Zubadan shows consumed hot water energy bigger than delivered hot water energy

Here goes ! I’ve asked on the Facebook page Heat Pumps UK which is a most helpful group of heat pump installers discussing their trade, and advising on all things Heat Pump. This is my summary of their comments on ​@Morana ‘s photo of the plant room with the Zubadan and associated pipework and buffer tank. I’m not saying I understand all this, but I hope Marana’s second opinion installer might get to see this and it might help:

Most comments are regarding the grey buffer tank with the 4 pipes, which results in “distortion”. There isn’t always a need to include a buffer tank, it depends on the individual design’s total volume of system water. Sometimes they have been installed unnecessarily, sometimes a smaller volumiser or low loss header is used instead.

With the 4 pipe buffer you have flows (hot) and returns (cool) all pumped into the buffer and probably at mis-matched rates, meaning hot and cool mix together, lowering the system water by several degrees. The more mis-matched the flow rates are going into the buffer, the worse the problem is.

An improvement would be a three pipe configuration, where the heating return is piped into the return back to the heat pump after the buffer.

One installers advise is as follows:

People talking about Buffer Vessel and distortion.

Whilst yes this can be a factor the more important query is whether a buffer vessel is required.

That would depend on the total system volume, the length of the pipes to the furthest heating emitter (ie radiator/ufh/etc).

This looks like it has been zoned into 2 different areas (upstairs/downstairs?) so would be helpful to know what types of emitters are installed on each zone along with how many plus the break down of the numbers on each loop.

Under Floor Heating is often installed with a blending valve to reduce the temperature so that no damage occurs to the flooring.

If the heat pump is trying to run a DHW cycle and the UFH is also running then you will be constantly blending cold water into the system at the same time - this would massively impact COP.

Have they used ESBE valves for diverting heating to the 2 separate zones?

If these are installed incorrectly they can in effect be letting by (or working as a blending valve) allow Hot Leaving water intended for the DHW Cylinder to go through the heating loop(s) again destroying your COP/efficiency.

A point about the readings shown on the Ecodan controller: the buffer distorts the delivered energy report, and even the heating flow temperature too. So the advice is to measure the flow and return temperature on the heating side of the buffer - measure on stub - and use this calculator* to see what was the delivered heat mass. You will need the flow rate of your pump (after the buffer)

As for a reference - You can check Ecodan flow rate in Service menu > Commissioning wizard - also you can adjust pump speed in the service menu

*https://heatpumps.co.uk/calculators/

Other comments point out that the refrigerant pipes are not well supported. Those are the two thin, part insulated in white (foam?), copper pipes that loop up and into the top of the Ecodan unit. If they were knocked they might easily come loose and refrigerant could leak out. That would be extremely unwise! Mine leaked into the open air which was very bad, but if it leaks indoors that must be worse.

Good luck ​@Morana I hope this is useful !!