Money Saving Boiler Challenge - Turn down boiler temp to save money and energy waste

[Deleted User]

BUFF said:

May I ask what boiler that is?

Nothing fancy, Ideal Logic+ C24. Had it for 3 years and has been brilliant, combined with a smart thermostat I literally set and forget and it just works. 

https://idealheating.com/installers/products/logic-plus-combi

I used 16,000kWh in the first year but I've only used 11,000kWh over the last 12 months. Hoping for less this winter now it is turned down even further to CH 50C and HW 45C which is as low as I think I can go - the default installed setting was CH 70C HW 65C.

I think that is quite good for a large 3-bed house with 4 people - 2 are teenage girls, we have our house warm and like a proper long shower, CH set at something like 20C from 6am - 10am then 18C daytime until 4pm-11pm again 20C, 18C overnight.

But I was paying 3.2p a kWh when it was fitted so I think I'll be trimming it back even further when the cold weather starts - hardly been on lately, about 8C outside and it hasn't come on at all this evening.

[Deleted User]

Glum said:

For those with a regular back boiler, it seems that it might be more efficient to turn the boiler temperature up to almost maximum (in winter). It sounds illogical but I assume that if the radiators heat up faster, the room stat switches the boiler off a bit sooner and the pump stops using power. Conversely, a cooler boiler might struggle to get the house warm enough to trip the room stat, so the boiler and pump are running for longer. By way of an example, old GlowWorm back boilers had a recommended boiler temp of 180°F or 82.2°C.

I would appreciate any comments. Let's assume that TRVs are not fitted. Is there an efficiency saving?

Heat up faster - certainly. 

A lower boiler flow temperature will indeed result in it taking longer to reach a set thermostat temperature. However, unless radiators are full of sludge etc then in most circumstances rooms will get up to temperature. How much gas you will save is a different question.

Houses with non-condensing boilers were designed with higher boiler flow temperatures in mind, and turning down the boiler flow temperature will not achieve the efficiency savings associated with a condensing boiler with a return flow temperature below 56C.

manamaga2512

This boiler challenge confuses me. We had a new boiler installed only a couple of months ago. An Ideal Logic+ C30.
The boiler challenge website states to turn the boiler to 60 degrees for best efficiency. Our boiler has an eco mode, and when setting the dial to the E mark (eco, and thus using less gas according to the manual) the temperature is actually 69 degrees. Which in my mind is a contradiction of the challenge.
Also, something else I can't get my head around. If you are reducing the temperature of the water which circulates round the radiators, and you have your room thermostat set to 19 for example. Surely it will take longer for your room to reach temperature because the rads are not as hot as they were, and thus the boiler will be working longer, using more gas and more money.
It just all makes no sense.

Leon_W

Just to help you get your head around boilers at lower temperatures and heat up times.

It's exactly the same concept as driving a car economically.  If you accelerate away from traffic lights with your foot flat to the floor to 50mph you are going use way more petrol than accelerating gently to 50mph.  The end result is the same, 50mph but doing so as economically as possible.

So, running your boiler at a lower flow rate temperature will still achieve the same desired room temperature but it will just take longer to get there.

Spies

Here's my flow and return graph for my Worcester Bosch 29cdi set at ~60c

The thermostat cycles the boiler a max of 6 times per hour for a minimum of 1 minute at a time.

Bit's with no return rise when flow does, is DHW demand.

Interesting no?

manamaga2512

Leon_W said:

Just to help you get your head around boilers at lower temperatures and heat up times.

It's exactly the same concept as driving a car economically.  If you accelerate away from traffic lights with your foot flat to the floor to 50mph you are going use way more petrol than accelerating gently to 50mph.  The end result is the same, 50mph but doing so as economically as possible.

So, running your boiler at a lower flow rate temperature will still achieve the same desired room temperature but it will just take longer to get there.

Yep, I get that, cheers. So what you're saying is despite the manufacturer guidance of using the eco mode on the boiler to use less energy.....ignore that and still turn down to 60?
This is my main issue of conflicting information. I mean surely the people best placed to advise on the best energy performance is the people who make the boiler? I dunno.

ariarnia

manamaga2512 said:

Leon_W said:

Just to help you get your head around boilers at lower temperatures and heat up times.

It's exactly the same concept as driving a car economically.  If you accelerate away from traffic lights with your foot flat to the floor to 50mph you are going use way more petrol than accelerating gently to 50mph.  The end result is the same, 50mph but doing so as economically as possible.

So, running your boiler at a lower flow rate temperature will still achieve the same desired room temperature but it will just take longer to get there.

Yep, I get that, cheers. So what you're saying is despite the manufacturer guidance of using the eco mode on the boiler to use less energy.....ignore that and still turn down to 60?
This is my main issue of conflicting information. I mean surely the people best placed to advise on the best energy performance is the people who make the boiler? I dunno.

i think theres a difference between a general 'works for anyone' option and works for your system in your house. the boiler will use the least gas on eco mode in a lab. but your house has a different number of radiators and amount of insulation than the lab set up (probably) so you should really play around with your boiler and see. 

i had a similar conversation with our washing machine manufacturers as their eco setting is recommended to use the least water and power but it only takes 4kg. so the 9kg wash turned down to 40 uses less power and water than running the eco mode twice. 

but the reason i was on this thread was to ask how those of us without a fancy display telling the return temp could work it out. we dont use our boiler much as we have a stove in the lounge but we this weekend we were doing our annual 'testing' to check it still works (our local plumber comes in june to check it's safe but we like to check around this time that there's no cold spots in the rads or anything). one thing i have noticed is that with our condensing boiler if i turn the temp down i don't see steam coming out of the exit pipe. does that mean it's condensing in the boiler and is a good thing? 

Workerdrone

I do wish my Logic+C30 had a multi line LCD display. I think mine was fitted in 2017/18 so I only have the single line display and no settings to show return temp. I run a homeywell evohome with the opentherm bridge so the dial for radiator temperature does nothing. Display just shows something like "Flow temperature controlled by room stat". I am curious to do a little monitoring to see how what the return temperatures are. Quite often when I check the boiler after its first fired up it shows super efficiency mode. Most of the rest of the time its showing high efficiency mode so I know its condensing.

Leon_W

manamaga2512 said:

Leon_W said:

Just to help you get your head around boilers at lower temperatures and heat up times.

It's exactly the same concept as driving a car economically.  If you accelerate away from traffic lights with your foot flat to the floor to 50mph you are going use way more petrol than accelerating gently to 50mph.  The end result is the same, 50mph but doing so as economically as possible.

So, running your boiler at a lower flow rate temperature will still achieve the same desired room temperature but it will just take longer to get there.

Yep, I get that, cheers. So what you're saying is despite the manufacturer guidance of using the eco mode on the boiler to use less energy.....ignore that and still turn down to 60?
This is my main issue of conflicting information. I mean surely the people best placed to advise on the best energy performance is the people who make the boiler? I dunno.

In a nutshell, Yes.

I've very recently had an Ideal boiler fitted so I'm familiar with the eco setting.  If you are still comfortable with an even lower flow temperature then go for it.

I've currently got my hot water at 50 and heating at 55.  With the heating flow set at 55 the boiler will remain in it's most efficient "condensing" mode where heat is reclaimed from the exhaust gasses.  

I daresay though. In the depths of winter I'll have to increase this to a higher setting when comfort becomes a trade off with efficiency.

BUFF

ariarnia said:

manamaga2512 said:

Leon_W said:

Just to help you get your head around boilers at lower temperatures and heat up times.

It's exactly the same concept as driving a car economically.  If you accelerate away from traffic lights with your foot flat to the floor to 50mph you are going use way more petrol than accelerating gently to 50mph.  The end result is the same, 50mph but doing so as economically as possible.

So, running your boiler at a lower flow rate temperature will still achieve the same desired room temperature but it will just take longer to get there.

Yep, I get that, cheers. So what you're saying is despite the manufacturer guidance of using the eco mode on the boiler to use less energy.....ignore that and still turn down to 60?
This is my main issue of conflicting information. I mean surely the people best placed to advise on the best energy performance is the people who make the boiler? I dunno.

i think theres a difference between a general 'works for anyone' option and works for your system in your house. the boiler will use the least gas on eco mode in a lab. but your house has a different number of radiators and amount of insulation than the lab set up (probably) so you should really play around with your boiler and see. 

i had a similar conversation with our washing machine manufacturers as their eco setting is recommended to use the least water and power but it only takes 4kg. so the 9kg wash turned down to 40 uses less power and water than running the eco mode twice. 

but the reason i was on this thread was to ask how those of us without a fancy display telling the return temp could work it out. we dont use our boiler much as we have a stove in the lounge but we this weekend we were doing our annual 'testing' to check it still works (our local plumber comes in june to check it's safe but we like to check around this time that there's no cold spots in the rads or anything). one thing i have noticed is that with our condensing boiler if i turn the temp down i don't see steam coming out of the exit pipe. does that mean it's condensing in the boiler and is a good thing? 

You can get thermometers that strap to pipes if you want a  permanent install or can use a contact thermometer.
& yes, if you aren't seeing steam from the flue it is either that the exhaust is so hot that it isn't condensing into visible vapour anywhere near the flue or it has already condensed within the flue. The latter would be a good thing .