Hi Emma, check what your house thermostat is doing set at 16/17degC. Is it switching the ASHP on and off continuously? If it is that's a very inefficient way to control the ASHP. Most room thermostats are fancy switches.
True, but if the "thermostat" is actually the Mitsubishi controller (either the main one or the optional wireless remote extra), that could mean it's running the heat pump in auto-adaptation mode, which is far better than an on-off thermostat but not as good as a well-tuned weather compensation curve with an on-off thermostat preventing overheating (in my opinion). It makes the radiators here hot to touch (probably 48° or more) if the temperature is increased by 2 or more degrees in one step.
A few pictures or more description of what names or logos are on the controls would help greatly.
This is in a cupboard with our water tank. I just noticed that this is running the heating in 'Eco heating' which looks like it is set to 46 degrees but I cant change the temp, and I don't know how to select which mode to run it in either. Checked and hot water on that controller is on 42 degrees and the normal heating mode was at 58 degrees.
From the home screen, you get to the mode changes screen by pressing the right-hand button once. The buttons under the left three items change the modes. For hot water, it cycles between off, on and timed.
To change the temperature, go to the home screen and long-press the menu key. Long press. 2 or 3 seconds. Then what looks like the usual menu will display, but selecting "Hot Water" will have an extra edit symbol beneath the normal/eco selector, where you can change the temperature settings. You can also use that menu to shorten the expensive 60° immersion heating to 1h every 2 or 3 weeks, depending how much of the legionella fear you share. The normal/eco thing seems mainly to decide if the pump is allowed to go to 100% when heating water or gets limited to about 70%.
Hope that helps. The ecodan controller manuals are online. There are several rather similar-looking ones, called FTC and then a number between 2 and 6 inclusive.
@kev-m please see attached controllers I have. It is currently in eco mode which is the weather compensation mode. However this is at 47 with no clear way of being able to adjust this temperature manually. It just flashes when I touch the controllers. I am able to adjust the normal mode, hot water and antifreeze though.
for adjusting the room temperature I just spin the dial on the Honeywell room thermostat which is in my hallway 1 degree. The rads I don’t really touch although they have the standard 1 through 5 dials.
thanks,
Emma
Hmm, that doesn't look like any Ecodan controller I've ever seen. I'll get back to you.
@kev-m@mjr yes its 12 years old, was installed when the house was built 🤣 so I guess the age could have an impact on how efficiently its running!
@derek-m yes I managed to find the controller manual and dig around in the weather compensation settings! It was on 58 degrees at -3 degrees and 48 degrees at 20 degrees.
I have adjusted the settings to 40 degrees at -2 degrees and 30 degrees at 15 degrees in line with the manual but open to other suggestions. The manual also suggests its best to have the water on just twice a day once in the early hours and then once when the heating is least likely to be on. I am not sure how you guys have found running the water and heating both on constant vs. timed water.
I have put the home thermostat now up to 19 which seemed to ramp up the kwh usage yesterday and overnight, but I am assuming this could be just as the home reaching correct temperature and this could settle a little?
Anyway thank you so much for all your help guys, I never would have thought to look into the weather compensation mode without you all! I have also sent a grumpy email to the people who last serviced it a couple of months back because they had it operating way outside of the manufacturer recommendations and told me completely incorrect information on how to run it.
Pleased to hear that you have managed to adjust the WC settings to something more suitable.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
@enc it depends on your settings. What you should find is that the house is warmer, but you use less power. It takes less energy to heat to 40 degrees than it does 58. Don't forget as well that if its a cold night you'll use more power anyway.
12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE
@kev-m@mjr yes its 12 years old, was installed when the house was built 🤣 so I guess the age could have an impact on how efficiently its running!
@derek-m yes I managed to find the controller manual and dig around in the weather compensation settings! It was on 58 degrees at -3 degrees and 48 degrees at 20 degrees.
I have adjusted the settings to 40 degrees at -2 degrees and 30 degrees at 15 degrees in line with the manual but open to other suggestions. The manual also suggests its best to have the water on just twice a day once in the early hours and then once when the heating is least likely to be on. I am not sure how you guys have found running the water and heating both on constant vs. timed water.
I have put the home thermostat now up to 19 which seemed to ramp up the kwh usage yesterday and overnight, but I am assuming this could be just as the home reaching correct temperature and this could settle a little?
Anyway thank you so much for all your help guys, I never would have thought to look into the weather compensation mode without you all! I have also sent a grumpy email to the people who last serviced it a couple of months back because they had it operating way outside of the manufacturer recommendations and told me completely incorrect information on how to run it.
Your controllers are the older type as used with the original FTC1/2; I hadn't seen one of these before.
Your new settings sound like something that will work better. The way it was before would be really inefficient with a minimum flow of 48 degrees. Just as an illustration; I found the difference between running mine at 45 degrees constant and using weather compensation was 20-25% so definitely worth doing.
I'd agree with your hot water approach; try and do most of the heating when it's warmest outside and the heating is least likely to be needed. As well as the HW being more efficient at these times, it's less likely to interrupt the heating. But the most important thing is to have enough HW when you need it.
If you turn the thermostat up it so that it heats the house to 19 instead of 16 then it will use more energy. If you want to get your weather compensation curve right then turn the stat up to 30 and see how hot the house gets. If it's hotter than you want then reduce/adjust the curve a bit. It takes a bit of trial and error to get it right, especially at warmer outside temps. Once you've got it about right then you can use the stat as a limiter to turn the ASHP off if the house gets too hot. It's more efficient like this and also gives a more constant temperature. Where it doesn't work very well is if you want to vary your house temperature a lot because a well adjusted compensation curve won't heat the house up very quickly.
Good luck; it sounds as if you are well on the way.
@kev-m seems like its vintage then! Would there be any benefit to updating the controller other than for ease of control or smarter data tracking?
Really hoping to start to see some improvements now. I think I am understanding what you are saying that we want to temperature compensation curve to do all the work based on outside temperature, and not the room thermostat turning it on and off. To figure out the temperature compensation curve initially we need to have a play around adjusting this without the room themostat interfering i.e. have stat on 30, so high when we do this? However, once we have the curve right we can adjust the stat back down to something more like 21 degrees?
This brings me onto my next question of radiators! We have three floors and 11 rads throughout the house, plus 3 towel rails. As it gets hot at the top of the house the bedrooms are quite uncomfortably hot at night, does it make sense to have these rads on 1 or 2 at all times and then the ones on the ground floor at a higher setting i.e 5? Or do we want them all on high and this heat at night time is due to the temperature compensation curve being too high at low temperatures?
Thanks again for all your help. You probably have to go through this whole conversation so many time with newbies to ASHPs!
@kev-m seems like its vintage then! Would there be any benefit to updating the controller other than for ease of control or smarter data tracking?
Really hoping to start to see some improvements now. I think I am understanding what you are saying that we want to temperature compensation curve to do all the work based on outside temperature, and not the room thermostat turning it on and off. To figure out the temperature compensation curve initially we need to have a play around adjusting this without the room themostat interfering i.e. have stat on 30, so high when we do this? However, once we have the curve right we can adjust the stat back down to something more like 21 degrees?
This brings me onto my next question of radiators! We have three floors and 11 rads throughout the house, plus 3 towel rails. As it gets hot at the top of the house the bedrooms are quite uncomfortably hot at night, does it make sense to have these rads on 1 or 2 at all times and then the ones on the ground floor at a higher setting i.e 5? Or do we want them all on high and this heat at night time is due to the temperature compensation curve being too high at low temperatures?
Thanks again for all your help. You probably have to go through this whole conversation so many time with newbies to ASHPs!
You should use the TRVs in the upstairs rads to limit the temperature in those rooms, yes. You should remove the actuator heads from the downstairs TRVs (or at least set them to fully open).
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
I am pleased to read that you have discovered the 'delights' of weather compensation and that you are making progress. The objective is to fine tune the WC curve for best overall efficiency. This could take a while to achieve since temperatures can change quite slowly, and having some reasonably accurate thermometers may be useful.
Start by recording the temperature in each room, and also near the thermostat in the hallway. I would suggest that you record the temperatures over a period of time and note variations. Also think about what temperatures you would prefer in each room for comfort. As a Chemist you will appreciate the need for accuracy and repeatability, so taking the temperature readings at 1 hour intervals, when possible, should be more than adequate. Don't make any further adjustments to your heating controls unless necessary. Check that the radiators have been bled. Do you know if the radiators have been balanced?
Once you have some useful data and that you are going to be at home for as reasonable period of time, start by setting all the TRV's fully open at 5 and record the effect on all the temperatures. When the room temperatures are stable, increase the thermostat setting from 19C to 25C and again record the room temperatures until they stabilise.
If the room temperatures increase, in either case, then it would indicate that the WC curve is set too high.
For maximum overall efficiency, you want your heat pump to provide the maximum amount of heat energy output, for the minimum amount of electrical energy input. Just as importantly, you need your radiators to transfer this heat energy into your home at the lowest possible LWT.
Once the room temperatures have stabilsed, as described above, measure the surface temperature at the top and the bottom of the central section of each radiator. This will hopefully give a good indication of how well each radiator is functioning, so note any measurable differences.
In a gas or oil heating system, the controls are often set up to switch the boiler on when the room temperature falls, and heat the radiators up to quite a high temperature. Eventually the air temperature in the room increases to the point where the thermostat switches off the boiler, and the radiators start to cool. The boiler therefore runs intermittently at a higher temperature than is actually necessary. It is similar than driving faster than necessary in your car, and then having to stop for a period half way, when you realise that you will arrive too soon.
In an ASHP system the objective is to 'drive at the required speed to arrive just on time'. The heat pump should therefore operate to provide the required amount of heat energy, to match the heat energy lost to the outside World, and hence keep the indoor air temperatures reasonably constant. To do this, the LWT, set by the WC, needs to produce the required amount of heat energy to match the heat loss, as the ambient air temperature varies.
I hope that the above makes sense, but if not then please ask questions, and if possible post your measurement results which others may find useful.
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