Help balancing all rads in my system - 2 not playing ball.

[mikeyw]

Thanks all - some fantastic information on here......going to try again this morning with a larger drop across the rads and aim to get the return temp to the boiler under 60C

Will let you know how i get on.

Mike.

 

[mikeyw]

Well i've had my 1st stab and getting a differential of around 20c across the rads.

It went ok in the main but it got me thinking further if I set the boiler at given temp ie max for example does if effect the energy consumption if you increase the temperature drop across the rad...i'm assuming it has to as the radiator isn't going to be as hot so you are using less energy. Surely there has to be a cut off point though where the rad becomes too cold so you are not actually outputtign enough heat into the room.

Anyway on the new differentials i'll meaure my usage on a 24hr period and see if it's fallen.....if it hasn't I may as well run them hotter so the house warms quicker and TRV's kick in quicker.

All very complicated this - surely the goverment should be pushing this process more if unbalanced rads waste energy !

 

[mikeyw]

Well my usage hasn't really fallen a great deal which is a shame - was hoping by balancing and then balancing with a greater differential ie 20C the gas usage would drop and the heat distribution across the house improve.

Like everyone i was hoping to reduce my gas usage but I spose at least upstairs is heated properly now so it was worth doing for that reason.

Any thoughts on why cosumption has remained pretty much the same ?

 

[mikeyw]

Guys - you obviously know you stuff far more than i do but just out of interest can someone point out on the vokera spec sheets where it tells you about the boiler differential ?

Every article i've read about balancign talks about the 11-12C rad differential.....they are obviously old school articles not written for modern boliers.

TIA,
Mike.

 

[Dan Robinson]

'tis normal for condensing boilers.

 

[mikeyw]

So all modern boilers work off the 20C diff ? - noticed the house felt a bit colder y/day reducing the drops to 20C

 

[D_Hailsham]

can someone point out on the vokera spec sheets where it tells you about the boiler differential ?

Read http://www.vokera.co.uk/download.asp?id={457825E8-27E2-431F-B5A8-2A41EEEC1F61}&type=literature

You will see that it says "Max heat output @ 80°C/60°C. That's a 20°C differential.


Note This is for the Compact HE, but the Compact HE is the same.


Balancing radiators does not necessarily save fuel. All it does is ensure that every radiator is giving out the heat specified by the manufacturer.

So all modern boilers work off the 20C diff ?

There are still some boilers which are designed for an 11°C differential.

noticed the house felt a bit colder y/day reducing the drops to 20C

Unfortunately radiator output varies with temperature. Manufacturers quote the output according to British Standard BS EN 442, which specifies a flow temp of 75°C, return of 65°C and room temperature of 20°C. If the flow and room temperatures are not changed but the return temperature is dropped to 55°C, the output will drop by about 15%.

Very crudely, the output of a radiator depends on the difference between the average surface temperature and that of the surrounding air. Lowering the return temperature will lower the average surface temperature and consequently the output. If you want to learn more look at http://www.engineeringtoolbox.com/heat-emission-radiators-d_272.html

In most cases this will not be noticeable as most radiators are oversized; you seem to be one of the exceptions! It would certainly be worthwhile raising the flow temperature, even if the return does get above 55°C. You may not be able to keep the boiler in condensing mode all the time.

If your house is warmer, but you are not using any more fuel, you have at least achieved something. The only way to really save fuel is to have a lower temperature in the house - and wear a jumper!

 

[mikeyw]

Thanks again Dave - so in an ideal world keeping the boiler in the condensing range ie under 55c will yield best effeciency.

I'll try to go for 74 out of boiler and 54 back in and work from there.