New Radiators

[Sycamore3House]

I had a new worcester Combi boiler fitted 2 years ago and loft insulation last year. If I change the radiators from single ones to double ones would this make the house warmer. The boiler is not the basic one it is the next one I think the 28i. The house is 2 bed upstairs with 2 rads and down stairs lounge dining room, kitchen & bathroom & hallway 5 rads. So 7 rads in total. the rads in the kitchen and bathroom are fairly new and are double ones with thermostatic valves. the others are not. Would it make the heating system more efficient and warmer if the other rads were changed? And also if there were thermostatic valves on also? This is now my next project.

[The Builder]

Rad sizing depends on a couple of things, Sycamore. The size (volume) of each room, and the level of insulation.

Your existing rads, even if they're singles, may possibly already be the right size. i.e. the right surface area to radiate heat.

If the rads are old enough, there is a very good case for upgrading them though. Modern ones are high output, and much more efficient. TRVs (thermo rad valves) are always a good upgrade for efficiency.

One rad on the system is usually left without a TRV. It's simply a "heat leak" to carry away excess heat when all other rads are shut down or just not calling for heat. This is to keep the boiler healthy, mostly.

So, the short answer to your question is........... maybe. You really do need to calculate your sizing requirements first.

Something like this will tell you how much energy you need for each room. From that you look up the heat output of any rad to see if it's the right one.

http://www.diy.com/help-advice/btu-radiator-calculator/Dev_npcart_100006.art

[Sycamore3House]

Thanks for that. I will have a look at the link. The biggest room one of the bedrooms has a radiator 60cm wide size. The other bedroom smaller has 160cm rad. Guess which one is cosier. Downstairs the bathroom smallest room in the house has a 1500mm double rad. I think the lounge and hallway then struggle to keep up. I understand what you mean about the one rad not having trv's though.
Thanks for your reply

[The Builder]

I forgot to mention - the heat-leak rad is usually one where control isn't so essential. Often on the landing or in a downstairs hallway.

Your main bedroom - it would have to be a very small room for a 60cm wide single rad. Unless it's 2 or 3 metres high of course :o)