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What is most efficient way to run heating for my Mitsubishi Ecodan Air Source Heat Pump?

  • 1 November 2022
  • 41 replies
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Userlevel 7
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Thank you! Heat geek gets a cop of 5.9 in a badly insulated office of his!

😢 2.75 here

Userlevel 1
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Not the easiest to figure out how to get the best ourt of it, im insulating my bungalow to the max….

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I got a COP of 1.75 for January and 2 for December 😫 😥

 

Absolutely lost with how to run this thing efficiently.

Userlevel 7
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What do you have @benZ ? 

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What do you have @benZ ? 

Hey, thanks so much for your fast reply. I have a Mitsubishi EcoDan EHPT20Q. The system is zoned in tk downstairs and upstairs. And there’s two Digistat’s for each area. 


I’m really unsure as to why it’s so inefficient 

I put the system in to the custom compensation curve, and running it at 19/20 but it seems to be costing a lot of money to do so. 
 

When I checked yesterday it had used 141 and delivered 248 😭

 

it’s a new build so all the radiators should be up to spec…? I’ve no idea. No one has takes me through it or anything. 

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@M.isterW also has an Ecodan so will be familiar with the controls, I have a Daikin, and I’m no expert but there are a few on here who now have lots of experience. The principles are the same. Open all the valves on your radiators, keep it running night and day and use the curve settings to control the temp in the house. Whereabouts are you ? The cop will reduce in very cold weather but should be better than 2

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@M.isterW also has an Ecodan so will be familiar with the controls, I have a Daikin, and I’m no expert but there are a few on here who now have lots of experience. The principles are the same. Open all the valves on your radiators, keep it running night and day and use the curve settings to control the temp in the house. Whereabouts are you ? The cop will reduce in very cold weather but should be better than 2

Thanks again for your speedy response. 
I’m based in Bristol. 
 

Sounds like I might’ve eventually got it setup right then. But I still don’t understand why it’s such a low COP. 

Presumably the low COP also be reflected in the cost of running it, because it seems pretty high at the moment. 

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Can you post a couple of photos of the installation? 

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Also @benZ what temp have you set for your hot water (mine is at 49 deg C) do you have that on a schedule or does it constantly reheat ? 
Lots of advice on the HeatGeek website 

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Yeah so this is where my knowledge of how to set it up the best slightly falls down. 
 

i have programmed the hot water to come on at certain times in the week. But the heating is on all the time. 
 

I have to be honest - I don’t really understand this….does it mean that there will be no hot water outside of this schedule? It’s as literal as it sounds? 
 

I live alone and this is my first house, and it’s a new system and way of working, to me - so my knowledge is limited and I apologise if I’m asking simple questions! 
 

I was running the hearing via the schedules on the WiserHome app originally. But from reading what people are saying, that’s not efficient. So now as far as I’m aware, it’s on constantly, with a. Compensation curve set on the unit itself. 

when it was following whatever schedule it was doing, there seemed to be lots of peaks and troughs of activity and the heat, too. 
I also found that for some reason it didn’t really follow the schedule set anyway, it would always switch the heating off overnight, regardless of what was programmed.

 

Im just at work today but I’ll post photos of the setup once I’m home tonight! 
 

Thanks again so, so much for your responses and help. It’s great! And I’m sure really helpful for others in this situation too. 
 

B
 

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You’re right, the wiser home app sounds like something clever devised for gas boiler systems. Your heat pump should be run just with its own controls, no third party devices.
Presumably you have a hot water cylinder. You may only need to heat this once per day if it’s just for yourself, depending on capacity and your own needs. If you can just heat the hot water say at 3pm it would be most efficient as that’s usually the warmest part of the day and the heat pump won’t have to work as hard to get the up to temp. Normally the pump needs to get to a temp of around 30-40 deg C for your radiators, whereas it needs to produce more like 50deg c for the hot water. If you set it for hotter water than 55degC it’ll make the immersion kick (in which has a cop of 1.00 so you really don’t want that).

The heat pump will either run the hot water or the heating, but not both together, so it’s best to run the hot water when you won’t miss the heating. So mid afternoon is ideal, night time not so much as it will be less efficient.

You may have a Setback set to lower the room temperature overnight, which may override your 24/7 setting. Again @M.isterW is your man there…

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You’re right, the wiser home app sounds like something clever devised for gas boiler systems. Your heat pump should be run just with its own controls, no third party devices.
Presumably you have a hot water cylinder. You may only need to heat this once per day if it’s just for yourself, depending on capacity and your own needs. If you can just heat the hot water say at 3pm it would be most efficient as that’s usually the warmest part of the day and the heat pump won’t have to work as hard to get the up to temp. Normally the pump needs to get to a temp of around 30-40 deg C for your radiators, whereas it needs to produce more like 50deg c for the hot water. If you set it for hotter water than 55degC it’ll make the immersion kick (in which has a cop of 1.00 so you really don’t want that).

The heat pump will either run the hot water or the heating, but not both together, so it’s best to run the hot water when you won’t miss the heating. So mid afternoon is ideal, night time not so much as it will be less efficient.

You may have a Setback set to lower the room temperature overnight, which may override your 24/7 setting. Again @M.isterW is your man there…

ah okay that’s really great and helpful information! Thank you!
I’ve just changed the DHW max water temp to 53, it was at 60  could that be a big influencer to  the efficiency do you think? 

Here are some pictures from the setup. The system in general, even from all of last year, which includes before I moved in, is running at an average COP of 1.8 or so.


So something must be wrong somewhere?!

 

I know technically these are more expensive to run based on the price of electricity per unit, but I was led to believe I would be getting more efficiency than this 😩
 

 

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I wouldn’t mind betting that if the hot water has been set to 60 deg C since it was installed that is the reason it’s apparently performing so poorly. You could go lower than 53 degC, mine’s on 49. As a guide a hot bath would be 40 max and a shower no more than 42 or so. 

There is a school of thought that stored hot water should be no lower than 60 deg, so heat pumps have a ‘disinfectant cycle’ to raise the water to 60 for at least 10 mins once a week. However, I’ve switched that off on mine, as have loads of others. The Heat Geeks have a blog about it and have convinced me it’s pointless.

It’s likely that the installer set this from the start to play safe, but he’s not paying the bills. 

Do you have the Ecodan HOMEOWNER_QUICKSTART_GUIDE_MAY_22.pdf ? You can download it if not. There are links to youtube videos for setting schedules etc

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I wouldn’t mind betting that if the hot water has been set to 60 deg C since it was installed that is the reason it’s apparently performing so poorly. You could go lower than 53 degC, mine’s on 49. As a guide a hot bath would be 40 max and a shower no more than 42 or so. 

There is a school of thought that stored hot water should be no lower than 60 deg, so heat pumps have a ‘disinfectant cycle’ to raise the water to 60 for at least 10 mins once a week. However, I’ve switched that off on mine, as have loads of others. The Heat Geeks have a blog about it and have convinced me it’s pointless.

It’s likely that the installer set this from the start to play safe, but he’s not paying the bills. 

Do you have the Ecodan HOMEOWNER_QUICKSTART_GUIDE_MAY_22.pdf ? You can download it if not. There are links to youtube videos for setting schedules etc

Hi there, I thought I would follow up with some more detail, just incase someone else encounters the same issue in the future.  
 

it’s been very confusing but I think I’m getting somewhere. 
I had the unit setup as above but it was still costing me a lot a day. 
I had the engineers round today, who said that I should be using the third party digistats with my unit. So they have switched those back on. 
Since they left, I have done some testing and even though the controllers are calling for heat, the units heating is in standby. 
I have since discovered after some testing, that the unit itself needs to have the heating in schedule mode for these controllers to work. 
Since changing this, each zone now calls for heat as and when it requires…this hasn’t been setup since I moved in last year, and the guys today didn’t do it either…which is strange…


But now the third party schedules work well, and I can call for heat in the two zones, based on room temp that the controllers are sensing. 
This is still running in conjunction with my compensation curve too. 

I’d also previously set a hot water schedule and a max temp of 51. 

I was told today not to use that, and also told that the manufacturer says to use a boiler temp of 63degrees. 
I’ve since changed this back as it doesn’t make much sense to me. I don’t need it interrupting the radiator temps all the time. 
I would say though that, 15 degrees is the amount the temp can drop in the hot water. So I can see why 63 would be set, so when it gets to 48 it comes back up.
 

So I guess it’s still in a testing phase for me personally. 
 

I did ask about the general efficiency and why is the COP running at a constant 1.8 since it’s been installed - and I didn’t get much of an answer to that. 
But at least I think I’ve figured out why the heating has had a mind of its own, despite changing schedules on the controllers. 
 

 

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Hmm. Thanks for the update. There are lots of people who don’t agree with what your guys have said about 3rd party controllers. Do give an update of how your COP is once it’s settled down with your new settings.

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This topic is getting lots of views in the last month. @Brennie66 what’s the latest with your Ecodan performance? Have any of our community members and their advice helped get a handle on how to get the most of your heat pump and minimise heating costs? 

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