i may’ve of found something , i was just in the cover of my heat pump , (i never shut it off ) but when i put the cover back on i discovered i lost connection with the esp32 , so went back in and rebooted the esp32 and my readings are now smoother again
so maybe the issue is the power supply or the esp32 itself ??
or maybe the battery is suffering with the colder weather
thoughts
is there a physical safety switch on the cover that removes power to the units PCB and intern cuts power to the ESP, then the unit reboots once the cover is replaced?
I would recommend isolating the monoblock next time.
you are correct i should of isolated it ( i am a electrician/engineer so should of known better 
but there is a relay to power the esp32 which kicks in but the esp requires 5 volts input but the heat pump only gives around 4.2 volts
there no safety switches it was one of the jumpers that i had knocked off
the red error is when i knocked off the wire but as soon as i reconnected it you can see how much smoother it is
https://emoncms.org/app/view?name=My%20HeatPump&readkey=1da9e37af3d5ac9669792233ea85675c
i suppose my next step is to try and get a solid 5 v supply to the esp32 via the usb connection
i will be the guinea pig and try next week
To be honest, if the esp is working sufficiently well to get you data, it’s working. It’s not measuring anything, just sending digital signals to the HP firmware to ask it to send information, which is either correct or doesn’t happen.
its also keeping a battery charged or trying to, the espaltherma instructions also mention something
just under the connector picture
Hi Chris,
I’m using a an M5Stack Atom lite as I found the M5stickC would stop the heatpump properly starting up after a power cut.
The M5stickC has a battery, whereas the Atom lite does not.
Swapping to the Atom lite fixed my startup issue, so assumed having the battery may have messed up the Comms following a power interruption.
FYI, am an embedded electronics application engineer and should also know better 
or the esp32 battery charger pulls more power when its cold to try and keep the battery charged, lets hope this is not the case when it goes cold again you do not see the issue again but its just something i noticed today ,
out of interest what voltage is your battery at ?
mine is at 4.25v atm and giving a smooth data
The ESP32 will be running on 3v3 with an LDO regulating the 5V supply. Id guess it would be happy with an input between 3 & 6v or so.
Cheers mark I will take a look at my voltage when it starts getting unstable again 
What if the transformer on the heat pump can’t cope ?
The Altherma will have a 5V regulator,ESP Altherma suggests it’s a 7805 which is more than beefy enough to run an ESP32 and then some but I have no idea what else the reg might be connected to internally.
As ESP Altherma suggests, try running from a dedicated USB supply and see what that does, though probably not practical long term as you prob don’t have an IP rated 240v socket suitably close.
The c stick does have a battery and display which the Atom lite doesn’t, so if current is limited the atom lite might be a better bet.
I’m using the Grove connector on the atom lite and crimped my own jst connector ( not fun) at the Altherma end to have a Dupont cable free setup. Did need to remap the serial pins in the code though.
