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thomasar

Messages
24
Just had a new boiler installed and looking for some efficiency advice, please. We have always set the Heating to run from 6:30 until 21:00 via the programmer and have regulated it from the thermostat. We have used the same setting for the Hot Water. We have a conventional system with our boiler in the kitchen and the Header Tank in a cupboard a floor up in a shower room. Normally, we have the Heating turned off via the programmer in the summer months but keep the Hot Water programme on from 6:30 until 21:00. Now that the cost of gas has ballooned plus the obvious effect of global warming I'm looking to be a bit more efficient. On the other hand, my wife and I are getting old and want to keep warm! I've now programmed the Heating to be on from 6:30 to 7:30, 13:00 to 14:00 and 16:00 to 22:00 on weekdays with the first setting changed to 7:30 to 8:30 at weekends. My son also lives at home and is working from home. He and my wife both normally shower early in the morning whereas I shower later in the day. I have set the Hot Water programme to 6:30 to 7:30, 12:00 to 13:00 and 17:00 to 18:00 on weekdays but, again, the first setting changed to 7:30 to 8:30 at weekends. However, when it gets really cold, I will be changing the Heating programme to "Once" so that it will be on for most of the day but governed by our thermostat temperature setting. Do these setting seem reasonable? Also, do I save any gas by reducing the time the Hot Water is on or is the heat produced from the boiler merely being diverted to the radiators instead of split between the radiators and the hot water tank?
 

Ric2013

Plumber
Messages
3,607
If you have a modern boiler, there should be a thermostat on your hot water cylinder as well as a room thermostat which will mean that although you may have the hot water switched on, the boiler won't actually kick in unless the tank needs heating and will stop heating the cylinder once it's hot through so I do think you are at risk of overcomplicating the settings slightly with all these on and offs.

There may be a case for having the cylinder heated just before you actually need the hot water, and with an insulated cylinder it may well be enough to just have it set to come on for an hour before the first shower and set to go off an hour after the second shower which will hopefully leave enough for your shower and washing up during the day. The only way you'll meaningfully reduce gas usage by reducing the time hot water is on is if you can avoid getting the cylinder red hot and then not using that heat so that the cylinder slowly goes cold (for example overnight) without the water even being used, though bear in mind that heat is probably being lost into your house and so is not a complete waste.

My feeling is that your boiler is unlikely to be a particularly complicated model and may run more efficiently if you try to get it to heat both hot water and radiators at the same time rather than first one and then the other, but there really is not a lot in it, and it sounds like you are already doing this anyway.

As for the heating, it's probably worth reading the meter (all the digits, even the red ones after the decimal point) and seeing whether you can use less gas to get the same amount of comfort having the heating on from morning till night. This actually depends on the property, and some houses seem to be better with the heating on permanently rather than try to keep warming up them from cold and for other houses the reverse is the case. The only way to find out is to run the experiment and there may be as much as 10% at stake. You can also play with having the room thermostat on at a lower setting rather than switching off completely (at night, say) and this may mean that when your thermostat is set back to the higher temperture you'll find you're comfortable at a lower air temperature than you would be if you were sitting in a hot room with your back to a stone-cold wall. If this works, you might consider changing to a programmable thermostat so you you can set different temperatures to apply at different times.

That said, I get the impression your one hour heating period is so you can snuggle up to the radiator in the morning and then once you're up and about you may not even be at home, or you don't feel cold if you are. If so, although the heating may be less efficient used in this way in terms of gas use per unit of useful heat, your overall gas consumption may still be lower. Sometimes fancy technology is never quite as effective as manual control used intelligently, and you can of course do the meter reading test.

What if you have a gas cooker?, you may be wondering. To be fair, any heat from the cooker is likely to come into the house anyway, but unless you're baking cakes all day one day and eating sandwiches the next, I don't think the normal variance in gas used from day to day in the kitchen is likely to be significant enough to throw your experiment in a meaningful way, particularly if you run the experiements over a few days.

As far as carbon emissions are concerned, the important thing is that we don't get caught in what has been referred to as Micro-Changes Bull----. So do bear in mind that while home heating is an important consideration, don't get so worked up about it to the point that you forget an annual flight you might be able to avoid entirely has a similar impact. There's a really interesting free book you can read online or download at this website: David MacKay FRS: : Contents - https://www.withouthotair.com/ Some of the data is not as up-to-date as could be hoped for, due to the untimely death of David MacKay, but it is still a valuable read and much easier to read than than you'd imagine given the complexity of the matter.
 

thomasar

Messages
24
If you have a modern boiler, there should be a thermostat on your hot water cylinder as well as a room thermostat which will mean that although you may have the hot water switched on, the boiler won't actually kick in unless the tank needs heating and will stop heating the cylinder once it's hot through so I do think you are at risk of overcomplicating the settings slightly with all these on and offs.

There may be a case for having the cylinder heated just before you actually need the hot water, and with an insulated cylinder it may well be enough to just have it set to come on for an hour before the first shower and set to go off an hour after the second shower which will hopefully leave enough for your shower and washing up during the day. The only way you'll meaningfully reduce gas usage by reducing the time hot water is on is if you can avoid getting the cylinder red hot and then not using that heat so that the cylinder slowly goes cold (for example overnight) without the water even being used, though bear in mind that heat is probably being lost into your house and so is not a complete waste.

My feeling is that your boiler is unlikely to be a particularly complicated model and may run more efficiently if you try to get it to heat both hot water and radiators at the same time rather than first one and then the other, but there really is not a lot in it, and it sounds like you are already doing this anyway.

As for the heating, it's probably worth reading the meter (all the digits, even the red ones after the decimal point) and seeing whether you can use less gas to get the same amount of comfort having the heating on from morning till night. This actually depends on the property, and some houses seem to be better with the heating on permanently rather than try to keep warming up them from cold and for other houses the reverse is the case. The only way to find out is to run the experiment and there may be as much as 10% at stake. You can also play with having the room thermostat on at a lower setting rather than switching off completely (at night, say) and this may mean that when your thermostat is set back to the higher temperture you'll find you're comfortable at a lower air temperature than you would be if you were sitting in a hot room with your back to a stone-cold wall. If this works, you might consider changing to a programmable thermostat so you you can set different temperatures to apply at different times.

That said, I get the impression your one hour heating period is so you can snuggle up to the radiator in the morning and then once you're up and about you may not even be at home, or you don't feel cold if you are. If so, although the heating may be less efficient used in this way in terms of gas use per unit of useful heat, your overall gas consumption may still be lower. Sometimes fancy technology is never quite as effective as manual control used intelligently, and you can of course do the meter reading test.

What if you have a gas cooker?, you may be wondering. To be fair, any heat from the cooker is likely to come into the house anyway, but unless you're baking cakes all day one day and eating sandwiches the next, I don't think the normal variance in gas used from day to day in the kitchen is likely to be significant enough to throw your experiment in a meaningful way, particularly if you run the experiements over a few days.

As far as carbon emissions are concerned, the important thing is that we don't get caught in what has been referred to as Micro-Changes Bull----. So do bear in mind that while home heating is an important consideration, don't get so worked up about it to the point that you forget an annual flight you might be able to avoid entirely has a similar impact. There's a really interesting free book you can read online or download at this website: David MacKay FRS: : Contents - https://www.withouthotair.com/ Some of the data is not as up-to-date as could be hoped for, due to the untimely death of David MacKay, but it is still a valuable read and much easier to read than than you'd imagine given the complexity of the matter.
Thanks for that detailed reply. The chap who installed the new boiler told me that he had set the thermostat on the hot water tank to 60 degrees and the boiler temperature 70 degrees as there should be a 10 degree difference between them. Th Rie boiler is a Worcester Greenstar 24 Ri. In cold weather we normally set the heating thermostat to 21.5 degrees and only use that as a control from 6:30 until 21:00 so my aim was really to reduce the amount of time that the hot water needed to be heated.
 

Chuck

Esteemed
Messages
2,453
Thanks for that detailed reply. The chap who installed the new boiler told me that he had set the thermostat on the hot water tank to 60 degrees and the boiler temperature 70 degrees as there should be a 10 degree difference between them. Th Rie boiler is a Worcester Greenstar 24 Ri. In cold weather we normally set the heating thermostat to 21.5 degrees and only use that as a control from 6:30 until 21:00 so my aim was really to reduce the amount of time that the hot water needed to be heated.
If the insulation on you hot water cylinder is good you won't save any energy with elaborate 'just in time' heating schedules just choose one that suits your lifestyle. A lot of people heat the cylinder at night (to avoid starving the radiators during the day in cold weather) with, if necessary, a boost in the early afternoon so there is water for the kids' baths at night.

Likewise, messing around with complicated on-off schedules for the radiators won't, in practice, make much difference to your energy consumption but the temperature swings may make you feel uncomfortable and/or give you problems with damp and humidity.

If you want to save energy the most effective way to do it is to (a) use less hot water and/or (b) reduce your thermostat. Most people would say 21.5°C is too hot for healthy adults. Reduce it gradually, say steps of 0.5°C every fortnight with the aim of getting into a range of 18-20. Put a pullover on if you feel cold!
 

Ric2013

Plumber
Messages
3,607
If the insulation on you hot water cylinder is good you won't save any energy with elaborate 'just in time' heating schedules just choose one that suits your lifestyle. A lot of people heat the cylinder at night (to avoid starving the radiators during the day in cold weather) with, if necessary, a boost in the early afternoon so there is water for the kids' baths at night.

Just in time hot water heating schedules might not save a terrible lot, but it seems to me that the least efficient stage of heating water is bringing it up the last few degrees, as the boiler is by then running well below its capacity if it is does not have radiators to serve at the same time. If we follow what you say 'a lot of people do', then while we aren't setting up a just-in-time programme, we are at least allowing the bulk of the heated water to actually be consumed before the cylinder is reheated, so I don't think our advice is really that different.

I suppose the issue of starving the radiators depends largely on the boiler output. I have a low output boiler by modern standards (though improved insulation means it's now oversized for my house) and I cannot say I notice any starvation of radiators if I try to heat water at the same time. What sort of size house do you have and do you know the kW rating of your new boiler?
 

thomasar

Messages
24
Just in time hot water heating schedules might not save a terrible lot, but it seems to me that the least efficient stage of heating water is bringing it up the last few degrees, as the boiler is by then running well below its capacity if it is does not have radiators to serve at the same time. If we follow what you say 'a lot of people do', then while we aren't setting up a just-in-time programme, we are at least allowing the bulk of the heated water to actually be consumed before the cylinder is reheated, so I don't think our advice is really that different.

I suppose the issue of starving the radiators depends largely on the boiler output. I have a low output boiler by modern standards (though improved insulation means it's now oversized for my house) and I cannot say I notice any starvation of radiators if I try to heat water at the same time. What sort of size house do you have and do you know the kW rating of your new boiler?
The boiler is 24 kW. We have a large house which covers 4 floors. The boiler is in the kitchen which is above ground level and has 1 small radiator which is always turned off. On that floor is also our main front and back doors with 1 large radiator in the passage leading to the front door and 2 large radiators in the main lounge. One flight up there are a main bedroom, a smaller bedroom and a shower room all with radiators. The radiators in the bedrooms are always turned off as the heat rises from below. Half a flight below the main lounge/kitchen floor we have another smaller lounge, another bedroom and a bathroom. The smaller lounge has 2 radiators with 1 radiator in the bedroom and bathroom. There is also a storage room with a large radiator but this is always turned off. Finally, another half flight lower there is a passage with 1 radiator, another bedroom with 1 radiator and a small room used as an office area without a radiator. We find that the 2 radiators on this floor never get more than lukewarm even when the other radiators are hot. Although we have a new boiler, the radiators have not been change since the house was built in the 1970s. When the new boiler was installed a couple of days ago, we also had a powerflush done the following day.
 

thomasar

Messages
24
If the insulation on you hot water cylinder is good you won't save any energy with elaborate 'just in time' heating schedules just choose one that suits your lifestyle. A lot of people heat the cylinder at night (to avoid starving the radiators during the day in cold weather) with, if necessary, a boost in the early afternoon so there is water for the kids' baths at night.

Likewise, messing around with complicated on-off schedules for the radiators won't, in practice, make much difference to your energy consumption but the temperature swings may make you feel uncomfortable and/or give you problems with damp and humidity.

If you want to save energy the most effective way to do it is to (a) use less hot water and/or (b) reduce your thermostat. Most people would say 21.5°C is too hot for healthy adults. Reduce it gradually, say steps of 0.5°C every fortnight with the aim of getting into a range of 18-20. Put a pullover on if you feel cold!
Thanks for the reply. I take your point about reducing the thermostat setting. So, would your advice be to have the heating setup all day from say 6:30 until 22:00 in the winter and control when it is on purely from the thermostat setting? Regarding the hot water, I can't understand how having it on for hours overnight could be efficient although just having it on from 6:30 until 7:30 so my wife and son could have early morning showers and then putting it on for an hour before I have a shower later in the day would seem a good idea. What I find confusing is that the manual which comes with our programmer recommends that the installer sets 1 of 3 programmes (standard, at home all day and energy efficient) but they all have the hot water and heating settings set at identical times although the on/off times vary slightly between each of the 3 programmes and between weekdays and weekends.
 

thomasar

Messages
24
Where in the house is the room stat?
It's in the passage of the floor which is half a flight down from the kitchen where the boiler is situated i.e. half a flight up from the bottom floor which is below ground level.
 

Murdoch

Esteemed
Res.Electrician
Messages
1,030
It's in the passage of the floor which is half a flight down from the kitchen where the boiler is situated i.e. half a flight up from the bottom floor which is below ground level.

how warm does your lounge actually get ?

our room stat is in our hall and it’s set to 19 degrees - the lounge gets warmer
 

thomasar

Messages
24
how warm does your lounge actually get ?

our room stat is in our hall and it’s set to 19 degrees - the lounge gets warmer
We set the stat to 21.5 degrees in winter which is pretty high. We have it the floor below the main lounge upstairs because my wife watches TV in that lounge quite often and wants it warm on that floor. We also want to have some heat in the lower floor to avoid any dampness and the rads there are much less warm than those on the floors above.
 

Murdoch

Esteemed
Res.Electrician
Messages
1,030
We set the stat to 21.5 degrees in winter which is pretty high. We have it the floor below the main lounge upstairs because my wife watches TV in that lounge quite often and wants it warm on that floor. We also want to have some heat in the lower floor to avoid any dampness and the rads there are much less warm than those on the floors above.

i would turn it down by 1 degree. AND also consider replacing it for one where you can have different temperatures at different set times of the day
 

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