Which kit for my ASHP


Hopefully this is in the right place.

I have been looking / wanting to add proper monitoring to my recent ASHP install.

I’m a bit unsure which heat monitor I’ll need though as my ASHP falls into 2 categories. So before ordering I want to check that I’ll need the 15kW heat meter as my flow rate can be high, though I believe my ASHP is rated at 5kW.

Technical details on the ASHP are here, I have the PRO-N variant.



So I’m assuming that the 15kW version would be suitable, even with a 5kW ASHP. It’s Just the £300 extra which could be potentially saved, by going with the 5kW flow meter.

Hi Andy,

The Sontex 789 that we recommend for up to 7kW heat pump will be fine for your 5kW system. To deliver 5kW at DT5 your flow rate will be maximum about 15L/min (0.87 m^3/hr). The maximum flow rate quoted on the datasheet for your heatpump will be the maximum flow rate the heatpump can handle without getting sustaining damage!

At 15l/min the Sontex 789 has a pressure drop of 0.25m which is negligible.

It’s great you’re considering adding monitoring to your Acond ASHP, this is a very interesting unit, a European manufactured R290 heatpump. How are you finding the control system?

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Thanks for the reply. Will hopefully get one around Christmas if I get a bonus this year.

Controls seem decent. Not really seen anything else to compare it with. The system runs Debian and you control the system from some webpages. It would also appear to potentially do modbus over TCP, but information is some what lacking. GitHub - JH-Soft-Technology/acond-heat-card: Acont heat pump interface for home assistant based on modbus TCP comunication

Web interface is much easier to use than the app and controller.

main page

last 24hr stats

temperature curve settings

Just as a follow up I asked the manufacturer about TCP Modbus after the above GitHub post and seeing it mentioned in other ASHP posts in various places.

They have sent me over the attached document. Don’t know if that’s going to be useful at all for monitoring or just get the kit.
I’m new to this TCP Modbus thing if you’d not guessed.

Acond_ModbusTCP v2.35 - ENG.pdf (497.3 KB)

Please attach documents directly to your post. If you link to a third party site, and that site
becomes unavailable, it causes confusion and devalues your post.

Edit - attached document to post. Moderator, BT

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That’s cool, it’s good to see more info is available via modbus. However, the parameters available via modbus look to be quite limited. There’s not enough information available to calculate COP.

To calculate COP we need flowT, ReturnT, flowrate and electricity input. As far as I can see only flowT and returnT are available via modbus direct from the heat pump.

Update: I’ve just seen that comp_capacity_actual looks like heat output in W, this metric coupled with electrical input is all you need to calculate COP. However, there’s no guarantee of accuracy using manufacture’s metrics compared with a MID approved heat meter, however it may be a useful starting point.

I like the look of the web interface, that’s so much better than fiddling with the LCD controller that most HP use.

Thanks for taking a look.

I think the best course of action would be to get the kit from yourself, as like you say it will be consistent (with heatpumpmonitor.org) So will look at getting the kit as soon as I am able.

Indeed a web page is so much easier and user friendly. The installers and ACOND themselves also have direct access to this as well. Friends have a Panasonic, the controls on that aren’t great to say the least.

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