Could someone suggest a best value for money radiator please?

[ericmark]

That must be the weirdest definition of efficiency I have ever read.

Not me, it is how manufactures define the efficiency of electric heaters, if a heater uses resistance to generate heat, then power in = power out, does not matter if a fan heater, oil filled radiator, storage heater or under floor heating. However unless heated 24/7 then warm up time is important, so the fan heater likely best, and storage heater likely the worst.

There is a different set of rules when looking at heat pumps and inferred, the same applies to gas, a gas fire has both inferred and convected heat, but once one uses water to move the heat around the house, then we look at losses from the pipes, efficiency of water heater, and how well the heat is removed from the radiator and put into the room.

However we also must look at how the heat leaves the home, so with a single glazed window, having fans circulating air will allow more heat to escape, with old houses we want still air, so where we sit is warm, even if there are cold pockets of air around the room, only real way to heat areas of the room is inferred, so fire in the room, but if the air flow is parallel to the windows, then you can get window area cooler than sitting area.

As soon as we insulate the home however, then we can circulate air, and so fan assisted radiators have to be the fastest way to heat the home. But where the problem lies is control, the fan assisted radiator has multi fan speeds which are triggered by room temperature, so colder the room, faster the fan runs, as it cools the water more the faster the fan runs, it causes the return water to cool more and the boiler modulation will cause the water to be heated more.

This works OK with one radiator and one boiler, however with multi-radiators and rooms, then the hot return water from rooms not being heated will turn down the boiler as slow down the heating of rooms that do need heating, unlike the TRV nothing reduces water flow, it does seem you can get building management systems that will control both hot water for heating and cold water for cooling and keep the building spot on, however the cost of the systems mean these are hardly going to be fitted in the normal home.

So although fan assisted radiators may be best, they don't work that well with modulating water heaters, and with simple on/off water heaters they cool down too fast. I am sure some one will come up with an integrated valve so that you can mix fan assisted and conventional radiators, at a reasonable cost, but at the moment having all fan assisted does not work, unless piped in series, having one in kitchen as a plinth heater great, but not whole house.

Never the less with conventional radiators with a modulating boiler we want the water stored in the radiator as low as possible for fast heating and cooling, there is no point fitting eTRV's with geofencing if it takes the room 3 hours to heat up, we are allowed one hour with commercial premises, we should be looking at the same with domestic, so as it detects our mobile phone is within 1/2 hour from home the heating comes on, and within the first 1/2 at home the main rooms are at the set temperature, it can't do this if it's heating 20 gallons of water first.

 

[D_Hailsham]

I gave up when you mentioned "inferred heat". I've never heard of it. What is it?

However, you appear to be confusing efficiency and effectiveness.

 

[george75]

Thanks for your comments