I think my ASHP is performing poorly and I want to know what questions to ask when the installer visits

I’m not personally familiar with buffers, so I recommend this article to get the background info: Low Loss Headers, the Complete Guide! - HeatGeek. Generally want to avoid adding a buffer, but sometimes it is necessary.

Other’s have had success removing a buffer, or converting it to a 3-port buffer, or to a volumiser:

Alternatively, you can try to balance the flow on both sides of the buffer as zones turn on and off, which could be done by monitoring the temperatures at the 4 ports:

Does the heatpump turn off when the consumption pump is off? Or does it keep running to maintain the temperature in the buffer tank?


There is one other LG Therma V listed on HeatpumpMonitor.org, which may be similar to yours.
12 kW, 200 m², fully insulated, mix of rads and UFH, no buffer. Might be a useful comparison.