old cast iron rads v new steel

[stevewright]

HI Guys

OK which is more efficient,

1) old cast iron rads with TRV's on a mixture of pipework but mostly 1"

2) or replace with new steel rads with TRV's on 15mm plastic pipe, no surface pipework will be seen

None of the rads are visible all have radiator covers so appearance don't matter

Boiler is German, high efficiency condensation boiler 24Kw.

Your thoughts please.

 

[doitall]

Depends on the occupancy, lifestyle and what you mean by efficient.

In the same building there would be no difference, except modern rads will heat up quicker, and should be designed to run at a higher temperature.

Large pipework can be useful heat, so would depend on the building insulation etc.

Modern boilers like very clean systems, old steel pipe is not always good, the same applies with old cast iron radiators.

 

[stevewright]

house occupied 24/7 with zone control, ie upstairs not heated during the day, living space not heated during day but office and hallway heated. All on programmed room thermostats.

efficiency means cheaper to run. Last years bill was over £3000. all existing pipework is in the walls not insulated as far as I can see.

System was flushed using recommended cleaner and drained before new boiler installation, but the rads are 50 years old and lots of them, in one room there's 5 rads all with 6 section 4@ 400mm x 1000mm 1@ 400mm x 4000mm seems over the top to me room calculates at 21000 BTU so I could get away with only 2 double panelled rads of much smaller size

 

[doitall]

You get x heat from a radiator and it should shut down on the TRV/room stat, so in that respect there will be no difference.

What would make a big difference is getting the pipes out of the wall, lagging them properly and boxing them in.

Cast iron radiators take longer to heat up than modern ones, but they do require a circulation of air to work, if you are boxing them in. On the other hand ci hold the heat much longer.

How is the zone control piped, from the plant room, or teed off the main runs.

 

[stevewright]

zone control is from the plant room on 3 separate pumps, take off a balance vessel which is fed by the boiler.

radiator cabinets where built when the system was first installed and have been built to take into account air circulation with gaps at the bottom etc.

Just worried that the system is taking to much energy to get to working temp with so many old rads and large pipework.

Would smaller pipework and modern rads give much quicker response times?? therefore saving gas.

 

[doitall]

Just worried that the system is taking to much energy to get to working temp with so many old rads and large pipework.

Would smaller pipework and modern rads give much quicker response times?? therefore saving gas.

I agree about the pipework, simply because you are loosing loads of heat into the walls.

Smaller pipework, would give you a better response time, with either type of radiator.

As I said, the two types should be run differently, steel rads heat up quickly, and cool of just as quickly, so it needs to be on longer than cast iron rads which heat up slowly but hold the heat better.

Without a doubt the pipework is where the biggest savings are.

 

[simond]

If you consider the environmental impact of scrapping the old rads and the fact that if left they will outlast the lifetime of a steel panel, I would keep the lovely iron ones.

They are beautiful and what if they take longer to warm up? If you want quick heat fit a warm air unit.

 

[Nige F]

They are beautiful and what if they take longer to warm up? If you want quick heat fit a warm air unit.

Not necesarily beautiful It`s like aKate Moss vs, a BBW