SteamyTea

Always worth asking MacSalvors, they usually have some in.

The A30, gets me places really quick.

That is the idea. I don't know individual models well enough, but by the time it has frosted up, it is too late. The Temperature/RH curve is tuned, not the sensor. The idea is to predict, or just sense, when the ambient conditions could cause frosting and then either reduce the ASHP output (lighter load) or switch it off for a period of time. Both would prevent frosting and the associated time or energy to defrost. It may be possible to do this with just one sensor, but without data it is hard to tell. One sensor would, in effect, just be monitoring just the ambient conditions and have, other than the theoretical frosting point (based on dew point), no idea what is happening after that air has passed though the radiator and cooled. The state of the radiator will be dependant on the temperature of the transfer fluid and the flow rate of the coolant.

Ah, Nest. Amazon has already stopped selling it. I can't see any real advantage in knowing the weather hours in advance for an ASHP. You might be able to 'top up a bit more' the day before, but I think they will be small gains in the scheme of things (tomorrows weather will be within 80% of today's. Just that the 80% is not defined too well ). That is why I think a stand alone device is probably the better solution, it should really be built into an ASHP as standard. One of the problems we have on this forum is that we have a higher level of knowledge and realise that there are problems, and we can usually work around them. This is not true of the general public who think that electricity comes from unicorn farts and a hot tap always delivers hot water.

If there was a local, and more importantly, dependable, web based weather service, that had up to the minute data for your location, I would agree. Trouble is there isn't. I have a Met station close to me, but cannot access the live data. I also think the IoT's potential is overstated and very little benefit to be had. And the security is going to be truly dreadful.

So here is a time series chart from yesterday, as long as the ASHP turns off (or reduces power output) before the air after the radiator is above 12.35°C (the highest dew point temperature), then there should be no serious frosting (though the radiator fins may be colder). By finding the sweet spot between the ambient air temperature and the 'exhaust' temperature, it should be possible to run at a higher CoP over a given time period. Obviously there is a minimum desired temperature for any hot water and the ASHP may not be able to deliver that, but that just leaves less of a top up. What it really boils down to is reducing the defrost cycles, but without cycling the ASHP too often during for frosting avoidance.

To a certain extend over sizing is the cure, but then if it does frost up it either takes longer to defrost, or more energy to defrost. The general idea is to sense when defrost may occur, and stop (or slow down) the ASHP. So taking a day like yesterday that was hot and dry, it could run a higher output temperature, today it could not. The tricky bit is getting a decent external Temp-RH curve to work with, and knowing how much that curve can be varied for different conditions.

Yes, and one that we can easily do on here I think. I always like to collect data first as that gives a baseline to work to. I will, and have remembered that I work with someone that has an ASHP. I think the whole estate has them and I know a couple of his neighbours too. Better make up a simple, reliable monitor that can work outside.

Extraordinary claims require extraordinary evidence. So where is that 0.1% figure from and what does it relate to. Isn't that like claiming there is a time and place for antisocial behaviour i.e football matches, Friday night in a rough pub.

I monitor the RH and Temperatures myself. Just a DHT22 and a Raspberry Pi. Easy and cheap to set up. You could try WeatherUnderground to find a local weather station. https://www.wunderground.com/

After a recent conversation with @joe90 about ASHPs frosting up, I have had a few minutes to think about this problem. As usual, data is needed. Does anyone monitor the input and output air temperature and relative humidity of their ASHP? This would be a couple of sensors either side of the radiator and in the airflow. Ideally knowing when the ASHP is on would be useful as well. My thinking of the frosting problem is to monitor the temperature and RH on either side and calculate the dew point temperature. Initially the ASHP could be turned off, for a set period of time, when it reaches the median dew point. This could be offset differently with experience and data for the fine tuning If anyone is at my end of Cornwall I would be willing to set up some logging, but as not many members are down here @bissoejosh being the only one I can think of and have no idea if he has an ASHP, it would be down to others to help me out. So help needed.

Bad news I say, I felt good yesterday and dreadful today.

Has the internal temperature changed? Also, the external RH can change quite rapidly for a seemingly small temperature change. All that is needed is a lot more data

I was pondering this internal RH problem last night. Regardless of whether you have MVHR or not, if your house is hotter than the external temperature, and you are not doing silly things with hot water, then the internal RH will be lower than the external RH. This is because internal RH tracks external RH and for any given mass of water in the air (the AH), the higher the temperature the lower the RH. I seem to remember that there was someone over at the other place who had used lime plaster and had trouble getting it dry (not a surprise with lime plaster, but that is another story). He played with his MVHR and it seemed to make no difference. I offered to measure his RH levels, but he never took me up on it as he was convinced that the problem was the MVHR, so turned it off and just opened the house up. One thought that has just crossed my mind, where is the RH monitor?

Get a decent garden shredder, shred it, bag it and take it to the dump. Burning is not really socially acceptable.

At least the problem is now officially recognised, even if the solution is way off the mark. https://www.airqualitynews.com/2018/05/22/defra-launches-clean-air-strategy/

They did https://en.wikipedia.org/wiki/BISF_house There was someone over at the otter place that had one. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9214&page=1#Item_20

I only visit Devon when the weather is dry

We used to use Vapac units as steam generators. They were designed as HVAC humidification units. You may be able to find something, like a wall paper steamer, that can do the same thing. Just stick the pipe in the ducts to the rooms, simple RH controlled switch, and job done. I am not sure where you are in the UK, but my external RH has been pretty low, down to 62% on the 19/05/2018, by the time that has warmed up in the house it is probably down to 45%. Edit: Just looked at yesterdays RH numbers at between 2 and 3 PM, RH was at 50%. No wonder I feel so good.

When my Father was a site engineer in the 1950's, high temperature pipework was insulated with a wet asbestos mix, applied by hand. There were 4 British engineers working on the project, 3 died of asbestosis before they were 70. My Father was the one that did not. This was out in the Far East and the majority of the labour force was Indian or Chinese. As far as I know, even back then, there was concerns about asbestos. In 1977 Iwent for an apprenticeship at a company called Railko who made bearings. They were using asbestos then and part of my duties would have been to monitor the air quality. When I mentioned this to my parents (as I was quite keen on the job), they said 'No Way'.

If you take away mass, which is just the stuff something is made from, energy is transferred by radiation only. So it depends what colour and finish the outside of your roof is. Shiny silver, don't worry, matt black, worry. I think a pure vacuum's decrement delay is only limited by the speed of light. So no. But that is before virtual particles comes into play.

Because a vacuum has no mass. Not strictly true in the case of a vacuum panel, but they are of such low mass and low SHC (the kJ/kg.K or kJ/m3.K) that they can be treated as zero mass. They insulate by stopping conduction, which is usually the dominant transfer of power (the W/m.K). (this is often known as a 2 1/2 D problem)

Here is the digger I use. If it is good enough for Charlie Dimmock to get pleasure from, then I am happy to hold it afterwards, while imagining her 25 years ago. http://www.poundland.co.uk/charlie-dimmock-wooden-handled-trowel

I often wonder how much 'illness' is just caused by misdiagnosing the symptoms, coupled with the health profession's arrogance that they are always right. Also it is far to easy to spot a pattern, where no pattern exists, from a small sample of cases. This is not a new problem, "Three Men in a Boat" was about ill health.

All you need is a bit of unwanted UFH pipe, a pump maybe and a valve or two. You could stick the pipe in a bucket full of anti-free (or salty water) as that may control the temperature a bi better. Let us all know if you give it a go.