Combi Boiler CH water temp

[newbiejim]

Is it better/more efficient to have water temp set highish (70) or low, circa 52?, just had new Vaillant Ecotec Plus 831 installed but as my living room is quite large and radiator placing not optimum due to shape I find to get living room up to circa 21 takes over an hour at boiler CH temp set to 70, at 52 it doesn't get near that after two hours, this with outside temp about 9.
I'm trying to work out what is optimum as when I came in from work at about 6pm in winter my old heating just couldn't get living room up to 21 by 9pm at all. I'm going to get British Gas remote thermostat too so I can optimise things.

 

[newbiejim]

I have a Valiant 824, & run mine at 55 degrees most of winter.

Look at the Valiant VRC 470f weather compensator.

http://www.vaillant.co.uk/trade/pro...-controls-t/produkt_vaillant/ht-vrc-470f.html

I looked at that but thinking the British gas remote control might be the better option?

 

[newbiejim]

Been thinking fitting a Valiant VRC 470f to my boiler, but also had a look at British Gas Remote, still undecided.
I'm about to replace the radiator in the front room, but still can't decide whether a single Type 22 double panel double finned radiator, or two single finned radiators.

I've just did all radiators, all type 22, still got 8mm micro bore feeding them tho, as a consequence it takes a wee while to get rads up to decent temp.One thing i feel is better about single convectors is that you don't have one convector close to wall and heating bricks up so to speak (might be flawed logic there lol).

One thing the weather compensator does that the remote doesn't is ramp the flow temp for CH up, can't decide which is the best option, would be superb to be able to switch on and off remotely. Wonder if the two could be used in conjunction?

 

[newbiejim]

Microbore 8mm., a bit small,10mm would have been better, but it's still a pain in the ass in my opinion, prefer 15mm for central heating myself
I would have fitted 15mm or 22mm for main runs, then reduce down to 8mm, preferably 10mm to radiators.
And I have reflective foil behind all my radiators, painted same colour as decor.

Look at Table 5a: Maximum heat flow rates through pipes in link, 8mm microbore is holding you back with regards to flow rates.

http://www.users.waitrose.com/~robinjames/SolarWaterHeater/pump/pipesizing.html

Cheers, I knew it wasn't the best solution but plumber would have cost me loads more to upgrade, they just don't want to do it, might attempt it myself.

 

[newbiejim]

In terms of thermodynamics, you get the fastest heat transfer when the temperature difference is highest. So using that rule in a conventional boiler, where the gas burns at a pretty much constant rate because it's got a fixed jet, heating water to 55C should be more efficient than heating it to 80C because it should extract more heat as it goes through the heat exchanger and you'll lose less out the flue.

I'm not sure if it's that simple with a condensing boiler, but I think the exhaust gas is condensed to get it below 100C and the heat that you'd normally lose is fed back into the incoming water.

Read something too that condensing boilers aren't condensing unless the return flow temp is below 55 so possibly loads not actually running as efficient as they can.

 

[newbiejim]

Right, I`ve ordered British Gas remote control, goin in on Monday.

 

[newbiejim]

Can you get the BG control without being with BG?

Is there anything else like it that you can get if you have to be BG?

Yes but I think it is £229, there are other options, THESE seem to be popular however I have read that early ones were flaky, British Gas is a one off payment and runs on their servers etc, imho prob best option.