Replacing old radiators - aluminium??

Covering rads reduces the heat output. They aren't a great idea. Could add 10 to 20% to your fuel bill.

The covers are designed to let as much heat out as possible but not all the heat gets out. It's like drying clothes on the rad. It costs more to heat the room

Rule of thumb is always cover a hot water cylinder and never cover a rad.

If the room doesn't heat up as much then it costs more to heat the room.

Trust me on it. I am a plumber 👍

As a sparks I assume you have done calculations on cable size required for things like an electric shower. If it's 8.5kw shower you'd be happy with 6mm on a 15 meter run. You most likely wouldn't put 6mm cable on the same run if it was going to be totally covered in insulation and running through the hot press because you know that covering something keeps the heat in.

Likewise a plumber calculating the BTU RAD requirement increases if it is going to be covered. Covering most things keeps heat in

Not necessarily, It depends on the particular circumstances.

Covering a radiator in any manner will reduce the heat output to the room by some degree, but that will actually reduce energy consumption per hour that the heating is switched on, as there is reduced heat transfer to the room and therefore reduced demand on the boiler. Much the same as fitting a slightly smaller radiator in the first instance.

A running cost increase could arise in circumstances where temperature controls are fitted within the room with the covered radiator, and there was significantly increased boiler runtime to satisfy the rooms set temperature (potentially overheating other rooms on the same circuit too).

I wouldn’t see radiator covers as a particularly bad idea. This is a 30 year old installation, often radiators won’t have been very accurately sized and balanced in the first instance, so I wouldn’t be getting too hung up on the impact of covers, unless the house is particularly slow to heat up in the first place.

Whatever the planned works, consider adding at least one room thermostat to the system and have an experienced heating guy accurately balance the radiators to meet the heat requirements in each room. The payback on this usually makes it well worthwhile.

Oh yeah, and more significant losses with condensing boilers too as they'll be less likely to get into condensing mode due to the poor delta-T.

If the system is correctly balanced you can achieve the same differential temp on a condensing boiler with radiator covers as without.

There are several issues with this train of thought. TRVs can't function if covered. The convection rad is designed so that the heat hits the ceiling and bounces to the ground a distance from the rad. So covering the rad doesn't allow the convection process to function correctly. These rads are literally designed not to have anything above them.

Even ignoring all the above and going ahead with the rad covers it can't be as efficient. The rooms will take longer to heat up. Most people will increase the settings on the TRVS or boiler to compensate for slower heating rooms. Increasing these increases the running cost of the heating.

The heat is stored in the cover & yes will eventually go back into the room but that's not much good if you are going to bed or leaving the house and this stored heat is released when you don't need it. As already mentioned above the boiler may not go into condensing mode as ofter so boiler efficiency drops.

Every rad in my home has a smart TRV. I couldn't control my heating with rad covers.

If you contact the technical department for any rad manufacturers they will tell you their rads aren't designed to be covered.

My own mother drys clothes on rads. Like a lagging jacket on a hot water cylinder this lags the rad & doesn't let all the heat into the room. The temperature of the water in the rad has to be set higher to put out the same amount of heat compared to the same rad without lagging

There is no doubt covers will affect convection and radiation leading to an overall reduction in heat output per m2/h. By how much depends on the type of cover, but it could potentially be significant.

But that doesn’t mean that you will use more energy to heat your house. Indeed if you were to look at a typical house built in 2004, unzoned, and without temperature controls. Fitting radiator covers will reduce the oil/gas consumption per hour that the heating is switched on, together with the heat output to rooms. The two will be roughly proportional.

The operation of TRV’s would be an issue alright. My own view would be that tying to take a room temperature right beside a radiator is problematic and the value of TRV’s is rather limited in the first instance and a poor substitute for a room thermostat.
The digital smart ones may have software to overcome some of these limitations.

Other than that it is largely a case of radiator sizing. A covered radiator is effectively smaller than an uncovered one. The practical impact of that will vary between dwellings and particular setups. However it is as likely to lead to a reduction in energy use as an increase.

It was a limited article alright. I was just showing that almost every link saying that rad covers (particularly wooden ones) reduced the efficiency of the system. In fact the only sites claiming no efficiency loss are sites selling rad covers.

Saying that in most cases rad covers don't present much of a problem is saying that they do have a least some impact in most cases.

The vast majority of homes have TRVs. People got them even if they didn't want them because they up the BER rating. You could get a rad cover that doesn't cover the TRV or tail but apart from looking out of place, you would push the cover tighter to rad & reduce airflow.

Personally I've never minded the look of rads. I rarely even notice them in people's homes at this stage. Even the old ones can be spruced up with the right paint.

It's a debate I don't think we'll get to finish. It's difference of opinion. I've looked & I can't find the smoking gun 😊

Agreed, and I don’t think there is any dispute around this. Yet, a homeowner may wish to fit radiator covers for reasons of aesthetics, and the question arises as to what is the material impact, of doing so.

The answer is it will vary depending on the individual circumstances, particularly the sizing of the radiator relative to the heat loss from the room at a given time, and the type of room temperature controls in place (if any).

But at a basic level, a radiator which is transferring less heat to a room (because of the cover) will be drawing proportionately less energy from the central heating circuit. Fitting a cover doesn’t impact on the energy efficiency of the radiator. It simply reduces it’s output a little, with a roughly corresponding reduction in oil/gas costs.

So what’s the problem? In a lot of cases there isn’t one. Care may need to be taken around the operation of TRV’s if fitted and potentially room thermostats. Similarly if a radiator is already undersized, then fitting covers will worsen the situation. In this regard homeowners should seek advice before fitting covers if the above arrises in their case.

Correct. This is why they recommend placing foil to the wall behind the rad to reflect some of the heat back in.

A radiator transfers most of the heat by 'convection'. So you may transfer some of the heat to the wall, but it still won't make up for the loss of the overall heat transfer.

Can't understand why the manufacturers of these radiator covers don't puts some small electrical fans in the housing to help the air flow through the system. Now there's a idea for 'Dragon's Den'!.