Thats the problem, you just don't know. Would you notice an extra £1 on a bill. It's how the scammers work on contactless fraud, very small amounts from a lot of people so they don't notice.
Optimising hot water schedule
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They will, once widespread - they're not installing them for your benefit.
But if you believe there advertising they save you money, even Einstein is now backing them and he has been dead for years. Think how much money the suppliers will save once meter readers become history and they can monitor and bill for energy real time.
They changed the wording of the ad after I and probably hundreds of thousands of others reported it to the ASA.
johna.clements
Established Member
Until they introduce dynamic pricing (i think there are some test being undertaken?).
I wonder how many meter readers who whilst being totally unqualified has spotted theft of electricity or an unsafe condition. I would assume that they would have some safety training to say stay away from this it maybe unsafe.
You will see the best saving when heating your hot water cylinder when the boiler (assuming condensing) is operating at its maximum efficiency e.g. when the return flow is relatively cold. Therefore it is always advisable to try and have the HW heating when on just after the CH comes on. If you check the boiler start-up sequence you will find it probably takes a couple of minutes for the boiler to get to full throttle so you should aim for just after this as this will avoid the cold water being circulated through the HW cylinder, cooling the tank down before the boiler ramps up. It will also mean the return will be a lot colder as it is heating the rads as well as maintaining the boiler at its maximum efficiency. Condensing boilers, if operated outside of the efficiency band are very inefficient. Depending on your rads etc. it may be prudent in the morning during winter not to ramp the room temperature up in one go*** e.g. have the boiler on for an hour as the return water temperature may be high so the boiler runs out of condensing mode - even if it is in condensing mode the colder the return the better.
*** If you have programmable radiator stats, you can use these to introduce colder water flow by opening up different stats, rather than turning the boiler off.
During the summer try and have the boiler fire up only once if you can e.g. consumption and Cylinder size may not allow this.
Food for thought. Hope this makes sense.
*** If you have programmable radiator stats, you can use these to introduce colder water flow by opening up different stats, rather than turning the boiler off.
During the summer try and have the boiler fire up only once if you can e.g. consumption and Cylinder size may not allow this.
Food for thought. Hope this makes sense.
I did have a brief look at return temps on my new boiler. I played around with the output temp.
With the new boiler and pump it is slower to heat up than the old non-condensing boiler. It is cheaper to run though.
Reducing the boiler output temp to bring down the return temp just meant the rads heat up very slowly.
I guess means the system needs the rads to be balanced properly to restrict the flow and bring down return temps.
I suspect few condensing boiler systems are properly set up.
Feels like I'll have a winter project to keep me busy for a while.
In the meantime I'm happy with the Smart meters. No need for tin foil hats in my house.
The data is useful, even if the IHD doesn't work due to firmware issues.
With the new boiler and pump it is slower to heat up than the old non-condensing boiler. It is cheaper to run though.
Reducing the boiler output temp to bring down the return temp just meant the rads heat up very slowly.
I guess means the system needs the rads to be balanced properly to restrict the flow and bring down return temps.
I suspect few condensing boiler systems are properly set up.
Feels like I'll have a winter project to keep me busy for a while.
In the meantime I'm happy with the Smart meters. No need for tin foil hats in my house.
The data is useful, even if the IHD doesn't work due to firmware issues.
I don't support the conspiracy theorists, but is does boil down to either a faulty meter or a second programme on your boiler? Our boiler has 5 separate programmes for example.
johna.clements
Established Member
or your gas is also connected to another property
I always subscribed to the idea the Hot Water Setpoint should be 60°C. Now that I have an air-source Heat Pump, the installer has recommended 53°C maximum. Anything higher will cost me ‘big time’. Surprisingly, 53°C now seems adequate. Admittedly, the mixer tap now needs to be ‘all the way round’ to the hot (that is, no added cold) but it’s got to be cheaper, no?
I’m beginning to think the old 60°C stemmed from when energy was dirt cheap the planet didn’t matter!
Just as an aside, if you’re wondering where I got the ° symbol from, on my iPhone I hover over the zero (0) and it pops up to the left as an option!
johna.clements
Established Member
If you are storing the water at 53C bacteria will grow.I always subscribed to the idea the Hot Water Setpoint should be 60°C. Now that I have an air-source Heat Pump, the installer has recommended 53°C maximum. Anything higher will cost me ‘big time’. Surprisingly, 53°C now seems adequate. Admittedly, the mixer tap now needs to be ‘all the way round’ to the hot (that is, no added cold) but it’s got to be cheaper, no?
I’m beginning to think the old 60°C stemmed from when energy was dirt cheap the planet didn’t matter!
Just as an aside, if you’re wondering where I got the ° symbol from, on my iPhone I hover over the zero (0) and it pops up to the left as an option!
If you are heating the water and then using it straight away no problem.
The lenght of time that the water is stored hot will determine how many bacteria will grow.
My HW cylinder is set to 60c (by the heating engineer)
I thought this was to kill off any Legionella.
Interesting that the official guidance from HSE is 50c min
https://www.hse.gov.uk/pUbns/priced/hsg274part2.pdf Page 31.
I thought this was to kill off any Legionella.
Interesting that the official guidance from HSE is 50c min
https://www.hse.gov.uk/pUbns/priced/hsg274part2.pdf Page 31.
johna.clements
Established Member
Part of page 8 of the above HSE doc
""2.6 Temperature control is the traditional strategy for reducing the risk of legionella
in water systems. Cold water systems should be maintained, where possible, at a
temperature below 20 °C. Hot water should be stored at least at 60 °C and
distributed so that it reaches a temperature of 50 °C (55 °C in healthcare premises)
within one minute at the outlets.""
Part of page 31 my highlight.
"For non-circulating systems: take temperatures at sentinel points (nearest
outlet, furthest outlet and long branches to outlets) to confirm they are at
a minimum of 50 °C within one minute (55 °C in healthcare premises)"
50C is the temperature at the tap after one minute of flow. You can not read the temperature inside the water storage tank, you do not know if the thermostat is working perfectly. You can not check it against another thermometer. The thermostat also may not be at the coolest place in the storage tank.
The wrong approach, condensing boilers work much better when the complete system has been designed around that type of boiler and not as a retofit in an old system. In a new design the radiators are sized larger to handle the lower flow temperature, with the old boilers with high flow temperatures you would aim for an 11° C temperature drop across a radiator. With a condensing boiler you need a 55° return temperature and using a 75° flow temperature gives a 20°C temperature difference across each radiator. To get this increased temperature difference you need larger radiators to deliver the same heat output because of the lower flow temperatures. Just turning down the boiler and reducing the flow temperature will mean less heat output and it will take longer to heat up a room so no savings. It is like a kettle, to boil a litre of water will require a given amount of energy, whether your kettle is 1Kw or 3Kw the energy used will be the same, only the time changes. This is over simplifying it because you need to take into account heat loss, as you slowly increase the temperature over a period of time your heat losses increase, heat it up fast over a short period of time and more of the energy performs useful work and is not lost.
My bad. I did a very quick skim
With legionella bacteria, they are inactive below 20°C and dead above 60°C. Some newer hot water systems have a legionella cycle where in cases where the temperature has been too low it will perform a hotter cycle. There is also less risk in sealed tanks, I believe this has something to do with nutrients.
Just had a chat with my heating engineer neighbour. He is upgrading the next door neighbour's system.
Only had time to discuss the unexpected use in the middle of the night.
He's had calls from other customers with similar unexpected use.
He thinks it might be a new software release from Nest that is running a Legionella cycle as suggested by Spectric.
I'll find out what software/firmware changes have happened recently.
I've also switched off the 'Radiant heat' feature, just to eliminate it.
johna.clements
Established Member
But why run it at that time. Maybe they got confused and it is running at 6pm Pacific Standard Time! then the hot water would be used"
Richard_C
Established Member
It strikes me that the risk of legionella in domestic premises is vanishingly small. The regulations apply to places like schools, hospitals and nursing homes where the consequences could be serious because of the numbers at risk, and things like cooling towers or plant where many people passing by might breathe in vapours.
There was a PHE report in 2016 covering the 3 previous years, total cases sub 400 each year of which between 40 and 50% were overseas travel related. Of those cases, there were few deaths mainly in older people - overall case death rate 7%. So - we can expect about 350 cases each year in the UK, of which 200 are 'home grown; infections of which 14 might die. I think with those case numbers we have bigger things to worry about in a population of 66 million. Take care but don't obsess about it perhaps.
The WHO guidance repeats what has been stated above: 50 degrees at the outlet, 60 at the boiler, and recommends weekly running of otherwise unused taps to prevent stagnation. I doubt many of us have hot taps which we don't use. Cold to be sub 20 degrees, which isn't likely to be a problem in the UK. Its a respiratory disease, you get it by breathing in sray or mist, not from washing your hands in it. I always wonder about the guidance because shower mixers bring the temperature down, but the water entering the mixer should be above 50 in any event. Still though, it could 'breed' in the shower head which never gets above 50 unless you enjoy coming out of the shower very pink. Maybe if we have been away for a few days - stagnant water in shower hose and head - we should run it as hot as hot can be for a few moments before we use it. Care home sthough have one set of regulations requring high temps to avoid legionella and another one requring mixers to be set below a threshold to avoid boiling the residents. Must be hard to reconcile.
Back to the original question, there is no single answer because its lifestyle related and we all live differently. Combi boilers and conventional HW tank systems have wholly different characteristics. We had new boiler, hw tank and so on 18 months ago. The tank is much better insulated than the old one. The hot water flow to the bathroom/shower is pretty efficient, to the downstairs handbasin its OK, to the kitchen it is awful. This dry summer we were collecting water in a washing up bowl to put on plant pots, typically we would run 5 litres before the water got hot at the tap. There are just 2 of us in the house now (what follows all changes if we have family or visitors to stay).
I used to lazily and unthinkingly have it coming on early am until after we had showered, then again late afternoon for a top up. Calling for heat up to tank thermostat temperature for 2 hours a day. Then I thought, when do we need hot (as in proper-hot) water? Really only to shower each morning plus a bit to wash up things that didn't or couldn't go in the overnight dishwasher run. I'm still unsure about running hot water to the kitchen if its just a small amount to do, a litre in the kettle warmed to 70 and added to a bowl of cold might be quicker and avoids the energy and water wasted in that long pipe run - must do some sums soon.
During the day and evening we only need warm-ish water. I have been pleased to find one 30 minute 'on' cycle just before we get up each day is plenty, and the boiler may only be firing for half of that time. No gas here so its oil, summer usage about 1 litre a day. If I have had a hard-work day in the garden or similar and want an evening shower I just press override and wait 20 minutes or so. No point setting that every day because I don't need it every day. But, we all vary in what we do and what we want so my one half hour cycle a day won't suit all.
As a general principle though, I now think about things a bit more and will set water and heating (coming soon with cool evenings) to the minimum timings and work up from there if I have to rather than my old "just leave it on when we are in" approach. On water, with a decently insulated tank you might be surprised how little you need the boiler to run.
There was a PHE report in 2016 covering the 3 previous years, total cases sub 400 each year of which between 40 and 50% were overseas travel related. Of those cases, there were few deaths mainly in older people - overall case death rate 7%. So - we can expect about 350 cases each year in the UK, of which 200 are 'home grown; infections of which 14 might die. I think with those case numbers we have bigger things to worry about in a population of 66 million. Take care but don't obsess about it perhaps.
The WHO guidance repeats what has been stated above: 50 degrees at the outlet, 60 at the boiler, and recommends weekly running of otherwise unused taps to prevent stagnation. I doubt many of us have hot taps which we don't use. Cold to be sub 20 degrees, which isn't likely to be a problem in the UK. Its a respiratory disease, you get it by breathing in sray or mist, not from washing your hands in it. I always wonder about the guidance because shower mixers bring the temperature down, but the water entering the mixer should be above 50 in any event. Still though, it could 'breed' in the shower head which never gets above 50 unless you enjoy coming out of the shower very pink. Maybe if we have been away for a few days - stagnant water in shower hose and head - we should run it as hot as hot can be for a few moments before we use it. Care home sthough have one set of regulations requring high temps to avoid legionella and another one requring mixers to be set below a threshold to avoid boiling the residents. Must be hard to reconcile.
Back to the original question, there is no single answer because its lifestyle related and we all live differently. Combi boilers and conventional HW tank systems have wholly different characteristics. We had new boiler, hw tank and so on 18 months ago. The tank is much better insulated than the old one. The hot water flow to the bathroom/shower is pretty efficient, to the downstairs handbasin its OK, to the kitchen it is awful. This dry summer we were collecting water in a washing up bowl to put on plant pots, typically we would run 5 litres before the water got hot at the tap. There are just 2 of us in the house now (what follows all changes if we have family or visitors to stay).
I used to lazily and unthinkingly have it coming on early am until after we had showered, then again late afternoon for a top up. Calling for heat up to tank thermostat temperature for 2 hours a day. Then I thought, when do we need hot (as in proper-hot) water? Really only to shower each morning plus a bit to wash up things that didn't or couldn't go in the overnight dishwasher run. I'm still unsure about running hot water to the kitchen if its just a small amount to do, a litre in the kettle warmed to 70 and added to a bowl of cold might be quicker and avoids the energy and water wasted in that long pipe run - must do some sums soon.
During the day and evening we only need warm-ish water. I have been pleased to find one 30 minute 'on' cycle just before we get up each day is plenty, and the boiler may only be firing for half of that time. No gas here so its oil, summer usage about 1 litre a day. If I have had a hard-work day in the garden or similar and want an evening shower I just press override and wait 20 minutes or so. No point setting that every day because I don't need it every day. But, we all vary in what we do and what we want so my one half hour cycle a day won't suit all.
As a general principle though, I now think about things a bit more and will set water and heating (coming soon with cool evenings) to the minimum timings and work up from there if I have to rather than my old "just leave it on when we are in" approach. On water, with a decently insulated tank you might be surprised how little you need the boiler to run.
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