Unless insulation has blown off some loft pipes, I don't know what could have happened, but I have a feeling the heat pump isn't working as well as it did last year, or the app is reporting different efficiency. On October 25th, for instance, the outside temperature was relatively constant at 13 or 14 degrees Celsius at most; the pump consumed 6.7 kilowatts of power, with 4.2 kilowatts utilised for heat and 2.5 for water; and the reported coefficient of performance (COP) was 4.2. We used 8.5kwh yesterday, with 7kwh going toward heat and 1.5kwh toward water, and the COP came out to 4.0. I get that those aren't terrible (particularly for a shabby, inexpensive installation that I "improved"), but it seems like the numbers back up my suspicions that something is off.
Is anyone else having the same doubts about the app data or the pump? What's the point?
Until absolutely necessary, I will not entertain the possibility that it is mechanical in nature.
Unanticipated decrease in efficiency of vaillant heat pumps
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generic_user2
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As an F-gas installer, I can tell you that these heat pumps can measure power input fairly accurately (though it's not entirely certain if they actually do; it depends on the individual OEM), but measuring power output is an entirely different scenario.
To determine the actual data being measured and what data is being pulled from pre-determined tables to provide a COP value to the user, one would need to see the entire equation for each model. However, in most cases, they will compare the refrigerant temperature before and after the evaporator and the compressor, and maybe even factor in flow rate.
The original equipment manufacturer (OEM) has no reason to install a plethora of sensitive and costly sensors and a complex computer system just to fulfilll your curiosity, even though seeing an accurate COP value on your app might be valuable to you.
When systems show respectable COP values while leaking refrigerant to the point where they are not producing any heat, you can tell it's not true.
Like the MPG numbers displayed by your car's computer or the miles per kWh numbers displayed by your electric vehicle, these are often inaccurate and, ostentatiously, presented in a more favourable light by the original equipment manufacturers (OEMs). That's why Bjorn Nyland's 1000km challenges videos don't mean anything; in them, he uses computer values adjusted for ODO accuracy, but he never shares the actual kWh pulled from the chargers.
Even installers selling the product are unaware that many of these monobloc air-to-water units have hidden resistive heaters for those chilly mornings because the manuals either don't mention it at all or present it as a single sentence buried in the manual's jargon.
To determine the actual data being measured and what data is being pulled from pre-determined tables to provide a COP value to the user, one would need to see the entire equation for each model. However, in most cases, they will compare the refrigerant temperature before and after the evaporator and the compressor, and maybe even factor in flow rate.
The original equipment manufacturer (OEM) has no reason to install a plethora of sensitive and costly sensors and a complex computer system just to fulfilll your curiosity, even though seeing an accurate COP value on your app might be valuable to you.
When systems show respectable COP values while leaking refrigerant to the point where they are not producing any heat, you can tell it's not true.
Like the MPG numbers displayed by your car's computer or the miles per kWh numbers displayed by your electric vehicle, these are often inaccurate and, ostentatiously, presented in a more favourable light by the original equipment manufacturers (OEMs). That's why Bjorn Nyland's 1000km challenges videos don't mean anything; in them, he uses computer values adjusted for ODO accuracy, but he never shares the actual kWh pulled from the chargers.
Even installers selling the product are unaware that many of these monobloc air-to-water units have hidden resistive heaters for those chilly mornings because the manuals either don't mention it at all or present it as a single sentence buried in the manual's jargon.
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generic_user2
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generic_user2
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This air-to-water system is something I strongly oppose.
Take a look at what the Japanese original equipment manufacturers are putting in their home market: completely air-to-air systems, because water-to-air ones are so slow, costly, and inefficient.
The fact that Daikin does not offer air-to-water heat pumps for residential use in their home market should have told you everything. (they do offer A2W for commercial heating and hot water systems)
Take a look at what the Japanese original equipment manufacturers are putting in their home market: completely air-to-air systems, because water-to-air ones are so slow, costly, and inefficient.
The fact that Daikin does not offer air-to-water heat pumps for residential use in their home market should have told you everything. (they do offer A2W for commercial heating and hot water systems)
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David_Smith2003
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By utilising third-party monitoring, we are able to achieve a COP exceeding 4 throughout the entire heating season with a Daikin Altherma. Check out heatpumpmonitor.org to see how others are receiving even more. Hence, they're not exactly wasteful!
On days when the weather is mild, the heat is our biggest problem.
On days when the weather is mild, the heat is our biggest problem.
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Hannah_Baker2000
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Although I can't speak to Vaillant, I can tell you that my Mitsubishi's water flow and volume meters have their own sensors that measure the heat output. It is possible that the sensors could become dislodged. In the event that there are problems with the gas system, you should receive a warning code. One great thing about air-to-water systems is that the refrigerant loop is already sealed and tested when it is installed at the factory. In the box, everything is contained. No issues with refrigerant loss in 60 years of owning refrigerators. After around 20 years, the motor and controls failed, and the box was also knackered. To make sure the sensors are securely fastened to the pipes or in their pockets, I would inspect the connections between the computer and the sensors.
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Hannah_Baker2000
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Hannah_Baker2000
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matthewlightburn
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Readings from two unrelated days, particularly when using the heat pump's own monitoring, shouldn't be relied upon too heavily. The two days are very similar, and other factors might be influencing them as well.
For example, unless your home is totally airtight, the wind on the 25th will increase the rate of heat loss. It is clearly visible here.
There is a great deal of variation between this place and Japan if we are to use them as an example. making it an inapplicable comparison.
Due to the prevalence of wet central heating, air-to-water systems have become the standard here. Instead of tearing out an existing system and installing a bunch of fan heaters, it's more convenient to convert a gas boiler to an air-to-water heat pump.
Depending on the specifics of the situation, each has its advantages and disadvantages.
With proper planning, installation, and operation, an air-to-water heat exchanger has the ability to be silent, consistent, and pleasant. All drafts are cancelled.
If you're just doing a couple of rooms, air-to-air is a relatively inexpensive option. Swift action. Can be heated and cooled with ease. Hire an F-gas installer, I'm afraid. If not properly installed, it could be drafty. Quieter than central heating that is wet. Especially vulnerable to unpleasant periods of coldness when they thaw. A distinct hot water system is required.
In the case of small properties without an existing heating system, low occupancy rates, and low heat demand, A2A is an excellent option. In most cases, A2W is the best choice for large properties with an existing heating system, high occupancy, numerous rooms, and a high-ish heat demand.
For example, unless your home is totally airtight, the wind on the 25th will increase the rate of heat loss. It is clearly visible here.
There is a great deal of variation between this place and Japan if we are to use them as an example. making it an inapplicable comparison.
Due to the prevalence of wet central heating, air-to-water systems have become the standard here. Instead of tearing out an existing system and installing a bunch of fan heaters, it's more convenient to convert a gas boiler to an air-to-water heat pump.
Depending on the specifics of the situation, each has its advantages and disadvantages.
With proper planning, installation, and operation, an air-to-water heat exchanger has the ability to be silent, consistent, and pleasant. All drafts are cancelled.
If you're just doing a couple of rooms, air-to-air is a relatively inexpensive option. Swift action. Can be heated and cooled with ease. Hire an F-gas installer, I'm afraid. If not properly installed, it could be drafty. Quieter than central heating that is wet. Especially vulnerable to unpleasant periods of coldness when they thaw. A distinct hot water system is required.
In the case of small properties without an existing heating system, low occupancy rates, and low heat demand, A2A is an excellent option. In most cases, A2W is the best choice for large properties with an existing heating system, high occupancy, numerous rooms, and a high-ish heat demand.
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matthewlightburn
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