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

Can you show a couple of photos of your system and the controller, or wherever you are seeing those figures.

We do not have melcloud, I think what we have is pretty basic, setting the hot water just from the zubadan controler. 

​@Morana I'll see if I can get the right people in here for a discussion because I'm not sure I can make total sense what is going on here. ​@BeePee is good and maybe he knows who else to summon

The difference between the energy produced and the energy consumed is greater than 1 (890 / 654) which shows the HP is working but not with a high COP as you would expect. The heating COP is 1.6 which is very poor and the hot water COP is 0.75 which just seems very wrong.

I'm hoping someone else can shed some light on the figures.

Hi ​@Morana 
I saw your figures and couldn't make sense of them. I have a gas boiler so not that well up on heat pumps. I have had a look at my gas usage for January
Hot Water ~ 100 (141) kWh
Heating ~ 1200 (748) kWh

Yours are in brackets.

So your energy delivered for water is similar (just two of us), for heating about half of mine. You didn't say what size house you live in. The calculation on our house using Heatpunk suggested a 7 kW heat pump. Less demand suggests a smaller or better insulated house.

I assume you have followed other guidance on the forum re-heat pump efficiency. Cooler water cylinder (50°C), limiting the use of TRVs, and using constant gentle heating (at flow temperatures less than 50°C).

​@Peter E  has mentioned that the apparent COP figures are poor (dreadful?). So bad that it would be better to ditch the heat pump and use an immersion heater! It's not easy to suggest what is wrong even with details of your system. It needs someone with a Mitsubishi heat pump to go over the settings.

Can you post some photos of the equipment itself showing the back of the outdoor unit and the pipe work around the hot water cylinder. 12kW is big. What size and age is your house? Where in the country are you? The more info you give the easier it is to see what’s happening. 

We have a 240sqm house new house in Romania where the wheater is a bit colder in these months -4 to 2-4 degres at night and 0-10 at day in this month of january (but not how it used to be). Pretty good insulated I would as it is made on wood structure and insulation, I noticed that at -1-0 degrees at night one room lost just 1 degree (from 23 at12 am to 22 at 8pm). We have underfloor heating in the entire house, and the ecodan hydrotank of 200l. Just 2 persons that are using hot water for bath at night. Using 2 thermostats, but yesterday we stopped them and we moved on the wheater compensantion curve to see how it works..hoping to a better COP for heating.

For hot water we asked the person who installed it and he said that the only explanation is that the pump is not showing the corect data..I don’t know what to say, I wanted to know of someone has ever saw something like this…

Photos will help…

Just looked up the recent weather for Bucharest, slightly warmer than here in the UK. Your house is about twice the size of mine so I would be delighted with your heat loss/demand figures (if they are true).

The Hot Water delivered figures look reasonable for a two person household - we generally run two baths a day.

It might be worth looking back at your electricity meter readings to see if they match the consumed figures. I can’t think of an easy way to determine/confirm the delivered heating figures.

I fully agree with ​@BeePee that an immersion heater would be better for the hot water. At least the energy used will end up in the tank. BeePee and I have a similar experience with poor efficiency heating hot water, although for us it is gas not a heat pump but it is a similar situation for a heat pump.

Hey ​@Morana 

Welcome to the Forum! 

I’m really glad to see you’ve already had some helpful replies from our community, I hope they’ve been helpful so far!

It might be helpful to share some photos of the equipment itself.

I’m not sure if the following topic might be of any use to you:

I hope these are ok:
 

It doesn’t appear to have much airflow around the outdoor unit. Also the only output from that seems to be the item covered in white tape. Where is the primary pipe work ?!
I’m no expert so perhaps someone might comment on the red vessel next to the indoor unit. On my system that’s at the very highest point in the pipework.

Meanwhile maybe another heat pump owner could see what’s what here. ​@M.isterW ?

The energy produced figures on Mitsubishi units are complete rubbish unless you have additional energy monitoring equipment installed.

I agree with Julia about the outdoor unit. It's too close to the surrounding walls so it could be pulling the cold exhaust back into the unit. That will reduce the efficiency.

Hello! We switched for one day on on wheater compensation curve..and it’s worse. The pump is constanly working wich I understand that is ok..but it consumed a lot, the temperature in the house is sometimes 25-26 degrees and the cop is even poorer. 
It consumed 54 and delivered 58.. and the wheater was mild, 0 to 9 degrees outside yesterday…something is very wrong.

Also checked the entire household consumed electricity, we don’t have separate for the pump, and I think the total  figure for consumed energy is about right..so it might display nonsense for hot water, but the total is not far from true…

How can it work with a cop of just 1.07 on compensation curve? I am so dispapointed, I thought this will help us fix the cop issue…

juliamc wrote:

It doesn’t appear to have much airflow around the outdoor unit. Also the only output from that seems to be the item covered in white tape. Where is the primary pipe work ?!
I’m no expert so perhaps someone might comment on the red vessel next to the indoor unit. On my system that’s at the very highest point in the pipework.

Meanwhile maybe another heat pump owner could see what’s what here. ​@M.isterW ?

I don’t know what is primary pipe work..can you please give more info? The indoor and outdoor units are communicating just through that white hose, it is a split Zubadan, maybe that is why.

It's only the "energy produced" figures that are incorrect so you can't calculate COP from.the figures on the controller (unless you have additional energy monitoring equipment attached to the system).

It sounds like your weather compensation curve hasn't been set up properly. It's overheating your house so you need to lower the curve. There are guides online that show how to do this.

Weather compensation works by providing water into your heating system that is just hot enough to heat your house to the required temperature. When it's colder outside you need warmer water going into the heating system. The weather compensation curve tells the system what temperature the water should be for any outside temperature. Your house was too hot so your curve is too high (it's telling the heat pump to provide water that's too hot). Heat pumps are more efficient the lower the temperature they run at so having the curve too high will make the efficiency worse.

Ah ! Sorry. If it’s a split system it’s just refrigerant flowing between the indoor and outdoor units, so they would be a lot thinner than I was expecting to see.. In fact that’s what my Daikin is !! 
 

Re the weather curve on the Ecodan/Zubadan system: ​@M.isterW , I think we’ve discussed before where the indoor temperature is measured - maybe a portable wireless device, but I can’t remember the details. ​@Morana do you have anything like a separate thermostat as part of your new system ?  Where is the indoor equipment shown in your photo ? If it’s taking the indoor temperature from that it would muddle up the desired room temperature. You mentioned previously that you use thermostats but that’s another topic, maybe it would be useful to look into that here.

No, we don’t have those Mitsubishi sensors for indoor temperature, I know that those are needed if you want to use Auto Adapt function for Mitsubishi and cap the inside temp….we were instead told to buy some Salus thermostats and use it with them. But with that poor COP we decided 2 days ago to remove the thermostats that cannot be used for Auto Adaptive and only use wheater compensation...and it went worse 😥 Now we did a change in the weather compensation, the pump is finally stopped for now (aprox 25 degress in the entire house, too hot, outside 10) 

Phew !! That sounds like progress 🙂. How hot is the hot water ?

I see the value for THW5 A and B (for DHW tank water temperature) is 48 deg which is similar to mine. Can you see the values for these:

Wow, before continuing I want to thank you for your answers, you are all so nice people here. I am not used of asking a question on the internet and actually someone really help me…

Here are the photos with the summary of settings; we mainly use hot water for baths at night, and a bit in the morning, so maybe there is another way to setup the water tank heating…

You’re very kind to say so ! I wish I knew more about your system but I hope we can come up with an answer for you somehow. Meanwhile I’ve had another thought…

Mine is also a split system, so refrigerant is pumped from the outdoor unit to the indoor unit to transfer the heat generated in the compressor. So at some point during the installation an F-gas licenced engineer has to charge the refrigerant from a pressurised gas bottle into the units. If for any reason there is not enough refrigerant the system will struggle to operate properly. Mine had a one-off serious leak and it lost about half of it !! The system still worked but with a low COP.

There’s no immediate way of knowing this except in cold damp weather when ice forms on the grill at the back of the outdoor unit.  Normally there should be an even coating of ice, but if the refrigerant is low you’ll see bands like in my photo. 

Now would be a good time to check !! The ice is periodically melted off so if there’s none there at first give it a while and it’ll be back, around 0 to 3 degrees 🥶 

Do you have screen 2/3 of the summary of settings? The numbers look fine on the other screens, as far as I can see.  ​@M.isterW would you agree?

I will look at the outside unit when it will freeze again..

I forgot to add this picture: 

Thanks. To my untrained eyes that all looks fine. 
Has the house temperature settled to a level where the heat pump is working again ? It looks like when you took the photo it wasn’t running as flow temp was 15 deg (if I’m reading that right).

From yesterday until now it was very hot inside ~ 25and outside around 13 degrees. I didn’t saw the pump running during the day, and I dont’t know if during the night it started as it didn’t needed. But now before midnight I checked the data, pump was just started I think

Then at midnight verified again the pump and it was stopped, but showed very high temp for water, the curve is set to a maximum of 30 for 0 degrees and for 8 is 27.

And the consumed energy for one day with the pump mostly stopped and warm outside is 21kw..how can this be possible?