Heat Loss using HeatPunk

[@davidcoates6768]

It'd be good to see how your boiler performs with upgraded radiators (capable of 35c), could see if it is worth upgrading the radiators in every house, even if they don't get a heat pump. I guess the limit would be how low your boiler will go down too though and then how much electric power the boiler uses vs gas.

[@tomasmcguinness]

My current rads can heat the house at a 40 flow on most winter days, 45 needed on colder days. There are two problems. First, I'm not sure the heat distribution is even. I suspect that we have an undersized radiator or two in the house. Second, my boiler is a monster (35kW), so whilst I'd be able to set the flow to 35 the main problem is that its minimum output is 5.5kW so we get significant cycling on mild days (especially with a heat loss of about 7!kW). I'll certainly be doing another video once I get time to add the radiators and have a look! Might be a case of making a fabric improvement rather than getting a bigger radiator. We'll see!

[@davidcoates6768]

@@tomasmcguinness I don't think the cycling on a gas boiler will impact as much as on a heat pump, in a worst case you may get the 80% that old boilers did vs 90%+ for condensing. It'd just be an extra bonus if you did get better efficiency. For me the main goal would be getting the house to heat up evenly, so that it isn't uncomfortable when cycling, with some rooms hot and some cold. Also I'd want to get the balance right between upstairs and downstairs, because I can't sleep when it is too hot. Is it more efficient to run the whole house at a cooler temp over night, or is it better to just shut off the upstairs overnight with a valve or thermostats, with convection from downstairs maintaining the cooler temperature in the bedrooms. You may want to design with some cycling anyway, so that you could go on your preferred tariff. You may want to try heating up the house to 23c at 4pm, without then requiring any heat until 7pm after peak. While this may not be the most energy efficient in your house, it would be the most cost and grid efficient, with more of the energy likely to come from renewables.

[@tomasmcguinness]

I believe the accepted wisdom is that it's better to keep the heat pump running overnight, with a set back temperature. This is usually accomplished with a lower flow temperature. If the system is well designed, the upstairs bedrooms would be cooler anyway (the radiators emitting less heat than other rooms) so lower the flow temperature would see those rads emit proportionally less. By maintaining a controller lower temperature, it's easier for the heat pump to pull the temp up a few degrees. If you turn the heating off completely, the drop might be more severe. I saw some evidence of this when I was going my testing. Having the boiler running for 24 hours used less gas than turning it off at night. Now this was during sub-zero conditions. You expend the energy getting the house up to temp and then it's must less costly to maintain.