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Experimenting with Temperature Sensors

Test number THREE
Loft Temperatures

The thinking behind how water was managed in the domestic house hasn't changed in decades, but energy efficiency thinking has change massively in the last decade or so. In the good old days, the header tank for the domestic Hot Water system and the Central Heating system were placed in the loft, usually above the houses airing cupboard. The general idea was that the hot water tank in the airing cupboard would heat the airing cupboard and escape through the ceiling beneath the header tanks and generally stop them from freezing. Then came loft insulation, and over the years the thickness has increased to the point now where very little heat escapes the upper floor. This must have a knock on effect of the loft becoming progressively colder as the insulation improves.

The header tank for the Hot Water is less likely to freeze as the constant use will keep it being filled with cold (but not freezing) water, unless you're on holiday for a week in which case, the header tank isn't being topped up. Its a different story for the Central Heating header tank, that should be static, no water movement at all.

So my test here is to monitor the temperatures of each header tank (the sensors are water proof, but just in case they are also wrapped in cling film), one ion the loft space near the header tanks and a final one below the header tanks and above the airing cupboard. This test is hopefully going to be kept going until after we've had a hard frost, but we'll see. The temperatures are read every minute and a quarterly hourly set are uploaded to this web page.

. Sun Oct 25 21:10:04 GMT 2015 .
CH HTHW HTLoft TempFloorTime

So, the loft temperature is colour coded and the final figure is how long it took to capture the (currently) 9 temperature sensors, the other 5 is doing some other monitoring.

CH HT is the Central Heating header tank
HW HT is the Hot Water header tank
Loft is the general loft air temperature
Floor is the space above the airing cupboard and under the Hot Water header tank.

The following graph shows the temperatures monitored during the course of Thursday 5th Feb. As usual, it poses some questions which I have yet to answer. The BLUE line is the Central Heating header tank. There's some spikes which make no sense, and fluctuates more than the Hot Water header tank which also doesn't make any sense. The one good thing, at the moment, is that the water temperatures do not seem to drop over the course of the day by more than a degree.
The loft ambient temperature (GREEN) is another story. The bump at around 07:15 is completely out of character, obviously the climb after that will be combined heat from the house and the daytime temperature and sunshine. The drop off at 3:30pm is the end of the day (getting on for sunset). The peak at about 20:30 was the loft hatch open for a short while.