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Looking for help with a Mitsubishi FTC2BR controller

Air Source Heat Pumps (ASHPs)

Last Post by Anonymous 9 months ago

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biggles

(@biggles)

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Joined: 9 months ago

Posts: 2

Topic starter 26/09/2024 3:33 pm

Hi everyone. Long story short, my installation did not qualify for a grant and the build project was well over budget, so got a plumber in for hardware install and sparky for wiring etc.

The heat pump is a 5kw Ecodan with FTC2BR bought as package. Stats, manifold, wiring centre are Wunda.

The sparky (who has since done a Mitsubishi installer course) says the FTC, shortly after start up, commands the circulation pump off, which then causes the heat pump to shut down as there is no flow. This happens on both DHW and UFH cycles. System uses a zone valve each rather than a 3 way valve.

Has anyone had a similar experience with the FTC2BR or could offer any insight into why the circulation pump is being commanded off? Mitsubishi technicals response to my sparky was basically 'bin the controller and buy an FTC6' which obv I’m not exactly happy to do…!

Thanks all, biggles.

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Anonymous 5011

(@Anonymous 5011)

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26/09/2024 4:29 pm

In addition to my reply on Buildhub. Have you considered dumping all the third party rubbish and then you have no need for the FTC2BR.

I doubt you need any of the third party stuff, just set to weather compensation and leave the heat pump to get on with it. If you have a thermostat that stops things you are flowing to hot and impacting CoP.

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biggles

(@biggles)

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Joined: 9 months ago

Posts: 2

Topic starter 26/09/2024 5:05 pm

Hi, yes, planning to use the stats as safety limits, ditto mixer on manifold as safety limit to avoid floor over heating, and run the ashp on weather compensation. I’ll use manually set zone valves for trimming.

But as I understand it, this is what the FTC2BR does (controlling the heat pump flow temp and therefore weather compensation ) so I don’t understand your suggestion of getting rid of it?

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Mars

(@editor)

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Joined: 4 years ago

Posts: 3299

26/09/2024 9:52 pm

@biggles welcome to the forums, and thanks for sharing your experience with us. It sounds like you’ve had quite a journey with your installation.

I reached out to Mitsubishi on your behalf to get some clarity.

Basically, the FTC2BR is specifically designed to work with a Building Management System (BMS) and isn’t a standalone controller like the FTC6. Essentially, it relays commands from the BMS to the heat pump but can’t control the heat pump on its own without third-party BMS inputs. Mitsubishi mentioned that this should have been clear to whoever sold the system to you, which suggests it may not have been purchased directly through them.

While I understand it’s frustrating to be advised to upgrade to the FTC6, Mitsubishi confirmed there’s a valid reason for it, given the limitations of the FTC2BR in a non-BMS setup.

I know this probably isn’t the news you wanted, but if you have any more questions or need further advice, feel free to ask - there’s a lot of knowledge in this community, and we’re here to help! Hopefully, we can get you pointed in the right direction.

This post was modified 9 months ago 2 times by Mars

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Anonymous 5011

(@Anonymous 5011)

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27/09/2024 12:12 pm

Posted by: @biggles

↑

Hi, yes, planning to use the stats as safety limits, ditto mixer on manifold as safety limit to avoid floor over heating, and run the ashp on weather compensation. I’ll use manually set zone valves for trimming.

But as I understand it, this is what the FTC2BR does (controlling the heat pump flow temp and therefore weather compensation ) so I don’t understand your suggestion of getting rid of it?

Maybe not the most efficient way to run your heat pump. Your trimming is just done by balancing the loops. Instead of off or on commands from the thermostat.

If you want to protect the floor just use a pipe stat, then you are not running the heat pump hotter than is really needed and you can ensure the system has an always open flow path.

Deleting the FTC2BR as explained above by Mars. It is just an interface not a controller. Basically a fancy relay box.

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Anonymous 5011

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27/09/2024 12:30 pm

Posted by: @biggles

↑

safety limit to avoid floor over heating

Just to show you what occurs when you switch from DHW heating - max flow temp 60 degs.

Screenshot 2024 09 27 12 21 49 42 40deb401b9ffe8e1df2f1cc5ba480b12

Within about 40 secs the flow temperature drops from 60 to 30 degs. Has a slight bounce back up 33 after a few minutes. My piping length to diverter valve is 10 to 12m each way, so quite long.

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