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Air Source Heat Pumps (ASHPs)

Last Post by tfb8 2 years ago

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tfb8

(@tfb8)

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Joined: 2 years ago

Posts: 5

Topic starter 17/10/2023 9:01 pm

Hi there

We moved into a 2 year old house last year with a Mitsubishi Ecodan FTC 5 system installed

Currently the system is configured for 2 zones, radiators upstairs and underfloor heating downstairs.

The downstairs feeds a manifold and is split into 6 zones each with their own thermostat. The system had been configured and set up more like a traditional boiler system with different temps and times across the downstairs zones and the thermostats are in silly places which means they kids (though they deny it) often turn them on or off when they reach for the light switches. The thermostats are wired back to a Wunda H-box 12 which controls the actuators for the manifold and gives a call signal to the FTC

The FCT is set for flow control for both the upstairs and downstairs at present. I’m not too worried about upstairs at the moment as last winter we didn’t really need much heat up there.

Last winter, taking advantage of off-peak tariffs we had been running the AHSP at full tilt during the night and then perhaps kicking it in during the evenings again, but this draws more power than our batteries can supply and so we end up drawing form the grid

What I want to do is change the operation to give me a constant temperature across all of downstairs. I bought a Mitsubishi wireless remote controller and have got that connected and paired and changed the mode to Room temp and set the sensor for Zone 1 to the wireless unit, the old stats are all on to open the valves on the manifold – the plan is to change them to manual valves at some point to balance the heat distribution

But the operation of the FCT still seems to be controlled via the Wunda H-12 giving a loop to IN1. The FTC only goes into heating mode if the loop is made and stops when the loop is broken, regardless if the wireless remote set point is above or below the room temperature.

Is there a setting I’m missing somewhere?

Regards

TFB

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HarriUp

(@harriup)

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18/10/2023 1:01 am

Hi @tfb8

I'm going to presume you have set the Dip switch SW1-8 to on to activate the wireless controller function at the FTC...

A thermostat wired to IN1 will control Zone 1, and that is a hard on/off signal. if it sends a call for heat the heating can run but if it is sending a signal for no heat then the the heating won't run. The wireless RC only sends the room temperature to the FTC and it is the FTC that then refers to its parameters including the set temperature to decide if the heating needs to run, and how hard to run it. But at the moment the IN1 input can act as a disallow heating command.

So with both connected to Zone 1 you have to ensure the Wunda is continuously calling for heat if you then want the FTC to use the wireless RC temperature to enable Room mode to operate. If you just want the wireless RC to be in control you'll need to disconnect the wired thermostat from IN1.

Mitsubishi EcoDan 8.5 kW ASHP - radiators on a single loop
210l Mitsubishi solar tank
Solar thermal
3.94kW of PV

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tfb8

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Topic starter 18/10/2023 10:55 pm

Yes, SW1-8 was set to on.

I tried to do a bit more testing today, but it seems the wireless remote transmiter has failed as it's now just showing "---" in the main display and buttons don't do anything (yep, tried new batteries).

It did seem yesterday that with a room temp of 20 and the wireless remote set to 26, which was echoed on the FTC's main controller, that the FTC just wasn't starting up - even the "heat pump running" icon wasn't displayed on the main controller.

I think I'll have to wait until the weekend before trying again.

TFB

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HarriUp

(@harriup)

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Posts: 108

19/10/2023 3:04 pm

Could be the pairing between the receiver unit and the remote has been lost, or an issue with the receiver unit.

Mitsubishi EcoDan 8.5 kW ASHP - radiators on a single loop
210l Mitsubishi solar tank
Solar thermal
3.94kW of PV

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tfb8

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Posts: 5

Topic starter 20/10/2023 8:26 pm

Fairly sure it's the transmitter not the reciever as I can't get the tranmitter to display anything but "---". won't bring up the options menu when you press the 3 buttons together.

Anyway, I found a Woolsey heating and plumbing about an hour away that showed one in stock. Ordered online and was told my item was ready to collect. Drive an hour through todays rain and they can't find the transmitter when I get there. Not impressed at all.
They claim they will have another one UPS'ed from another branch to me, but I'm not holding my breath at the moment

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JamesPa

(@jamespa)

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Joined: 3 years ago

Posts: 3161

20/10/2023 10:53 pm

Silly question but is one of them battery operated and if so has the battery run out?

I have a wireless thermostat for my gas boiler. It fails when the battery runs out at the thermostat end, and it recently started failing every time there is a power cut, I presume because the battery for the battery backup at the powered end has run out. The latter failure is fixed just by pressing the re-pair button, but it goes again next time the power goes off. At some point I need to disassemble it and find the battery that does ( or rather doesn't do) the backup!

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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Rod

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Posts: 24

23/10/2023 2:09 pm

If I'm understanding you right, are you saying you just want to control the system off one thermostat? If so, you can do this using the WundaSmart app. Each room thermostat, under Wundasmart 'advanced settings', will be set to operate the relay in the wundasmart box. For all thermostats other than the one you want to control the temp, disable the relay action and set the temperature to something that won't be reached, e.g. 25c. They will all take heat whenever it's available, but the heat pump will only turn on when the one controlling the temperature closes.

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tfb8

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Topic starter 24/10/2023 11:30 am

Not so much control via just one thermostat, but more to get it away from set flow temperatures and to a variable flow temp. For which it needs to know the temp of the area, not just a hard on/off signal.

Woolsey have delivered a new remote transmitter so I'll have another go when I get time.

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Rod

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24/10/2023 3:20 pm

@tfb8 If the Winda is still sending control signals, then the relay setting for the Wunda zones must still be set in the Wundasmart app; You can remove it in the advanced parameters section of each zone so that Wundasmart never closes the relay even if the zone needs heat. The manifold valve will still open, it just assumes heat will arrive, it doesn't demand it through the relay.

Alternatively, you can open up the FTC5 panel and remove the cables fron IN1!

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tfb8

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Topic starter 24/10/2023 4:29 pm

and hence the original problem, with the cables removed from IN1 the FTC didn't respond to the room temp being below the desired temp on the remote controller - even though the FTC was echoing the readings of the remote controll. i.e. both showing room temp of 20 and desired temp of 26. This is with dip switch 1-8 set and the mode set to room temp and the address of the remote set as the temp sensor for the zone.

So my original question - is there another setting I have missed?

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