Do you need IAT for this to work? Don’t currently have it in OEM but could add it. I could just assume 20 Deg as that is what I have the Mistsi set at.Can you add it in manually?
You don't need to record IAT to use the tool, if your IAT is usually 20C then as the tool defaults to 20C you shouldn't need to change anything. What happens when you press the Auto Fit button?
Here is my results from heatpump monitor.org. Not sure what the vertical line of points at 20 degc is about and it seems to be skewing the line. But the general scatter suggest about 8kw heat loss at -3
Can I just add another 'vote' in favour of measuring heat loss using consumption if you can. Here is the data (from my gas boiler) which I used to size my (~8kW) heat pump; measured loss is 7kW, two three hour surveys said 16kW
Agreed, however it is not so easy when replacing an oil boiler. When replacing my oil boiler I did not think to time on/off usage over a fixed period as suggested earlier in this thread, and estimating annual usage is not trivial when the oil tank is filled on different dates and the amount of oil in the tank is never accurately known. Then combine this with guesstimates of boiler efficiency anywhere between 60-85% and you end up with a figure with large margins of error.
We estimated annual usage of ~1600L of oil which at 90% efficiency (boiler was ~7 years old) would equate to around 15,000kWh of heat per year, and this aligned reasonably well with our heat loss survey.
Our heat pump has delivered around 10,000kWh of heat per year, so our estimates and survey heat loss figures were very much on the high side. At 60% boiler efficiency, the numbers would have been spot on. In reality, the real boiler efficiency was somewhere in between as we also had some insulation upgrades performed at the same time and have no real handle on how much difference these contributed to reducing the heat loss.
Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 7.2kWp solar (south facing), Tesla PW3 (13.5kW)
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.
Agreed, however it is not so easy when replacing an oil boiler.
Indeed not, I think, unless you take measurements regularly, it reduces to a 'sense check' in this case based on annual consumption or the like. Still good enough to spot a factor of 2 oversizing, which clearly occurs, but not good enough to decide exact size.
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
however it is not so easy when replacing an oil boiler. When replacing my oil boiler I did not think to time on/off usage over a fixed period as suggested earlier in this thread, and estimating annual usage is not trivial when the oil tank is filled on different dates and the amount of oil in the tank is never accurately known. Then combine this with guesstimates of boiler efficiency anywhere between 60-85% and you end up with a figure with large margins of error.
Again, agreed. There is also the likely change from timed to continuous heating, which further complicates things. For all practical purposes, using past oil consumption to determine heat loss is in effect a non-starter. But with a gas boiler, which is what most people have, and either a smart meter or another way of accurately measuring energy use over time, it can be done.
Midea 14kW (for now...) ASHP heating both building and DHW
Here is my results from heatpump monitor.org. Not sure what the vertical line of points at 20 degc is about and it seems to be skewing the line. But the general scatter suggest about 8kw heat loss at -3
however it is not so easy when replacing an oil boiler. When replacing my oil boiler I did not think to time on/off usage over a fixed period as suggested earlier in this thread, and estimating annual usage is not trivial when the oil tank is filled on different dates and the amount of oil in the tank is never accurately known. Then combine this with guesstimates of boiler efficiency anywhere between 60-85% and you end up with a figure with large margins of error.
Again, agreed. There is also the likely change from timed to continuous heating, which further complicates things. For all practical purposes, using past oil consumption to determine heat loss is in effect a non-starter. But with a gas boiler, which is what most people have, and either a smart meter or another way of accurately measuring energy use over time, it can be done.
I wouldn't say its a non starter. If you can get annual consumption somehow it is still a sense check that will point out any survey results that are way out (particularly those that are grossly overestimated). Very far from ideal, but perhaps still better than no measurements at all.
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
