Ecodan Zones/Wireless controller
Hi, I've recently moved into a new build which has an Ecodan PUZ-WM60VAA set up with DHW, Zone 1 > UFH, Zone 2 > rads.
There's one Heatmiser stat for the rads upstairs. UFH has stats in each room.
This is obviously setup like an old-school boiler, inefficient for a heat pump and leads to short cycling.
I purchased a couple of the wireless Mitsubishi stats and set them up, put the system into room temp mode (auto adapt?). However, I soon learned that the Heatmiser stats do actually call for heat and the system will not stop heating until it hits their limit, even when the wireless stats are showing a temp higher than the target.
I disabled 2 dip switches (SW2-1 & SW3-1) which prevents the stats controlling the heat and just act as pump control. This seems to work for the UFH however, Z2 will not heat independent of Z1 and with Z2's pump running will not put any heat into the radiators even while Z1 is flowing at 40c.
It seems the solution to this is: "For 2-zone temperature control, check DIP SW2-7 is set to ON (2-zone temperature control) and DIP SW2-6 is set to ON (With Mixing Tank)"
These are both off, I'm assuming I don't have a mixing tank and cannot just enable these?
I'm looking for a solution, maybe I need to hound the developer?
Tank image:

There’s quite a lot going on here, so we'll try to break it down with some unofficial insights from Mitsubishi. It sounds like your system is set up with two zones at the same design temperature rather than two zones with different temperatures. If that’s the case, SW2-6 & SW2-7 (which are for systems with a mixing tank) wouldn’t apply here. Instead, it seems SW3-6 is managing the two zones with the same temperature settings, and that’s correct for your system as it stands.
When it comes to third-party stats like Heatmiser, they usually work best when the Ecodan’s weather compensation is set up properly. The stats can then manage room temperatures and schedules. One potential tweak might be to check if the Heatmiser stats allow you to adjust the hysteresis (basically the delay between on/off signals). Widening this could help reduce short cycling. Another workaround some people use is combining zones or removing actuator heads to simplify the system and move towards an open-loop design, which can also reduce cycling.
For the Mitsubishi stats, Zone 1 should be fine in Auto Adaptive mode, but Zone 2 has to either follow the weather compensation curve or run in fixed flow mode. To get Zone 2 heating independently, you’ll probably need to look at what’s controlling its pump. It might require adjusting the signal cables or wiring, but it’s hard to say without seeing the full setup.
At this stage, it might be worth getting a heating engineer to take a closer look – they’ll be able to advise on pump controls, wiring changes or any other tweaks to get everything working smoothly. Mitsubishi’s Homeowner Helpline (0161 866 6064) could also be helpful for further advice.
Also, this video might help:

Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
- 22 Forums
- 2,096 Topics
- 46.1 K Posts
- 97 Online
- 3,383 Members
Trusted Installers
Struggling to find a reliable heat pump installer? A poor installation can lead to inefficiencies and high running costs. We now connect homeowners with top-rated installers who deliver quality work and excellent service.
✅ Verified, trusted & experienced installers
✅ Nationwide coverage expanding
✅ Special offers available
Latest Posts
-
RE: Mitsubishi cycling while on chilled water output
@judith not power consumption just the overall efficien...
By downfield , 1 hour ago
-
@jamespa Thanks for the advice - very helpful. I had al...
By abam48 , 1 hour ago
-
RE: Weather compensated secondary circuits with Biomass
Hi @andycoo we do an LK 110 standalone weather compensa...
By Sune , 2 hours ago
-
RE: Adding battery storage to SolarEdge PV system
@chandykris No need to apologise at all! I forgot to ad...
By Toodles , 20 hours ago
-
RE: Say hello and introduce yourself
Yes please do Suggesting a loss in the region...
By JamesPa , 20 hours ago
-
RE: Surface mount or bury primaries for heat pump installation?
Can we have some links to those you're considering plea...
By Transparent , 21 hours ago
-
RE: Commencing on an ASHP Installation Process
That outside pipework would concern me. Surely rigid se...
By benson , 2 days ago
-
As I have reported elsewhere we turned on the cooling o...
By downfield , 2 days ago
-
-
@el3b Hi, sorry to hear that, it is advisable to instal...
By ASHP-BOBBA , 3 days ago
-
RE: Difficult positioning of air source heat pump
@rikiarn Out of intrigue, the thread reads as though Ai...
By Sheriff Fatman , 3 days ago
-
RE: Mitsubishi Ecodan Fails to Heat Water despite temperature drop
@m1kegibson If you are able to access the service me...
By HarriUp , 3 days ago
-
RE: When will heat pumps and install prices come down?
... which of course is impossible because the world mov...
By JamesPa , 3 days ago
-
RE: Battery storage to run Heat Pump.
I would be surprised if the battery chemistry is going ...
By Transparent , 4 days ago