# Vaillant Arotherm Owners Thread **URL:** \ **Category:** Sustainable Energy\ **Tags:** heatpumpmonitor, heatpumps\ **Created:** [18 November 2022 09:18 UTC](https://community.openenergymonitor.org/t/vaillant-arotherm-owners-thread/21891 "2022-11-18T09:18:47Z")\ **Posts on this page:** 1\ **Showing post:** 18
**Author:** ![Zarch](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/zarch/32/7947_2.png) [@Zarch](https://community.openenergymonitor.org/u/Zarch)\ **Post date:** [30 November 2022 18:37 UTC](https://community.openenergymonitor.org/t/vaillant-arotherm-owners-thread/21891/18 "2022-11-30T18:37:34Z")
> [@AndyS](#): > > Once I can monitor the dT I am going to test with and without the additional pump. As it is in the flow, it may cause a big head loss if the impeller is not powered. If not needed, there is a great opportunity to replace with an 1-1/4" heat meter I guess! Perfect!! Yeah, all the pipework sizing sounds more than adequate for the heat pump, which is a good sign. I’ve played a lot with my install since it was put in, most of the changes driven by monitoring data. I know a heat meter and associated kit is expensive, but i’m not sure how you could determine things are all working without it. If you look at my data [https://emoncms.org/energystatsuk](https://emoncms.org/energystatsuk) You’ll see during heating that it hasn’t really hit DT5, same with Adam Heat Geek install. It seems to prefer to max out the flow rate and squeeze the DT. Most of the time my DT is 2 or 3. Perhaps when it’s -3 and it needs to output 5.5kW it might get closer to DT5? I was worried about this DT2 / DT3 at first having read ‘heat pumps work at DT5’, but it doesn’t seem the case. Even Glyn and Trystans seem the same. When you think about it, if you’re sticking with a fixed pump speed / flow rate, it’s only DT in the 'heat output = ’ equation that you can modify? --- _[View the full topic](https://community.openenergymonitor.org/t/vaillant-arotherm-owners-thread/21891)._