Hi I’m hoping someone can help with a strange issue I seem to be having with my Axiom Heat Meter. When starting a DHW cycle it is reporting so crazy heat output values. For example at 8AM this morning it reported 44kw output. I’ve checked for air in the system but all bleed point seem to be ok. I’ve attached a picture of the heat meter location in case this helps.
Thanks in advance
Barry Ward
This is just a transient spike from the switch to DHW. Some warm water from before the switch goes trough the heat meter’s flow temperature sensor and cold water from the DHW circuit flows through the return sensor. I also see similar spikes when my system switches between space heating and DHW. I don’t think this is a defect.
Thanks. I’m not hugely concerned by it but it is scewing the graphs somewhat and hasn’t always done it. I was consider looking at trying to normalise the data in the feed but at the same time don’t want to effect the accuracy of the data being recorded.
You have a flow temperature of almost 50°C before the DHW cycle. Directly after the 3-way-valve switches, this hot water still flows throug the heat meter but the initially cold (<20°C) water in the DHW heating loop gets pushed through the return sensor before being heated up. So for a very short time you have a dt of 30°C. This effect will be strong when you’re currently heating with high flow temperatures and be less evident when it gets warmer again and you use lower flow temperatures.
