# Mitsu Zubadan Flow Temperature Issue

**URL:** <https://community.openenergymonitor.org/t/mitsu-zubadan-flow-temperature-issue/29576>\
**Category:** Heatpump\
**Tags:** mitsubishi, zubadan\
**Created:** [6 January 2026 14:57 UTC](https://community.openenergymonitor.org/t/mitsu-zubadan-flow-temperature-issue/29576 "2026-01-06T14:57:35Z")\
**Posts on this page:** 1\
**Showing post:** 11

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**Author:** ![Timbones](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/timbones/32/20308_2.png) [@Timbones](https://community.openenergymonitor.org/u/Timbones)\
**Post date:** [7 January 2026 17:48 UTC](https://community.openenergymonitor.org/t/mitsu-zubadan-flow-temperature-issue/29576/11 "2026-01-07T17:48:57Z")

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> [@bontwoody](#):
>
> Total output is currently 9167 W at DT50 (_ **edit 50C flow** _) so in theory it should be enough

~~Oh my, that’s not much at all - DT50 means 50° _above room temperature_, and radiators output less at cooler temperatures. At a flow temperature of 50°C would emit only 4 kW of heat, and 60°C would emit 6kW.~~

> [@bontwoody](#):
>
> However the plots of heat loss as measured by the ecodan suggest it hasnt been able to supply more than 6kW and that was when I was running it at a constant flow temperature of 60C (target) yesterday.

This heating system is limited by the _radiators_ not the heat pump. If the property has managed to maintain a steady internal temperature, then 6 kW might be all the heat you need at 0°C. The _heat loss coefficient_ works out to be about ~300 W/K.

Here’s stats for [my property](https://heatpumpmonitor.org/system/view?id=1) for comparison:

- [Heat loss at design temperature](https://heatpumpmonitor.org/heatloss?id=1) is **5.6 kW** or 240 W/K
- Radiator output at DT50 is **19,000 W**
- Heatpump is Ecodan R32 11.2 kW (oversized)
- Minimum flow temperature is 40° before it cycles
- Flow rate is at the low end, around 11 l/min
- Annual COP is around 3.6

So, bigger (or thicker) radiators will allow the heat pump to run cooler while still delivering the required amount of heat.

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_[View the full topic](https://community.openenergymonitor.org/t/mitsu-zubadan-flow-temperature-issue/29576)._