What's your monthly SCOP

matt_drummer

NedS said:

michaels said:

NedS said:

As there are a few of us with ASHPs installed, I thought I'd start a thread to compare monthly SCOPs so we can see how we are performing.

I had my 12kW Samsung ASHP installed in June. It's been heating DHW over the summer and we are just now starting to get a feel for heating. It's an oversized unit, so we won't be able to run continuously until it gets a lot colder, but it's been heating the house nicely with 32C flow temps during October.

My monthly SCOPs:

June-August: 3.75 (DHW only)

September: 4.05 (improved as occasional heating)

October: 4.75 (combined DHW and heating)

With the current mild weather (12-14C), I am getting a COP of 6 for short heating runs at 32C flow temps (the lowest I can run). This will warm the house at a rate of around 1C per hour.

Anyone else want to share theirs?

What sort of cycling are you getting with a big heat pump and mild temps, do you control via water temp or a themostat?

Because we are on Agile rather than a fixed tariff, I am controlling the 'cycling' manually with the room thermostat (effectively turning demand for heat on/off). As it's oversized (and it's mild), it only needs to be on for a couple hours per day, so makes financial sense to ensure those couple hours are during the cheaper slots on Agile. Today we ran for a couple hours this morning when we got up, then off for a couple hours and back on for an hour between 2-3pm. It will be off now until 7:30pm, after the peak evening rates.

We will certainly need to see temps below 10C, maybe even approaching zero before we can run anything like continuously, even on minimum output. But that certainly doesn't seem to be massively impacting efficiency at present as I can still achieve a COP of 6 for short (1h) heating run in mild weather.

When it's colder and we are doing longer runs (but still not continuous), I may programme it to be on / off for 30min periods depending on the Agile pricing. Over the next few months I will find out what ambient temp matches my minimum 32C flow temp, and thus what ambient temp I can just leave it to run.

I have just been looking at data from a 12kW Samsung

It's a bit of a monster!

Minimum output seems to be about 5kW of heat.

Is that what you are finding?

michaels

matt_drummer said:

NedS said:

michaels said:

NedS said:

As there are a few of us with ASHPs installed, I thought I'd start a thread to compare monthly SCOPs so we can see how we are performing.

I had my 12kW Samsung ASHP installed in June. It's been heating DHW over the summer and we are just now starting to get a feel for heating. It's an oversized unit, so we won't be able to run continuously until it gets a lot colder, but it's been heating the house nicely with 32C flow temps during October.

My monthly SCOPs:

June-August: 3.75 (DHW only)

September: 4.05 (improved as occasional heating)

October: 4.75 (combined DHW and heating)

With the current mild weather (12-14C), I am getting a COP of 6 for short heating runs at 32C flow temps (the lowest I can run). This will warm the house at a rate of around 1C per hour.

Anyone else want to share theirs?

What sort of cycling are you getting with a big heat pump and mild temps, do you control via water temp or a themostat?

Because we are on Agile rather than a fixed tariff, I am controlling the 'cycling' manually with the room thermostat (effectively turning demand for heat on/off). As it's oversized (and it's mild), it only needs to be on for a couple hours per day, so makes financial sense to ensure those couple hours are during the cheaper slots on Agile. Today we ran for a couple hours this morning when we got up, then off for a couple hours and back on for an hour between 2-3pm. It will be off now until 7:30pm, after the peak evening rates.

We will certainly need to see temps below 10C, maybe even approaching zero before we can run anything like continuously, even on minimum output. But that certainly doesn't seem to be massively impacting efficiency at present as I can still achieve a COP of 6 for short (1h) heating run in mild weather.

When it's colder and we are doing longer runs (but still not continuous), I may programme it to be on / off for 30min periods depending on the Agile pricing. Over the next few months I will find out what ambient temp matches my minimum 32C flow temp, and thus what ambient temp I can just leave it to run.

I have just been looking at data from a 12kW Samsung

It's a bit of a monster!

Minimum output seems to be about 5kW of heat.

Is that what you are finding?

Our 12kw LG (possibly 5+ years old) seems to modulate down to a draw of about 1.3kw at the lowest - I guess the associated output will depend on the COP - should be over 4 with current temps but I guess could go as low as 2 with a high flow temp and sub zero ambient.

NedS

matt_drummer said:

NedS said:

michaels said:

NedS said:

As there are a few of us with ASHPs installed, I thought I'd start a thread to compare monthly SCOPs so we can see how we are performing.

I had my 12kW Samsung ASHP installed in June. It's been heating DHW over the summer and we are just now starting to get a feel for heating. It's an oversized unit, so we won't be able to run continuously until it gets a lot colder, but it's been heating the house nicely with 32C flow temps during October.

My monthly SCOPs:

June-August: 3.75 (DHW only)

September: 4.05 (improved as occasional heating)

October: 4.75 (combined DHW and heating)

With the current mild weather (12-14C), I am getting a COP of 6 for short heating runs at 32C flow temps (the lowest I can run). This will warm the house at a rate of around 1C per hour.

Anyone else want to share theirs?

What sort of cycling are you getting with a big heat pump and mild temps, do you control via water temp or a themostat?

Because we are on Agile rather than a fixed tariff, I am controlling the 'cycling' manually with the room thermostat (effectively turning demand for heat on/off). As it's oversized (and it's mild), it only needs to be on for a couple hours per day, so makes financial sense to ensure those couple hours are during the cheaper slots on Agile. Today we ran for a couple hours this morning when we got up, then off for a couple hours and back on for an hour between 2-3pm. It will be off now until 7:30pm, after the peak evening rates.

We will certainly need to see temps below 10C, maybe even approaching zero before we can run anything like continuously, even on minimum output. But that certainly doesn't seem to be massively impacting efficiency at present as I can still achieve a COP of 6 for short (1h) heating run in mild weather.

When it's colder and we are doing longer runs (but still not continuous), I may programme it to be on / off for 30min periods depending on the Agile pricing. Over the next few months I will find out what ambient temp matches my minimum 32C flow temp, and thus what ambient temp I can just leave it to run.

I have just been looking at data from a 12kW Samsung

It's a bit of a monster!

Minimum output seems to be about 5kW of heat.

Is that what you are finding?

Yes, it's essentially a de-rated 16kW unit.

When running in forced on mode, it will reach equilibrium with a LWT / flow temp of around 32.5-33C, which matches a de-rated output of around 4.6kW for my radiators. So yes, that's about right.

The electrical input (draw) is reported as around 8-900W when ticking over at minimum, but this includes the two pumps that are drawing ~50W each, so minimum input is maybe 700-800W. At some point I measured electricity used at the meter over 30 and 60mins when it was ticking over, I can't remember the exact figures, but it was around 800W/h recorded at the Emlite meter.

Assuming 0.75kW minimum input and 4.6kW heat generated, that corresponds to a COP of around 6 which is in the right ballpark for a LWT of ~33C at ambient temps around 14C. So that all seems very believable.

I would have much preferred a unit that could modulate down to a 4-500W input, but they would not budge from their MCS heat loss calculations which I think are high (probably due to the air changes per hour they used for our very old house even though it is completely renovated with modern double glazing)

NedS

matt_drummer said:

NedS said:

matt_drummer said:

Yes, I saw in your other recent post after I asked.

So, the Samsung controller tells you the heat generated and then you divide that by the electrical consumption?

It's normal with heat pumps to include the circulation pump(s) in the calculation of COP but as you say, when comparing to gas or oil, it's actually a better comparison by leaving out the circulation pump(s) electricity consumption.

My figures include my circulation pump as do most others on heatpumpmonitor.org

I don't know how accurate the reporting from the Samsung controller is but I am glad that it seems to be working well and you are happy.

I can take the electricity used from the Samsung controller too, which includes the pumps, but it also includes the immersion usage so I'd need to try to strip that out to make it meaningful, which makes things more complicated. Also, the Samsung controller records immersion usage for the whole time the system thinks it is on, even if the immersion has cut out on it's own thermostat (I said it gets complicated!)

Sounds weird, the Samsung controller records electricity that isn't being used, doesn't sound like a reliable source of information?

Anyway, what I was really asking is where you get the heat produced from and what does it represent?

They all do it differently, Daikin report all heat produced whereas Vaillant report only heat produced in addition to electricity used.

So with a Vaillant COP is (heat reported + electricity)/electricity

With a Daikin COP is heat produced/electricity

Does your Samsung include heat added by the immersion? To assess whether everything is actually working well you need to know exactly what the heat produced reported by your controller actually is.

What is the immersion used for anyway, mine is turned off at the consumer unit.

I'm not sure how the Samsung controller is measuring electricity used, but for the immersion I have set in the settings that it's fitted with a 3kW immersion, so the controller assumes it's using that 3kW whenever the software says the immersion is in use (e.g, legionella cycle, or DHW in forced or power mode whereby it's supplemented by the immersion). However, the immersions own thermostat cuts out at around 56C (ugh, far too low!), but the Samsung controller is unaware so still thinks it's drawing 3kW and records as such.

Heat produced is taken directly from the Samsung controller, as that's all I have in the absence of a proper heat meter. I could try to calculate it from flow rate and dT, but my dT values are only recorded to the nearest degree (whole numbers), and with a narrow dT of ~3C (33C flow, 30C return), the errors would be unacceptably large, so I'd probably need additional temperature sensors on flow and return. I do not know how the controller is calculating heat generated.

I'm not 100% sure if it includes heat generated by the immersion or not. As you say, it's not really an issue because it is not normally used. I do not run a legionella cycle, and only use the immersion when Agile prices are negative to help heat the DHW as hot as possible and use as much electricity whilst I'm being paid for doing so. When calculating my COPs, I exclude (or correct for) days where the immersion has been used.

matt_drummer

NedS said:

matt_drummer said:

NedS said:

michaels said:

NedS said:

As there are a few of us with ASHPs installed, I thought I'd start a thread to compare monthly SCOPs so we can see how we are performing.

I had my 12kW Samsung ASHP installed in June. It's been heating DHW over the summer and we are just now starting to get a feel for heating. It's an oversized unit, so we won't be able to run continuously until it gets a lot colder, but it's been heating the house nicely with 32C flow temps during October.

My monthly SCOPs:

June-August: 3.75 (DHW only)

September: 4.05 (improved as occasional heating)

October: 4.75 (combined DHW and heating)

With the current mild weather (12-14C), I am getting a COP of 6 for short heating runs at 32C flow temps (the lowest I can run). This will warm the house at a rate of around 1C per hour.

Anyone else want to share theirs?

What sort of cycling are you getting with a big heat pump and mild temps, do you control via water temp or a themostat?

Because we are on Agile rather than a fixed tariff, I am controlling the 'cycling' manually with the room thermostat (effectively turning demand for heat on/off). As it's oversized (and it's mild), it only needs to be on for a couple hours per day, so makes financial sense to ensure those couple hours are during the cheaper slots on Agile. Today we ran for a couple hours this morning when we got up, then off for a couple hours and back on for an hour between 2-3pm. It will be off now until 7:30pm, after the peak evening rates.

We will certainly need to see temps below 10C, maybe even approaching zero before we can run anything like continuously, even on minimum output. But that certainly doesn't seem to be massively impacting efficiency at present as I can still achieve a COP of 6 for short (1h) heating run in mild weather.

When it's colder and we are doing longer runs (but still not continuous), I may programme it to be on / off for 30min periods depending on the Agile pricing. Over the next few months I will find out what ambient temp matches my minimum 32C flow temp, and thus what ambient temp I can just leave it to run.

I have just been looking at data from a 12kW Samsung

It's a bit of a monster!

Minimum output seems to be about 5kW of heat.

Is that what you are finding?

Yes, it's essentially a de-rated 16kW unit.

When running in forced on mode, it will reach equilibrium with a LWT / flow temp of around 32.5-33C, which matches a de-rated output of around 4.6kW for my radiators. So yes, that's about right.

The electrical input (draw) is reported as around 8-900W when ticking over at minimum, but this includes the two pumps that are drawing ~50W each, so minimum input is maybe 700-800W. At some point I measured electricity used at the meter over 30 and 60mins when it was ticking over, I can't remember the exact figures, but it was around 800W/h recorded at the Emlite meter.

Assuming 0.75kW minimum input and 4.6kW heat generated, that corresponds to a COP of around 6 which is in the right ballpark for a LWT of ~33C at ambient temps around 14C. So that all seems very believable.

I would have much preferred a unit that could modulate down to a 4-500W input, but they would not budge from their MCS heat loss calculations which I think are high (probably due to the air changes per hour they used for our very old house even though it is completely renovated with modern double glazing)

It all sounds about right.

As I said before, when comparing COP it is normal to include circulation pump electricity consumption in the calculation. Most heat pumps are monoblocs and the circulation pump is always included.

How do you get on with that much heat?

I assume you had other upgrades as part of the ECO4 scheme?

I didn't get the impression that it was a vast residence, 5kW of heat at 14c outside is quite a lot

I really struggled with that much heat with my old 9kW Daikin and even my new one is too much. 

NedS

The Samsung monobloc is somewhat unique (as I understand it) in that it does not include any circulation pumps, so these are installed separately, in my case as part of a pre-plumbed DHW cylinder. So the metered spur to the ASHP records usage for the heat pump only, excluding the circulation pump(s). The Samsung controller however records slightly higher figures which includes the pumps and controller usage.

We also had insulation upgrades to solid stone walls as part of the ECO4 scheme.

At current ambient temperatures, a flow temp of ~32-33C is raising the internal room temp by around 1C per hour. With the heating off overnight, the temp drops to around 17C, and takes ~2h to reheat to ~19-19.5C which is the set point during the day. We then turn off between 4-7pm, whereby the temp drops back to around 18C and we reheat again in the evening to 19.5C. We get a little overshoot and normally end up around 19.8C which is perfect for us.

If starting from cold, it takes around 30mins to get up to temp, drawing ~2kW to start, and ramping back down to 1kW as the LWT approaches it's WC set point. Once it's settled, the compressor seems to ramp down to 25% and draws around 750-800W idling. If it's restarting from warm (for example, if it's been off for an hour), then the initial start up period is much shorter to reach the WC set point flow temp. We have a 50L volumiser which helps retain heat in the water when restarting after a short off period.

So being (very) oversized is not a complete disaster. We can run for short periods efficiently, can switch off completely overnight, and still reheat the house relatively quickly and efficiently at low flow temps. Once we reach a point where we'd need to run higher flow temps (say 40C or above) to reheat a cold house, it may be worth considering leaving it on overnight ticking over at 32C flow temps, but I think we'd be down below 5C constantly to reach that point. For now, it isn't worth having it kick in for an hour or two overnight in cheap slots as that heat would be gone by morning anyway, and the bedrooms are plenty warm enough for sleeping.

Our MSC heat loss calculation was ~7.5kW at -2C. They went with the 12kW model as the 8kW model can only deliver 6.5kW of heat at 50C flow temp at the design temp of -2C (which was their design spec). If I actually need 7kW of heat, the 8kW model would be running flat out to provide that so they played safe and went with the 12kW model. It's just a shame there is nothing in between in the Samsung range. Once I've had it a year or two, if anything ever happens to it, I'd not hesitate to swap it out for an 8kW once I'm confident it can cope.

michaels

NedS said:

The Samsung monobloc is somewhat unique (as I understand it) in that it does not include any circulation pumps, so these are installed separately, in my case as part of a pre-plumbed DHW cylinder. So the metered spur to the ASHP records usage for the heat pump only, excluding the circulation pump(s). The Samsung controller however records slightly higher figures which includes the pumps and controller usage.

We also had insulation upgrades to solid stone walls as part of the ECO4 scheme.

At current ambient temperatures, a flow temp of ~32-33C is raising the internal room temp by around 1C per hour. With the heating off overnight, the temp drops to around 17C, and takes ~2h to reheat to ~19-19.5C which is the set point during the day. We then turn off between 4-7pm, whereby the temp drops back to around 18C and we reheat again in the evening to 19.5C. We get a little overshoot and normally end up around 19.8C which is perfect for us.

If starting from cold, it takes around 30mins to get up to temp, drawing ~2kW to start, and ramping back down to 1kW as the LWT approaches it's WC set point. Once it's settled, the compressor seems to ramp down to 25% and draws around 750-800W idling. If it's restarting from warm (for example, if it's been off for an hour), then the initial start up period is much shorter to reach the WC set point flow temp. We have a 50L volumiser which helps retain heat in the water when restarting after a short off period.

So being (very) oversized is not a complete disaster. We can run for short periods efficiently, can switch off completely overnight, and still reheat the house relatively quickly and efficiently at low flow temps. Once we reach a point where we'd need to run higher flow temps (say 40C or above) to reheat a cold house, it may be worth considering leaving it on overnight ticking over at 32C flow temps, but I think we'd be down below 5C constantly to reach that point. For now, it isn't worth having it kick in for an hour or two overnight in cheap slots as that heat would be gone by morning anyway, and the bedrooms are plenty warm enough for sleeping.

Our MSC heat loss calculation was ~7.5kW at -2C. They went with the 12kW model as the 8kW model can only deliver 6.5kW of heat at 50C flow temp at the design temp of -2C (which was their design spec). If I actually need 7kW of heat, the 8kW model would be running flat out to provide that so they played safe and went with the 12kW model. It's just a shame there is nothing in between in the Samsung range. Once I've had it a year or two, if anything ever happens to it, I'd not hesitate to swap it out for an 8kW once I'm confident it can cope.

Could you upgrade the rads so the -2 flow temp could be lower?

I find it annoying that our LG has no night time 'set back' which out previous Viessman gas boiler had on weather comp mode.  We don't really want to switch it off overnight and actually don't currently have the controls to do so.  Being such a newbie I would actually like it to get much colder so we can see how it performs against more of a challenge....

Spies

Daikin MMI shows a really rough bar graph so I can't play this game unfortunately

NedS

michaels said:

NedS said:

The Samsung monobloc is somewhat unique (as I understand it) in that it does not include any circulation pumps, so these are installed separately, in my case as part of a pre-plumbed DHW cylinder. So the metered spur to the ASHP records usage for the heat pump only, excluding the circulation pump(s). The Samsung controller however records slightly higher figures which includes the pumps and controller usage.

We also had insulation upgrades to solid stone walls as part of the ECO4 scheme.

At current ambient temperatures, a flow temp of ~32-33C is raising the internal room temp by around 1C per hour. With the heating off overnight, the temp drops to around 17C, and takes ~2h to reheat to ~19-19.5C which is the set point during the day. We then turn off between 4-7pm, whereby the temp drops back to around 18C and we reheat again in the evening to 19.5C. We get a little overshoot and normally end up around 19.8C which is perfect for us.

If starting from cold, it takes around 30mins to get up to temp, drawing ~2kW to start, and ramping back down to 1kW as the LWT approaches it's WC set point. Once it's settled, the compressor seems to ramp down to 25% and draws around 750-800W idling. If it's restarting from warm (for example, if it's been off for an hour), then the initial start up period is much shorter to reach the WC set point flow temp. We have a 50L volumiser which helps retain heat in the water when restarting after a short off period.

So being (very) oversized is not a complete disaster. We can run for short periods efficiently, can switch off completely overnight, and still reheat the house relatively quickly and efficiently at low flow temps. Once we reach a point where we'd need to run higher flow temps (say 40C or above) to reheat a cold house, it may be worth considering leaving it on overnight ticking over at 32C flow temps, but I think we'd be down below 5C constantly to reach that point. For now, it isn't worth having it kick in for an hour or two overnight in cheap slots as that heat would be gone by morning anyway, and the bedrooms are plenty warm enough for sleeping.

Our MSC heat loss calculation was ~7.5kW at -2C. They went with the 12kW model as the 8kW model can only deliver 6.5kW of heat at 50C flow temp at the design temp of -2C (which was their design spec). If I actually need 7kW of heat, the 8kW model would be running flat out to provide that so they played safe and went with the 12kW model. It's just a shame there is nothing in between in the Samsung range. Once I've had it a year or two, if anything ever happens to it, I'd not hesitate to swap it out for an 8kW once I'm confident it can cope.

Could you upgrade the rads so the -2 flow temp could be lower?

No, the rads were already all replaced during the installation and we went as large as possible (at K2 types). Looking at my spreadsheet, the rads can actually emit 7.4kW at 40C flow temp, so I suspect we'll end up with flow temps in the mid to high 30's as I don't think our actual heat loss will be as high as 7.5kW.

NedS

michaels said:

I find it annoying that our LG has no night time 'set back' which out previous Viessman gas boiler had on weather comp mode.  We don't really want to switch it off overnight and actually don't currently have the controls to do so.  Being such a newbie I would actually like it to get much colder so we can see how it performs against more of a challenge....

Can you not just set back the room temp with a room thermostat, to say 18C overnight?

Alternatively, with my Samsung, I have the option to change the WC/LWT by +/-5C, so can use that to easily reduce the flow temps in the radiators overnight, thus giving out less heat.