Octopus Heat Pumps

matt_drummer

koru said:

MultiFuelBurner said:

I do think quietness is a handful for some. When stated as significant what's the dB difference between Daikin and Valiant for matching output ASHP.

Also check what the normal dB level.is outside and lastly is the ASHP going where a fossil fuel flu once was and what was the reading of that when in full chat.

Daikin is 62. Vailant is 55 or 53, but I can't work out which would apply to me. As it is a logarithmic scale, this means the Daikin is at least 50% louder and perhaps nearly 100% louder.

Outside it is pretty quiet, unless the wind brings motorway noise this direction.

There are 3 possible locations and two of them are close to the gas flue. I might use my phone to do a reading for that.

Daikin say that all their heat pumps are 62dB.

The 16kW, the 9kW I had and the 8kW I have now.

My 8kW is much quieter than my 9Kw, it is virtually silent.

The noise levels quoted in the brochures are not necessarily true.

They do however cause an issue if planning consent is required as I know only too well.

I wouldn't assume that the Vaillant will be quieter in the real world. I doubt there is very little in it.

koru

Reed_Richards said:

matt_drummer said:

................
The planning of the heating system is the most important part, SCOPs of 3 these days are really poor, somewhere between 4 and 5 is easily achievable as any Heat Geek trained installer will tell you.

I must admit I'm a little surprised by this.  Can you tell me what operating conditions are needed to achieve SCOPs of 4 to 5, or point me to a heat pump spec. sheet that does?    

https://professional.vaillant.co.uk/downloads/aproducts/renewables-1/arotherm-plus/arotherm-plus-spec-sheet-1892564.pdf

matt_drummer

Reed_Richards said:

matt_drummer said:

................
The planning of the heating system is the most important part, SCOPs of 3 these days are really poor, somewhere between 4 and 5 is easily achievable as any Heat Geek trained installer will tell you.

I must admit I'm a little surprised by this.  Can you tell me what operating conditions are needed to achieve SCOPs of 4 to 5, or point me to a heat pump spec. sheet that does?  My promised SCOP was 3.2 for heating and 2.95 for hot water; I don't have monitoring equipment but that must be roughly what I do get.  And that was a retrofit installation at the end of 2020, not that long ago.  I could certainly do better by increasing the surface area of my radiators so as to use a lower water temperature but that would be very awkward in some rooms; indeed there are two rooms where the radiators are already undersized because there was no obvious space for a bigger one.

Also, with an ASHP you have to heat your rooms with water that is hotter than the room temperature you require whilst with an air-to-air heat pump you only heat the air to the temperature you want the room to be so that has to give you a greater efficiency and a higher SCOP, or be potentially capable of so doing.  I do regret not giving more consideration to this option before I installed an ASHP.    

There are loads of heat pumps here that achieve this. You can look at all the publicly available data on this website, you will see what heat pumps do the best, what the outside temperatures are when they are doing it, the flow and return temperatures, the flow rates and the internal temperature. You can see the heat produced and the electricity consumed.

HeatpumpMonitor.org

Most of them have MID certified heat and electricity meters so the data is reliable. This is real life performance, not spec sheets or installer promises, this is what these heat pumps can do.

My heating was 510% efficient yesterday. The worst it has been is 410% and that was because of an anti frost setting issue.

My new 8kW Daikin that I have had for two weeks has a combined efficiency for heating and hot water of 480% and that has included some inefficiencies due to my messing around with it.

The best performing systems have been properly designed with the correct size heat pump and emitters, no zoning or trvs if at all possible and some form of monitoring.

All of the best performing heat pumps have decent monitoring, those owners don't rely on guesswork, installer promises, or gut feeling to know how their heating system is performing.

It is very difficult to set up a heat pump without some way of monitoring the performance, of course it is possible and it is likely the home will be heated but how efficient it is, who knows?

I don't expect to encounter many, if any, days where my heat pump is less than 400% efficient.


On the subject of air to air heat pumps, I think you will still need to heat the air to a higher temperature than the room temperature you actually want, you can't have something for nothing as there are still the same heat losses. 

You also have an indoor unit to power as well as the outdoor unit.

I had air to air and those were my findings.

Reed_Richards

Thank you @matt_drummer, that's really helpful.  But the Daikin figures show that the SCOP improves as the size of the heat pump increases; that's the opposite of what you found and it's not obvious to me what factors could make it true.

I can see that performance monitoring would be very useful in optimising your heat pump efficiency but without it you'll never really know if you succeeded or not.  So the people that do claim to have achieved the best efficiencies must be the people with the monitoring data to back up their claims.


 

matt_drummer

Reed_Richards said:

Thank you @matt_drummer, that's really helpful.  But the Daikin figures show that the SCOP improves as the size of the heat pump increases; that's the opposite of what you found and it's not obvious to me what factors could make it true.

I can see that performance monitoring would be very useful in optimising your heat pump efficiency but without it you'll never really know if you succeeded or not.  So the people that do claim to have achieved the best efficiencies must be the people with the monitoring data to back up their claims.


 

Why look at Daikin figures?

You have a real time source of data available to you, I have given you the link, have you looked?

Here is my heat pump, it was changed on 20 February 2024.

Emoncms - app view

You can watch it in real time just the same as I can.

Nobody claims anything, this is real data from actual heat pumps in service.

The ones with MID metering like mine are using billing grade heat and electricity meters.

Whatever the manufacturer says is just blurb in a brochure.

You are not seriously questioning the accuracy of this monitoring are you?

matt_drummer

Reed_Richards said:

Thank you @matt_drummer, that's really helpful.  But the Daikin figures show that the SCOP improves as the size of the heat pump increases; that's the opposite of what you found and it's not obvious to me what factors could make it true.

I can see that performance monitoring would be very useful in optimising your heat pump efficiency but without it you'll never really know if you succeeded or not.  So the people that do claim to have achieved the best efficiencies must be the people with the monitoring data to back up their claims.


 

I sense an undertone here.

You believe that heat pump owners with monitoring make up data to claim that their heat pumps are more efficient than they really are?

Do you believe that the performance quoted by a manufacturer is absolute and cannot be beaten/

The factors that show why a bigger Daikin heat pump is less efficient than the smaller one are there for you to look at.

You have all my data and links to many topics discussing the problems encountered. I am not alone which I am sure you will have gathered from reading the topics.

Heat pumps are just a source of hot water, they are as efficient as the are, all that matters is what you attach them to.

The key to good efficiency is attaching the right heat pump to the right house, it is not so complicated.

In the nicest way possible, you are a bit of a dinosaur, you truly believe that if you can't do it then it can't be possible and if t was possible it would cost so much money to not be worth the bother.

I suspect you are an old man who is just stuck in his ways and can't keep up with how other smarter people can just do it better.

koru

Reed_Richards said:

Thank you @matt_drummer, that's really helpful.  But the Daikin figures show that the SCOP improves as the size of the heat pump increases; that's the opposite of what you found and it's not obvious to me what factors could make it true.

 

The Daikin figures must be drawn up on the assumption each model is fitted in a house that has a heat loss that suits it. Matt’s problem was that the 9kW was too big, so his house lost much less heat in most outdoor temperatures than the minimum the 9kW pump could produce, so it was forced to cycle on and off. I imagine the daikin figures would be true if fitted in a house with near to 9 kW heat loss.

Reed_Richards

I'm not at all questioning the accuracy of any reported data or for one minute believe that anyone would fabricate such data.  

I'm now past retirement age so if that makes me an old man then I guess I am; I don't feel old though.

Obviously I would like to pay as little as possible to keep my house as warm as I want it to be but not to the extent that I want to remove existing radiators and replace them with bigger ones for a second time nor replace my heat pump with another one until it is out of warranty and develops a fault beyond economic repair.  But mindful that this will happen one day I do like to try to understand the fine details of how heat pumps work and keep up with improvements in the technology. 

matt_drummer

koru said:

Reed_Richards said:

Thank you @matt_drummer, that's really helpful.  But the Daikin figures show that the SCOP improves as the size of the heat pump increases; that's the opposite of what you found and it's not obvious to me what factors could make it true.

 

The Daikin figures must be drawn up on the assumption each model is fitted in a house that has a heat loss that suits it. Matt’s problem was that the 9kW was too big, so his house lost much less heat in most outdoor temperatures than the minimum the 9kW pump could produce, so it was forced to cycle on and off. I imagine the daikin figures would be true if fitted in a house with near to 9 kW heat loss.

My 9kW did not cycle on and off, my house just got very hot.

There is no house on the planet that is suitable for the 9kW Daikin.

The reality is that it produces about 6,3kW when you really need it due to defrosting and 4kW as a minimum. 

Show me a house that needs between 4kW of heat and 6.3kW of heat during an average heating season.

Reed_Richards

My house was calculated to need about 9 kW of heat when it is -3.4 C outside, according to the MCS evaluation.  So in principle it would need 4.5 kW of heat when it is about 9 C outside.  I'm not sure how you relate this data to a heating season average.