Replcaing Radiators.


Hi,
I am doing a bit of decorating just now in my main living room and was considering replacing the radiators. They are very old, maybe from around the 80s. They are absolutely solid but not so sure they are so efficient as newer ones with fins etc. Without changing the thermostat setting, am I likely to get more heat from the newer style radiator than these old ones? My thinking was the newer ones release more heat as they are made from a thinner metal?
Any advice very welcome.
Cheers
John.
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Incubus wrote:

Nope. Metal is a very good heat conductor, so that won't make a difference.
Your boiler has a rating in kW. Radiators have a rating in kW. Whoever designed your system should have matched the radiator total kW to the boiler kW. Although, at that time, they were probably working in other units than kW.
If you replace your present radiator with one the same size, but with fins - it will have a higher kW rating. To make use of that, you need to either switch off/down other radiators in the house, to keep the total constant - or get a higher output boiler.
SO, you could replace your big radiator with a much smaller new finned one, or an even smaller fan-assisted one. That would take up less room but wouldn't heat the room faster.
Or you could install a similar size radiator, with fins and turn down heating elsewhere in the house. That would heat the room faster. But somewhere else in the house would suffer.
Or you could wait until the boiler needs replacing, put in a bigger one and then replace radiators with higher output ones. -- Sue
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Boiler should be >= radiator power. Chances are, if system was designed correctly, your boiler will have sufficient headroom.
The effect will be faster heat up of that room. The only downside is that if the house thermostat is in that room, it might prematurely switch off the heating before the rest of the house is up to temperature. If the house thermostat is not in that room, fit a thermostatic radiator control valve on the new radiator, so it doesn't overheat the room. In theory you should rebalance the system (which in this case will be a light increase to the flow through that radiator), but failing to do this would only result in a slight reduction in the extra power output from that radiator.
--
Andrew Gabriel
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writes:

I can confirm what Andrew says. We had an old 80's radiator in the hall and none upstairs on the landing. Changed the hall rad for a modern one of the same physical size and it happily heats both the hall and the landing which previously was on the cool side. Obviously the boiler was man enough to cope with it, but ours is a microbore system where each rad is supplied separately from a manifold, so it is also possible that the old rad was not extracting its full quota of heat - if that makes sense.
--
Keith W
Sunbury on Thames
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Hi Not to disagree with previous posts I offer the following as food for thought. As you posted 80's system this suggests a conventional heating system (not combi) and solid rads may be cast iron or plate steel. In those days we worked in BTU's (still do) and boiler/rad efficiency was at best 60% (in some cases 40%) Modern radiators are thin plate steel computer designed for maximum output and heat throughput. Basic physics 101 tells us heat travels by 1 of 3 ways Conduction,convection and Radiation. So a thinner wall aids conduction large area (fins etc) aids radiation and a fan aids convection. Add to this the inside is free from 20+ yrs of sediment and they are a lot lighter. Many a thread has unspun on this and other NG's regarding efficiency,pipe size,pumping speed,pipe runs and more but in the end for the DIYer which is what this group is about if you want a new radiator get one. The system will heat it even if it's the size of a wall the only drawback will be how long it will take. All the calculations are based (when you break it down)on a certain temperature rise in a specific time .(in a nut shell). Replacing the rad' seems like a good idea but consider (no! do try) flushing the system at the same time and service the boiler.
HTH
CJ
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Thinner wall is about reducing material usage, costs, and weight. It won't make a scrap of difference to conduction because steel is such a good conductor anyway. It will however reduce the radiator life unless you are much more careful about corrosion protection than you need to be with older radiators.
--
Andrew Gabriel
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Hi,
thanks for the replies - they have definately given me plenty to think about. I do have a very old conventional heating system. It is on the reduced parts list with British Gas so I keep my fingers crossed that it does not break down! I get a lecture form the BG engineer every year when he comes to service it (I've been told replacing it will be expensive as I need to change my gas pipe from 15 to 22 and that will require quite a bit of work)
I think I will just leave the system as it is (possibly get a flush) and wait until the boiler goes (which i'm guessing from some of the noises it has been making will be soon) and try and get a decent package with the boiler and radiators all thrown in.
Thanks for the advice,
John.
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Most people move the boiler position when they get a new un fitted, especialy if they are going from an old style open flue boiler and a hot water cylinder to a combi,
Bung the new boiler in the loft, or the cupboard where the HWC used to live if you really have to, have a new 22mm gas pipe run to it, they run them externaly nowadays, so not a hassle to have put in, unless you really must have it internal, then it will cost you.
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