Thanks for the detail Tom. I decided to double the o/p of my rads and replaced the existing single panels with double (11's to 21's). This should provide the same heating at a lower boiler temp, and on very cold days, increase the available heat to keep me warm. Also, I'll only heat the space I use, and just keep other rooms from freezing up with the frost protection from the "Thermostatic Radiator Valves".
😂 In response to the posts that Derek is “pissing in the wind trying to educate homeowners ‘ & middle class women having watched a few RUclips vids That is so not true - I’m a 63 year old female that knew sweet “FA” about how to get the best out of my CH system but have learned a lot & enough to adjust flow temps etc through watching these videos. Shame the CH Engineer who fitted my new system 18 months ago couldn’t be bothered to do all this for me or even balance the system following installation & that I didn’t know as much as I do now to demand that he should. BTW I’m working class as they come
It's shocking so many so called CH engineers dont give this guidance. I got 6 so called 'gas safe' engineers round to quote for upgrading my 25 year old boiler to an new more efficient one and fitting TRVs. 3 suggested a combi to replace the heat only boiler despite the house being large having 4 beds, a bathroom, separate en suite with shower and 5 sinks. Of these 3 plus another 1 didnt bother sending me a quote. In the end, I had just 2 quotes to finally choose from.
This is quite useful. Bottom line is that you are fighting heat loss. Your ad is designed to give max output at 75 degree flow. Reducing flow to 55 reduces output of rad by 50%. If the rad outputting at 50% power cant overcome heat loss effectively then you cant run at these low flow temp.
Succinct is the word that comes to mind that best explains your brilliant presentation. From the video, it's simple to apply delta T to a given rad output and factoring in the correction figures. A lot of engineers would do well to watch this video, it will help when watching more advanced calculations. Did a quick check on your example with my Mears from way back, and assuming one outside cavity wall, your rule of thumb is about bang on! Bearing in mind Mears we're always recond to oversize by about 10%.
I first found you in a rant about gas Safe only going anywhere near a gas appliance. Goodness me. What a difference! Excellent videos, helping the nation and delivered in a true professional manner. You have to wonder though why the UK is so far behind with load compensation and modulation. As commented further down... I nearly got a dual channel thermometer to setup the radiators. But a used FGA cost less and indeed does more. 2 days flushing the system and converted to sealed. 50 sheets of kingspan to go in and a full vapour barrier. I want to see low gas use for Christmas.
It's worth mentioning that radiators were generally oversized as Derek mentioned, also outputs were calculated with an outside temperature of -1C. The average winter temperature is about 8C, so there's scope to heat rooms at lower temperatures with existing rads.
Love your channel. I even go back over the simple stuff just to stay fresh and to fill in the gaps… also to avoid any potential complacency! Keep up the good work and keep the vids coming 👍
I went 15 years with an unbalanced system which left the lounge radiator cold. By watching RUclips videos and buying a contact thermometer I have a balanced system with a 10c temperature drop across all radiators. My new Ideal Vogue boiler was fitted 2 days ago, which has the hot water set to 42c while the heating is initially set to 50c. If I get cold I will just turn it up rather than do the calculations but hopefully by running it for longer it will cope.
Great video I am a retired Plumber/ corgi gas safe eng. since the gas conversion of the early 1970s when the government told everyone we would all be loaded due to gas in the North Sea Hamilton Brothers. Incidentally I also worked offshore on Gas/Oil rigs for years. What is the point in having central heating and being cold turn your stat down to save xxx£s but still paying extortionate bills and not even warm in your own home they tell you to buy stats weather compensators but they never seem to mention payback. By the time you get your money back you need new controls, sorry about the winge I appreciate your videos many thanks.
Another excellent and useful advice and calculations that can be done to check the capacity of the existing central heating system at the lower flow temperatures. Thank you. Appreciated.
You said ‘They shouldn’t really be painted white. They should be painted black.’ No. Objects only radiate in the visible spectrum if they are literally red hot or white hot. White paint has very good emissivity at a radiator's working temperature. It should be BTU/hour, not BTU, but please use watts. There are free heat loss calculators online. I found Myson best because it shows the calculation.
50C is not a typical flow temperature for a heat pump. For well-insulated houses, we usually design to 40C (MWT or 37.50) and for period properties we design to 45C flow (42.50C MWT). 52.5C flow (50C MWT) would be rather inefficient and we advise other measures first, such as bigger radiators, insulation, or both. If you have over 50C flow on a heat pump your sCOP will be rather low.
You can put your heating analyser temperature probes on the radiators to get the exact temperature readings, flow return and Delta temperatures and it also gives room temperature, this is the easiest way to confirm if your radiator is OK for the job .Good flue gas analysers have multiple functions for testing heating and plumbing systems. Efficiency , temperatures, and pressures
Every time I replace a rad I put the biggest bugger in I can that fits/doesnt stick out too far. Being as mine are controlled by programmable valves not worried about oversize. Most of mine are now double panel single fin. New rads also contain less water than the old type and therefore heat up quicker. Underfloor heating is the best, much more comfortable
Just had a house renovation completed and flooring down .i trusted the plumbers with radiators sizes and come winter feel they are not large enough as I have thermostatic controls and combi boiler is set to 75 still feel the only room u feel heat is the kitchen which is the only Big radiator.Profit for must have been the smaller cheaper radiators in 3bed house. I now agree get the biggest radiators you can in your rooms to feel warmer…. Live and learn to trust only yourself in future.I got new boiler all pipes replaced as they were too small and all radiators.
I know some have suggested the videos too technical but, a home owner faced with these high bills might want to learn a bit and take on board the general message of the video , you can try and work it out with Derek's help or you can also do as suggested and turn the temp down on the boiler a bit at a time until you get to the point where your not getting the house warm enough , at least then you will be saving some money on your bills .
To simplify Derek's post, as , for my sins I've been specifying and advising customers since 1972 when I went self employed, heat transfer and efficiencies are quite involved. From the end users perspective, insulate any pipes that get hot, only heat water( if you have a storage cylinder) to a temperature that you're happy with without adding cold water. Set the temperature of the water in the radiators to achieve , ideally, 20C or less, but in any case your comfort level. I always advised customers to dress in doors as you would outside. Take your overcoat off but keep your jumper on, not so difficult unless money's no object.
The money i've saved on heating bills means that i've now got a 4 wheel drive - i went to the scrapyard,bought 4 wheels and put them in my drive....and i'm now driving around in a brand new TRV xx
We set flow temperature at 40-45C as the boiler is capable of modulating down - it just means the CH is on for longer. Obviously for the hot tank we leave it on 60C for 30mins in the morning.
Radiators should almost always go underneath single and double glazed windows otherwise cold draughts will probably form 🙂 Any loss of heat though the outside will be less than the losses owing to the fact the home owner has the heating on higher and longer to try and eliminate the cold draught.
Easy mode - put a sensor on the flow at the heat source… drop the flow temp and see what you get out of the rads. I’m at ~45 degrees. Still happy with the performance.
It seems a little odd going into so much accuracy with the radiator outputs when the multiplier is just a 2,3,4 etc. It's a good theory but trial and error will likely be the way it's decided eventually
Not sure but my very old 40 year old system drops about 20 degrees from 64 out to 45 return which will enable condensing at quite a good rate. Should point out I have a newer 20 year old condenser boiler.
I am scratching my head at present as some of our new extensions are wet UFH, some of the original house is on a mix of traditional radiators (singles with twin fans various sizes upstairs) and a number of vertical radiators downstairs (those actually come with T30, T50, T65 calcs on the suppliers web site for BTU) - so bit of 'man maths' required I think to work out how to reduce the flow temp to optimise our set-up - at least I know what T30 etc means now
Jesus, mine never reaches 20 as I’ve got the flow down to 50 and don’t leave it on all day as even that’s too expensive. For 20 degrees it would cost me about £15 a day to run my heating even for ten hours, and I simply can’t afford to spend £450 a month on heating simply to be able to walk around the house without a jumper on. I’m currently spending about £6 to heat the whole house to a comfortable temperature that doesn’t have a chill for most of the day.
Tomkat Gas training, thank you for your excellent video. As a rule of thumb then and without checking the design of a system with rad sizing etc, is it fair to assume that with a modern condensing boiler, that if you gradually turn the CH flow temp down and every room still reaches temperature, that you're saving money and that the boiler will be working more efficiently ?. I've heard on youtube that if the CH flow temp is too high, that the boiler wont condense, though no explanation was given. If the flow temp is too high, will the boiler be damaged ??.
Boilers have thermostats inside of them to shut them down if they get too hot. Boilers are well designed from a safety point of view. The reason that condensing helps is that when the return temp is cold enough the vapour in the flue gas to condense on the pipes carrying the returning water. When something condensed the heat from the flue gas is passed to the return water coming back to be heated by the gas so it effectively needs less heat to make the outgoing water the set temperature. The following figures are made up so they are not accurate but will help. If your water is coming back at 40 deg and your flow temp beds to be 50 and it takes 1kw to raise the temp of the water by 1deg then your going to burn 10kw of gas. Now if you have condensing in the mix and that can add 5 deg to the water then you return temp water is 40 deg it goes into the condenser gets heated up by 5 deg and is now 45 deg, so to get it up to 50 deg flow temp you only need 5 kw of gas. Like I said made up numbers but hopefully that illustrates why condensing is good.
@@davideyres955 . Thank you for your reply, I understand the basics of what condescending is trying to achieve. My Worcester 30i was installed and left at the following flow temperature settings : Heating 75 c DHW 55 c I don't know whether this is factory settings or whether these temps were set by the installer. As I understand that condensing only affects the heating mode, is 75 c too high a flow temperature?. All rads get hot at much lower flow temperatures and following your advice on a RUclips post, I've experimented and reduced the heating flow temperature to 65 c. I'm guessing that 75 c will waste gas ?. If I check the heating return temperature, what are the parameters for condensing, ie what is the minimum and maximum for efficiency?. Thanks.🤔
Good rule of thumb guide Derek. Out of interest, can you tell me why you opted for imperial not metric (or both)? I know some of the 'Old school' in the trade still like to hang on to the good old BRITISH units, but I would think most DIY viewers are probably more familiar with metre. And Btu's! Even more confusing for most outside the trade whatever age. That said good video mate, always look forward to them 👍🏻
@@gekypanathinaikos3879 well that's stating the obvious! I'm simply asking why ONLY use imperial. Watts are now widely used as well. That's how youngsters entering the trade are taught in college these days, and metric would have been taught to them in their schools.
@@tonyadams380 Hmm, yes I must admit in this day and age it seems strange that BTU's are still used. A lot of people claim metric units (kilograms for instance) are difficult to understand yet have no problem when they visit mainland Europe. Surely the profession should be pushing for the universal unit power and energy and using watts.
@@chrisross1703 I remember my brother-in-law (an architect) still quoting heating in BTU's in the 1980's At college HND was in BTU's, to start with, then latterly changed to Watts. By implication BTU's are imperial whereas Watts are definitely universal so general adoption made sense. Also a BTU is an incredibly small unit for general commercial and industrial purposes. Mind you, so is a Watt, hence the use of kW . 🙂
Slightly different subject, Is it safe to fit a multi boiler to a lath and plaster wall (partition)? (I had one fitted and a bit wary) Where can I find the regulation guidance?
You could but your output would be less in those rooms with now undersized rads. Usually you wont need to replace all the radiators since your existing largest rads could be moved to the smallest rooms and then you'll only need to buy less new larger rads.
Hi . Does it makes any change? Now I've just lowered mine to 48 Celsius as well ,as landlord installed an overpowered combi boiler of just "35kw" , at 52 Celsius flow set I got a reading of 55 when boiler works, I don't know if it's ok
Hi dereck , got our boiler down to 55 oc , what about pump speeds ? Would that have an impact ? We are on a sealed system, and manage with pump speed on 1 9 rads on 15ri
Hi Derek, kind regards! Now I've just lowered mine to 48 Celsius ,as landlord installed an overpowered combi boiler of just "32kw" from recommendation of the "engineers", at 52 Celsius flow set ,it shows actually a reading of 55 when boiler turns on and gets on full thrust. Is it normal for temperature to go over what is set ?
Will get a little over shoot Combi are often over sized to give you a good hot water flow rate . Wouldn't worry on the heating as that will modulate down anyway ,plus you have turned flow temperature down
If a rad has a maximum btu output for example of 6041, does that mean that the TRV has to be set at fully open (5) setting on the dial to get the 6041 btu output? If so, does that mean that in order to reduce the flow temp to say 55c, you have to have the rad’s fully open whereas they might have been set at say (3) before to regulate the room temp when the original flow rate was typically 75c? If so, what use are the TVR’s performing if they have to be set at fully open for a reduced flow rate of 55c and does that mean that the boiler will be running most of the time and if so, will it be more expensive to run in the 55c condition with the valves fully open as opposed to the original 75c flow temp and a setting of (3) on the TVR ?
The amount of jobs that I attend where the man of the house is sat in the garage cowering away from his angry house wife that has watched a couple of utube videos and now is a time served gas engineer is mind boggling
trying to word this without being impolite but probably still failing, but surely its easier and better to use all metric units not a mix of imperial and metric.
Are there any cons sizing your radiators too big? Lets say you prepared for heat pump and installed very low flow temperature radiators but ended up using gas boiler or solid fuel instead.
My combi boiler only has numbers from cold to max with 1-6 in between. What number equates to 55c please? The last time an engineer called, he left it at 5.
Happy new year! Thanks for replying! Being given the fact that after setting flow temp at 48celsius, when I measure the return water temp on the pipe which has installed the magnetic filter is below 28celsius..
Because my boiler temp regardless of how much heat is being called for only reaches 62 even though the target flow temp is set to max of 75 for heating on my vailliant eco tech plus 832 combi I'm a woman BTW and want to make sure my boiler running sufficient as I had a normal boiler before with a cylinder and landlord changed it to a combi?
I think your pissing in the wind with this one Derek Most home owner's watching this will not have a clue what you are talking about..... 😀 Also most home owners are use to having radiators so hot you carn't keep your hand on for long , if it's not heating the room up they will turn the stat up..... Don't even mention to them about Delta T's. 😜 Cheers..... 👍
That is so not true - I’m a 63 year old female that knew sweet “FA” about how to get the best out of my CH system but have learned a lot through watching these videos. Shame the CH Engineer who fitted my new system 18 months ago couldn’t be bothered to do all this for me or even balance the system following installation & I didn’t know enough to demand that he should
Can you tell all middle class women to stop telling me how to bleed a radiator and then never repressurise their pressurised combi system that has a low pressure sensor
Maybe check out how many people die or even contract Legionella before embarking on safetyism. About 50 per year, 20 of them got it from abroad, and less die from it. You are about as likely to die from lightning. maybe wear a Faraday cage everytime you go out? Encouraging people to emit more fumes and waste on money is overall worse than the negligible amount of people that could get Legionella (which incidentally starts dying even at 50c).
@@BarringtonDailey Legionella is also killed by the Chlorine or Chloramine they treat the water with. In a domestic environment where the hot water, shower etc is used on a regular basis the risk from Legionella is possibly vanishingly small irrespective of the hot water temperature.
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Thanks for the detail Tom. I decided to double the o/p of my rads and replaced the existing single panels with double (11's to 21's).
This should provide the same heating at a lower boiler temp, and on very cold days, increase the available heat to keep me warm.
Also, I'll only heat the space I use, and just keep other rooms from freezing up with the frost protection from the "Thermostatic Radiator Valves".
😂 In response to the posts that Derek is “pissing in the wind trying to educate homeowners ‘ & middle class women having watched a few RUclips vids That is so not true - I’m a 63 year old female that knew sweet “FA” about how to get the best out of my CH system but have learned a lot & enough to adjust flow temps etc through watching these videos. Shame the CH Engineer who fitted my new system 18 months ago couldn’t be bothered to do all this for me or even balance the system following installation & that I didn’t know as much as I do now to demand that he should. BTW I’m working class as they come
It's shocking so many so called CH engineers dont give this guidance. I got 6 so called 'gas safe' engineers round to quote for upgrading my 25 year old boiler to an new more efficient one and fitting TRVs. 3 suggested a combi to replace the heat only boiler despite the house being large having 4 beds, a bathroom, separate en suite with shower and 5 sinks. Of these 3 plus another 1 didnt bother sending me a quote. In the end, I had just 2 quotes to finally choose from.
Retired for a couple of years now but still great fun watching your videos; very professional and very helpful to all the young apprentices I’m sure.
This is quite useful.
Bottom line is that you are fighting heat loss.
Your ad is designed to give max output at 75 degree flow.
Reducing flow to 55 reduces output of rad by 50%.
If the rad outputting at 50% power cant overcome heat loss effectively then you cant run at these low flow temp.
Succinct is the word that comes to mind that best explains your brilliant presentation. From the video, it's simple to apply delta T to a given rad output and factoring in the correction figures.
A lot of engineers would do well to watch this video, it will help when watching more advanced calculations.
Did a quick check on your example with my Mears from way back, and assuming one outside cavity wall, your rule of thumb is about bang on!
Bearing in mind Mears we're always recond to oversize by about 10%.
I first found you in a rant about gas Safe only going anywhere near a gas appliance. Goodness me. What a difference!
Excellent videos, helping the nation and delivered in a true professional manner.
You have to wonder though why the UK is so far behind with load compensation and modulation.
As commented further down... I nearly got a dual channel thermometer to setup the radiators. But a used FGA cost less and indeed does more.
2 days flushing the system and converted to sealed. 50 sheets of kingspan to go in and a full vapour barrier.
I want to see low gas use for Christmas.
It's worth mentioning that radiators were generally oversized as Derek mentioned, also outputs were calculated with an outside temperature of -1C. The average winter temperature is about 8C, so there's scope to heat rooms at lower temperatures with existing rads.
But then again it is currently -5°C, I wouldn't want my heating not getting to temperature at these not common, but occasional lows
Love your channel.
I even go back over the simple stuff just to stay fresh and to fill in the gaps… also to avoid any potential complacency!
Keep up the good work and keep the vids coming 👍
Thanks for watching
I went 15 years with an unbalanced system which left the lounge radiator cold. By watching RUclips videos and buying a contact thermometer I have a balanced system with a 10c temperature drop across all radiators.
My new Ideal Vogue boiler was fitted 2 days ago, which has the hot water set to 42c while the heating is initially set to 50c. If I get cold I will just turn it up rather than do the calculations but hopefully by running it for longer it will cope.
Nice one Derek im sure anyone outside of the industry switched off early but the message was top draw.
Great video I am a retired Plumber/ corgi gas safe eng. since the gas conversion of the early 1970s when the government told everyone we would all be loaded due to gas in the North Sea Hamilton Brothers. Incidentally I also worked offshore on Gas/Oil rigs for years. What is the point in having central heating and being cold turn your stat down to save xxx£s but still paying extortionate bills and not even warm in your own home they tell you to buy stats weather compensators but they never seem to mention payback. By the time you get your money back you need new controls, sorry about the winge I appreciate your videos many thanks.
Another excellent and useful advice and calculations that can be done to check the capacity of the existing central heating system at the lower flow temperatures. Thank you. Appreciated.
You said ‘They shouldn’t really be painted white. They should be painted black.’ No. Objects only radiate in the visible spectrum if they are literally red hot or white hot. White paint has very good emissivity at a radiator's working temperature. It should be BTU/hour, not BTU, but please use watts. There are free heat loss calculators online. I found Myson best because it shows the calculation.
50C is not a typical flow temperature for a heat pump. For well-insulated houses, we usually design to 40C (MWT or 37.50) and for period properties we design to 45C flow (42.50C MWT). 52.5C flow (50C MWT) would be rather inefficient and we advise other measures first, such as bigger radiators, insulation, or both.
If you have over 50C flow on a heat pump your sCOP will be rather low.
Derek was only applying the principles to radiator systems!
@@johnward5006 check 9:32 again
@@UrbanPlumbers My point was, Derek was basing his presentation on a boiler as a heat source. As we all know, heat pumps are another scenario.
So in reality heat pumps are heaps of shite and not worth fitting in Scotland with some of the winters we have
@@mynameis9739 Very low ambient temperatures need to accounted for, particularly for heating water to 55-60c. Needs careful consideration.
You can put your heating analyser temperature probes on the radiators to get the exact temperature readings, flow return and Delta temperatures and it also gives room temperature, this is the easiest way to confirm if your radiator is OK for the job .Good flue gas analysers have multiple functions for testing heating and plumbing systems. Efficiency , temperatures, and pressures
Every time I replace a rad I put the biggest bugger in I can that fits/doesnt stick out too far. Being as mine are controlled by programmable valves not worried about oversize. Most of mine are now double panel single fin. New rads also contain less water than the old type and therefore heat up quicker. Underfloor heating is the best, much more comfortable
Just had a house renovation completed and flooring down .i trusted the plumbers with radiators sizes and come winter feel they are not large enough as I have thermostatic controls and combi boiler is set to 75 still feel the only room u feel heat is the kitchen which is the only
Big radiator.Profit for must have been the smaller cheaper radiators in 3bed house. I now agree get the biggest radiators you can in your rooms to feel warmer…. Live and learn to trust only yourself in future.I got new boiler all pipes replaced as they were too small and all radiators.
I know some have suggested the videos too technical but, a home owner faced with these high bills might want to learn a bit and take on board the general message of the video , you can try and work it out with Derek's help or you can also do as suggested and turn the temp down on the boiler a bit at a time until you get to the point where your not getting the house warm enough , at least then you will be saving some money on your bills .
To simplify Derek's post, as , for my sins I've been specifying and advising customers since 1972 when I went self employed, heat transfer and efficiencies are quite involved. From the end users perspective, insulate any pipes that get hot, only heat water( if you have a storage cylinder) to a temperature that you're happy with without adding cold water. Set the temperature of the water in the radiators to achieve , ideally, 20C or less, but in any case your comfort level. I always advised customers to dress in doors as you would outside.
Take your overcoat off but keep your jumper on, not so difficult unless money's no object.
Russell Crowe has made a film about a Roman heating engineer which might be relevant - it's called Radiator......
The money i've saved on heating bills means that i've now got a 4 wheel drive - i went to the scrapyard,bought 4 wheels and put them in my drive....and i'm now driving around in a brand new TRV xx
Lol 😆 🤣 😂 😹
We set flow temperature at 40-45C as the boiler is capable of modulating down - it just means the CH is on for longer. Obviously for the hot tank we leave it on 60C for 30mins in the morning.
Thank you for video really useful i am student confused about Delta T and this video help to understand
Radiators should almost always go underneath single and double glazed windows otherwise cold draughts will probably form 🙂 Any loss of heat though the outside will be less than the losses owing to the fact the home owner has the heating on higher and longer to try and eliminate the cold draught.
Easy mode - put a sensor on the flow at the heat source… drop the flow temp and see what you get out of the rads. I’m at ~45 degrees. Still happy with the performance.
It seems a little odd going into so much accuracy with the radiator outputs when the multiplier is just a 2,3,4 etc. It's a good theory but trial and error will likely be the way it's decided eventually
Thanks really interesting and informative. We all need to save money on fuel but sensibly. Well explained.
Not sure but my very old 40 year old system drops about 20 degrees from 64 out to 45 return which will enable condensing at quite a good rate. Should point out I have a newer 20 year old condenser boiler.
I am scratching my head at present as some of our new extensions are wet UFH, some of the original house is on a mix of traditional radiators (singles with twin fans various sizes upstairs) and a number of vertical radiators downstairs (those actually come with T30, T50, T65 calcs on the suppliers web site for BTU) - so bit of 'man maths' required I think to work out how to reduce the flow temp to optimise our set-up - at least I know what T30 etc means now
Have you considered making a tutorial on the new digital central heating controls? I have a new ESI controller and have no idea how to adjust it
What is the problem with oversized rads if we have trv’s and a room stat?
I have all different sized rads in my home some are really small in small rooms and medium size in lounge and the 2 double bedrooms are very big
Good effort mate 👍..20°c isn't warm enough for me tho .. thanks for your efforts
Me too. What wold you change for say 23 deg room temp down and 21 up?
Put on another layer of clothes and make an effort to move a bit more. With the price of fuel we need to make 19 or 20 degrees work for us.
@@juliebrooke6099 I've got it on at a mere 15C to ward off damp, and a heated jacket lol
Jesus, mine never reaches 20 as I’ve got the flow down to 50 and don’t leave it on all day as even that’s too expensive. For 20 degrees it would cost me about £15 a day to run my heating even for ten hours, and I simply can’t afford to spend £450 a month on heating simply to be able to walk around the house without a jumper on.
I’m currently spending about £6 to heat the whole house to a comfortable temperature that doesn’t have a chill for most of the day.
Tomkat Gas training, thank you for your excellent video.
As a rule of thumb then and without checking the design of a system with rad sizing etc, is it fair to assume that with a modern condensing boiler, that if you gradually turn the CH flow temp down and every room still reaches temperature, that you're saving money and that the boiler will be working more efficiently ?.
I've heard on youtube that if the CH flow temp is too high, that the boiler wont condense, though no explanation was given.
If the flow temp is too high, will the boiler be damaged ??.
Boilers have thermostats inside of them to shut them down if they get too hot. Boilers are well designed from a safety point of view.
The reason that condensing helps is that when the return temp is cold enough the vapour in the flue gas to condense on the pipes carrying the returning water. When something condensed the heat from the flue gas is passed to the return water coming back to be heated by the gas so it effectively needs less heat to make the outgoing water the set temperature.
The following figures are made up so they are not accurate but will help.
If your water is coming back at 40 deg and your flow temp beds to be 50 and it takes 1kw to raise the temp of the water by 1deg then your going to burn 10kw of gas. Now if you have condensing in the mix and that can add 5 deg to the water then you return temp water is 40 deg it goes into the condenser gets heated up by 5 deg and is now 45 deg, so to get it up to 50 deg flow temp you only need 5 kw of gas. Like I said made up numbers but hopefully that illustrates why condensing is good.
@@davideyres955 .
Thank you for your reply, I understand the basics of what condescending is trying to achieve.
My Worcester 30i was installed and left at the following flow temperature settings :
Heating 75 c
DHW 55 c
I don't know whether this is factory settings or whether these temps were set by the installer.
As I understand that condensing only affects the heating mode, is 75 c too high a flow temperature?.
All rads get hot at much lower flow temperatures and following your advice on a RUclips post, I've experimented and reduced the heating flow temperature to
65 c.
I'm guessing that 75 c will waste gas ?.
If I check the heating return temperature, what are the parameters for condensing, ie what is the minimum and maximum for efficiency?.
Thanks.🤔
Good rule of thumb guide Derek. Out of interest, can you tell me why you opted for imperial not metric (or both)? I know some of the 'Old school' in the trade still like to hang on to the good old BRITISH units, but I would think most DIY viewers are probably more familiar with metre. And Btu's! Even more confusing for most outside the trade whatever age. That said good video mate, always look forward to them 👍🏻
he uses BTUs so he must use imperial after that, otherwise the multiplication factors he applies in the formulas wont be accurate
@@gekypanathinaikos3879 well that's stating the obvious! I'm simply asking why ONLY use imperial. Watts are now widely used as well. That's how youngsters entering the trade are taught in college these days, and metric would have been taught to them in their schools.
@@tonyadams380 Hmm, yes I must admit in this day and age it seems strange that BTU's are still used. A lot of people claim metric units (kilograms for instance) are difficult to understand yet have no problem when they visit mainland Europe. Surely the profession should be pushing for the universal unit power and energy and using watts.
@@jesserawson898 It makes no sense at all when every other form of heating uses watts. BTW I'm 67 and have never used BTUs since school days!
@@chrisross1703 I remember my brother-in-law (an architect) still quoting heating in BTU's in the 1980's
At college HND was in BTU's, to start with, then latterly changed to Watts. By implication BTU's are imperial whereas Watts are definitely universal so general adoption made sense. Also a BTU is an incredibly small unit for general commercial and industrial purposes. Mind you, so is a Watt, hence the use of kW . 🙂
Slightly different subject, Is it safe to fit a multi boiler to a lath and plaster wall (partition)? (I had one fitted and a bit wary) Where can I find the regulation guidance?
could you make a video on how to work out heat input m3/h
We can’t reduce the flow temperature, unless , every rad in the house is oversized at the same ratio?
You could but your output would be less in those rooms with now undersized rads.
Usually you wont need to replace all the radiators since your existing largest rads could be moved to the smallest rooms and then you'll only need to buy less new larger rads.
Forgive me the title says 55c flow temperature but in the video you state 55C return temperature - which is it for maximum condensing?
I have access to an infrared non contact thermometer (-50C to 550C). Can it be used for checking flow/return temperatures?
Turned my boiler down to 48deg, it will be interesting to see how it performs when it starts getting colder.
Hi . Does it makes any change? Now I've just lowered mine to 48 Celsius as well ,as landlord installed an overpowered combi boiler of just "35kw" , at 52 Celsius flow set I got a reading of 55 when boiler works, I don't know if it's ok
Jury is out at the moment, house is fine but requires heating on for slightly longer.
It will take hours to come up to a comfortable temperature when it's really cold.
@@essanjay8604 , turned it up today to 55 with the incoming cold weather we are due.
Hi dereck , got our boiler down to 55 oc , what about pump speeds ?
Would that have an impact ?
We are on a sealed system, and manage with pump speed on 1
9 rads on 15ri
Hi Derek, kind regards! Now I've just lowered mine to 48 Celsius ,as landlord installed an overpowered combi boiler of just "32kw" from recommendation of the "engineers", at 52 Celsius flow set ,it shows actually a reading of 55 when boiler turns on and gets on full thrust. Is it normal for temperature to go over what is set ?
Will get a little over shoot
Combi are often over sized to give you a good hot water flow rate .
Wouldn't worry on the heating as that will modulate down anyway ,plus you have turned flow temperature down
At 48celsius flow, return comes at 26-28celsius
If a rad has a maximum btu output for example of 6041, does that mean that the TRV has to be set at fully open (5) setting on the dial to get the 6041 btu output? If so, does that mean that in order to reduce the flow temp to say 55c, you have to have the rad’s fully open whereas they might have been set at say (3) before to regulate the room temp when the original flow rate was typically 75c? If so, what use are the TVR’s performing if they have to be set at fully open for a reduced flow rate of 55c and does that mean that the boiler will be running most of the time and if so, will it be more expensive to run in the 55c condition with the valves fully open as opposed to the original 75c flow temp and a setting of (3) on the TVR ?
TRVs act on air temperature not water temperature. They close when the room reaches the temperature set by the TRVs
TRV is an Open/Close switch working on a room temp sensor. When Open it will circulate whatever flow temp water is supplied by the boiler.
What about a self modulating boiler
Can’t I just run the boiler at 55c and see how well it does this winter. Oh and my wife 74 years old would freeze at 20c she require 22c.
Yeah 20 is OK if you're on the move a lot of the time - not warm enough if you're sitting in the evening.
The amount of jobs that I attend where the man of the house is sat in the garage cowering away from his angry house wife that has watched a couple of utube videos and now is a time served gas engineer is mind boggling
trying to word this without being impolite but probably still failing, but surely its easier and better to use all metric units not a mix of imperial and metric.
What about the old women ( generally) who go around fealing rads , and want them boiling hot ?
lol room is 30 but its colder at the bottom than it is at the top
How does raising or lowering the ch pump speed affect heat output? Would a lower pump speed allow for a lower boiler flow temp?
Slower warmup
Thank you 🙏
It's like reaching 0-60 in 3secs or 8 secs different times same goals
Are there any cons sizing your radiators too big? Lets say you prepared for heat pump and installed very low flow temperature radiators but ended up using gas boiler or solid fuel instead.
Over heating the room
@@tomkatgastraining Huh??? Was that said with brain in neutral? 🙂
@@jesserawson898 no if rads are too big for the room the room will overheat
@@tomkatgastraining Ah, so TRV's are ineffective in shutting down the radiator in question. Hadn't realised that. Thanks.
@@jesserawson898 nothing to do with the TRVs it’s the heat held in the radiator and then released into the room
My combi boiler only has numbers from cold to max with 1-6 in between. What number equates to 55c please? The last time an engineer called, he left it at 5.
I used to have mine set at 4 at the beginning of Winter then up to 5 when frost was on the ground.
What should be the return temperature to stay in condensation mode ??
Below 55 degrees c
Happy new year! Thanks for replying! Being given the fact that after setting flow temp at 48celsius, when I measure the return water temp on the pipe which has installed the magnetic filter is below 28celsius..
Should your boiler temp reach the max flow temp regardless of the temp set on room stat tia
Because my boiler temp regardless of how much heat is being called for only reaches 62 even though the target flow temp is set to max of 75 for heating on my vailliant eco tech plus 832 combi I'm a woman BTW and want to make sure my boiler running sufficient as I had a normal boiler before with a cylinder and landlord changed it to a combi?
Thanks
I think your pissing in the wind with this one Derek
Most home owner's watching this will not have a clue what you are talking about..... 😀
Also most home owners are use to having radiators so hot you carn't keep your hand on for long , if it's not heating the room up they will turn the stat up.....
Don't even mention to them about Delta T's. 😜
Cheers..... 👍
May be their gas bill will encourage home owners to make the effort, it's only simple arithmetic at the end of the day.
Omg,those Tic tock brigade are better experts than any of us heating engineers.
I am a home owner and understand Delta T through watching RUclips.
@@MrRawMonkey He said MOST not ALL homeowners! Clearly you have done research to understand this, unlike MOST homeowners.
That is so not true - I’m a 63 year old female that knew sweet “FA” about how to get the best out of my CH system but have learned a lot through watching these videos. Shame the CH Engineer who fitted my new system 18 months ago couldn’t be bothered to do all this for me or even balance the system following installation & I didn’t know enough to demand that he should
Looks like ive been readying rad soec sheets wring for years😂
❤️❤️❤️ Del
Can you tell all middle class women to stop telling me how to bleed a radiator and then never repressurise their pressurised combi system that has a low pressure sensor
👍👍👍
👍
Mike Fahy
55 degrees for domestic hw . isnt hot enough .
Heat only and system boilers should have two flow temps .
The 55 oc is heating not for the water
@@tomkatgastraining Most heat only cant give two flow temps ..
@@mgbroadsterJ exactly. So to avoid legionella the temp needs to be so high the bloody things don't condense.
Maybe check out how many people die or even contract Legionella before embarking on safetyism. About 50 per year, 20 of them got it from abroad, and less die from it. You are about as likely to die from lightning. maybe wear a Faraday cage everytime you go out? Encouraging people to emit more fumes and waste on money is overall worse than the negligible amount of people that could get Legionella (which incidentally starts dying even at 50c).
@@BarringtonDailey Legionella is also killed by the Chlorine or Chloramine they treat the water with. In a domestic environment where the hot water, shower etc is used on a regular basis the risk from Legionella is possibly vanishingly small irrespective of the hot water temperature.
rabbish central heating radiators I don't use
Simple answer, NO
Guess you didn’t watch the video then
Ery god bit please just tell me in 5 mins i. CAn take it
We can’t reduce the flow temperature, unless , every rad in the house is oversized at the same ratio?
That is the role of TRV’s surely
👍👍