@derek-m I think any optimisation will end up in the hands of the consumer - unless it can be done remotely or via AI, but that would require far more sensors than any home owner realistically has. Generally they'll have one zone, maybe two with a thermostat controlling them.

For me, I simply adjusted the flow temperature until the room with the thermostat reached and mostly maintained its temperature with low on/off cycles.  However I've adjusted the minimum weather compensation, I haven't yet adjusted the maximum. When it gets really cold I am certain the -2, 55 degree setting will need to change - the room we NEED to keep warm just has too much glass and my wife refuses to get curtains. I expect i'll bump it to something like 2 and 55 or maybe i'll go a bit higher and keep it at -2. The amount of days we actually get -2 can be counted on one hand and that would be in the darkest hours when our power is cheapest.

Below you can see power demand/use for yesterday and the actual purchased energy from the grid. Given our base load is 0.3kw the ASHP is chugging away at 1.5kw/h during that period. I want to see what happens when we are around 1 or 2 degrees.

@batalto 

You are probably correct that in most cases, optimisation will need to be performed by the customer, unless they are willing to pay someone to carryout the task for them. At least with active weather compensation, once optimised, it should provide reasonable efficiency throughout the year.

This is probably why most installers are keen to fit thermostats, which are a  'fit and forget' solution, that do not require optimisation. I don't know of any systems that are self adapting, but Brendon may know of some.

As I am sure that you are aware, optimising an ASHP system is something that cannot be done overnight, and in fact may have to be done over a full year. One of the benefits of being on a forum like this, is that people like yourself can feedback data on how their system is performing, so that newcomers at least at least have some starting parameters from which they can further optimise their system.

@heacol I had a look in the loft and the buffer tank just has one pipe. Also below is a list I was left from the Freedom HP install of what they installed, and where

@batalto As Suspected, It is a fit and forget configuration designed by Freedom Heat Pumps to prevent call backs due to the inability of their installers to understand the limitations of heat pumps and heat pump controllers, unfortunately with any compromise, there is a cost, and that cost is being born by you, forever with high running costs, but it stops you calling Freedom, job done. This is what you need to change if you want to run the system on either load or weather compensation.

Changes you need to make before it will work, if you do not make these changes any tweaking temperatures or controller settings will have little effect and may make things worse.

If you have a Midea unit as in the picture, you can install an internal thermostat or use the controller to control your internal temperature, if you have good thermal mass you can use weather compensation only and there is no need to move the controller.

Remove all other controllers, thermostats, actuators etc from your system including all TRV's n radiators except in the bedrooms.

These changes are contrary to what you may be used to, think or being told, however, you no longer have a gas boiler, you have a heat pump. They are completely different and have to be treaded differently. If you are not prepared to make any changes, do not complain about high running costs.

@heacol Graham hendra is on this forum. I'd be very interested on his take, given he was the one who supplied everything to my installer. @grahamh

@batalto B e my guest, ask him, I do not agree with how he designs and seel systems. They are designed and sold, so he does not get a telephone call, not for the best performance of a system.

It is up to you whether you take my advice or not, you are the only one that is going to lose out, not me. I have been designing heat pump systems for 30 years, I think I may have picked something up along the way. I have air source systems currently running at COP's for the last week of above 5, can you say yours is doing that?

Guys, i dont work at freedom heat pumps, i did, but not anymore. You need to speak to them for tech, after all they get paid to do it.

But i did design that diagram back in the day, its the best way to do it. I had the misfortune of spending hours with a stopwatch measuring how the unit works and how to get the best out of it. trust me the diagram is without doubt the best way to run that unit. 

you can do whatever you like, its your unit, but if you want help i would stick to the diagram. 

Posted by: @derek-m

@kev-m 

What I am saying is that what works for one house will not necessarily work for another. It could be that your home requires a flow temperature in the low to mid 30's. For optimum efficiency, you new to run your system with the lowest water flow temperature that meets your heat demand. Don't get tied up with actual figures.

From the calculations that I performed several weeks ago, lowering your indoor temperature by 1C should give an approximate 10% reduction in energy consumption. Lowering your heat demand by 20% with improved insulation, should give an approximately 25% reduction in energy consumption. Increasing the size or output of heat emitters also reduces energy consumption.

All of the above would allow your system to operate at lower water flow temperatures and hence improved efficiency.

It is for people who have already installed ASHP's to decide what if anything they can do, or wish to do, to improve the efficiency of their system.

For those people considering having an ASHP installed, one of the key factors should be how is the system to be controlled, particularly how will weather compensation be incorporated. If a proposed installer cannot offer a design that fully incorporates weather compensation, I would question their knowledge of ASHP systems and how their operation can be optimised. From many of the comments I have read on the forum and elsewhere, it would appear that there are many companies who can install an ASHP, but far fewer who can optimise its operation. 

 

Sorry, @derek-m, just catching up.  I agree with all of that.  I'm a big fan of lowering the indoor temp; I just have to get Mrs M on board! I'm no expert and I'll be watching this forum closely and will do my own experiments.  

In terms of my own system, it is using weather compensation and it does work; I can see it from the monitoring I have.  Whether it's set at the right level; I don't know.  It's what the supplier left me with but I am going to experiment.  What I don't have is Mitsubishi's 'auto adaptation' where it also uses the room temperature to further adjust how it works.  I don't think this will work for me because I have 3rd party thermostats.  Whether it would be any better I don't know but I would hope so.  The hardware and options are on page 15 of the FTC6 manual; choosing which option is used is done through the remote control panel. 

https://library.mitsubishielectric.co.uk/pdf/book/Ecodan_FTC6_PAC-IF071-3B-E_Instruction_Book_RG79F363L01#page-1

For auto adaptation I would need to either move the main remote controller, use a remote temp sensor or use a mitsubishi wireless remote controller.  If I tried it now it would use the temp in the airing cupboard, if it worked at all.  I'd be interested in your view.   

By the way I'm happy enough messing around with this stuff but most people won't be.  If ASHPs are going to take off people need something they can use without having to worry about flow temperatures, weather compensation and modulation.  

@kev-m 

Hi Kev,

I suspect that you are correct that auto adaptation would not work successfully with your present system. If you were to switch it on, you would probably find that the controller would sense that the temperature is too high, so would lower the compensation curve, which would in turn reduce the water flow temperature. The end result would be warm airing cupboard, cold elsewhere.

I think that your present system is probably the best that you can achieve without making modifications. As you say, further improvement may be possible with optimisation of the weather compensation. One other thing that you could check is the deadband setting of your thermostats, since some of the modern ones are adjustable. It needs to be set at the lowest value, normally 1C on most thermostats I have seen. The deadband range should be stated in the specification section of the manual for your thermostat.

I fully agree that the majority of people do not wish to concern themselves with water flow temperatures, COP or SCOP values, weather compensation curves and the like. They want a system installed that works when required. This is one of the reasons why designers/installers will chose thermostats in preference to temperature sensors, the installer is more likely to understand thermostats and so is the customer. Another important factor from the installer's point of view, is that they do not have to spend time optimising a system, which they may not fully understand themselves and may mean them having to return in the Winter months to make optimisation adjustments.

I have nothing against thermostats, they work fine, but their biggest drawback is that most manufacturers will insist on incorporating a minimum deadband of 1C. So instead of having a constant temperature within a room as set by the thermostat, a graph of the actual temperature would be a sawtooth. With a thermostat set at 21C, when the temperature falls to 20C the thermostat switches on the heating, when the room temperature rises to 21C the thermostat switches off the heating. This means that most people would set the thermostat probably 1C higher, for personal comfort. There is no reason why a deadband of 0.2C or even 0.1C could not be used, provided that there is an inbuilt time delay to prevent the thermostat switching on and off, due to someone walking past and creating a slight draft.

I would be very interested to see the data from your system and would be happy to work with you to optimise your system.

@derek-m,

Derek,

thanks for the offer, I may well take you up on it. I looked at the thermostat manual and there's something called calibtation/swing, settable 0.5-2.0.  It was set a 0.5 so I'll leave it there.  

Posted by: @heacol

 

This video might be of interest - 5.30 mark he starts talking about the system elements. As a note, we don't have a buffer tank, only the red expansion vessel. Interesting they talk about the low loss header as a requirement of the Midea warranty.

@batalto A buffer tank and a low-loss header are the same thing.  If you look at the Midea manual, there are schematics with and without system separation. I have installed a number of  Midea units and actually went to the launch of this new R32 unit in Italy a couple of years ago, You can keep them, but that is my opinion.