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Fujitsu Waterstage WOYG160LJL Air Source Heat Pump

Barrovian1963 · 2025-02-15T07:22:52Z

Hello, I'm posting here in the hope that someone is familiar with my Fujitsu ASHP model and could provide to guidance. We moved into our new build home three years ago and have been trying to get to grips with it ever since. It works, but I'm really not convinced it is operating at an optimal level. It is controlled by five Heatmiser Neo Stats downstairs underfloor heating and one upstairs on the landing. The radiators upstairs have TRVs. The handover was basically, set the temps you want on the Heatmisers and leave it alone. I've spent the last two winters trying to get the ASHP to run 'low and slow' without much success. The ASHP is either on full pelt or its off. My knowledge of heating systems, terms used etc are basically nil so I feel very much in the dark. Before I waste everyone's time with a detailed post trying to explain what I've tried and the results does anyone think they might be able to help? Many thanks.

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Air Source Heat Pumps (ASHPs)

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Barrovian1963

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Topic starter 24/02/2025 7:01 am

@gary Good morning, thanks for taking the time to reply. Yes, you've described my system exactly. This is what I was suggesting I might try to @jamespa in my earlier post but you've expressed it much clearer. My thoughts were that if I left just one heatmiser connected I'd have a modicum of remote control over the ashp even if it was only a basic on / off. At the moment, I'm trying it with all the heatmisers set high to keep the actuators open to see how it goes. But I'll keep the removal idea in reserve.

Thanks

John.

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Gary

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24/02/2025 8:05 am

@barrovian1963 the thermostats are wirelessly connected to the wiring centre, the wiring centre is connected to the heat pump, when a thermostat calls for heat the wiring centre tells the heat pump to turn on and sends a signal to the actuators to open.

You don't need any actuators connected for the thermostat and wiring centre to tell the heat pump to turn on that side of things will still work correctly.

What I ended up doing was removing all the actuators and unpairing all of the thermostats from the wiring centre except the hall way one. Now when the hall way calls for heat all of the circuits are open.

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JamesPa

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24/02/2025 8:16 am

Posted by: @barrovian1963

↑

@gary Good morning, thanks for taking the time to reply. Yes, you've described my system exactly. This is what I was suggesting I might try to @jamespa in my earlier post but you've expressed it much clearer. My thoughts were that if I left just one heatmiser connected I'd have a modicum of remote control over the ashp even if it was only a basic on / off. At the moment, I'm trying it with all the heatmisers set high to keep the actuators open to see how it goes. But I'll keep the removal idea in reserve.

Thanks

John.

Nothing wrong with a remote on/off switch. I used to use my 40 year old hall thermostat that way when I had a boiler (as a thermostat it was essentially useless, its now redundant and removed).

This post was modified 10 months ago by JamesPa

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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Barrovian1963

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Topic starter 24/02/2025 9:15 am

Posted by: @jamespa

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3 times per hour is reasonable. Are you sure it isn't doing defrost rather than cycling because of overcapacity?

Can I just ask a (another) basic question, going back to my obsession with cycling. What is considered a 'cycle'? Is one period on followed by an off period one cycle, or is it two cycles? i.e. on/off =1 or on/off =2 cycles.

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JamesPa

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24/02/2025 1:18 pm

Posted by: @barrovian1963

↑

Posted by: @jamespa

↑

3 times per hour is reasonable. Are you sure it isn't doing defrost rather than cycling because of overcapacity?

Can I just ask a (another) basic question, going back to my obsession with cycling. What is considered a 'cycle'? Is one period on followed by an off period one cycle, or is it two cycles? i.e. on/off =1 or on/off =2 cycles.

A period of on followed by a period of off is one cycle, but only if followed (or preceded) by more on-off periods. One on/off transition on its own is a change of state.

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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Barrovian1963

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Topic starter 24/02/2025 2:24 pm

Posted by: @jamespa

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A period of on followed by a period of off is one cycle, but only if followed (or preceded) by more on-off periods. One on/off transition on its own is a change of state.

So before I exhaust your patience completely, 10mins on 10mins off is one 20min cycle. Therefore it's cycling 3 times an hour and while not ideal shouldn't be grounds for too much concern?

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JamesPa

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24/02/2025 4:35 pm

@barrovian1963 yes. Not ideal but not disastrous either. There are tricks to increase the period/reduce the frequency eg increase flow temp hysterisis if it's adjustable. Once we get to say mid march you could consider timed heating if it suits your lifestyle.

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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Barrovian1963

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Topic starter 24/02/2025 4:59 pm

@jamespa Thanks. I’m going to try and leave well alone for a while ( not to mention giving you a break from my constant questions ) and see how we go. If it’s ok then, I’ll come back in a month or so if I think further fiddling might help.
cheers,

John.

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JamesPa

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25/02/2025 1:45 pm

No problem if you want to ask more questions but without a doubt leaving these things from time to time is a good idea. only by doing so do you get to find out what they really do and lead a normal life.

This post was modified 10 months ago by JamesPa

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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