Replacement Boilers & Building regs….Sneaky NASTY rule change?

[Stevekane]

Well Deema your house is very similer to ours, solid brick walls, double glazeing, decent but not excessive loft insulation, when our heating goes off at around 9.30pm the house starts cooling down quite quickly, and in cold weather the temp in the front room will have dropped to around 12c in 4 hours or so, Ive always had the opinion that the hest just flies out, now if I wanted to maintain even a reduced temp its got to involve burning gas.

 

[Spectric]

However, after a little experimenting, running at a constant temperature (it is lower at night 17C, but not off) and heating our unused rooms is more efficient that keeping unused rooms cool and selective timed heating.

I have found the same with leaving our heating on constantly, not at a constant temperature but with a minimum setpoint of 15°C overnight and raising it as needed during the day. Also heat will transfer to colder areas, so having un heated rooms is ok if they are totally sealed from the rest of the heated areas but could well suffer damp and mold. If they are not sealed then although un heated they will soak up heat from elsewhere and potentially increase the time needed to reach setpoint and so use more energy.

 

[woodieallen]

I do know of one guy who reasoned thus (oilfired boiler applies).

There is a pre-purge phase which wastes oil and then a post-purge phase so why not have a nice long burn and store that heat somewhere. Like a well-insulated storage tank. You then turn the boiler off and draw down the heat as and when you require it from the tank. System designed to keep the boiler temp below 55 degrees to maximise efficiency. Side benefit....that heat store could easily be coupled to a large woodburner or solar panels.

He found there was a downside. Come end of April- early May, he felt he could turn off the heating as he had had a few warm sunny days. So that tank slowly emptied of heat. Then....a sudden cold snap which meant that before he could heat his house up, he first had to heat up that heat store.

 

[Jameshow]

Well Deema your house is very similer to ours, solid brick walls, double glazeing, decent but not excessive loft insulation, when our heating goes off at around 9.30pm the house starts cooling down quite quickly, and in cold weather the temp in the front room will have dropped to around 12c in 4 hours or so, Ive always had the opinion that the hest just flies out, now if I wanted to maintain even a reduced temp its got to involve burning gas.

What Deema is saying is that your house will cool from 18c to 12c in 4 hours, another 4 hours it's at 6c coldest before dawn btw then it takes a heck of a lot of gas /oil to heat it back up to 18c by 8am. More than keeping it at say 16c

 

[ian33a]

What Deema is saying is that your house will cool from 18c to 12c in 4 hours, another 4 hours it's at 6c coldest before dawn btw then it takes a heck of a lot of gas /oil to heat it back up to 18c by 8am. More than keeping it at say 16c

I'd agree with that: we run ours at about 18, some rooms at 19 during some parts of the day. At night we run many of the larger rooms with a 2 degree set back. The house remains warm during the day (as we are almost always there). In really cold weather one or two of the larger rooms struggle to maintain the above temperatures. The boiler does cycle, more than I would like, but the heating is gentle on account of it being hydronic underfloor. When we tried setting the set back much lower or even turning off some rooms the house struggled to maintain a decent equilibrium and when the the weather was cold it felt like the boiler was almost constantly running. We've kind of found a method that suits us and our needs for now. It's not cheap to run the heating but the house is pretty large and old so it was never going to be cheap anyway.

 

[davethebb]

Deema, Spectric, et al, all raise interesting points regarding why you see your fuel consumption is lower when you keep your heating on most of the time and all give valid reasons as to why and why not this it is the case. It is a very complex scenario with multiple factors coming into play

One point (factor) I would also like to add is the fact that you both have non-condensing boilers. These typically do not run efficiently when pushed to their maximum. There will be a significant increase in efficiency if you run these at a relatively low output which is what you are doing by effectively reducing the heat demand at any one point in time e.g. you don't have a massive hill to climb to suddenly raise the room temperature by 5 degrees for instance.

 

[Stevekane]

What Deema is saying is that your house will cool from 18c to 12c in 4 hours, another 4 hours it's at 6c coldest before dawn btw then it takes a heck of a lot of gas /oil to heat it back up to 18c by 8am. More than keeping it at say 16c

Well I cannot argue with Deemas figgures thats for sure, its clearly working for him and quite a few others, but as you know, flies in the face of the advice on energy saving in recent years, maybe better insulation?
To clarify, our house temp will drop to arround 12c within a few hours but thats around where it settles if very cold outside, mostly it will be a little warmer than that, and with a few large high output rads the temp is up to 16c or so within the hour even with the DHW taking a good share, but I take your point, the boiler is at that time running almost constantly,,
Steve.

 

[johnny]

I have to disagree. The only way leaving the heating on all the time could be more efficient is if the boiler is running more efficiently due to being in condensing mode.
Would you leave your kettle on permanently on the grounds that it took a lot of energy to get that room temperature water up to boiling point?

thats an interesting question ...
On our last few kettles we have had the option to leave it on a 'top up' setting whereby it keeps the water in the kettle constantly hot by periodically turning on and off . It takes approx 10 seconds to boil the water ready for a cuppa as apposed to well over a minute every time you boil a little water for a cup of tea or coffee throughout the day. if you are a big tea,coffee drinker like me it should work out cheaper than constantly boiling cold water every time.

 

[John Brown]

I can't pretend to understand the vagaries of oil burners at different output levels,or pre-purge cycles. I know that condensing boilers and heat pumps are more efficient at lower temperatures, but I wasn't aware that non-condensing boilers behaved the same way.
I also don't know enough about the condensation in the walls theory, but I've only found the one reference to it so far, which makes me suspicious.
What I have trouble with is this strange notion that it takes all this energy to heat the building, and then very little to keep it warm. That basically flies in the face of science, and analogies with climbing a hill are misplaced. The best analogy I can come up with right now would be trying to fill a vertical cylinder with water, when there's a leak at the bottom. The higher the head of water, the faster the flow from the leak.

But it's a pointless discussion and one that I can't be bothered to engage in any longer. All I was interested in(and still am) was some scientific premise for the heat-on-all-the-time theory, and so far nothing has surfaced.
I am not ereked, whatever that means, and Deema has tried, and succeeded in making me look stupid by introducing the Taguchi, which I thought was that little device with the buttons that my granddaughter failed to keep alive, but I feel the discussion is just going round in circles. I'd like some science, but all that's offered is anecdote.
As I said earlier, I'd love to be wrong about this, it would make my life warmer, easier and less expensive, so I will continue to read this thread in the hope that a viable theory emerges.

 

[1steven]

I can't pretend to understand the vagaries of oil burners at different output levels,or pre-purge cycles. I know that condensing boilers and heat pumps are more efficient at lower temperatures, but I wasn't aware that non-condensing boilers behaved the same way.
I also don't know enough about the condensation in the walls theory, but I've only found the one reference to it so far, which makes me suspicious.
What I have trouble with is this strange notion that it takes all this energy to heat the building, and then very little to keep it warm. That basically flies in the face of science, and analogies with climbing a hill are misplaced. The best analogy I can come up with right now would be trying to fill a vertical cylinder with water, when there's a leak at the bottom. The higher the head of water, the faster the flow from the leak.

But it's a pointless discussion and one that I can't be bothered to engage in any longer. All I was interested in(and still am) was some scientific premise for the heat-on-all-the-time theory, and so far nothing has surfaced.
I am not ereked, whatever that means, and Deema has tried, and succeeded in making me look stupid by introducing the Taguchi, which I thought was that little device with the buttons that my granddaughter failed to keep alive, but I feel the discussion is just going round in circles. I'd like some science, but all that's offered is anecdote.
As I said earlier, I'd love to be wrong about this, it would make my life warmer, easier and less expensive, so I will continue to read this thread in the hope that a viable theory emerges.

I remember someone producing some figures recently that it cost them 7% more to have the heating on constantly but they said they felt more comfortable. Sitting in a windy Croft built in 1800 I would like to be comfortable. wind today is 60+ mph.

 

[ivan]

Many years ago I had a cast iron room sealed gas boiler running a hot water cylinder and rads, 1/2 and 3/4 copper. We rigged up a system to take the cylinder out of circuit when up to temp., and the boiler temp (circulating water) controlled by exterior temp. We put an hours meter on the boiler, which ran for fewer hours when left permanently on. Temps reduced by 5F at night, ~70F by day. Was 1960's build house with added cavity foam and about 6" fibre in the loft. No floor insulation, 3 bed detached.

 

[woodieallen]

I can't pretend to understand the vagaries of oil burners at different output levels,or pre-purge cycles. I know that condensing boilers and heat pumps are more efficient at lower temperatures, but I wasn't aware that non-condensing boilers behaved the same way.
I also don't know enough about the condensation in the walls theory, but I've only found the one reference to it so far, which makes me suspicious.
What I have trouble with is this strange notion that it takes all this energy to heat the building, and then very little to keep it warm. That basically flies in the face of science, and analogies with climbing a hill are misplaced. The best analogy I can come up with right now would be trying to fill a vertical cylinder with water, when there's a leak at the bottom. The higher the head of water, the faster the flow from the leak.

But it's a pointless discussion and one that I can't be bothered to engage in any longer. All I was interested in(and still am) was some scientific premise for the heat-on-all-the-time theory, and so far nothing has surfaced.
I am not ereked, whatever that means, and Deema has tried, and succeeded in making me look stupid by introducing the Taguchi, which I thought was that little device with the buttons that my granddaughter failed to keep alive, but I feel the discussion is just going round in circles. I'd like some science, but all that's offered is anecdote.
As I said earlier, I'd love to be wrong about this, it would make my life warmer, easier and less expensive, so I will continue to read this thread in the hope that a viable theory emerges.

Does this help you John ?

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatloss.html

 

[Spectric]

that you both have non-condensing boilers

I have a Worcester system condensing boiler but run cast iron radiators to drop the return temperature so it runs in condensing mode.

 

[Spectric]

Another aspect is that the fabric of a building will initially heat up and hold heat. With no heating the building will cool and when the heating comes back on not only do you have to heat the air but also the building, could be another factor in all this.

 

[Jameshow]

Another aspect is that the fabric of a building will initially heat up and hold heat. With no heating the building will cool and when the heating comes back on not only do you have to heat the air but also the building, could be another factor in all this.

Esp older stone houses. Chalk and cheese to a modern block and plasterboard house!

 

[Suffolk Brian]

Greatly interested in this thread. My wife and I live in an end terrace property, brick construction, double glazed, built about 1935. Cavity wall insulation, some loft insulation. We have a Vaillant condensing boiler, close to 15 years old. We also have a "Wiser" boiler control system, with wiser rad. thermosats on every radiator. I should add at this point that my wife is a cold mortal - a very cold mortal.......
Lately I seem to be bombarded by adverts urging me to get a new, better, more efficient, blah blah, boiler. So, my interest is, how long will it take to recoup the price of a new (blah blah) boiler, in terms of gas savings? Probably not in my lifetime? Comments please.....

 

[ian33a]

Greatly interested in this thread. My wife and I live in an end terrace property, brick construction, double glazed, built about 1935. Cavity wall insulation, some loft insulation. We have a Vaillant condensing boiler, close to 15 years old. We also have a "Wiser" boiler control system, with wiser rad. thermosats on every radiator. I should add at this point that my wife is a cold mortal - a very cold mortal.......
Lately I seem to be bombarded by adverts urging me to get a new, better, more efficient, blah blah, boiler. So, my interest is, how long will it take to recoup the price of a new (blah blah) boiler, in terms of gas savings? Probably not in my lifetime? Comments please.....

It all depends how old you are Brian. If you are somewhere between 25 and 30, you will probably see a benefit.

If you are an older duffer like me, I would hold on to it and hope that, when it gulps it's last breath of gas, there will be something much cheaper to run than the current crop of new technology on offer.

The days of cheap energy are over. Even my son has learned to turn off the lights.

 

[Spectric]

We have a Vaillant condensing boiler, close to 15 years old

A system boiler or a combi ? If it is serviced and the guy is not making negative comments or making jokes about it then keep it especially if you are fifty plus.

 

[StephenArfer]

Gas savings are not the only issue. If you come to sell your house, a modern boiler and heating system will add more value than its cost. Or look at it from the other way around, if the system is old, then their offer will be reduced by a significant amount, probably greater than the update costs.

 

[paulrbarnard]

Gas savings are not the only issue. If you come to sell your house, a modern boiler and heating system will add more value than its cost. Or look at it from the other way around, if the system is old, then their offer will be reduced by a significant amount, probably greater than the update costs.

This is true. The house we just bought had a new boiler fitted because the previous sale had fallen through due to not being able to agree a price drop based on the survey calling out the old boiler.
It worked well for us as the owner went ahead and replaced the boiler thinking they wouldn’t be able to sell without it and because of the wildly fluctuating market we managed to get the house at a good price.