Mitsubishi WR2 heatpump COP issue

[awesome]

Hi everyone,

I have just installed a P250 WR2 Mitubishi electric ground source heatpump, which is a VRF system. On the water side the input temperature from a water well is 12.5 degrees centigrade with a flow rate of 5.1 m3/hour.
I decided to do a quick COP test the other day, where I turned on just 3 of the 10 fan coils i have in the house, where all 3 of them were in heating mode. The combined apparent heating capacity of these coils was 8.5Kw, however I calculated the electricity draw from the heat pump to be around 5.1Kw, which gives a COP value of around 1.7. <This value also doesn't tkae into account the power used by the pump..

This to me seems not very energy efficient at all:eek:, what do you guys think?

Many thanks,

Adam

[kevinxt]

Just an idea, the system is rated for 25 kW with a P250, you will therefore only be using about 1/3 capacity at 8.5 kW, the system will be wound down on the inverter. Measuring a COP in this way can be a little difficult, you will need to have the correct equipment in place, energy meters etc to get a good idea of what you are using. Don't give up on it be very interesting in your results.

[awesome]

Hey Kevinxt,

Yeah your right, but it seems strange that the specification on this side of the machine states it's max power consumption to be 6.0 Kw and when I turn the house all on it can draw around 7.5 Kw which makes no sense, plus it makes the electric meter nearly spin off its axis.
I am a little concerned as the company who installed the HVAC system couldn't get two of the rooms working due to them over brazing the lines and causing a blockage; so I am wondering whether they have slightly blocked some of the other lines and the compressor is having to work much harder to achieve what it wants. Could this be possible?

Cheers

Adam

[kevinxt]

Ouch sounds like you might have a few issues there, we have installed a number of these systems and they all work very well indeed. COP at least 3 or better in most circumstances. You want to give me an email with your details? kevin@ftrefrigeration.co.uk

[awesome]

Yeah, I will send you my details now. A chat would be good.

[JoeAT50A]

If you are using AG-150A or TG-2000A, there is a way to log the COP of your individual System.
If not very difficult to determine your capacity (Load). Even without KWH meter result is acceptable.
If you need more acturate COP, place a KWH (optional item) for every outdoor unit.
And you would able to log via web monitoring or via TG-2000A. See attached picture.
6519

[awesome]

Hi Joe,

Yes I am using a AG-150 centralised controller, however as of yet I have not got it connected to the computer network. Do you need an additional license to access this?

I also notice your efficiency is floating around 3, this is what I should be having, if not better as I am on a 'open source' water system.

Thanks

Adam

[JoeAT50A]

Hi Adam,
Of course you must have "web monitoring" license to do configurations via LAN.
I don't know how much they charge you for this license PIN code.
Ask here if you have any troubles to monitor COP.
If I have time I will explain more. Anyway I have place KWHr also.
Without KWH meter readings are also quite similar 2 to 3% differ from with-KWH meter.
Hope that will help.

[awesome]

Hi Joe,

I am guessing a Kwh metre would need to be put into place for the TG2000 to monitor the power consumption, or does the condenser have the ability to do this itself? Either way I am assuming Mitsubishi would charge a fortume for this software and all I really need is a quick snapshot on how my VRF system is performing.

Thanks

Adam

[JoeAT50A]

Hi Adam,
Different in KWH meter pulse width (0.01ms) and you need to have 1 to 1 kWH and KWH pulse output (2wires) will send directly to outdoor controller board CN-3K. A bit costly solution anyway.
Without KWHr meter result is quite reasonable, that's why we recommand this for COP monitoring purpose.
TG2000A can monitor COP as well. But nothing to do with energy monitoring and relavant KWH meters. Even though you have KWH meters and PI controller unit, COP monitoring required one kWH per system.

[awesome]

Hi Joe,

So could I just use the TG2000 software to find out the VRF systems energy output? I could then simulataneously determine the units power consumption. I only have one condensing unit.

Cheers

Ad

[JoeAT50A]

Hi Adam,

No issue, you can monitor COP via TG-2000A or web monitoring.
Recent models Y and R2 are OKay to do so. I mean, around 2008 and earlier models need to upgrade the software of outdoor unit. Hope that will help.

[JoeAT50A]

Hi Adam,
Please activate this when doing configuration of TG-2000A.
6523

[awesome]

Hi Joe,
I notice you know your stuff with regards to the mitsi equiptment. I have contacted mitsi about the TG2000 and they are quoting around 1000 pounds for the software which seems a bit steep for the limited period of time I am going to be using it. However you said you can do the energy output monitoring via the 'web monitoring' software; would you be able to show me a screenshot of this?

Many thanks,

Adam

[awesome]

Hi Joe,

Sorry to pester you again, but I have just been looking at the web monitoring user manual and you are correct. The only thing that confuses me is the graph shows three trends, which are: Elecrical power, Electrical energy and efficiency. As I wont be using an Kwh pulse input I would assume Elecrical power, Electrical energy won't be shown, and therefore efficiency cannot be calculated.. Or does 'electrical power' mean the units output?

Cheers

Adam

[Bigfreeze]

Hi Joe,

Sorry to pester you again, but I have just been looking at the web monitoring user manual and you are correct. The only thing that confuses me is the graph shows three trends, which are: Elecrical power, Electrical energy and efficiency. As I wont be using an Kwh pulse input I would assume Elecrical power, Electrical energy won't be shown, and therefore efficiency cannot be calculated.. Or does 'electrical power' mean the units output?

Cheers

Adam

Are you really willing to spend £1000 to get a COP reading from your HP when all you need is a snapshot?
Firstly check what the system is rated at. It should be at a water in temp of 10C, water outlet temp 35C (heating side). Find out what power it should be drawing at these figures. This figure won't include the borehole pump so you'll need to exclude that. Then take you reading. It won't be 100% accurate but it won't be far off. Then come back with those figures and we could figure out where you're at

[awesome]

Hi Bigfreeze,

No certainly not, but I have done simple calculations before, and the system is certainly under performing. To calulate the systems energy removal from the water side, I would need to know the flow rate, input temp (12.8 degrees), output temp at that flow rate and specific heat capacity of water. I have performed this calc, but it seemed to be under performing at the time.

Another test I done was as I said in my first post:

"I decided to do a quick COP test the other day, where I turned on just 3 of the 10 fan coils i have in the house, where all 3 of them were in heating mode. The combined apparent heating capacity of these coils was 8.5Kw, however I calculated the electricity draw from the heat pump to be around 5.1Kw, which gives a COP value of around 1.7" < Discluding water pump power.

I just now would like to see what the mitsi unit is picking up, as I have a suspicion the systems compressor is running too fast due to a partial refrigerant line blockage.

Cheers,

Adam

[Bigfreeze]

Hi Bigfreeze,

No certainly not, but I have done simple calculations before, and the system is certainly under performing. To calulate the systems energy removal from the water side, I would need to know the flow rate, input temp (12.8 degrees), output temp at that flow rate and specific heat capacity of water. I have performed this calc, but it seemed to be under performing at the time.

Another test I done was as I said in my first post:

"I decided to do a quick COP test the other day, where I turned on just 3 of the 10 fan coils i have in the house, where all 3 of them were in heating mode. The combined apparent heating capacity of these coils was 8.5Kw, however I calculated the electricity draw from the heat pump to be around 5.1Kw, which gives a COP value of around 1.7" < Discluding water pump power.

I just now would like to see what the mitsi unit is picking up, as I have a suspicion the systems compressor is running too fast due to a partial refrigerant line blockage.

Cheers,

Adam

If you had partial blockage of a refrigerant line it would show up pretty quickly. Ideally on your cooling side you would have no more than a 2-3 degree drop in water temp. If you do, either you have a blockage issue or your pump is too small.
You mentioned you require 5.5m3 of water on the cooling side (which sounds about right for 24kw) . You also need to turn on all fan coils but make sure you are only metering the draw from the compressor.
If you are getting a COP of 1.7 that is horrendous.

[JoeAT50A]

Hi Adam,
Pricing wise, I have no comment for this.
You coud do it without KWH via web monitoring.
Here is the details:
You WR2 outdoor software version should be Ver 4.08 or later. (FYI 4.08 is arond 2008 or earlier)
Your WR2 outdoor serial number should be 98xxxxx or later.
Then you can start mornitor via web monitoring.
Don't worrry about electrical energy valvue, graphs are same for both with or without kWH meter.
Mitsubishi used internal values to pick and calculate for the electrical erergy and capacity as well.
What you have to pay is web monitoring license I believed. Hope not expensive one.
Try without kWH meter method, you could be able to judge whether acceptable or not.

[JoeAT50A]

6524If you willing to try with KWH meter, result will be a higher accurate.
I used this KWH (see attached picture).
With KWH procedures are slightly complicated.
Spec of KWH >>
Pulse width 30~300ms
Unit of pulse: 0.01kWh per pulse
Contact rating voltage: >=DC15V
Contact rating current: >=0.1A

And required PAC-SC36NAE and PAC-CN32WHMC optional cable adaptor.