Posted by: @elab

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Hi,

I recently had a Mitsubishi Ecodan 11.2 kW ASHP installed and I have a concern regarding the flow rate.

In the "Commissioning Wizard" it's showing as 20 l/min with the pump speed setting at 3. I changed this to 5 and it's gone up to 24 l/min

My understanding is that the Ecodan targets a delta t of 5 degrees so I need a flow rate of about 32 l/min to get the full output power.

Most of the plumbing to the outdoor unit is  28 mm so I'm surprised it's low. I was wondering if someone who has one of these units can have a look at their flow rate and pump speed settings as a comparison?

Thanks.

The FTC6 manual suggests 14-32 l/min as the acceptable range so 32 would be right at the upper end.  My 14kW Ecodan is running at about 24l/min, also well within the acceptable range.  The most I have seen it output is 12-13kW so I'm fairly happy and so was the engineer who serviced it. My delta T probably averages nearer 4 than 5.    

I would guess your ASHP will never need to deliver 11.2kW constantly in a steady state.  It'll do it in bursts when heating the house up, defrosting,  heating DHW, etc. 

How is the ASHP working otherwise? 

Posted by: @elab

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In the "Commissioning Wizard" it's showing as 20 l/min with the pump speed setting at 3. I changed this to 5 and it's gone up to 24 l/min

My understanding is that the Ecodan targets a delta t of 5 degrees so I need a flow rate of about 32 l/min to get the full output power.

 

Hi @elab 

How are you getting on with getting your flow rate sorted? Do you still need help targeting a DeltaT of 5?

in your post I can’t see what your current temperature difference (DeltaT) is. 

If you are trying to increase your DeltaT then the flow rate needs to be reduced to allow the heat to transfer to the circulating water. So it also follows that if you are trying to reduce your DeltaT then the flow rate needs to be increased, therefore spreading the heat transfer to a larger volume of water, at a slightly lower temperature. 

As @kev-m states, each size heat pump has a different designed flow rate range. In your case the 11.2 kw ecodan has a stated flow range between 14 lpm and 32 lpm.

you can check your current flow rate on your main controller screen.

hope this helps.

Posted by: @sunandair

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Posted by: @elab

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In the "Commissioning Wizard" it's showing as 20 l/min with the pump speed setting at 3. I changed this to 5 and it's gone up to 24 l/min

My understanding is that the Ecodan targets a delta t of 5 degrees so I need a flow rate of about 32 l/min to get the full output power.

 

Hi @elab 

How are you getting on with getting your flow rate sorted? Do you still need help targeting a DeltaT of 5?

in your post I can’t see what your current temperature difference (DeltaT) is. 

If you are trying to increase your DeltaT then the flow rate needs to be reduced to allow the heat to transfer to the circulating water. So it also follows that if you are trying to reduce your DeltaT then the flow rate needs to be increased, therefore spreading the heat transfer to a larger volume of water, at a slightly lower temperature. 

As @kev-m states, each size heat pump has a different designed flow rate range. In your case the 11.2 kw ecodan has a stated flow range between 14 lpm and 32 lpm.

you can check your current flow rate on your main controller screen.

hope this helps.

 

@sunandair, @elab hasn't been seen on the forum since 1st May so I don't think s/he is worthy of any more attention! 

Thanks @kev-m 

I was beginning to wonder, when they hadn’t responded to your post. But I thought “you never know”.

thanks for your comment.