Any English Language forum? And question about some manufactures' device reliability.

[valentinpopa]

Thank you for your help. I try all examples from here: https://www.mdt.de/download/MDT_SP_S...art_AKH_03.pdf and all are working fine but in my case I chose example 4 Setpoint shift via 2 byte (absolute value). I implemented also logic so now all are working fine but now I need some help with fine tuning. For moment I set my system only for heating. and I seen that thermal valve is all most close when difference is very small. For example setpoint is 16 and actual is 15.8. As I read this is normal that thermal valve will not open at maximum in such case but to be sure that I get maximum from my heating system I need more infos. My heating is base on underfloor heating and I have 11 zones. with 21 thermal valves. Of course in some rooms I use 2 or 3 thermal valves for same zone.
1) PWM cycle time default is 10 minutes but I seen people which tell that more is better like 30 minutes. What you recommend?
2) Minimum limitation of control value. Default is 0. Do I need to put 10 or 20 to keep valve a little bit open instead complete close?

[knxPaul]

To start with 2) given the situation that a closed valve results in 1% temperature deviation: Be satisfied with that. If you open the valve the temperature will rise obviously.

1) the PWM cycle can lead rising and falling temperatures. You need a continuous temperature measurement for more than one cycle time, here 10 minutes, and 10 or more measurement points, visualized at best graphically to see this effect. In the case of 2) you will not be able to see the temperature ripples and 10 minutes are better than 30 minutes.

3) If you really want to tune your heating system you have to do a hydraulic adjustment: The aim is to get the desired temperature in every room when all valves are 100 % open or removed. This is a usual routine when a start of operation is done for the heating system. You have to wait until no temperature change can be measured. To reach this aim the throttles for every zone has to be adjusted. This work is supposed to cover several days.

[valentinpopa]

Thank you for your answer.
I had same opinion but all time I prefer to ask people which know better.

Regarding hydraulic adjustment I need again one opinion because maybe I have a problem here.
My house is like this.
Ground floor have around 130 m2 and first floor around 90 m2 also at ground floor I step down 2 stairs. Because of this I have 3 distributors. One for living and garage (lowest part), one for upper part (part with two stairs up) and one for first floor.
All 3 distributors are on same circuit and for these I use pomp GRUNDFOS ALPHA2 32-60 180. When I looking to hydraulic part at ground floor debidmetre are at 1.5 l/min and up I have only 1 l/min. Now all debidmetres are open complete because installers told me that all will be fixed when automation is in place.
From my knowledge I know that debit must be at list 1.5 l/min.
Now I need your opinion because I have multiple variations.
1) I can close a little bit debidmeters at ground floor and lets say that I can obtain 1.2 l/min in all house. It will work like this or I really need 1.5 l/min?
2) Change pomp with GRUNDFOS ALPHA2 32-80 180. which is more powerful and also calibrate all debidmeters at same value.
3) Add extra Grundfos pomp at first floor. Pomp identical with actual one.
4) Leave all debidmeters open at maximum like installers did?

[knxPaul]

this answer is a hard job for me. As far as I understand the word 'debidmeter' this is a tool for measurement of volume per time. My search engine found a text that adds the context of hydraulic adjustment. Your sentence 'Now all debidmetres are open complete' shows an extra feature of your debidmeters: They can reduce the flow of heating water like a resistor or restrictor or throttle. This function is needed for the hydraulic adjustment. This hydraulic adjustment is described here:

1. leave all debidmeters open at maximum,
2. wait until the temperature doesn't change any more,
3. compare measured temperatures with desired temperatures. This can be done in every zone with separate debidmeter.
4. Reduce the debidmeter in that zone with the highest difference measured temperature minus desired temperature.
5. Because of multiple dependencies you have to repeat this procedure from step 2. on until all rooms have the same difference measured temperature minus desired temperature.

The situation you reached now should avoid the problem of huge variation of valve positions described in #16

1) close a little bit debidmeters at ground floor is what I expect, but please do not look at 1.2 l/min measurement; the effective temperatures are essential.
2) I can't see any reason for a more powerful pomp.
3) extra Grundfos pomp at first floor brings more complexity; I prefere 'keep it simple stupid', so no reason for this action.
4) see my points 1 to 5. After the hydraulic adjustment is done the debidmeters will have different positions.

[valentinpopa]

These is debidmeter for me: https://www.construkt.ro/debitmetru-...YaAodEEALw_wcB Maybe english word is flow meter.
Because not all rooms are identical some circuits can be longer compared with others. For example a bathroom normally is smaller compared with a bedroom and can have a circuit with 70m compared with bedroom where maybe circuit is 100m. So for me hydraulic adjustment means that all circuits have same water flow or same l/min but if I understood correct for you hydraulic adjustment means this and correct me if I wrong.
1) Leave all debidmeters open at maximum and boiler at some value. Lets say 30 degrees
2) When temperature not rise anymore I will have different temperatures between my rooms. Maybe in living 16 degree and in up bedroom only 14 degree
3) In this moment I must reduce debidmeter in living and all rooms with high difference till all rooms have same temperature
So without automation if I start heating I must have same temperature in all rooms
With other worlds is not important like l/min to be same in all circuits but temperature to be same in all rooms without automation started like people which don't have automation. All this fine tuning will require many many days till temperature is same in all rooms. Right?

[knxPaul]

Yes! your 3) describes exactly what I wanted to say - with one exeption: not all rooms should have the same temperature but all rooms should have the temperature which is desired. Because the reachable temperature depends on the boiler temperature as well this is very difficult to optimize. For this reason I work with differences. Example:
you want to have 20 degrees in living room, bedroom 18 degrees and bathroom 22 degrees.
when you reach 17 degrees in living room, bedroom 15 degrees and bathroom 19 degrees your hydraulic adjustment is perfectly reached and you only have to rise the boiler temperature to cope with the 3 degrees temperature difference.

When you see the same temperature in each room with all debidmeters open at maximum start reducing the debidmeter in the room you want the lowest temperature, I expect the other temperatures will rise slightly. Then proceed with the next room you want to lower the temperature.

this fine tuning will require many days but it is worthful because this helps the automation later on significantly.

[valentinpopa]

Ok. I understood perfectly. Installers told me that in case that I have automation in each room this hydraulic adjustment is not need because automation will do all things. And yes will work but difference is that instead heating all rooms at desired temperature in same time coldest room will be heated last one when most of valves will be closed. Of course for installers is more easy. They put automation like Salus, Rehau, Purmo or any other automation and them job is done. For them to do this fine tuning is losing of money
Now maybe you have an idea. For visualisation I use Jigsaw KNX from comfortclick.com which is working fine but I want to see some infos regarding how my heating is working. My boiler is Viessmann vitodens 111-w 32 and from this one I have two wire which I connected to my switch actuator. When the two wire I put them together boiler burner is working else is stopped. Till here all are fine but I want more dates. For example when in rooms I want 20 degree and I already have 19.8 valves are most of time closed and because of this water from boiler go in circuit but because circuit is small since all valves are all most closed water return at all most same temperature and temperature in boiler increase till 60 degrees and then burner is stopped and started when water in boiler is around 18 degree. In this case in my KNX system what I see? I see that boiler burner command is on but I don't know 100% that burner is on.
So my questions are:
1) Exist any KNX device which communicate with Viessmann boiler and give me back more infos?
2) increasing water temperature in boiler at 60 degree when valves are all most closed is a normal working even if I set my boiler to 35 degree for heating?

[knxPaul]

Now I am overstrained and unable to cope.
1) I have no idea but search this forum - I found a direct link possible here

2) Your Viessmann has his own regulator -> for the boiler output temperature. Giving him a setpoint of 35 degree is not enough for a solid working, the heat exchange device needs a minimum of heat consumption to work properly.

• So when all valves are allmost closed the setpoint is to high and should be lowered.

The root cause is that a boiler has a minimum power he can't fall below. This minimum power should be consumed by the whole underfloor heating at least - otherwise the water temperature in boiler increases.

[kmk85]

And please have an eye on the sum of all flow meters. In best case, when all valves are tuned to the needed flow, to get the wanted temperatur, the sum should be more or less the maximum flow output of the pump. Otherwise the pump works against a resistance…

I recommend an excel sheet with the the pipe length of the respective section multiplied with the inner surface area of the pipe to get the volume. So you can have a look regarding the time needed to pass the whole pipe. With an orientation to this, I would do the first setting. May add oder reduce it a bit in dependancy to the distance from boiler to distributer. Then start to optimize. Pump should run in 100% for adjustment!

But in any case the heating should work fine w/o the controllers/automation before start to use them. And of course, this need time, adjust, check and so on.
I also would use external thermometer for that, I ordered 6 on amazon - check if these show the same value (in my case just one was -0.3°C). Correct the value by marking with permanent marker. Place these in the middle of the room e.g. on a table. Also adjust a may needed offse in your knx components, if needed. They mostly don't represent the value from the thermometer, because they are placed to the (outer)wall or higher ceiling...

In best case this happen during different times (night, day…). And also you do this during a period w/o effects of sun, means during cloudy times. To have a representative setting in your knx! Only then you are able to use the automation...

Sounds hard, yeah its hard… 😅

Sent a PM with eMail, I can provide you a sheet…

[knxPaul]

3) In this moment I must reduce debidmeter in living and all rooms with high difference till all rooms have same temperature
So without automation if I start heating I must have same temperature in all rooms

sleeping one more night and thinking about this I would like to add: To be precisely it is the most reachable temperature for each room you should aim to set up doing the hydraulic adjustment. Turning off the heating in one room for some time will not have much influence on the other rooms but turning temperature at maximum in one room will not reach higher temperatures than the reduction of the debidmeters allow.

And another point to think of is: There should be a energy balance: The energy amount the boiler provides should be the same as the total house 'comsumes' as heat dissipation to the environment. One part of this is the air exchange in the rooms. Doing this air exchange with an automated system can even bring extra heat into the rooms via recuperator (heat exchange device from outgoing air to incoming air).

Pump should run in 100% for adjustment.

This is an important note! The energy amount the pump moves from the boiler to the underfloor heatings depends on the temperature difference and the flow rate. Modern boilers with pump speed regulation help to keep the energy balance mentioned above but complicate the hydraulic adjustment.

[kmk85]

if needed, sent me your email...

[valentinpopa]

Wow. Nice excel. I understood all you wrote up but is not so easy to do it for moment since my house is now in construction and I still not live there. For moment I still don't have all rooms thermostats. So I keep my house at minimum temperature.
I rally thank you for all infos and because it get a lot of time to fix it I will do it next winter when I will live in my new home.
For moment all are working good and I see no problems except the part when all valves are all most close and boiler temperature increase and stop which is good because boiler stop since valves are all most close and temperature increase too much in boiler but even if boiler command is on boiler gas burner start only when temperature in boiler is around 16 degrees. If I put burner command to OFF for few seconds and ON again burner started even if temperature is 30 degrees. My expectation is that when boiler temperature increase too much boiler burner stop because an overheating protection but if temperature in boiler for heating is set to 35 degrees and temperature go bellow 35 burner to start again. I don't know if I can set my boiler to stop if temperature in boiler is > 45 and start if temperature < 30.
So is this possible or is this a normal behavior for underfloor heating?
Of course I can put a heating probe on outside boiler circuit and measure temperature there and start/stop burner if temperature is not in my interval even if open valves command is ON

[knxPaul]

Looking at the manufacturers Internet page in german I found a quite complex boiler you mentioned in #22. This one has a quite intelligent own regulation system you describe only the top of the whole "iceberg". This kind of boiler would like to run most of the time. It is essential to choose a power that fits to the demand of the house, not larger. The challenge is the dependency of the heating power demand from the temperatures outside. The temperature storage capability of an underfloor heating should help to cover the day and night cycle.
I evaluate "start/stop burner" regulation not to be adequate to cope with this task.
Instead I would try to use the boiler internal temperate regulation to keep the room temperatures constant, day and night. There is poor documentation; my boiler from a different company measures feed and return temperatures to calculate the requested heating power and adopt the boiler power by a modulation method.
Monitoring the heating system you should reduce the boilers temperature setpoint if you notice valves are all most close.

[valentinpopa]

1) How to use the boiler internal temperate regulation?
2) How to reduce the boilers temperature setpoint if I notice valves are all most close?
I ask all these because from my boiler I have only two wire out and when I connect them together burner start and disconnecting them burner stop.

[knxPaul]

In Europe a manual should be part of the delivery which can answer these questions. Using my search engine I found https://www.viessmann.at/de/wohngeba...ens-111-w.html in german and for english https://www.viessmann.co.uk/products...vitodens-111-w
Use the installation instructions and look on page 59: "Set flow temperature for external demand" is explained there.

EDIT: Looking once again I found that the boiler internal temperate regulation may be an option you have to pay for extra.