What's your monthly SCOP

matt_drummer

I have no idea.

I just use it.

I m pretty sure I know how to get more out of it than they do.

However, it's not all roses. Their control system cannot cope with my setup so it's not an easy ride, fortunately I sit in front of a computer most of the day so I can monitor it.

My radiators are too big for the heat pump.

My flow temperature is set at 29c in these conditions and I drop it to 28c overnight. It's enough for my heat loss.

I will be running it at 33c on Saturday when it is over 10c outside.

The heat pump is too big and really doesn't like running below 30c.

I will have to change it for something else at some point, or perhaps I should say, I would like to change it for something else.

The SCOP is great, but living with it, not so good.

NedS

michaels said:

How are the current temps impacting cop? We probably averaged zero outdoors for the last 24 hours and our cop is probably only about 2.75. Shame that you need the most output when the cop is lowest! 

Yesterday evening, I measured our heating run. It was 0C outside, and we ran a flow temp of 32-33C for around 3-4 hours with a COP of 3.27. There were 3 defrost cycles - first time I've witnessed one of those. The flow temps dropped back to around 20-22C and took a while to get back up to temp again, and that's with an over-sized heat pump, plenty of system volume and a 50L volumiser.

Ended the day with a COP of 3.54 overall as daytime temp was ~4C, so a little warmer than the evening.

I'm pretty pleased to have a COP above 3 for 0C outside - that's about the harshest weather we see. I can see how defrost cycles will absolutely kill the efficiency - I could hear the heat pump working harder trying to pull air through the blocked up fins which seemed to be driving up electricity usage trying to extract heat from a reduced/inhibited flow of freezing air. It's amazing they can produce any heat at all, but they do.

The other thing that is killing efficiency for us is the system cycling the circulation pump during cold weather to prevent freezing. We turn the heating off overnight as the bedrooms are warm enough, and if the outside temp drops, the system cycles the pumps to prevent freezing, which circulates cold water through the DHW cylinder and sucks all the heat out of it, so in the morning the DHW cylinder temp has dropped to 20-22C when normally it would have only dropped to around 35-36C, and now we are reheating DHW from cold rather than warm. This kind of defeats the purpose of having glycol in the system in my opinion, which I guess is really only there to prevent freezing in the event of a prolonged power outage during freezing temperatures.

Spies

2.65 COP this morning whilst running at 47c flow temp at -5c

matt_drummer

NedS said:

michaels said:

How are the current temps impacting cop? We probably averaged zero outdoors for the last 24 hours and our cop is probably only about 2.75. Shame that you need the most output when the cop is lowest! 

Yesterday evening, I measured our heating run. It was 0C outside, and we ran a flow temp of 32-33C for around 3-4 hours with a COP of 3.27. There were 3 defrost cycles - first time I've witnessed one of those. The flow temps dropped back to around 20-22C and took a while to get back up to temp again, and that's with an over-sized heat pump, plenty of system volume and a 50L volumiser.

Ended the day with a COP of 3.54 overall as daytime temp was ~4C, so a little warmer than the evening.

I'm pretty pleased to have a COP above 3 for 0C outside - that's about the harshest weather we see. I can see how defrost cycles will absolutely kill the efficiency - I could hear the heat pump working harder trying to pull air through the blocked up fins which seemed to be driving up electricity usage trying to extract heat from a reduced/inhibited flow of freezing air. It's amazing they can produce any heat at all, but they do.

The other thing that is killing efficiency for us is the system cycling the circulation pump during cold weather to prevent freezing. We turn the heating off overnight as the bedrooms are warm enough, and if the outside temp drops, the system cycles the pumps to prevent freezing, which circulates cold water through the DHW cylinder and sucks all the heat out of it, so in the morning the DHW cylinder temp has dropped to 20-22C when normally it would have only dropped to around 35-36C, and now we are reheating DHW from cold rather than warm. This kind of defeats the purpose of having glycol in the system in my opinion, which I guess is really only there to prevent freezing in the event of a prolonged power outage during freezing temperatures.

Your COP calculation won't be correct using the data from your Samsung controller.

It only reports heat generated.

The defrosts remove heat from the house.

The defrosts are negative energy and you need a heat meter to record this and deduct it from the heat generated to arrive at the net amount of heat for the electricity consumed.

matt_drummer

Spies said:

2.65 COP this morning whilst running at 47c flow temp at -5c

Surprisingly good.

Probably cold enough that defrosting isn't an issue?

I had my first defrost this morning at -2c although it wasn't a full on iced up defrost, just a mini reset.

I still haven't seen ice on this 8kW Daikin.

My 9kW Daikin would ice up terribly.

NedS

matt_drummer said:

Your COP calculation won't be correct using the data from your Samsung controller.

It only reports heat generated.

The defrosts remove heat from the house.

The defrosts are negative energy and you need a heat meter to record this and deduct it from the heat generated to arrive at the net amount of heat for the electricity consumed.

I kind of get what you are saying, but how is "the defrosts remove heat from the house" different from heat being removed from the house by me leaving a door or window open, or running hot water down the sink? I've recorded the heat going in to the house and the electricity used to generate that heat.

On the basis of your argument, if we subtract any heat removed from the house, the net amount of heat generated will always be zero (as would the SCOP), as we cannot store the heat indefinitely and it has to go somewhere.

The defrost cycles are reflected in subsequent higher energy figures, as I've now had to use more energy to replace that which was lost due to defrost cycles. To also subtract it from heat generated would be double counting?

matt_drummer

NedS said:

matt_drummer said:

Your COP calculation won't be correct using the data from your Samsung controller.

It only reports heat generated.

The defrosts remove heat from the house.

The defrosts are negative energy and you need a heat meter to record this and deduct it from the heat generated to arrive at the net amount of heat for the electricity consumed.

I kind of get what you are saying, but how is "the defrosts remove heat from the house" different from heat being removed from the house by me leaving a door or window open, or running hot water down the sink? I've recorded the heat going in to the house and the electricity used to generate that heat.

On the basis of your argument, if we subtract any heat removed from the house, the net amount of heat generated will always be zero (as would the SCOP), as we cannot store the heat indefinitely and it has to go somewhere.

The defrost cycles are reflected in subsequent higher energy figures, as I've now had to use more energy to replace that which was lost due to defrost cycles. To also subtract it from heat generated would be double counting?

It is because the heat generated has not been used to heat the house, it has been used to defrost the heat pump.

Convention is that the COP/SCOP only includes heat that ends up heating the house.

It is how heat pump performance is compared just as it should include the electricity consumption of the control system and circulation pump(s)

Any systems on heatpumpmonitor.org that do not include all of this are marked as such.

I only tell you this to make any of your comparisons meaningful, it won't make any difference to your life.

NedS

matt_drummer said:

NedS said:

matt_drummer said:

Your COP calculation won't be correct using the data from your Samsung controller.

It only reports heat generated.

The defrosts remove heat from the house.

The defrosts are negative energy and you need a heat meter to record this and deduct it from the heat generated to arrive at the net amount of heat for the electricity consumed.

I kind of get what you are saying, but how is "the defrosts remove heat from the house" different from heat being removed from the house by me leaving a door or window open, or running hot water down the sink? I've recorded the heat going in to the house and the electricity used to generate that heat.

On the basis of your argument, if we subtract any heat removed from the house, the net amount of heat generated will always be zero (as would the SCOP), as we cannot store the heat indefinitely and it has to go somewhere.

The defrost cycles are reflected in subsequent higher energy figures, as I've now had to use more energy to replace that which was lost due to defrost cycles. To also subtract it from heat generated would be double counting?

It is because the heat generated has not been used to heat the house, it has been used to defrost the heat pump.

Convention is that the COP/SCOP only includes heat that ends up heating the house.

It is how heat pump performance is compared just as it should include the electricity consumption of the control system and circulation pump(s)

Any systems on heatpumpmonitor.org that do not include all of this are marked as such.

I only tell you this to make any of your comparisons meaningful, it won't make any difference to your life.

Got you, and as you say it's about making comparisons meaningful (like for like) for sites such as heatpumpmonitor.org

Reed_Richards

matt_drummer said:

NedS said:

matt_drummer said:

Your COP calculation won't be correct using the data from your Samsung controller.

It only reports heat generated.

The defrosts remove heat from the house.

The defrosts are negative energy and you need a heat meter to record this and deduct it from the heat generated to arrive at the net amount of heat for the electricity consumed.

I kind of get what you are saying, but how is "the defrosts remove heat from the house" different from heat being removed from the house by me leaving a door or window open, or running hot water down the sink? I've recorded the heat going in to the house and the electricity used to generate that heat.

On the basis of your argument, if we subtract any heat removed from the house, the net amount of heat generated will always be zero (as would the SCOP), as we cannot store the heat indefinitely and it has to go somewhere.

The defrost cycles are reflected in subsequent higher energy figures, as I've now had to use more energy to replace that which was lost due to defrost cycles. To also subtract it from heat generated would be double counting?

It is because the heat generated has not been used to heat the house, it has been used to defrost the heat pump.

Convention is that the COP/SCOP only includes heat that ends up heating the house.

It is how heat pump performance is compared just as it should include the electricity consumption of the control system and circulation pump(s)

Any systems on heatpumpmonitor.org that do not include all of this are marked as such.

I only tell you this to make any of your comparisons meaningful, it won't make any difference to your life.

But does that mean that those heat pumps that have a significant "vampire load" drawing power when supposedly inactive can conceal that fact in the figures they quote?

matt_drummer

Reed_Richards said:

matt_drummer said:

NedS said:

matt_drummer said:

Your COP calculation won't be correct using the data from your Samsung controller.

It only reports heat generated.

The defrosts remove heat from the house.

The defrosts are negative energy and you need a heat meter to record this and deduct it from the heat generated to arrive at the net amount of heat for the electricity consumed.

I kind of get what you are saying, but how is "the defrosts remove heat from the house" different from heat being removed from the house by me leaving a door or window open, or running hot water down the sink? I've recorded the heat going in to the house and the electricity used to generate that heat.

On the basis of your argument, if we subtract any heat removed from the house, the net amount of heat generated will always be zero (as would the SCOP), as we cannot store the heat indefinitely and it has to go somewhere.

The defrost cycles are reflected in subsequent higher energy figures, as I've now had to use more energy to replace that which was lost due to defrost cycles. To also subtract it from heat generated would be double counting?

It is because the heat generated has not been used to heat the house, it has been used to defrost the heat pump.

Convention is that the COP/SCOP only includes heat that ends up heating the house.

It is how heat pump performance is compared just as it should include the electricity consumption of the control system and circulation pump(s)

Any systems on heatpumpmonitor.org that do not include all of this are marked as such.

I only tell you this to make any of your comparisons meaningful, it won't make any difference to your life.

But does that mean that those heat pumps that have a significant "vampire load" drawing power when supposedly inactive can conceal that fact in the figures they quote?

I'm not sure I understand the question.

But all fully monitored and MID certified heat pump installations on heatpumpmonitor.org include everything including standby power consumption.

SCOP in this case is all the heat delivered to the house divided by all the electricity consumed by the heat pump and any ancillary items.

Standby, or vampire loads as you call them, are all part of the electricity consumed by the heat pump.

Installations that exclude certain items are marked as such so that every viewer knows exactly what they are comparing.

If you are talking about manufacturers performance claims the I think most of them only quote performance when the compressor is running.

None that I know of go into great details about defrosting as it is so variable and none ever quote minimum power consumption.

Daikin do quote standby loads in their documentation if I remember correctly.