Most economical /cheapest way of running our boiler

ferry

We have the Ideal Logic C33 combi boiler and it has the 'e' economical setting so naturally we assume running the boiler in this setting is the cheapest way to run it but we can turn that dial down further. Would this therefore be a cheaper way to run the boiler? 

ThisIsWeird

It's unlikely you'll improve much on that 'e' efficiency, at least not without changes to your radiators. But, yes, the lower you have the boiler's output, the theoretically better is its efficiency.

If you turn it down too far, tho', there will come a point where your boiler will struggle to heat your home quickly and effectively enough, so that will clearly be going too far!

That is a 'condensing' boiler. Traditional boilers just had a large flame burning under a water jacket, with much of the heat passing right up and out the flue - a bit like having a pan of water on a large gas flame - hold your hand over it, and it'll be 'ouch' due to the escaping heat.

Condensing boilers like yours have a more complex and finely-matrixed 'jacket' that the flue gases have to pass through to get expelled, and the idea is to have the returning water to this jacket being cool enough - 50-odd degrees-ish - so that the hot products of combustion (including a sizeable amount of invisible steam) are condensed out, and its heat extracted - the condensate trickles out that white plastic pipe under your boiler). If you place your hand in the exhaust gases from your own boiler, you'll likely find it luke-warm, and certainly not 'hot'. 

Is that read-out the CH's? If so, at 69oC it is a bit higher than ideal - that'll likely equate to a return temp in the high 50s or so, not bad, but could do a bit better... IF this temp heats your home with no obvious issues, then by all means try tweaking it down a few degrees at a time. But do check that your home is still being heated effectively - eg, when does the boiler come on in the morning? How long does it take to get your house up to the required temp? Keep a note of that, and make sure it doesn't fall away noticeably; there's little point in trying to save a couple of % if it means that your house takes an extra hour to get up to temp - an extra hour of the boiler running...

You may find that turning the output down a good few degrees at this point in the season - outdoors temps in the very low teens - is absolutely fine, but when the ambient drops a few more degrees, it just won't be hot enough any more. You can, of course, just tweak the output up again, but the ultimate solution is 'weather compensation', which is an outdoor sensor (or more sophisticated versions use the internet weather forecast!) which will automatically teak the flow temp up and down to suit.

I have my flow at roughly 60-odd degrees at the moment, and this works fine to heat the home to my default 18o - I'll take it up a degree if we are feeling a bit chilly - but I know I'll need to significantly increase that flow temp as winter sets in. I will adjust the output perhaps 2 or 3 times over the season.

The other way to get your boiler working at peak efficiency - ie flow (and, hence, return) temps as low as possible is to fit larger radiators. A 'large' radiator will give the same output to a room at a water temp of 50oC as a smaller rad will with 65oC. It wouldn't make any sense to replace good rads, of course, as this will cost many £undreds, but should the situation arise - say you alter the layout of a room, open-plan the layout, add an extension, etc - then DO seriously consider this; if you need to replace rads in any case, then go 'large'! More 'fins'. Extra 'panel'. Or add an extra radiator. Then you can tweak down the flow temp and still be warm...

Zandoni

You can turn the dial down further and it will be even more efficient, you'll have to monitor how warm your radiators are though.

Do you have a good programmer and thermostat?

ThisIsWeird

Oh, and your system pressure is far too high

Why is it at over 2 bar? When was it last topped up? And does that number stay constant, or does it rise and fall significantly when the boiler is hot and cold?

markin

I'm not sure it would actually use more gas but if its taking 4hr rather than 2 it become inconvenient, once you have it steady over many days at say 10c outside put a pencil mark.

The advanced way is to clip a probe to the pipe and check the return temp is as low as you get it.

ferry

Thanks guys. I thought that when i took the picture as it rises to about 2.5 but it normally sits at 1.2 bar when cold

Exodi

It's just the flow temperature, 'e' looks to be around 69 degrees, I keep mine a tad lower (though some sources say you can run it even lower, say 60 degrees - but trial and error).

Erm also, it looks like your pressure is running around 2.2 bar... that's about double what I run mine at.

I'd bleed your radiators to bring that down a bit, somewhere between 1 and 1.5 bar.

Albermarle

You may find that turning the output down a good few degrees at this point in the season - outdoors temps in the very low teens - is absolutely fine, but when the ambient drops a few more degrees, it just won't be hot enough any more. 

I have my flow at roughly 60-odd degrees at the moment, and this works fine to heat the home to my default 18o - I'll take it up a degree if we are feeling a bit chilly - but I know I'll need to significantly increase that flow temp as winter sets in. I will adjust the output perhaps 2 or 3 times over the season.

Same for me. So far this year I have the boiler flow temperature set at around 63. I would go a bit lower, but it is not a combi so I need that temperature to keep the HW hot enough. When the proper cold weather comes I will push it up, but not above 70, even if we have a real cold snap, as any higher will mean the boiler running inefficiently.

FreeBear

markin said:

I'm not sure it would actually use more gas but if its taking 4hr rather than 2 it become inconvenient, once you have it steady over many days at say 10c outside put a pencil mark.

The advanced way is to clip a probe to the pipe and check the return temp is as low as you get it.

Going one step further, hook the probe up to a computer and log the data over time. Add a few more sensors to record external & internal temperatures along with pump & flame on times from the boiler - Be sure you want to go down that rabbit hole first....

I'm currently running my boiler with a variable flow temperature between 30°C and 50°C depending on how much heat is being called for by the thermostat - Seems to be working reasonably well and the house is heating up just as fast as it used to do with an ancient Baxi back boiler.

ThisIsWeird

ferry said:

Thanks guys. I thought that when i took the picture as it rises to about 2.5 but it normally sits at 1.2 bar when cold

Do you have your boiler serviced? If so, ask about that the next time - that's too large a swing, and it indicates an issue with your expansion vessel. Hopefully just a 10-minute pump-up jobbie.

Keep an eye on that max pressure - if it goes above 2.5bar, you are getting into the territory (~3bar) of it possibly blowing open the safety valve and dumping some of your system water. You'll then be into a cycle of too high - dump - too low - top up - too high - dump - you get the idea...!

ferry

Thanks guys great advice