My ASHP Installation: Mitsubishi Ecodan 14kW
I had the electrician back out today to look at the immersion, as I had reported it coming on alongside the heat pump during regular heating of the hot water and underfloor/rads. He took one look at the meter, which shows a low reading in his eyes (well yes because it's been off more than because of various repairs, plus I only turned the heating on a few weeks ago!) and refused to do anything else. I have videos of the immersion coming on (lights flashing on the meter) alongside the heat pump when heating hot water and UF/rads but he refused to look at them or entertain the idea that Vaillant posited of putting the immersion on it's own spur. The Arotherm plus is more than capable of doing the legionella cycle on it's own due to the refrigerant used, as all there advertising says, but instead I am being forced to use the immersion and not have any control over it, or at the other times it is coming on too. It is so mild outside too. He did not look at any settings on the controller either.
@saz I am also concerned that my recent installation is using the immersion top heat up the water. My non ASHP electrical use has rocketed but I am only using 2 Kwh per day to heat a 250 litre tank.
I have turned off the immersion at the fuse box so I can see if its been eating up the electricity
@mikefitz Hi, and these systems shouldn't need to even use the immersion at this time of year I think? It's a good idea to do comparisons, that's what I intend to do. I'm so annoyed with the electrician and his attitude, extremely unhelpful to say the least. Total waste of time.
@saz, @mikefitz, I believe that some ASHPs have a setting that determines when the immersion heater kicks in. On another forum I read, someone said theirs was set to use the immersion whenever the flow temp exceeded 40 degrees. I've no idea if that's possible with your systems but it would be worth a look at the settings/manual.
"Standard" low temperature heat pumps are designed to be efficient up 45C. The immersion is there to get the temperature north of that, and to help with legionella cycles. Our HW is set to 44C. For most people that water feels very, very hot on the skin. Anything hotter than that will be start to feel uncomfortable so you'll turn the cold water on to offset this. As far as I know, most systems are set up for the immersion to kick in when the temperature requirement is over 45C (or maybe 50C). Up to that point, the heat pump should be heating it.
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I’ve just re-read your installation post @kev-m (over the first couple of pages) and I have to say it went really well, and it’s worth reading for anyone considering a heat pump installation. How involved were you in the process?
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