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Post by DIYDafty on May 6, 2023 13:28:52 GMT
Been trying to understand how much more cash efficient a condensing boiler is. My boiler pumps out a lot of hot gas into the air and I thought the idea of the condensing boiler was to convert more of that into usable heat? I found this site which I like as it simply gives one overall number for a lot of boilers including my 20 year old one. Someone tell me if these numbers are all made up or about right? I've not idea. But assuming its right my boiler scores 78% as you can see. Trouble is a brand new state of the art boiler seems to get only 88%. And is that its maximum efficiency when the temps through it are low (I think) and all controls set optimally? That would mean a maximum cash gain of just 10% per year. So the boiler would need to last at least 10 years to recoup its cost. Have I got that about right? Pretty depressing.... my boiler www.homeheatingguide.co.uk/efficiency-tables?model=008662baxi boilers as an example (scroll down for the table) www.homeheatingguide.co.uk/efficiency-tables?make=Baxi |
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Post by battle1066 on May 7, 2023 8:30:23 GMT
Been trying to understand how much more cash efficient a condensing boiler is. My boiler pumps out a lot of hot gas into the air and I thought the idea of the condensing boiler was to convert more of that into usable heat? I found this site which I like as it simply gives one overall number for a lot of boilers including my 20 year old one. Someone tell me if these numbers are all made up or about right? I've not idea. But assuming its right my boiler scores 78% as you can see. Trouble is a brand new state of the art boiler seems to get only 88%. And is that its maximum efficiency when the temps through it are low (I think) and all controls set optimally? That would mean a maximum cash gain of just 10% per year. So the boiler would need to last at least 10 years to recoup its cost. Have I got that about right? Pretty depressing.... my boiler www.homeheatingguide.co.uk/efficiency-tables?model=008662baxi boilers as an example (scroll down for the table) www.homeheatingguide.co.uk/efficiency-tables?make=BaxiYour logic seems to fit with what I see for your info posted and requires a couple of considerations in my opinion. Mainly older boiler parts tend still to be priced very realistically which means why change. Yet the savings in gas consumption needs to be considered since the price of gas is forecast to remain high. So I would be looking at the hidden cost more closely before I upgraded. These hidden cost are everything from addition control equipment to get those efficiency figures and decoration to the work area after the install. |
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Post by crowsfoot on May 7, 2023 9:14:18 GMT
All done in a lab' of course under the strict conditions of a fully equipped laboratory and not in a some ones home!
Factor human beings into the equation as well and everything changes.
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Post by dickpuller on May 7, 2023 9:23:18 GMT
Been trying to understand how much more cash efficient a condensing boiler is. My boiler pumps out a lot of hot gas into the air and I thought the idea of the condensing boiler was to convert more of that into usable heat? I found this site which I like as it simply gives one overall number for a lot of boilers including my 20 year old one. Someone tell me if these numbers are all made up or about right? I've not idea. But assuming its right my boiler scores 78% as you can see. Trouble is a brand new state of the art boiler seems to get only 88%. And is that its maximum efficiency when the temps through it are low (I think) and all controls set optimally? That would mean a maximum cash gain of just 10% per year. So the boiler would need to last at least 10 years to recoup its cost. Have I got that about right? Pretty depressing.... my boiler www.homeheatingguide.co.uk/efficiency-tables?model=008662baxi boilers as an example (scroll down for the table) www.homeheatingguide.co.uk/efficiency-tables?make=BaxiAh yes Dafty, the condensing boiler manufacturers have scaled down their efficiency rating over recent years. Now even you would’ve heard about VW etc & their claims on emissions??!! Its bonkers with boilers, there’s no way they can accurately state efficiency. Every single installation is different!! It’s irrelevant & completely pointless worrying about efficiency, if your massive Palatial Mansion is a drafty, poorly insulated old gaff!! The three most important things to save money on home Heating is; insulate, insulate & insulate!!! |
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Post by tomplum on May 7, 2023 21:20:25 GMT
The whole industry is fraught with people wanting your money, The old guys had it right from post war to 1960's, they built the homes to last, All brick walls inner and outer, a 2 inch cavity , this provided a thermal wall of air that could circulate, copper piping, proper wood doors, skirting and arc's , A boiler that would last 40 years plus with little or no maintainance , cast iron down spouts and gutters, insulation only on pipes and tanks, The only real improvement is placcy doors and windows, loft and cavity insulation can help with the heating but, makes a good home for rodents too,  |
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Post by crowsfoot on May 8, 2023 8:36:45 GMT
The latest thinking on boiler efficiency is to run your boiler for longer at the coolest temperature possible in order to reach the designed system temperatures.
Just over 10 years ago we was being told to run your boiler on the highest temperature in order to reach the designed system temperatures as soon as possible.
I've no doubt we will be told something totally different again in another few years...
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Post by dickpuller on May 8, 2023 9:34:36 GMT
As said before by my good self, Low Temperature Heating Systems is understandably the way to save fuel on systems. For a natural gas condensing boilers the Flue ‘Dew Point’ is around 55°C, so you really don’t want the water Return temperature above 50°C. With the optimum ΔT of 20°C between the Flow & Return at the Boiler, so at its maximum 70/50°C. Obviously, lower will save you more money with a modulating condensing boiler.
With an Air Source Heat Pump, for optimum appliance efficiency, it’s even lower. ΔT of 5°C & the Flow & Return 45/40°C. So as you can see, high circulation is required. Which means limited flow resistance, big tube sizes, limited Valves & fittings.
But again, as said before, the controls & Building fabric insulation are the keys to efficiency.
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Post by DIYDafty on May 22, 2023 15:08:41 GMT
Right, cards on the table, I have been considering a boiler project for a long time. My plan wouldn't be to replace but to hang one next to the existing one. Then using suitable full bore valves and pipework be in a position to turn one on and the other off. The idea being I could run the new "efficient" boiler most of the time and if I run into problems just swap to the old one. That would give me plenty of time for installation too.
Problem is I just can't bring myself to do if I'd only safe 10% per year. On the other hand my boiler throws out so much heat through the flue - if a condensing boiler capturered all that it would surely be more than a 10% improvement.
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Post by battle1066 on May 22, 2023 17:10:52 GMT
Right, cards on the table, I have been considering a boiler project for a long time. My plan wouldn't be to replace but to hang one next to the existing one. Then using suitable full bore valves and pipework be in a position to turn one on and the other off. The idea being I could run the new "efficient" boiler most of the time and if I run into problems just swap to the old one. That would give me plenty of time for installation too. Problem is I just can't bring myself to do if I'd only safe 10% per year. On the other hand my boiler throws out so much heat through the flue - if a condensing boiler capturered all that it would surely be more than a 10% improvement. If the existing system meets your needs why waste your time and money - spend the loot on the twins and enjoy the security of knowing your flush. |
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Post by DIYDafty on May 22, 2023 17:46:24 GMT
Right, cards on the table, I have been considering a boiler project for a long time. My plan wouldn't be to replace but to hang one next to the existing one. Then using suitable full bore valves and pipework be in a position to turn one on and the other off. The idea being I could run the new "efficient" boiler most of the time and if I run into problems just swap to the old one. That would give me plenty of time for installation too. Problem is I just can't bring myself to do if I'd only safe 10% per year. On the other hand my boiler throws out so much heat through the flue - if a condensing boiler capturered all that it would surely be more than a 10% improvement. If the existing system meets your needs why waste your time and money - spend the loot on the twins and enjoy the security of knowing your flush. Well maybe but if come next winter the boiler packs in beyond my capability to repair I'll definitely get the blame. There's no way I'd try and do it myself in the middle of winter as it would take me until the following summer so I'd be at the mercy of whoever I call to do a good job. I agree my plan is a bit over the top but it would also scratch the itch of doing it.... Might even need to pay even more than usual to get it done quickly. |
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Post by jcplumb on May 22, 2023 19:56:20 GMT
Not a gas man and I don't pretend to be. If I have a gas problem I phone a gas man (I do get mates rates though). So my answer is simply from the point of someone who has gone from a non condensing system boiler with HWC to a condensing combi.
The change was about 5 years ago iirc, my yearly gas usage has now halved from what it was when I had my old boiler.
The old boiler was a Gloworm space saver, maybe one of the gas guys can say if that was a gas hungry boiler or not. I do know that it never once broke down in the 20ish years I had it, it was never serviced either.
In the old days when gas was less expensive, the zero maintenance costs would outweigh the higher energy usage. With gas prices as they are now I doubt that's the case any more.
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Post by crowsfoot on May 23, 2023 7:33:00 GMT
Right, cards on the table, I have been considering a boiler project for a long time. My plan wouldn't be to replace but to hang one next to the existing one. Then using suitable full bore valves and pipework be in a position to turn one on and the other off. The idea being I could run the new "efficient" boiler most of the time and if I run into problems just swap to the old one. That would give me plenty of time for installation too. Problem is I just can't bring myself to do if I'd only safe 10% per year. On the other hand my boiler throws out so much heat through the flue - if a condensing boiler capturered all that it would surely be more than a 10% improvement. You don't really want to complicate plumbing DD and my advice keep things as basic as possible so this idea gets a no no from me. JCs experience on saving £££s by swoping over from conventional to condensing boiler is the total opposite to what mine was. Same thing with heat pumps - some customers would tell me it's horrendously expensive whilst others would tell me it's very cheap to run, you just can't seem to get a definite right answer on this from the ground floor. Could it be the human being factor making the difference? How reliable are meters for accurately measuring the consumption of the energy we use? |
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Post by dickpuller on May 23, 2023 17:58:21 GMT
Right, cards on the table, I have been considering a boiler project for a long time. My plan wouldn't be to replace but to hang one next to the existing one. Then using suitable full bore valves and pipework be in a position to turn one on and the other off. The idea being I could run the new "efficient" boiler most of the time and if I run into problems just swap to the old one. That would give me plenty of time for installation too. Problem is I just can't bring myself to do if I'd only safe 10% per year. On the other hand my boiler throws out so much heat through the flue - if a condensing boiler capturered all that it would surely be more than a 10% improvement. I don’t really know what to say about this??!! I’ve held back from replying - as an idea it’s a bit bonkers!! Your proposal would take a bit of designing & installing. There’s so many ways this hair brain plan can go wrong! Huge consideration needs to be given to the hydronic, Gas, electrical services, to say these are out with your abilities - is a gross understatement!! Lets just start with the Hydronics, how do intend to ‘Valve off’ any boiler, there’s not only the inherent danger, but you could simply be heating one boiler with another!! Then there’s the Gas installation, have you any remote idea how you’re going to do that? Then there’s the electrics/controls for starters, if you retain 240vac basic On/Off controls, the condensing boiler will never work at its optimum. If you can’t rely on your existing SE gas boiler, simply replace it with a condensing boiler. Upgrade your controls, upgrade your home insulation & you’ll save money. |
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Post by DIYDafty on May 24, 2023 13:29:20 GMT
Right, cards on the table, I have been considering a boiler project for a long time. My plan wouldn't be to replace but to hang one next to the existing one. Then using suitable full bore valves and pipework be in a position to turn one on and the other off. The idea being I could run the new "efficient" boiler most of the time and if I run into problems just swap to the old one. That would give me plenty of time for installation too. Problem is I just can't bring myself to do if I'd only safe 10% per year. On the other hand my boiler throws out so much heat through the flue - if a condensing boiler capturered all that it would surely be more than a 10% improvement. I don’t really know what to say about this??!! I’ve held back from replying - as an idea it’s a bit bonkers!! Your proposal would take a bit of designing & installing. There’s so many ways this hair brain plan can go wrong! Huge consideration needs to be given to the hydronic, Gas, electrical services, to say these are out with your abilities - is a gross understatement!! Lets just start with the Hydronics, how do intend to ‘Valve off’ any boiler, there’s not only the inherent danger, but you could simply be heating one boiler with another!! Then there’s the Gas installation, have you any remote idea how you’re going to do that? Then there’s the electrics/controls for starters, if you retain 240vac basic On/Off controls, the condensing boiler will never work at its optimum. If you can’t rely on your existing SE gas boiler, simply replace it with a condensing boiler. Upgrade your controls, upgrade your home insulation & you’ll save money. Probably is a bit bonkers which is making me more keen to do it.  I think the attached specification answers all your questions The little circles with crosses are valves and the big rectangles are the boilers. To run left hand boiler assuming right is running, then first shut down right. Then close the valves on the right. Then open valves on the left and finally start the left. I am aware this would not meet today's health and safety as it would be possible to have incorrect combinations of valves open/closed. I was looking at some kind of programmable manifold but likely would cost too much. Attachments:
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Post by dickpuller on May 24, 2023 16:32:19 GMT
😂😂
Sorry Dafty, I shouldn’t piss myself laughing & try to help. But this clearly indicates you’ve the logic of a 8 year old. This is not fannying around with Push Fit Pipe or fitting an outside tap, this is serious install work. It requires a hell’ve a lot more design than that!!
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