Forums

Search with Wattson
Forums
Renewable Heating
Air Source Heat Pum...
Ecodan 14kW flow ra...
 
Notifications
Clear all

Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!

Ecodan 14kW flow rates too low?

 
Air Source Heat Pumps (ASHPs)
Last Post by mjr 3 years ago
9 Posts
6 Users
1 Reactions
2,314 Views
RSS
 Benseb
(@benseb)
Estimable Member Member
Joined: 4 years ago
Posts: 109
Topic starter 27/10/2022 9:01 am   [#568]
A question for those of you in the know

We have an Ecodan 14kW. It was installed about 12m from the tank (due to aesthetics and an existing oil tank concrete base). 

The installer used preinsulated pipe which was buried.  But it was 28mm which I’m now picking up isn’t big enough. 

We have an 80L buffer. Two pumps, one on the flow and one on the return from the heat pump to the buffer, which seems to be standard for Mitsi according to their manuals.

40-70 pumps on full. 

Our flow rate is 29-30. It’s not affected by radiators etc as the buffer separates the internal circuits off. 

I’ve been told the flow should be closer to 40. So I guess the only way is to replace the preinsulated pipe?

Just gathering opinions really. We will probably see out this winter and see what COP we get (was installed 3 years ago but have just tuned the WC curve etc)

Installer says flow rate is fine!


250sqm house. 30kWh Sunsynk/Pylontech battery system. 14kWp solar. Ecodan 14kW. BMW iX.


   
Quote
Mars
 Mars
(@editor)
Illustrious Member Admin
Joined: 5 years ago
Posts: 4516
27/10/2022 9:47 am  

I can only speak from our own experience and the optimal flow rate for the Global Energy Systems ASHP is over 30 litre and it doesn't trigger alarms. 40 litre seems high, but I'm not an expert. Will be interesting to see what others say. 


Get a copy of The Ultimate Guide to Heat Pumps

Subscribe and follow our YouTube channel!


   
ReplyQuote
 Oswiu
(@oswiu)
Estimable Member Member
Joined: 4 years ago
Posts: 121
27/10/2022 9:57 am  

28mm pipe can carry 16.8kW of power if the difference in temperature between flow and return is 5C, which it probably is. This means that assuming the pipe is not kinked or set up like a rollercoaster, it is not the pipe limiting the flow to 30L/m by itself.

My best guess is that your unit is modulating its power downwards because your house doesn't need 14kW right now. I actually emailed Mitsubishi to ask what their minimum output is yesterday, so I can update with what they say if they get back to me.

Have you been cold the previous three winters? If not, I would just wait to see what happens and not worry about it. Assuming the flow rate was limited by something - be it a pipe or a connection or a pump or anything else - it's still able to provide almost 11kW. It's possible that the length of the pipe run is having a limiting factor, but I don't know how to work that out. Again, I'd wait and see what happens when it's actually cold.



   
ReplyQuote



 Kev M
(@kev-m)
Noble Member Member
Joined: 5 years ago
Posts: 1276
27/10/2022 1:46 pm  
Posted by: @benseb
A question for those of you in the know

We have an Ecodan 14kW. It was installed about 12m from the tank (due to aesthetics and an existing oil tank concrete base). 

The installer used preinsulated pipe which was buried.  But it was 28mm which I’m now picking up isn’t big enough. 

We have an 80L buffer. Two pumps, one on the flow and one on the return from the heat pump to the buffer, which seems to be standard for Mitsi according to their manuals.

40-70 pumps on full. 

Our flow rate is 29-30. It’s not affected by radiators etc as the buffer separates the internal circuits off. 

I’ve been told the flow should be closer to 40. So I guess the only way is to replace the preinsulated pipe?

Just gathering opinions really. We will probably see out this winter and see what COP we get (was installed 3 years ago but have just tuned the WC curve etc)

Installer says flow rate is fine!

Our 14kW Ecodan also uses 28mm pipe.  We have no buffer.  The minimum output of your Ecodan is on p 69 of the link below.  The 14kW Ecodan needs 40l/min at its nominal speed. 

Hopefully you won't need anything like 14kW most of the time so a lower flow won't matter.    

https://library.mitsubishielectric.co.uk/pdf/book/ATW_Databook_R32_2020#page-68-69

 



   
ReplyQuote
 Benseb
(@benseb)
Estimable Member Member
Joined: 4 years ago
Posts: 109
Topic starter 27/10/2022 1:59 pm  

That’s a good point about output. I’ve been checking when it’s just ticking over at 25-30c flow temp. 

I’ll check again when it gets cold. 

it was fine last year aside from one day when it was about -6c outside and I got a flow fault. But that’s below design temp anyway. We have an immersion in the buffer tank that we can use with excess solar so switched that on when it was ultra cold. 

let’s see what this winter brings!


250sqm house. 30kWh Sunsynk/Pylontech battery system. 14kWp solar. Ecodan 14kW. BMW iX.


   
ReplyQuote
 Derek M
(@derek-m)
Illustrious Member Member
Joined: 5 years ago
Posts: 4425
27/10/2022 4:07 pm  
Posted by: @benseb
A question for those of you in the know

We have an Ecodan 14kW. It was installed about 12m from the tank (due to aesthetics and an existing oil tank concrete base). 

The installer used preinsulated pipe which was buried.  But it was 28mm which I’m now picking up isn’t big enough. 

We have an 80L buffer. Two pumps, one on the flow and one on the return from the heat pump to the buffer, which seems to be standard for Mitsi according to their manuals.

40-70 pumps on full. 

Our flow rate is 29-30. It’s not affected by radiators etc as the buffer separates the internal circuits off. 

I’ve been told the flow should be closer to 40. So I guess the only way is to replace the preinsulated pipe?

Just gathering opinions really. We will probably see out this winter and see what COP we get (was installed 3 years ago but have just tuned the WC curve etc)

Installer says flow rate is fine!

Hi Benseb,

The fact that it has been operating correctly for three years should provide you with the answer.

Setting weather compensation should not have a detrimental effect on operation, and should improve overall efficiency. Remember the old adage 'if it's not broken, don't fix it'. 😎  



   
👍
1
ReplyQuote



 mjr
(@mjr)
Reputable Member Member
Joined: 4 years ago
Posts: 301
27/10/2022 4:41 pm  
Posted by: @kev-m

Our 14kW Ecodan also uses 28mm pipe.  We have no buffer.  The minimum output of your Ecodan is on p 69 of the link below.  The 14kW Ecodan needs 40l/min at its nominal speed. 

Why be like that and not also say the minimum output of an Ecodan is generally 3-4kW in above-zero ambient temperatures.

Although are you sure this isn't about a monobloc unit on page A-58? That has a wider 2-7kW minimum range depending on ambient and flow temperatures. I think if you bump into the 6+kW minimum often, that can be problematic and may mean the heat pump is oversize.



   
ReplyQuote
 Kev M
(@kev-m)
Noble Member Member
Joined: 5 years ago
Posts: 1276
27/10/2022 5:32 pm  

@mjr 

Be like what?  I was trying to be helpful and show the questioner the whole picture rather than just quoting one number.  That link has lots of other information too.  I always like to see a link rather than just an opinion. 

And yes I quoted the wrong page so thank you for pointing that out; the monobloc 14kW Ecodan is on p 58.    



   
ReplyQuote
 mjr
(@mjr)
Reputable Member Member
Joined: 4 years ago
Posts: 301
27/10/2022 5:42 pm  
Posted by: @kev-m

I always like to see a link rather than just an opinion. 

I like to see both. I admit it irritates me a little when only a link is mentioned because before getting our heat pump, I read lots of forum posts where no answer was given, only a link, and that link has broken: maybe the linked site moved the file, or maybe the link was incorrect all along. So please, think of future people reading these discussions ☺



   
ReplyQuote



Forum Jump:
  Previous Topic
Next Topic  



Share:

Join Us!

Worth Watching

Latest Posts

Members Online

Click to access the login or register cheese
x Powerful Protection for WordPress, from Shield Security PRO
This Site Is Protected By
Shield Security PRO →