Efficiency of Electric Heating

[JohnW2]

I was thinking that maybe you could have a HW supplied fan heater - "hydronic" is the ridiculous word to search for.

That is surely what standard 'wet' (CH-connected) plinth heaters (like I have in my kitchen) are, isn't it? - although I've never heard them called 'hydronic'!

Kind Regards, John

 

[JohnW2]

Only in that, in the case of a shared boiler, the conservatory controls usually can only turn the conservatory heating 'off' independently, but not 'on' independently. ... This would mean that when it was cooler in the conservatory than the rest of the house and just a bit of warmth was required of an evening, it would be necessary to turn on the central heating, but it wouldn't come on because the room where the main thermostat was located was warm enough.

Not with a 'zoned' system. In my house I have several zones, each with a motorised valve (controlled by it's own 'on/off'switch and its own thermostat in the zone concerned) which, in turn, causes the boiler and pump to fire up when the valve opens. Hence, if one wants to heat one zone, that will work fine, regardless of (and without influencing) what is going on in any other zones.

The way around that, I suppose would be to have a separate zone for the conservatory piped back to its own motorised valve and wired to a separate programmable thermostat. Never seen this done though.

As above, if you came to my house, you'd see it done across several 'zones' - and I imagine that exactly the same is true of any other 'zones' heating system. After all, there would be no real point in having separate zones if whether or not one can heat one of them (or the extent to which one can heat them) depends on what is happening in other zones, or if heating one zone affects what happens in other zones!

Kind Regards, John

 

[ekmdgrf]

My mother is looking to buy a convector heater with thermostatic control for very occasional winter use of a small conservatory. So asked me for advice regarding which model would be the cheapest to run. I told her there would be no difference as electric heaters were all 100% efficient, in that a 3 Kw heater from any manufacturer would consume 3 Kw of electricity and produce 3 Kw of heat. She understood, and I left it at that.

I hate to be pedantic but presumably the heater will have some status LEDs, where some of the input energy will be converted to light and perhaps you'll loose some of the energy to sound too, so not truly 100% efficient

I think this thread gives a great insight into the complexities of metrology.

The key metric is not efficiency but running cost. I have no idea off the top of my head of the efficiency of gas but a figure that I've often heard quoted is that 1KW of gas is 1/3 of the cost of 1KW of electricity. So say a gas heating system is 50% efficient and electricity is 100% efficient, it's still cheaper to burn 2KW of gas than use 1KW of electricity.

The other metric is that the heating should be measured by user experience rather than temperature. The objective of the exercise is to make the user feel comfortable not to heat the room to a given temperature. Think about it this way: in summer it's been 30C for five days, the next day it's 20C, you say to your neighbour "brrr, it's chilly today!" In winter it's been 0C for five days, the next day it's 10C, you say to your neighbour "it's really warm today!"

 

[bernardgreen]

I hate to be pedantic but presumably the heater will have some status LEDs, where some of the input energy will be converted to light and perhaps you'll loose some of the energy to sound too, so not truly 100% efficient

If the light and sound are trapped in the room then eventually the energy in them will be converted into heat.