Help needed with Mitsubishi FTC2BR controller

[Tim S]

Hi everyone. My 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…!

[JohnMo]

You really should look to simplify your system.

 

Questions 

Do you have a buffer? If so is it temperature controlled by the heat pump.

 

If you don't have a buffer all your zones are going to cause you a bunch of issues. Notably short cycling if you only get down to a couple of small circuits.

 

Do you have a mixer and pump on the UFH manifold?

[Tim S]

Planning stats as limit switches, mixer on manifold as over temp safety, no buffer as it’s an insulated slab of 35 ton mass, I’ll run weather comp from the FTC2BR if can get the blasted thing to stop depowering the circ pump…… hence my question…!

[JohnMo]

22 minutes ago, Tim S said:

mixer on manifold as over temp safety

Do you really need it. Switch over from DHW to UFH a couple of

litres of hot water pumped into the 35T of concrete. Zero effects. Plus your mixer will always add a minimum of 5 degs to your flow temperature as they always mix flow and return irrespective of mixer settings.

 

Looked at the installer manual, have selected the scheme to match your install, noted there were loads of options available?