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Vitocal 200s D13 cooling period

Hello,

 

We have a Vitocal 200s heatpump and saw in the menu that there are heating period and cooling period with false/no values.

 

During winter time, the heating period was true/yes, so I don't really understand why it does not have the same for the cooling period right now. Is there any configuration what we missed?

 

Active cooling is enabled and the system does the cool water for the cooling and hot water to use.

 

Thanks,
Tamas

16 ANTWORTEN 16

Hello Tamas!


If your heatpump is creating cool water, than it should also show "cooling period" is "true". This is a precondition to start "active cooling" at all. This condition is defined by "room temperature" + cooling offset (Parameter 7004 [default 40=4K]).


Best regards

 

Gwyn

Hello Gwyn,

Thanks for your reply.

The cooling is working, it provides cool water (~17 Celsius) for the pipes in the ceiling but the "cooling period" is still false.

Currently, the room temperature is set to 22, the offset is 4.

 

The temperature is around 23-24 Celsius.

 

The background of my question is the energy efficiency, it seems that it works almost all day and I thought that the configuration is not perfect.

 

Best regards,
Tamas

Hi Tamas!


Unfortunately, I have no idea what may go wrong and what is standard for your WP. If it is constantly running, I think this is fine. Usually there is more the problem of your kind of heat pump with active cooling that it is starting and stopping all the time. You may have a look at the diagnosis menu to see how often it is stopping and restarting a day.


I hope you have a proper dew point sensor, because 17°C may be at or above the limit on humid days. Running with 19-20°C would be safer on humid days.


Best regards

Gwyn

Hello!

 

"You may have a look at the diagnosis menu to see how often it is stopping and restarting a day."

Where to check exactly?

 

"I hope you have a proper dew point sensor"

I am not sure I have. Our technician not really an expert :), maybe better to set it 19-20. Shall I change the offset? Or directly in the service menu?

 

Thanks,
Tamas

Hello Tamas!

 

"You may have a look at the diagnosis menu to see how often it is stopping and restarting a day."

Where to check exactly?

If I correctly guess your controls you can find it under Service (Menue + Ok for 4s) -> Diagnose -> Wärmepumpe -> Anzahl Einschalt. Verd. Not sure about the English terms used and whether your heat pump uses German or Englisch.

 

"I hope you have a proper dew point sensor"

I am not sure I have. Our technician not really an expert :), maybe better to set it 19-20. Shall I change the offset? Or directly in the service menu?

Usually the heat pump should not cool unless you have installed a dew point sensor, but there are technical ways to overrule this blockade.


You may increase the cooling temperature using the cooling characteristics. The problem of the control is, that the "active cooling" re-uses the hysteresis values from the heating (Parameter 7304 On [20=2K] and 7313 Off [40=4K]) for controlling the water temperature.


If you increase the cooling characteristics too much the cooling will stop early and will only start after a long time when the building has heated up, which may totally disturb your current good cooling experience. If you change the hysteresis, the pump my break the new limits during the startup phase and immediately stop again which is bad for the compressor and the lifetime of your heat pump.


But I don't know enough about the setup of your system to correctly predict the behavior.


May be you have air conditioning in addition that also dries the air? If you run this in addition, the risk is significant lower.


Best regards


Gwyn

Hello @gwynlavin,

Sorry for the late reply.

I checked the menu, found the followings:2B1F06FD-1903-41AA-B5DC-DA1FD877CC99_1_102_o.jpeg

 

756B792E-8623-4BB0-B582-4B081745D56E_1_102_o.jpeg

 

Compressor startings and hours in complete.

On the other hand, when I checked the colling settings, I don't really see cooling characteristic curve option (I hope I translated it correctly). So I cannot change the temperature of the cold water for cooling in relation with the room temperature.

 

And as I wrote it still not show that we are in the cooling period.

 

Thanks,
Tamas

One more thing, we have a Vitovent 300-W, I guess it kerps the humidity in low level.

 

tamas

Hi Tamas!

 

Can you post the picture showing that you are not in cooling period?

 

The pictures you posted are showing that your average compressor runtime is 10.5 min which is  a really bad value. Not sure whether cooling or heating is responsible, but the heat pump only gets efficient if it is running for clearly more than 30 min. Anyhow, the pictures confirm my suspicion that the cooling it is not working as expected but constantly starting and stopping.

 

Usually, the reason is that the heat pump is not getting rid of the cold/heat fast enough, because the the floor heating has a too restricted flow of water transporting the energy. To understand the details, you need to observe what is happening in your heating system closely, looking how quickly temperatures of the different sensors rise and sink. Base on the observation you can find out where the bottleneck is. To test you may need to remove the heating control from your floor heating, so that they are permanent open. Unfortunately, I have no sources in English that I can point you to for more information.

 

Best regards

 

Tronje

 

PS: The heat pipes in your pictures should be insulated.

Hello @gwynlavin,

Sure, please check, it is in Information -> System:
Fűtésprogram (means something like heating season) Nem - No

Hűtési időszak (cooling period) Nem - No

9EB37383-56D7-41AA-86D3-BA36654F7E08.jpg

So I think the Active Cooling is enabled but maybe the system not use it? As I wrote previously the cooling menu seems so be very limited now, I think I was able to configure the "cooling curve"...

I will take care of the pipes soon 🙂

Thanks,
Tamas

Hello Tamas!

 

Sorry, for the late reply. This really looks like a bug: the state is telling "no cooling period" but cooling is still working. Can you look up the "Software Version" of your system under "System -> Diagnosis -> System Information"? I would be very curious about the version. There is also something like a "Coding Plug" information that may be interesting.

 

You may check with your WP installation company whether this is an actual known issue of your "Software Version" in combination with the "Coding Plug", however, since it is working ... you should primarily contact them to solve the compressor on/off behavior: your heat pump is not designed for such an on/off stress. How old is it? From what I see I estimated, that it will die in 4 to 8 years (in max), if you continue to let it work this way.

 

Best regards


Gwyn

Hello Gwyn!

 

No problem, I really appreciate the help what you provide. I checked the System Information:

5E1155C9-3F3A-4873-9E64-04824B6F5BBE_1_102_o.jpeg

It has been deployed in November, 2022.

 

I will try to contact the installation company but I think it could be in relation with smart home heating/cooling control. We have lot of circles for heating/cooling and every circle controlled by the smart home system. If the temperature goes up in one of the rooms, it will open one circle and I guess the heat pump will start to work but as it will reach the necessary temperature ~20 Celsius in 10 minutes approx in the return/coming pipes, then it will stop down... maybe it will be re-triggered if will not be cooled down with one "cycle" (I guess that's not enough)

1E887614-A565-46B7-A8A1-697ACBE9D2D8_1_102_o.jpeg

 

Thanks,
Tamas

Hi Tamas!


My respect to your installation company about how they insulated the pipes in the heat circuit distributor - I hope this is the right term.


Yes, this (dumb) smart controls are exactly the problem, because they completely disrupt the synchronous storing of the positive/negative energy into the floor. So what is the problem here?


A low temperature heat pump comes with one main restrictions compared to a gas or oil heating, it is not supposed to provide the dynamic temperature adjustments of oil and gas heating systems to allow overheating the floor of a single room in a short time that allows individual heat control, however modern insulated houses provide this anyway.


Instead a heat pump is supposed to provide a continuous energy flow over a long time keeping the building at a nearly constant temperature. As a consequence, the smart controls are a disturbance because they are often programmed to prematurely interrupt the energy flow instead of allowing the heat pump to provide the whether controlled target temperature of the house.


So usually the problem is, that the temperature curve and the heat pump output is set to be too aggressive, and would heat the building to a level that is actually not wanted. If your hydraulics is setup correctly, the approach is to remove all smart controls or to set them to a level at which they are always open (≥30°C room temperature). Than you reduce the temperature curve of the heat pump to a level, where the house and most rooms are reaching the expected/planned room temperatures.


In best case most rooms are reaching the same planned optimal temperature at the same time. If this happens, you can put the controls back on and set them to the planned temperature or a slightly above level. If some room is deviating from the planned temperature, you begin to slightly adjust the energy flow of the deviating rooms through the flow meters. Circuit of too cold rooms get slightly opened, while circuits of too warm rooms get slightly closed. Than you wait for some time until all rooms have adjusted to the changed settings and repeat the process trying to reduce the temperature curve further.


One thing to have in mind is, that by changing on flow, all flows in the heating system will adjust, since your secondary pump will try to deliver the same flow as before. So reducing one flow meter will lead to a slight raise in all others and thus increase the temperature, while increasing will lead to reduced temperature in all others - so you are just redistributing the energy. So if the overall energy in the system is to much you need to further reduce the temperature curve and finally you can fine tune by slightly adjusting the secondary pump.

 

The goal of the procedure is to make most rooms running on optimal temperature without any control. You need to achieve this for 50 to 70% of your rooms to finally stabilize the heat intake of your floor heating from your heat pump. If you reach this level, you will have very long synchronous phases, where the floor heating stores the energy in all rooms, with similar long phases in between, where the secondary pump is just slowly redistributing small amounts of energy between the room.


To complement this change you usually want to switch the sensor control of the heat pump from the out-sensor to the in-sensor and reduce the hysteresis between start and stop to a small a mount of just 2K. This makes sure that the room temperature is changing less within the cycles and prevent your rooms better from overheating through sunshine, since the in-sensor is measuring the solar gains thereby and adjusts the output of the heat pump quicker to the reduced consumption.


At the same time this change secures the heat pump against micro cycles where the temperature strucks the limit on the out-sensor through the initial high energy flow during the heat pump startup. You can imagine that the curve on the in-sensor is much flattened and that the heat peak usually needs 10 to 20 minutes to reach the in-sensor.


But be aware, you need to do the fine-tuning in the heating seasons with outside temperatures of around 0°C and repeat adjusting the temperature curve with outside temperatures of 5°C and -5°C so that the curve works equally well on the whole range without the circuit controls taking over.


May be your installation company can assist you in this process and also explain this better, but the temperature fine tuning usually has to be done by the residents. The general principle behind this is best explained in German by the Flow 30 Principle and the process is described as Temperature-based (Hydraulic) Balancing.


Best regards


Gwyn

Hello @gwynlavin,

I just changed the cooling as you wrote but I have more worse numbers if I do a calculation about the last days, 3,6 minutes average compressor runtime since the picture. I will call the company tomorrow with these details.

Thanks again!

I will keep this topic open for few more days.

Tamas

Hi Tamas!

If you currently run with 3.6 min cycles, you at least can hope that the heating cycles are much longer. Active cooling via floor circuits is always complicated because of the limited temperature difference and the of the missing convection during cooling. As a consequence, it is harder for the floor to consume enough negative energy during the cooling. A good estimate for then potential cooling energy consumption is 7W/m²K.

So on a hot day with the cooling on 20°C and the RT close to floor of 25°C, you can expect the floor to take 35W/m²K from active cooling. Thus, in a 200m² house the overall consumed cooling would only be 7kW. Unfortunately, often only half the house needs cooling which reduces the request to 3.5kW, which is above the minimal output - and not all days are hot.

 

Best regards

Hello @gwynlavin,

I see, one more addition is that the cooling is via ceiling circuits so I guess it even less since it doesn't need to cool down concrete, it is in metal frame (Wavin system) so the cold water just running through the system.

Best regards,
Tamas

Oh, well done. You now can count with ~11W/m²K instead of 7W/m²K and may be the difference on the ceiling is also 1-2K higher than at the ground which makes it easier for your heat pump to permanently get rid of the cooling energy. And I assume your cooling is reacting much quicker compared to a floor heating - I usually need to start cooling hours ahead of the heat period.

 

The bad part is what you mentioned: it provides little capacity for storing the cooling energy, so it makes it also more likely that the heat pump needs to switch on and off when the cooling requirement is reduced. I assume your are not using the floor heating to increase the cooling capacity and store some of the cooling energy?

 -

I was also considering ceiling circuits when planning my house. Today I think, that putting the cooling circuits deep into the concrete of the ceiling may have been the most effective solution with respect to keeping a building cool during a long heat period. One would need to start cooling down the ceiling two or more days ahead to store the around ~0,6kWh/m², but this is quite possible to do. Today I understand, why smart people combine a concrete core activated heating with a floor heating - at least for the top most ceiling this is a really great addition with really little costs.

Unfortunately, I forgot to request the 6 additional circuits it would have taken in my house to implement this in my top most concrete ceiling. I assume this would have made it easy to keep the upper floor 2K colder than now.

 

Best regards

 

Gwyn

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