athlonoc Posted May 20, 2023 Share Posted May 20, 2023 Recently my HW recycling starts before the 10 degree drop as set up in the controller setting. HW is set to 55 Degrees Temp drop is set to 10 degrees This never use to happen but recently in the last 3 or so weeks I've noticed it reheats when it's dropped to somewhere between 49 and 51 degrees, indicating that it's ignoring the request to only heat when it drops to 45 degrees. Any idea on why this might be happening all of a sudden? Link to comment Share on other sites More sharing options...
JohnMo Posted May 20, 2023 Share Posted May 20, 2023 So only guessing here. It could be it's learning and (really a bit of question) could it be struggling to reheat the 10 degree drop in one heating attempt? So it's starting to heat earlier. Heating to 55 isn't that good for CoP, a lot on here, heat to about 47-48, the you can set the hysterisis at 2 or 3 and heat pump has way less to do. Link to comment Share on other sites More sharing options...
DanDee Posted May 23, 2023 Share Posted May 23, 2023 On 20/05/2023 at 09:31, athlonoc said: Recently my HW recycling starts before the 10 degree drop as set up in the controller setting. HW is set to 55 Degrees Temp drop is set to 10 degrees This never use to happen but recently in the last 3 or so weeks I've noticed it reheats when it's dropped to somewhere between 49 and 51 degrees, indicating that it's ignoring the request to only heat when it drops to 45 degrees. Any idea on why this might be happening all of a sudden? sounds like there may be a delay with the THW5 sensor which is effectively your hot water sensor, although on the controller it will show 49-51 as you've mentioned, it may actually be sending a signal back to say its at the 10 degree drop point, to test this theory, decrease your temperature drop to -15 and see see if this then delays the heat pump coming on to recycle. if it does .. the THW5 Sensor needs replacing. although for what it is, I would just keep the maximum temp drop to 15 to allow for that delay. hope this helps. Link to comment Share on other sites More sharing options...
athlonoc Posted June 3, 2023 Author Share Posted June 3, 2023 The installers have now been back and stated it is because the flow rate is so low. This was adjusted at the pump and at the ecodan controller a few months ago due to the noise of the system affecting our sleep. That has now been increased to provide a flow rate of 17l / min So far so good with the 10 degrees drop being maintained but the downside is that we can now hear the system when running. , however it doesn't seem as bad as before but the weather is warmer so not working so hard I guess. Also there seems to be a lot of discussion about tank temperature settings. I'm going to drop tank temperature to 50 and keep the 10 degree drop. Any thoughts on whether a 5 degree drop at this temperature is likely to be more efficient? Link to comment Share on other sites More sharing options...
PhilT Posted June 3, 2023 Share Posted June 3, 2023 2 hours ago, athlonoc said: the downside is that we can now hear the system when running. I have this too. It happens with radiator systems. So we only run our hot water during the early afternoon, as it gives the best possible CoP, controlled entirely by the timer, so temp drop isn't relevant for us. 45degC is plenty but there are only 2 of us. Also we have the heating switched off between 11 and 6 at night, again mainly due to the background hum issue Link to comment Share on other sites More sharing options...
athlonoc Posted June 9, 2023 Author Share Posted June 9, 2023 PhilT, I was told I shouldn't timer the HW and just let it heat up, then drop in temp, then reheat. However I have solar panels 4.6kW system and I think I would be better getting it to charge on a timer once the sun is up. I guess there is no logical reason for the installers to say you shouldn't set your HW to a timed program? Link to comment Share on other sites More sharing options...
ragg987 Posted June 9, 2023 Share Posted June 9, 2023 (edited) The heat pump will be least efficient at higher water temperatures, so if you are constantly topping it up AND aiming for a high 55C that seems to be the worst case. I use a timer to heat our 300l tank to 42C then we consume it all day and to up the following night. This is because I am on 7.5p night rate. Prior to the dual rate I heated at the warmest time of the day to improve HP efficiency, as per @PhilT above. And to take advantage of solar power during the day. In the current sunny weather excess solar diverter heats the water and I don't need to run the HP. I suspect you were advised to keep it off timer as a HP takes longer than a gas boiler to heat the water. So less risk of running out. Edited June 9, 2023 by ragg987 Link to comment Share on other sites More sharing options...
ragg987 Posted June 9, 2023 Share Posted June 9, 2023 Example CoP results here https://www.researchgate.net/figure/COP-of-the-air-to-water-heat-pump-with-different-load-side-inlet-temperatures-Based-on_fig1_326114264 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now