Ecodan - 2 zone system U1 Error

[funkerman]

Hi,

I have an Ecodan (8.5kw) running a split configuration, zone 1 rads and zone 2 UFH. The zone 1 setup has been working perfectly since install 3 and half years ago. Recently I added the UFH - testing it with a single zone on a small area with a loop of approx 40m.

I can fire up the pump by calling for heat from either zone, this works well. However when I run both the underfloor and and rads at the same time, after a while I get a U1 error come up on the Ecodan's control panel.

The manual is a little vague but I susepct it's a flow error. The underfloor has been set to run at 1lpm as per the kit documentation. The flow on the underfloor is around 40 degrees, with a few degrees less on the return.

Any ideas or suggestion as to why this might be happening. When the pump was first installed two circulation pumps were required for the flow and return. The UFH has a circulation pump on the manifold, so the system has 3 in total.

Any help advice would be very much appreciated.

Thanks in advance,

Rob.

[Brian_UK]

From what I can find about the U1 code it seems that you may have got air into the primary circulation system.

Check that your automatic air vents, if fitted, are working and/or check the manual air vents.