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Please help with the settings ecodan

Air Source Heat Pumps (ASHPs)

Last Post by Sheriff Fatman 10 months ago

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nose1972

(@nose1972)

New Member Member

Joined: 10 months ago

Posts: 2

Topic starter 11/01/2026 1:54 pm [#2726]

I have a 160 square meter house, first floor 6 radiators and second floor 4 radiators. The pump is a puhz-sw100yaa. I have a 100l buffer tank and a secondary pump. I am interested in the pump speed on the ftc 6, it has from 1 to 5. Mine is at 2 with a flow rate of 20l/m. Is that ok or should I increase or decrease the flow rate? Which is better?

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Sheriff Fatman

(@sheriff-fatman)

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Joined: 2 years ago

Posts: 224

11/01/2026 6:30 pm

Hi and welcome to the forums.

Does your system use a Mitsubishi cylinder or is it a 3rd party one?

The FTC6 settings from 1-5 only work on Mitsubishi cylinders, so have no effect on 3rd party ones (which I discovered only because someone on here told me).

If you increase it to 3 or 4, for example, does the flow rate change? If not, then there's probably a manual pump controller somewhere that will do this.

You should be able to find a databook for your model that provides information on the recommended flow rates. I did a quick search and found a service manual that stated a nominal flow rate, but the unit should operate within a range. The nominal rate shown was 32.1l/min which suggests yours might be at the low end of the range. I found my relevant databook within Mitsubishi's site, but had to search for installer data rather than customer data to find it, but hopefully this gives you a start point.

130m2 4 bed detached house in West Yorkshire
10kW Mitsubishi Ecodan R290 Heat Pump - Installed June 2025
6.3kWp PV, 5kW Sunsynk Inverter, 3 x 5.3kWh Sunsynk Batteries
MyEnergi Zappi Charger for 1 EV (Ioniq5) and 1 PHEV (Outlander)
User of Havenwise (Full control Jun-Dec 2025, DHW only from early Dec)
Subscriber to MelPump App data via CN105 Dongle Kit

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nose1972

(@nose1972)

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Joined: 10 months ago

Posts: 2

Topic starter 11/01/2026 6:51 pm

@sheriff-fatman

when I increase it to number 3, the flow increases to 25l/m, is it better to set it to 3 or max 5

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Sheriff Fatman

(@sheriff-fatman)

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Joined: 2 years ago

Posts: 224

12/01/2026 1:25 am

Are you trying to address any particular performance issue with the system at the moment? What prompted the desire to look at flow rate to begin with?

I've been experimenting with different flow rates at present, but that's with a view to seeing if it has any impact on efficiency to improve COP. Results are inconclusive at present and I'm experimenting within the databook tolerances for my specific heat pump.

Without knowing why you're looking to change flow rate, it's hard for anyone to provide a great deal of insight.

If no burning issues, the logical answer would be to leave it alone if it's performing well, assuming that this is how it was set by the installer.

Alternatively, assuming it's now set on 3, I would perhaps now leave it there for a day or two and see how it performs relative to the previous setting, in the knowledge that it can easily be set back if required. I'd be inclined to stay away from 1, 4 or 5 at the moment until we can understand the underlying issue behind the query. There's no default answer as to which setting is 'better', as per your original query, but we have to logically start from the basis that the installer was competent and set it to 2 at commissioning for a reason.