Heat pump efficiency - not sure how to drive down the usage? (rental property)

Hi ​@juliamc.  We stay in a big new build house.  upstairs is radiators.  5 bedrooms.  ideal temp is around 20 in daytime and in evenings I want it to drop to around 18.  I use the timer feature on the ecodan to do this but not sure if that is smart.  

Downstairs we have underfloor heating.  Big space.  2 large dining/kitchen/living room areas.  small study and big front entrance.  Ideal temp again 19.5 to 20.  Hope this helps

​@M.isterW would appreciate your help

gdebruin wrote:

 

 

Hi ​@juliamc.  We stay in a big new build house.  upstairs is radiators.  5 bedrooms.  ideal temp is around 20 in daytime and in evenings I want it to drop to around 18.  I use the timer feature on the ecodan to do this but not sure if that is smart.  

Downstairs we have underfloor heating.  Big space.  2 large dining/kitchen/living room areas.  small study and big front entrance.  Ideal temp again 19.5 to 20.  Hope this helps

​@hydrosam here you can see all the details of the property I was speaking about

I'm not the best person to ask because my system is a little odd... but let's see what we can do.

The Ecodan can run in 3 modes.

Fixed temp, where the output of the heat pump is at a constant temperature.

Weather compensation, where the flow temperature is adjusted as the outside temperature changes.

Auto adapt, where the system uses the house temperature to determine the best flow temperature.

Most people find auto adapt to be the best option because it allows you to have the house at your preferred temperature without having to muck about with getting the compensation curve right. But, you need a temperature sensor in the house. The main controller (called the FTC) can work as a temp sensor or you can buy a separate remote sensor.

So, where's your FTC? I can't see it on any of the photos.

Hi. 
looks like a neat install, which is something at least. 
 

So, what size of heat pump do you have? 

Was the heat pump installed for you or already there before you moved in? 

How is the heating controlled? Do you have a one internal thermostat, multiple thermostats, or none? Can see at least one in the photos, ideally we want to avoid using them. 

Do you know how to alter the running temperature? Sometime referred to as weather dependant curve (depends on brand).

What temperature are you heating domestic hot water to? Ideally less than 50C. 

Thank you everyone for the help. The heatpump was already in when i moved in. I scanned through some

paperwork and it looks like puhz-w112vaa if that means anything. Yhere is one wireless themostat controller upstairs and all rooms are set to the temp upstairs. There are radiators with individual thermostats on them but they are all to max. Downstairs is underfloor heating and each room is controller individually by the lk wireless system. 
 

airflow on compensation curve is upstairs high 40 on 0 outside temp.  Min 25 on 15 outside.  Downstairs is high 40 on 0 outside. Min 30 on 15 outside. 
 

does this help?

DHW is Water is 48deg

Can you see what COP you get ? On your display you can see electricity in and heat output, both in kWh. If you divide heat by electricity the result gives the COP coefficient of performance. On a cold day it will be less than a milder day, but it should be around 3.5 or higher. 

Morning ​@gdebruin,

Congrats, you’ve earned yourself a Heat Pump Badge 😁. I can see that our Community has already been super helpful with this topic and I hope you get all the answers you need. In the meantime, I just wanted to direct you to some previous Forum topics that you might find useful:

It looks like you've got third part controls (i.e. not Mitsubishi's own controls) and that's not a good thing. If you've set the system to weather compensation, on the Mitsubishi FTC controller, then it should run without a third party thermostat turning it on and off.

Can I suggest you find the Mitsubishi Ecodan group on Facebook and ask them for help. There are people far more knowledgeable than me in the group. They will want to see pictures of all of your controls (FTC, thermostats etc).

https://m.facebook.com/groups/674120483503581/

Ah ! Well spotted ​@M.isterW !!

Quoting from a previous thread on here: “Working through the ‘magnifying glass’ icon’ you can get consumed and delivered energies for  the last 2 months and for the year to date to work out the COPs.”

So the system has been getting a COP of 3.17 over the period displayed. 
I’m sure if you do as suggested previously ⬆️ and run it on “weather compensation” you will get an improved COP. 

It looks like you have an 11kw output heat pump, fairly large for a well insulated, new build property. The COP figure ​@juliamc has calculated is at the low end of what you would expect. 
Firstly the hot water temperature is about right. Do you need to heat the tank twice a day? If you can drop it to once per day, in the afternoon, that will improve efficiency for that part of the system, but it’s not going to make a huge difference.

For the heating, the two zones and external thermostats are not ideal. As ​@M.isterW suggested Ecodan specific Facebook groups are your best bet to getting this system setup best. Initially I’d be looking to tweak the compensation curve. Have both ground and first floor the same, lower the top end 40C at outside temp of -4C, (so more like 38C at 0C outside) and have the bottom end set at 30C at 15C outside (radiators don’t work well running much below 30C).

Is the house occupied most of the time? What heat schedule do you run? Keeping the schedule simple will help, and with a heat pump that size it maybe cheaper to only heat morning and evening  

The measured heat delivered figure on Ecodan systems is very inaccurate, unless you have additional energy monitoring attached. So I wouldn't trust the numbers on the controller.