Hi Simon, so the way this works is below 60 degrees your boiler enters ‘condensing mode’. This means that heat is recycled back into the system and therefore less gas is required each time to heat the water again. At 80 degrees your boiler won’t enter condensing mode so all the surplus heat is lost (hence more expensive). Adjusting this setting is basically helping your boiler to run as efficiently as possible.

I am.sure that a boiler will run in condensing mode right up to the point that the return water temperature gets close to the flow temperature. There are other ways to improve heating efficiency by cleaning the middle of double radiators for example this will improve airflow which will extract more heat from the radiator, remove any items from on or around radiators, if you want to dry clothes hang them near the radiator not on them, when I was young we had a clothes airer hung from the ceiling in the kitchen which had a large coal fire / cooking range.

This is from Viessmann who are the world leaders in energy efficient boilers. What temperature should a boiler be set at? Most modern boilers will have a digital dial that allows you to set the output temperature. For combi boilers, the recommended output temperature for the radiators is 75 °C and for the water is between 50 °C and 60 °C. You shouldn’t need to adjust these output temperatures as you may alter the boiler’s efficiency. Please note that for best efficiency with Viessmann boilers we would recommend weather compensation, this automatically adjusts the heating boiler flow temperature to the optimum temperature to external weather conditions.

@@marklord7329 I'm sorry but they're wrong to say 75 deg is correct without adding the proviso that for best economy a lower setting e.g. 55 - 60 should be tried for the radiators (especially in Spring & Autumn). Most heating companies install rather undersized radiators imo (the disadvantage of competitive quoting, small rads are obviously cheaper than larger ones). They do say this in a latent way in recommending radiator temperature weather compensation since this aims to ensure that the radiator temperature is only just warm enough to meet the heating demand. My house has very generously sized Thorn radiators (installed in 1978). The double panel ones are a very open design without fins that never clog up with cobwebs & dust. I find a boiler flow temp of about 60 deg adequate because whoever sized the rads knew what they were doing and it was a private job (for their parents) so money wasn't such an issue. When I had to repipe the rads (because the pipes were leaking under the concrete ground floor) by dropping down from the ceiling I took the opportunity to move all radiators away from windows to preferably an inside or party wall with my neighbours (I'm end of terrace) so that long curtains could be used at the windows and no outside walls were heated. The original Thorn floor standing gas boiler (with cast iron heat exchanger and again from 1978) at an age of about 28 years old I replaced with a Worcester condensing boiler which was of course far more efficient. The Thorn boiler was still operating (on a second Honeywell gas valve) and would of probably gone on for decades more.

@@Martindyna it does say that for best efficiency to use weather compensation

How big is your house Kirsty and what temps did you try?

Make sure your radiators are balanced properly. I've dropped the flow temperature on my boiler to 56 degrees and yet radiators are still lovely and hot, apparently it is something to do with gaining energy at the point of condensing. I'm not the scientist or the plumber but it seems to work. Use the acronym RCC, Radiated, Convected Conducted to do your own home survey on how to prevent heat loss.

Hi John, yes that would be good! I think it also depends on how far your boiler is from where you need that hot water as well. I think everyone’s circumstances are slightly different so you must find the right balance in your household. If you have a dishwasher for example, then the slightly longer wait time is less of an issue.

Turn your tap on to a low flow rate it will get warmer quicker

Is this true of all combi boilers ? I have a Worcester

@@mikeallison7753 no it is not true, boilers condense at 55c which is why the new building regs have come in. A lot of combis and depends on your Worcester model do not condense in HW mode some do. A lot of boilers and controls now allow us to set variable flow temps dependant on load and demand.

Yes unfortunately there is no ‘one size fits all’ when it comes to this topic so a bit of trial and error will be required and you’ll need to see what works best for your household. If a lower flow rate results in you being cold, as you say, add more layers or just increase the flow rate back up again. Either way, it’s probably worth a shot to see if a saving can be made 👍

Working fine in my house - almost 20 years old pipework, running at 55 C and it’s -9C outside.

@@bordersw1239 you probably already have oversized radiators, in the past system design was pretty much ignored by installers and they put in pipes and heat emitters as rule of thumb or by using rudimentary radiator sizing calcs. If you have 15mm and above pipework it’s possible that it will also flow well enough to work. If you are in an area where you have the temperature you mentioned it’s very likely that the system is oversized to counter act, rudimentary calculators sized rads to minus 1 degrees C so if it works in minus 9 then they were installed to suit it. My only concern with the original post was that it didn’t include all the facts and could be misleading.

@@gashead2 upvc microbore pipes and small radiators, apart from the kitchen and downstairs loo. Largest bedroom has a 900mm x 600mm K1 radiator, 20ft lounge has two 600mm K2’s.

@@bordersw1239 levels of insulation will be good in your property. I am not saying it won’t work but if you missed it before I said it won’t work for everyone so I added the cautionary info that was missing from the original post. If it works for you great, are you saving money and still comfortable? We are all different and comfort settings will down to the individual.

That’s controlled on your room thermostat usually..

Thanks Paul. This advice is based on the principal that a lower flow rate means that your boiler enters 'condensing mode' more often which means energy is recycled back into the system, increasing efficiency and therefore requiring less fuel to re-heat the water again (something I should have explained in the video!). If you run your flow temperature too hot, yes your rooms will heat slightly quicker but you'll waste more energy in the process. If it's helpful, I can look to create a separate video around this specific topic?

For sure. Every system and home is different so just find the balance that works for you 👍

This is usually controlled by the room thermostat..

Hi Mark, thanks for your comments. The advice in this video is based on having your combi boiler operate as efficiently as possible by entering condensing mode more often. By lowering the flow temp to 60 degrees, more heat can be recycled back into the system and therefore lowers your energy consumption.

In my well insulated 3 bed brick 1960s semi in Yorkshire I have been able to reduce flow temp to 32c out/26c return keep the heating on from 6am to 9pm at 20-21c even with -5c outside. So much depends on the fabric of your property.

Hi Mike, this isn’t a simple answer I’m afraid as it depends on a number of variables and each house and heating system is different. Basically though, the lower the flow temperature, the more often your boiler will be in condensing mode. A bit of trial and error will be needed but you should be able to find the right balance for your home. It may also be worth checking with your boiler manufacturer as they may be able to offer better guidance

@@businessvideo_pro thank you

That’s the internal temp of the boiler..

Thanks for the reply. Dumb question incoming. What does the internal boiler temperature influence or control (if anything), or is it just informational? For example, if the internal temp displayed 65, but water flow temp was set at 55, would a demand for hot water flow from the tap mean that the boiler would or wouldn't heat the water?

Hi, this could possibly be because the thermostatic valve is closed on the radiator but would recommend having a certified professional come and look at this for you.

Agreed. Every system is different so important to find the right balance for your home.

Good tips and yes everyone will have a different set up so important to do what is best for your home.

Yes. At lower flow temperatures the combi boiler is in condensing mode more often. This means the combi boiler can capture more heat and recycle it back into the system and therefore saves you money. New research from the 'Salford Energy House' found that lowering your heating flow temperature resulted in gas usage savings of up to 9% by lowering the temperature from 80°C to 60°C. It's worth noting though that Innovation charity 'Nesta' recommends not turning your flow temperature below 60°C to ensure homes are properly heated.

@@businessvideo_pro thanks for the reply, it was on 80 for the central heating, I've changed it to 60 and 50 for the hot water, I've also set my thermostat to 20, it was on 30 lol

Great! Just remember if you’ve dropped from the 30 to 20 on your room thermostat, your house will feel much colder than before. Although, I’m at 19 degrees on my room thermostat and the house is nice and cosy 😊. With all of this though, it’s trial and error so if you’re a bit cold, nudge the temperature back up a little until you find the perfect setting 👍

@@businessvideo_pro thanks for all your help, much appreciated !

@@businessvideo_pro this advice doesn't work for older less efficient properties it is really important to bear in mind the structure that you are heating when giving out advice like this, also important to note is the type and size of boiler. This advice applied badly will only be noticed when the next bill comes in and that could be a huge difference and with prices as they are not the best time to be reacting to well intentioned but misleading advice.

Hi Josha, just be careful as hot water cylinders can be breeding grounds for bacteria such as Legionella. Current advice is to keep you hot water cylinder above 60 degrees to prevent Legionnaires' disease

@@businessvideo_pro Yes, I'm aware of that. The thing is the device can only be set to 70 or 55 degrees C. There's a small degree of chlorine in the water which is usually enough to prevent it.

This only applies if you have a hot water cylinder installed which in a combi set up you won’t have. If you do have a hot water cylinder in your home then you must keep the hot water above 60 degrees in order to kill any bacteria present.

@@businessvideo_pro That's it. Regardless of how you heat your water, you need to have a hot water temperature between 55 and 62 deg. C (not higher if possible) to avoid eg. Legionella bacteria growing in your entire installation - heater, pipes and so on - and at the same time reduce deposits of limescale in the hot water system as much as possible.

Yes Eco mode is usually switched on by default..

So bacteria can build up in non-combi set ups if you have a hot water tank. This is because the hot water can sit for longer periods of time allowing bacteria to breed. This is why it’s important to keep your hot water above 60 degrees if you have a hot water cylinder as Legionella can’t survive above this temperature. In combi set-ups, you don’t have this issue as there is no hot water cylinder and hot water is heated on demand when you turn the tap on.

Check out this video re adjusting gas boilers - kzfaq.info/get/bejne/iciTia6Glrfcemg.html , bit long winded but interesting and correct . You are spot on with this video though .

Combi boilers heat mains water instantly so no bactetia can breed as there is no storage

@@businessvideo_pro Even in systems with stored hot water, the risk of Legionalla bacteria flourishing in sufficient numbers to cause problems is very small. There has never been a case of Legionella in the UK that has been traced to a domestic heating installation. In part, this is because previous practices have heated stored domestic hot water to 60C+, but as energy efficiency becomes more of a concern, there is a risk that the bacteria might become more common. Legionalla only multiplies when the water temperature is between 20 and 45C, and even water at 50C will kill bateria, but it takes quite a while for it all to die, and this process will be slowed down if water is drawn off. If the tank is occasionally heated above 60C and kept above this temperature for 30 minutes, the majority of the bateria will be killed and 50C will be find for a fortnight.

Yes this should not be done if you have a hot water tank. This advice is for combi systems only.