Faulty Ultraheat 2WR5 meter

rtman · 23 May 2020

Hello

The heat meter in my property has stopped working and I am trying to troubleshoot and fix it, if that's possible, before purchasing a new one. The model is Ultraheat 2WR5381-5BC61-0TB2, decoded parameters below:

2WR5381-5BC61-0TB2

38:
Nominal flowrate 2.5 m³/h, length 190mm,
nominal pressure PN16, connection threaded 1";
1:
Mounting in return, return sensor directly integrated
into the volume measuring unit, (only possible for
threaded connection up to qp 6):
5b
Sensor Pt500, replaceable, directly in water, type DS
/M10x1/immersion depth 27.5 mm, cable length 1.5 m;
C
Split variant with 1.5 m control cable;
6
With 230 V alternating voltage, cable length 1.5 m;
1
With pulse module
0
Logo ULTRAHEAT
T
Dial plate in English, not country-specific
B
Display: MWh with 3 decimal places
(as of qp 15 with 2 decimal places);
2
Tested according to CEN 1434 class 3,
with lock mark.

When I enter Service Loop 1, the Current Flowrate and the Current Heat Output parameters are shown with an "u" sign in front of the values. According to the installation instructions, the explanation is:

The flow rate, the heat output, and the differential
(temperature difference) are acquired with the
correct sign. If the lower response limit is violated, a
u is displayed in front of the value.

I am not sure how to understand this line. The meter registers flow and return temperature, which are accessible via Loop 1.

What I've done so far is: disconnected the PT500 sensors and read the values below:
Return: 598Ω, corresponding to 51° C approx.
Supply: 602Ω, corresponding to 53° C approx.
The Supply value is shown in Loop 1 and was correct. I don't think there's a way to show the Return value on the display. This may point out that there's a fault in internal measurement of the Return temperature. The display is not showing any F errors.

Below is a picture of the meter. Can someone suggest how to check for other faults before buying a new meter.

Thanks

oldbuffer · 23 May 2020

Is the meter your property to work on? Normally they belong to the organisation providing the heat so that you can be charged appropriately. Bit like an electricity, gas or water meter.

rtman · 23 May 2020

I live in a building with a number of flats, and the heating is provided by a central boiler, which is sort of like a shared asset. We have a building manager who deals with bills but if anything breaks, we pay for it ourselves.

And it's the building manager who contacted me with the news that I need to buy a new meter, because the existing is not registering any consumption.

endecotp · 23 May 2020

rtman said:
I don't think there's a way to show the Return value on the display.

The display is showing two temperatures, which are the flow and return temperatures.

rtman · 24 May 2020

@endecotp - yes, thanks... I should read datasheets more carefully.

I connected to the meter via UltraAssist and it appears it correctly registers flow and temperature difference, and calculates the kWh value with a correct sign, see attached picture. However the display still shows an "u" in front of these values, meaning they're under the operation limit. The operation limit is set to 20% from qi (0.2 * 0.025m3/h) - I am able to read that but not modify it.

Any ideas how to proceed in order to find the fault?

MeldrewsMate · 24 May 2020

I just had a look at the instruction manual. The illustration for loop 1 shows the current FLOW and RETURN temperatures from left to right as 92 C and 55 C.
Your photo shows the FLOW at a lower temperature than the RETURN.

If you agree there is a simple choice of test:

Test 1. Disconnect the cable to the supply sensor (terminals 5 and 6). Does the FLOW temperature indication change to a silly figure or error message?
Could it be that you have had some rascal sneak into your flat and swap the cables over, because SUPPLY should be warmer than RETURN?
Could it have been the same rascal that measured the resistance of each sensor?

Test 2. Take the SUPPLY sensor out of its sensing pocket and leave it to cool slightly. Do you see the SUPPLY temperature drop on the display?

If your wires have NOT been crossed then take BOTH sensors from their pockets and tape them together in air. Do they display very similar readings?
Put them in hot water (if they're waterproof, of course); Again do they display similarly?

MM

MeldrewsMate · 24 May 2020

Page 6 of your instructions, para 3:

The flow rate, the heat output, and the differential (temperature difference) are acquired with the correct sign. If the lower response limit is violated, a u is displayed in front of the value. The current temperatures are displayed as integer values in °C together on one display line.

The sign refers to "differential = (Supply - Return)". That'll be a negative value if your display is to be believed.

Also on page 6:

Heat meters up to DN25 may only be installed with direct immersed sensors according to German calibration law!

We're not yet a part of the German superfederal system, but that statement makes sense, so be careful if you're considering removing either sensor.

endecotp · 24 May 2020

rtman said:
the display still shows an "u" in front of these values, meaning they're under the operation limit.

Are you actually using any heat at the time you make this observation?

What makes you think the meter is not functioning correctly?

rtman · 24 May 2020

@MeldrewsMate: The meter is installed on the return line. The flow is therefore negative. The temperature difference is also negative, and the resulting calculation for the energy has the correct sign.

I did check the sensors and they're working fine. The meter is also registering the water flow as seen in the "Flowrate" field.

@endecotp: I am turning on the heating and can see the flowrate and temperature differential increasing. When I turn off the heating, the temperature differential approaches 0.

What makes me think that the meter is not functioning correctly is that it's not accumulating the consumed energy, and my building manager is complaining that I am using hot water without paying. The meter readings stay the same from several months.

endecotp · 24 May 2020

rtman said:
What makes me think that the meter is not functioning correctly is that it's not accumulating the consumed energy, and my building manager is complaining that I am using hot water without paying. The meter readings stay the same from several months.

Is this not-changing value shown on the display of your meter, or is it read remotely via some sort of interface cable?

rtman · 24 May 2020

The meter is supposed to display the following in the "normal" mode:

Accumulated thermal energy and volume are not changing.

The meter is connected to the BMS via a pulse output module, that's how the building manager bills me. I haven't tested the actual module for faults.

endecotp · 24 May 2020

rtman said:
The meter is also registering the water flow as seen in the "Flowrate" field.

But:

rtman said:
volume are not changing.

Right?

rtman · 24 May 2020

That's correct I think. You can see flow rate and temperature differential in Loop 1. Accumulated values are shown in the User loop. While values in Loop 1 are changing, values in User loop are not updating.

On top of that the accumulated volume shows 7 m3 which can't be correct. It's been above 40000 when I moved in; to my knowledge, there's no way to reset it.

MeldrewsMate · 26 May 2020

I will have to bail out here, as I don't know enough about this specific device to give good specific information, however:

If your flowrate indicator is showing a flow, but your totaliser isn't integrating into total volume, and your sensors are in the correct place, and the display shows they register reasonable values, and the total volume that was higher than 40,000 when you moved in but is now 7, and the pulse output to the building manager's office has not increased, and there's been no external interference....then it all points to an internal failure of your main (German made) Landis & Gyr unit.

rtman · 27 May 2020

@MeldrewsMate, it also looks that way to me. I think I managed to isolate the fault, which is, as the meter shows, "operation limit below target". I can't find any explanation on what is causing that error and how to rectify it. Nor I can get a hold of someone who has experience with Landis+Gyr meters, which appear to share a common interface. I feel I've done what I could do.

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Faulty Ultraheat 2WR5 meter

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