Starting out on my heat pump journey

[Stinsy]

I've repurposed the old Shelly sensors off my boiler on to the primary flow and return, just to see what's going on.

It doesn't quite make sense, below is a hot water heating cycle, now I would expect some more separation in the flow and return temperatures when heating the tank. but there isn't really any and its completely different to Joe's hot water cycle.

Any thoughts?

I know it's only crude with the temperature sensors tucked in behind the insulation on the pipework in the utility room, but it's just odd how flow & return stays the same for almost an hour then the big seperation. We have lovely hot water so its clearly working.



Edit: To add the heat pump was only drawing power between 21:31 and 22:22, it then drops back to about 5w

I don't see major problem! It isn't as if the flow/return temps get to 50℃ in a few mins, which would indicate the primary circuit is struggling to give off heat to the cylinder. Takes about 40mins. The super-close flow/return temps are just a function of a very efficient heat exchanger giving off enough power at low Δt.

[Ronski]

Thanks, just seemed odd, you'd expect the return to be cooler as it's passed some heat into the tank.

I did a little Googling earlier, and that suggested Vaillant don't alter the flow rate.

Like I say, we've got nice hot water, and that's costing about 18p a day, which is less than the gas standing charge.

[Stinsy]

Thanks, just seemed odd, you'd expect the return to be cooler as it's passed some heat into the tank.

I did a little Googling earlier, and that suggested Vaillant don't alter the flow rate.

Like I say, we've got nice hot water, and that's costing about 18p a day, which is less than the gas standing charge.

All good!

Some parts of all this aren't immediately obvious! It takes big fat pipes shifting a lot of water and an efficient heat exchanger, but you can transfer a lot of energy with a very small Δt. And doing so is exceptionally efficient.