Looking to replace double panel radiators

[xyz321]

Hi, please bear with me while I try to explain this. Our house is a 1950s semi and I have ways wondered if it's too cold unless I run quite a bit of heating. House has all the insulation at recommended levels and all doors/windows are double glazed and mostly draught free. When we bought the house I was looking to replace all 6 radiators but didn't do it due to cost. All radiators are double panel type. They all heat up but obviously with no fins they are not very efficient I guess. Recently we had our trusted heating engineer out for yearly boiler service and I asked him. He said these old ones have quite thick cradle metal (which I understand is good for life of radiator) but obviously due to that they take ages to warm up and heat is also consumed a bit more also after years of working they are bound to have internal sludge build up.. . He didn't try to sell me his services to replace radiator but was only offering his opinion when I asked a question so I trust this was at least in his opinion
genuine advise. Boiler is sufficiently rated as per him for larger BTU of new radiators..

So I want to ask is it worth replacing these with new ones. Is this Logic of metal thickness any true and has someone who has replaced similar radiators noticed any difference to heating after change...

 

[it's not that hard]

I gave up central heating some 20 years ago,but remember about 30 years ago when radiators with fins first came out,asking then what were the fins for I was told that they distribute the heat around the room better,the fins making the rising heat flow upwards and outwards,whereas the old type like you have, the heat just drifts off them,
my tip if you have new ones,when you have the btu's calculated get a radiator with a few more btu's as you can always turn down a rad but can't turn it more than it's maxium.

 

[D_Hailsham]

Here are some outputs for comparison. It's watts per metre length for a 300mm high radiator.

Single unfinned: 483W
Double unfinned: 752W
Single finned: 541W
Double, single finned: 820W
Double, double finned: 1039W

So changing from double unfinned to double, double finned will give you 38% more output.

 

[JohnD]

how hot are they?

Top, middle, bottom and edges?

To deliver their best, they should be "too hot to hold" on the top, and "too hot to hold for long" on the bottom.

Are some hotter than others?

In days gone by, when people were not used to CH (and still today when people are trying to minimise costs) they fitted radiators that were/are somewhat undersized.

 

[Agile]

A lot of incorrect facts being given above.

For a start ALL rads are 100% efficient ! All the heat you put in is given out !

Replacing existing rads will save no energy!

But with modern finned rads the heat out can be higher. That will use more energy but can result in a warmer room.

But the main reason for replacing rads should be to give a more modern appearance.

Tony

 

[Steelmasons]

Replacing existing rads will save no energy!

That will depend upon cleanliness of existing radiator , of course "energy can be saved" with a like for like replacement.

 

[D_Hailsham]

Replacing existing rads will save no energy!

That will depend upon cleanliness of existing radiator , of course "energy can be saved" with a like for like replacement.

No it won't; in fact more energy will be used if the rad is clean.

A radiator is not like a boiler where you put in 20kW and get 19kW out (ignoring condensing for the moment). If you put 2kW into a rad you will get 2kW out. A dirty rad with blocked fins may not be able to give out 2kW but only 1.9kW, in which case the input reduces to 1.9kW.

 

[Steelmasons]

So tell me Mr Hailsham.....would a heat emmiter that is partially blocked (impaired output) signal the room stat (installed in same vicinity) to switch off the heat source or would the boiler carry on cycling?

 

[Steelmasons]

You need to look at the bigger picture Mr Hailsham..

 

[Doggit]

I'm sure someone will correct me, but modern rads will have less body metal than the ones in your system, so should heat up quicker. The fins work in two ways, one being more metal to conduct heat into the room, and secondly, to allow air to pass up through the fins, and transmit heat in to the room more efficiently - hence the reason that they should be kept clean.

In essence, I suspect you've got a cold house, partially because it's a single skin house, partially because rads were sized for 60 degrees in the bedrooms and the bathrooms, and partially because the rads very likely have sludge in them - check for cold spots on the bottom of the rads as they heat up.

Try changing one of the rads for a similar sized one, and see what the difference is, but make sure to put radiator foil behind the rad using premixed wallpaper paste.

 

[D_Hailsham]

So tell me Mr Hailsham.....would a heat emmiter that is partially blocked (impaired output) signal the room stat (installed in same vicinity) to switch off the heat source or would the boiler carry on cycling?

An emitter (blocked or not) cannot signal the room stat. So your question is meaningless.

 

[xyz321]

I'm sure someone will correct me, but modern rads will have less body metal than the ones in your system, so should heat up quicker. The fins work in two ways, one being more metal to conduct heat into the room, and secondly, to allow air to pass up through the fins, and transmit heat in to the room more efficiently - hence the reason that they should be kept clean.

In essence, I suspect you've got a cold house, partially because it's a single skin house, partially because rads were sized for 60 degrees in the bedrooms and the bathrooms, and partially because the rads very likely have sludge in them - check for cold spots on the bottom of the rads as they heat up.

Try changing one of the rads for a similar sized one, and see what the difference is, but make sure to put radiator foil behind the rad using premixed wallpaper paste.

Thanks. House is not a single skin house and has cavity wall insulation already. I cant feel any cold spots on existing radiators. Perhaps it is down to sludge and originally not being sized correctly.

 

[Nige F]

I believe the rads were sized for 60 degrees, as Doggit said . Also it MAY be a one pipe system .

 

[Steelmasons]

So tell me Mr Hailsham.....would a heat emmiter that is partially blocked (impaired output) signal the room stat (installed in same vicinity) to switch off the heat source or would the boiler carry on cycling?

An emitter (blocked or not) cannot signal the room stat. So your question is meaningless.

In layman terms then....the heated space may not reach design temperature and hence not satisfy temperature set @ room stat.....is that better?

 

[D_Hailsham]

So tell me Mr Hailsham.....would a heat emmiter that is partially blocked (impaired output) signal the room stat (installed in same vicinity) to switch off the heat source or would the boiler carry on cycling?

An emitter (blocked or not) cannot signal the room stat. So your question is meaningless.

In layman terms then....the heated space may not reach design temperature and hence not satisfy temperature set @ room stat.....is that better?

Much better and more accurate; your original description was sloppy.

If the loss of output is so significant that the room stat does not turn the boiler off then, of course, the boiler will keep running. Whether the boiler starts cycling is another matter altogether; other factors come into play.