At some point in the future, I intend to heat the house with an Air Source Heat Pump. For this to be viable, the heat sources (in this case radiators) need to run at a low temperature. When running at lower temperatures, the radiators and pipe cannot move as much heat energy into the room as before. Because of this, sometimes radiators need to be increased in size and pipes changed to a larger diameter. This can be discovered by doing detailed heat loss measurements of each room and calculating how much heat energy needs to be delivered to each room to keep it warm enough at a certain outdoor temperature. This is time consuming to do and isn't always accurate as the materials used in the walls may not be obvious. A very good article about this can be found here https://energy-stats.uk/what-size-heat-pump/ A more practical method is to turn down the temperature of the the water being circulated by the gas combi boiler and see which rooms feel cold when the outdoor temperature drops. Once you have identified problem rooms then you can make further investigations to discover the appropriate solution. The house had all its radiators installed using 10mm copper microbore branching from a 22mm copper run from the combi boiler. After investigation I changed all the microbore for 15mm plastic pipe and upgraded the size of most of the radiators. (Sometimes this could be done by swapping the existing radiator between rooms). The one exception was the bathroom which was plentry warm enough with the existing towel radiator and microbore pipe. I feel I should mention here that some people are not keen on using plastic pipe for low temperature heating with radiators, partly because the bore is smaller than equivalent sized copper pipe. Im a bit more easy going about it and it is quite easy to to use 15mm plastic pipe for the radiators by only using one 90 degree bend on each tail, which has to be good for flow rate. I also use the thinner metal pipe inserts, rather than the plastic. At the end of the day, if the solution you have chosen keeps the room warm enough at the flow temperature you have chosen, it doesn't matter whether that water is supplied by a gas combi or heat pump (as long as the flow rate is the same). I was confident that I would get good heat pump COP (efficiency) at 40 degrees C flow temperature.
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An important part of knowing what choices to make for the future is knowing what is happening now. In my old house I really found it frustrating that even though I knew what my solar panels were producing, I couldn't find out how much energy I was importing or exporting or where my energy was being used.
I decided not to make the same mistake again and chose to invest in a monitoring system. Reading around, the obvious choice seemed to be the system made by Openenergymonitor.org and in hindsight it was a very good choice. I am able to monitor and graph how much energy I am producing from my solar panels, importing from the grid or exporting to the grid, and thats just the start. I intend to have more solar panels fitted and the system can easily be expanded to include those too as well as monitoring a myriad of of variables such a temperature and heat pump efficiency in the future. |
AuthorEx Radiographer, Information Analyst, Teacher and Self-builder. Now retired Archives
December 2023
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