high and use the wireless controller for room adaptation.

@peterr 

Let me know how you get on.  I think the wireless controllers are hard to find at the moment but as I said you can get one of these

and wire it into the FTC

@kev-m A quick update.

After thinking about the problem for a little while and re-reading the manual I came up with really simple solution - swap the existing sensors over!  I can't believe our installer didn't think of it, or that I didn't think of it sooner.

We have a wireless controller already, that was located on the top floor of the house and being used to control the radiators, so I simply went into the system settings and swapped that to be the sensor for the UFH zone, and the FTC controller to be the sensor for the radiators.  The wireless controller is now downstairs in our dining room, set to 20C, with all the UFH zone stats set to ~21C.  Overnight it dropped to about 6C here.  The house was already warm because it had been a nice sunny day, so the house didn't cool down enough for the ASHP to kick in until about 2am.  Once it kicked in the temperature stabilised at 20C and has been there ever since.  Flow temperatures not getting anywhere near the 50C I was seeing previously.  Now wondering if I can convince the wife that 19C is an acceptable temperature 😀 

The final thing I have to do is tweak the setting on the FTC controller to keep my office, which is on the top floor, at a comfortable temperature.

I am hoping that this should keep the house at a more stable temperature.  We are in quite an exposed location on the edge of the Fens, so when the wind blew the house was chilling down a bit when we were just using weather compensation.  Although we hopefully won't find that out now until next winter!

@peterr 

I assume it's the Mitsubishi wireless controller you're talking about.  I didn't think you could have the wireless and the main FTC controller monitoring separate zones; I thought when the wireless was installed, it in effect became the main FTC sensor.  I could well be wrong though.

If the ufh stats are at 21 and the wireless one is set at 20 then that should let auto adaptation work properly downstairs. Upstairs, it depends on whether the FTC main controller can be set separately to the wireless one.  If so, you can choose your temp and off you go.  If not then I assume your upstairs zones will open up when downstairs calls for heat and will get the same flow temperature as downstairs (which will be decided by auto adaptation). In effect, you'd have one big zone. 

I also don't see how auto adaptation would work if the FTC and the remote sensor both monitor room temps. Which one would it use?

All very interesting.  BTW I assume you have the latest FTC manual for this?

Kev 

@kev-m 

Yes, it is the Mitsubishi wireless controller that I am using.

You raise an interesting point because obviously there is no way to have two independently controlled flow temperatures. Although we have, notionally, 2 heating zones, I am not able to change how each one operates independently.  Space heating can either be room, flow or curve.  Whatever I set becomes the heating mode for both zones.  The way it is working at the moment, zone 1 appears to be the "master", controlled by the wireless.  Zone 2 (which hasn't turned on since I made the changes) will, I think, be a "slave" where its 2-port valve is controlled by the FTC, and the flow temperature is set by the "master".

I do have the latest version of the manual, but trying to relate what it says to the way our system has been plumbed and wired is not easy!

I will continue to experiment and see what happens with flow temperature when zone 2 starts calling for heat.

Thanks for your comments - always useful to have somebody else's take on things.

Peter.

@peterr Mitsubishi almost certainly have mixing valves and controllers for second and third circuits. Ideally each circuit would have a mixing valve thus minimising flow from buffer.

why not ring or email Mitsubishi to find out?