Mitsubishi Ecodan Auto Adaption trial to stop cycling.

Air Source Heat Pumps (ASHPs)

Last Post by F1p 3 weeks ago

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@sand

(@sand)

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Joined: 4 years ago

Posts: 88

Topic starter 18/12/2025 12:09 pm

We have a 11.2 kWh over sized heat pump, ufh downstairs and rads upstairs. We have been running on WC cold end 41⁰ @-4⁰, warm end 30⁰ @7⁰and got the curve pretty spot on but the unit would cycle at oat over 9⁰. House built 2020 well insulated.

Only way to stop cycling was to keep turning the unit off, let it settle and turn back on as oat temps dropped.

Changed over to auto adaption 11 days ago, a bit reticent to do this due to comments of auto adaption not working well with ufh.

Made changes on FTC5 changed the interval to 60mins and thermo diff from +5/-5 to +3/-9 no idea 🤔this was just guess work, but thought I could just play with the numbers.

We have 2 mitsibishi wifi stats.

The unit has settled, I assume this is algorithm learning.

Yesterday it ran smoothly most of the day see images from Mel pump Mel cloud. It ran yesterday from 1:10pm to 9.25 am this morning with one cycle.

I've managed to drop the curve to 39⁰@-2 cold end and 27⁰ @10⁰ warm end, never been able to do this before as it would cycle. It runs at 29⁰ which it could do on WC, unfortunately won't go lower but at least it seems to have stopped cycling.

Rads warm rooms @29⁰ we don't heat up water to heat rads, then cool uhf. We keep upstairs wifi stat in master bedroom which is over unheated garage and we can get this up to 20.5⁰ but mainly 18.5⁰ /19.5⁰, all other bedrooms go over 21.5⁰. downstairs stat is in the hall, we have rewired to just have one stat downstairs this is set to 21.5⁰ but over shoots to 22.5⁰ which is our perfect room temp.

We run ashp 24/7.

It's early days, not been very cold since changeover so will be interested to see how it copes in cold weather. Not sure it's saved money and never been able to read COP but at least it seems to have reduced cycling which was my aim.

This topic was modified 3 weeks ago 2 times by @sand

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F1p

(@f1p)

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Joined: 2 months ago

Posts: 38

18/12/2025 4:43 pm

The interval you talk of, i think, will be 60min for any thermostat changes to take effect - which might not be exactly what you want.
E.g. you turn the thermostat down from 20 to 18 at night, this means the controller wont actually take action on the 18C until 60min after it happened

Thermo Diff i think has made the big difference here, it allows your Flow Temperature to Overshoot the Flow Setpoint by +3C and then not restart again until it drops until -9C
Usually you would want the +5C as its more likely to overshoot in warmer weather

A little further down in MELPump you will see "Target heating temperature" which is the Flow Setpoint that Mitsi AA has chosen.
Impressive low frequency there though!

This post was modified 3 weeks ago 2 times by F1p

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