Are radiators energy efficient?

[Lorna3]

I'm doing up my house and wasn't sure about which heating option to choose. I thought that radiators were really inefficient but then I found this report from MARC, what do you guys think?

:


Aimed at assessing the future role of steel panel radiators in an evolving market, the report highlights that:
• Due to their flexibility, steel panel radiators and convectors are the best way of introducing energy-efficient heat generators into existing properties, with renovation and retro-fit accounting for in excess of 90% of the UK and other major western European markets.
• Steel panel radiators work well with low water temperatures, making them an ideal choice for eco-conscious developers and home owners.
• Steel panel radiators have quick reactions to temperature control, with small heat losses, meaning efficiency is not lost with long heat-up times. This is a benefit of the lower thermal mass of steel panel radiators.
• The total energy efficiency of steel panel radiator-heated buildings is excellent.

MARC chairman John Colling said: “During the last 60 years, most technologies have gone through revolutions. With steel panel radiators, it has been more evolution, with the introduction of the advanced welding technologies developed by radiator manufacturers in the 1980s, allowing convector panels to be welded directly onto the radiator waterways. The effect of this was to produce the same amount of heat output from radiators using less primary steel and water content, a major step forward in the drive for energy efficiency and carbon emissions.

“The reason for this is that steel panel radiators work very well and, in reality, nobody has found anything better. While other types of heating system have emerged as popular options, the steel panel radiator can compete on all levels and is still very much the number one choice, thanks to the evolution which has kept it up to speed with the needs of homeowners, legislation and trends such as the drive for a green economy.

“Myths such as steel panel radiators creating a stuffy atmosphere, or not providing thermal comfort throughout a room are simply that: myths.

 

[Big Graham]

Fuzzy, not long moved into new house, so its an existing system which i will rectify.I`m in Scotland, we had a full month this year when it did`nt go above zero.We had long periods of time where we were below minus 10.The climate does seem to be changing.2 years in a row we have had freezing conditions for a month at a time.Time to amend your calcs guys.As for the churches, I have been looking at the skirting stuff, a friend mentioned another product which uses far radiant heat, apparently its fairly cold to touch but produces this kind of heat.Need to research that 1 !!!

 

[Big Graham]

Radiators cant heat a large volume space efficiently, You can design them any which you like but this is an impossible task.Remember the word being efficient !!!.The problem with large fans at ceiling height creates horrendous levels of convection i.e. the old lady sitting at the back of the church lets rip (breaks wind) 10 seconds later the vicar is choking, smelling her cabbage, potatoes and ham from the night before.I`ve came to the conclusion the radiant heat is best.The product to use is a difficult choice.

 

[fuzzy]

i dont understand how your example affects efficiency?
If you are refering to comfort conditions of best type of heat you may have an argument but i dont get why you say efficient?
i would also argue rads are good for large open spaces, but it depends on the type of open space. often large open areas such as reception areas use convectors fan assisted, this is to improve heat up time as rads are slow but effective way of heating the space. with doors opening frequently they loose the heat fast so need a fast heat up time to componsate
most churches have rads, and 1 pipe systems, which is only the same as a rad in a tube!

 

[Big Graham]

Ok, Lets talk efficiency.You install a condensing boiler thats lets say 92% efficient.8% lost from fuel going in and transfer loss within the boiler mechanism.Get back to my large church, efficient, comfort.If the church at ground level is 15 C, then thats not comfortable.But ur rads 15m up have produced 22 to 23 degrees below the roof !!!!!!!!!!! Rads have kept the pigeons warm but the poor church goers are freezing.Defending a technology thats ur bread and butter is all fine and well, but rads are not efficient.The church will need a minimum of 220kw thats keeping the pigeons warm.Thats potentially on a sunday for 3 hours 660kwh and the people will probably still be cold.Lets now install a biomass boiler with a dual system of underfloor and a suggestion of skirting heating.We now need around 180 kw maybe less.3 hours and we have a total of 540kwh and radiated heat is better than convection rads.And there may be a payment from the RHI.660 ? or 540 ?.Your last post you said rads are slow but effective, which is it slow? or effective ?.

 

[Big Graham]

Convected heat from rads can travel around 0.3 to 0.7 meters per second, by the time it rises in high rooms, it will lose a lot of its energy .Perhaps through a long period of time the heat will build up from the top working its way down to floor level, after all if a roof has a U-Value of 1.0, its losing heat constantly by then how many kW have been emitted to create that heat build.Thats not to mention that someone doesnt keep opening and closing the doors and letting the heat out.Then we get the people that say as long as the place is insulated rads are great.So when we go the plumb centre and asked for a 28kW boiler, 7 rads and oh give me 20 rolls of rockwool.Wheres the insulation in the rad manual.

 

[doitmyself]

Ok, Lets talk efficiency.You install a condensing boiler thats lets say 92% efficient.8% lost from fuel going in and transfer loss within the boiler mechanism.Get back to my large church, efficient, comfort.

I think the word you are looking for is "effective".

Efficiency is the ratio of output to input, as in your boiler example. The efficiency of a radiator is 100%.

You are really asking: what is the most effective way of heating a church?

 

[fuzzy]

Thanks doitmyself, thats the point i was trying to make

 

[fuzzy]

Your last post you said rads are slow but effective, which is it slow? or effective ?.

both, rads are not fires , they do not create instant heat, they are not designed to give instant radiated heat, a fire is. They are very effective, the heat rooms of all sizes if sized and situated correctly.

you make the point of the u value of the roof and the doors opening, thats not the fault of a radiator, it would be the same which ever heat emmitter you used.

If heat up time was a problem for you, would you not be better selecting a fan assisted convector possibly in conjunction with rads as many other designers of large areas use? regardless, the effieciency of the emmitter would be the same, although the comfort may be more like what your after

 

[fuzzy]

i would install a combination of fan assisted convectors, radiators and were possible overhead convectors, all off the same boiler.
what is the total heat loss of the church? thats the first bit to get right

 

[gaspastemania]

Cant believe this is still going on !!

 

[fuzzy]

the point hasnt been accepted i dont think, could rumble on a lot further

 

[gaspastemania]

personally if i was that concerned about heat loss , kilowatts , energy efficiency,warm air agitating cold air molecules i would be thinking get a grip and move to oz !!

 

[Toddyplumb]

Many years ago a guy designed a plastic tube with a fan in that circulated the warm (high up ) air down the tube and around peoples feet. Cant remember what it was called , im sure it won some sort of award

 

[quality]

Comin back to radiators, they are efficient in their application but never or not in a church

 

[CES]

In warehouses you get de-stratification fans which is probably similar to what you're on about Toddy, although I dont think they would be any good in a church as they can be quite noisy.

 

[Toddyplumb]

CES yep I bet thats the things

 

[WHPES]

Our church installed IR heaters which seem to be the best. Trouble is they don't heat your feet. Ideally, UFH would be best.

The church in a neighbouring village had its system installed by a local guy who put all the pipework and radiators under the pews, so it is actually very comfotable for all except for the vicar!

 

[fuzzy]

as i say, most chuches if not all churches i have worked on have a combination of rads and coils on a large one pipe system, thay work fine

to improve the heat up time and the issue of possibel stratification the easiest way would be to instakk fan covector, these can be high level and simply blow the warm air down.

i would if designing combine rads and fan convectors

 

[Big Graham]

Thanks quality, a man that understands.Rads in a tight environment work as good as they can.With the big spaces however, we have another problem, condensation.Temperature differences within a space of more than 5C starts the condensation problem, hot and cold spots.Water running down certain areas and its normally in the area where heat source meets the cold penetration.I say penetration because if there is not enough heat in the area the cold starts to penetrate in.Heat is automatically attracted to cold.This debate is still going on because everyone of you guys have good knowledge in this area but we don`t have the perfect solution.

 

[fuzzy]

correct ventilation would remedy the condensation issue