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Kamstrup Multical 402 - which MBUS module to install?

Does anyone have any recommendations regarding the most suitable MBUS module to install in a Kamstrup Multical 402 heat meter for use with the OEM Heatpump Monitor? Kamstrup list several options, for example M-Bus + 2 pulse inputs (VA, VB); M-Bus + 2 pulse outputs (CE, CV); and M-Bus + 2 pulse inputs (VA, VB), MULTICAL® III Data Package. I would appreciate any guidance on the benefits of each type.

Hello @Westerner, I wasn’t aware that there where different kamstrup 402 m-bus modules, what does it say are the differences?

Here are the MBUS wired modules available, @TrystanLea. MBUS with two pulse inputs, Order no. 402-0-20 Module no. 5550-1030; MBUS with two pulse outputs, Order no. 402-0-21 Module no. 5550-1007; and MBUS with MULTICAL III compatible data package (two each pulse inputs and outputs), Order number: 402 0 29, Module number: 5550-1140. I assume that the pulse output modules are the ones to go for, but would appreciate guidance from anyone who has actually used the MBUS modules in a Kamstrup 402.

Hello @Westerner I realise there’s a picture of the one I used here https://github.com/openenergymonitor/HeatpumpMonitor/blob/master/images/kamstrup.jpg Im not currently at the location of that heatmeter so cant check it directly. I think its MBUS + 2 pulse inputs , i think i can just make out 5550-1030 on the pic.

Thanks @TrystanLea. I wondered what use people were making of the pulse inputs/outputs - it seems none! May I ask where you bought your module from? The 402 is now superseded, and module suppliers seem to be thin on the ground. Did you have any problems with installing the flow meter into the outlet pipe? My heatpumps pipes are multi-layer composite (MLCP), so I need adaptors to connect the flow meter to the pipe.

Hello @Westerner I originally bought mine from stockshed.com but I have since moved house and now have another heatpump but with a Sontex multical 531 with MBUS. Im using copper, the sontex came with appropriate reducers

Westerner, the “pulse inputs” option allows you to connect, for example, a cold water meter or an electricity meter to the heat meter, and have this appear in the data that you retrieve over MBUS. If you have a look at the register definition I think there are dedicated places for this to be recorded.

If you choose the “pulse output” option, that gives you the normal Volume and Energy pulses, which you might want to use with a data logger instead / as well as the MBUS output. This is handy for lab use if you might use it in different setups.

It doesn’t matter at all if you only care about reading the meter over MBUS, so choose whatever is cheaper or available.

Thanks Evan. I bought the pulse outputs version, but having read your explanation I think I should have gone for the pulse inputs version! Do you by any chance know where I can get a BSP F Branch Tee UK Compression 25mm x 25mm x 1/2" fitting? I can only find them in either 22mm or 28mm.

Is that for the heat meter temperature probe?

Copper pipe size will be 22 or 28mm, so unless you’re using actual threaded iron pipe… ?