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[roseway]

One of the measures which the government is pushing to cut energy costs is to reduce the boiler flow temperature from 75 to 60 degrees. The government advice says that this "may" mean that it will take longer to heat up the rooms. Can someone explain how this is supposed to work? Firstly, there's no "may" about it - it obviously will take longer if the radiator temperature is lower. And if the boiler has to run for longer, then this will nullify any saving from running at a lower temperature.
Any comments?

[broadstairs]

My boiler has an external temperature sensor and alters the boiler central heating flow temperature so when it's warmer the flow temperature is lower and vice versa. It has always worked like this. Experience shows it works well.

Stuart

[HPsauce]

It makes no sense other than your rooms will be colder for longer so using less energy on warming before you give up and go to bed.
But can't you achieve that by turning down the thermostat?

There "may" be some other factor about boilers (of certain designs) operating more efficiently overall if only heating water to a lower temperatrure, but I'd like to see the logic/explanation first. No chance of getting that I feel......

[benji09]

 I thought there was a chance of power cuts to the electricity supply this winter, so I  am sure that running the central heating pump for longer periods must help no end! Unless the idea is really to cut the heat of your hot water for your washing up, thus saving energy. If not that reason, the idea sounds rubbish..........

[broadstairs]

Some idiot of an engineer disconnected the external temp sensor back in the summer as he thought , wrongly, it was causing an issue and I forgot about it until only a week or so ago. When all this about saving gas & electricity came up I remembered and got a guy out to fix it (perfectly capable of connecting it myself but I made a point of getting they guy back to sort it  ) anyway since it was reconnected the heating has been getting the house up to temperature in the same timeframe as it was before with the boiler flow temp 10°C lower, it was about 60°C with sensor disconnected and now it about 48-50°C. My boiler is a combi and the hot water has a separate control and is not affected by the outside temp.

The whole point of this system is to vary boiler flow temp dependent on external temp, there is a graph in the handbook showing how it varies, and so it will come back up to 60-70°C or more when the outside temp falls close to or below freezing. All I can say is that it seems to work and we have sensible gas usage, been fairly constant in the 7 years we've had the boiler and is lower than the one it replaced.

Stuart

[HPsauce]

I've updated our rather (very!) old system with a new controller that gets external temperatures from weather forecasts via t'internet (Drayton Wiser).
It has a wireless themostat that I can place more sensibly, and move if necessary, compared to the old wall-mounted unit.
It also learns how the system/house responds and over about 3 years now has proved very effective in getting it up to temperature but not overshooting.
Compared to the old simple mechanical thermostat it can be a bit slower getting the house warm but it rarely goes way over, whereas the old system regularly would due to heat retained in the pipes and radiators.
Overall it works well, unless SWMBO decides to "play" with it. Best left alone!

[Alex Atkin UK]

So to summarise, just turning it down would likely be a bad idea, big surprise.

There's a lot of stupid advise being pushed around to save energy, particularly the idea of turning off radiators in unused rooms.  You're just asking to have a mould problem if you do that and fixing that will more than outweigh the cost in energy saved, never mind the health problems it can cause.

I also get really sick of it being said that leaving devices on standby wastes energy.  It might not be as cheap or efficient as using gas, but anything electrical pulling energy produces heat, that heat is released into the house, so it reduces your heating bill.  So its not wasted at all.

I've literally heated the house for the last month on computers alone as things are a bit of a mess right now so the radiators were blocked.  Rather get heat from doing scientific research than use electric heaters.

[HPsauce]

Outside lighting (even the PIR sensors use power) is probably a pretty blatant waste of energy. Lots of it appearing in the run up to Christmas of course....... 

[Chrysalis]

I am not convinced there is a saving from it, more likely they want people to do this to reduce peak time demand, and one way to convince them is to tell them they will save money.

For the same reason a kettle is more efficient than a saucepan to heat water even though it has higher peak power draw.

What will save money is if people turn down room thermostats but as of yet the government has not issued this advice.

Central heating can be wasteful in itself as you have to heat all the pipes etc. thats all basically waste, anything that heats slowly/gradually in a home that has insulation issues will also be wasteful.  But there has been for a long time assumptions that anything gas is cheaper than anything electric, usually based on that gas is cheaper per KwH, but not taking into account efficiency.

I am one of those who will wear more clothes before turning the heater on, and I do question the merits of heating my entire property vs just the room I spend the most time in.

My advice is seal windows, cling film whatever, turn down thermostat 1-2C, those should be easy wins without much compromise.  Even just taping edges of curtains against wall is quite effective.

[craigski]

Can someone explain how this is supposed to work? Firstly, there's no "may" about it - it obviously will take longer if the radiator temperature is lower. And if the boiler has to run for longer, then this will nullify any saving from running at a lower temperature.
Any comments?

https://www.heatgeek.com/condensing-boilers-efficiency/

Lots on this forum will spend a lot of time fine tuning their broadband to eek out a few more Mbs.

If you enjoy tinkering, it worth checking if the radiators are balanced, ie the delta on flow & return of each radiator.

A nice guide here:

https://www.heatgeek.com/balancing-heating-systems-the-ultimate-guide/

[HPsauce]

There "may" be some other factor about boilers (of certain designs) operating more efficiently overall if only heating water to a lower temperatrure, but I'd like to see the logic/explanation first.

Excellent information about condensing boilers, I can see how a lower temperature (but with higher flow to compensate) makes sense. IF you have the right controls.

We have an old-school gas boiler with gravity (convection) hot water heating and a fixed-speed heating pump so that probably doesn't apply to us in any sensible way. 

[craigski]

Modulation will apply though:

https://www.heatgeek.com/what-is-boiler-modulation/

[broadstairs]

I'm always surprised that people have their central heating room thermostats set in the mid 20's we have always had ours around 19°C and it is more than enough, and yes if it gets colder we wear more clothes even indoors - always have done.

Both of use were brought up in houses with no central heating, just a fire (usually coal) in the main room which had to be cleaned out and re-lit every morning. Yes we had a boiler (coal/coke) just for hot water. So we've always been used to lower temps around the house.

Stuart

[Alex Atkin UK]

Central heating can be wasteful in itself as you have to heat all the pipes etc. thats all basically waste, anything that heats slowly/gradually in a home that has insulation issues will also be wasteful.  But there has been for a long time assumptions that anything gas is cheaper than anything electric, usually based on that gas is cheaper per KwH, but not taking into account efficiency.

That's true, given UK houses are built with ventilation between floors, where the pipes are.

The council didn't lag any of our pipes between floors, that's normal for between the ground and first floor but they didn't do under the house either.  We complained and they did some of it, but were sure they couldn't do it under the kitchen as the hot tap does cold very quickly once you've turned it off.  You get that pattern of cold water, then hot, but quicker than if its been off a while when even the lagged pipes have gone cold.

I'm always surprised that people have their central heating room thermostats set in the mid 20's we have always had ours around 19°C and it is more than enough, and yes if it gets colder we wear more clothes even indoors - always have done.

Both of use were brought up in houses with no central heating, just a fire (usually coal) in the main room which had to be cleaned out and re-lit every morning. Yes we had a boiler (coal/coke) just for hot water. So we've always been used to lower temps around the house.

Stuart

Its not that simple though, some people regulate their body temperature more than others.  My mum gets cold at 21C with multiple layers on due to diabetes, then theres the fibromyalgia which means wearing layers can be too painful.

I also have weird bouts of feeling too hot or too cold, even at the same temperature.  But too hot is worse as I get drowsy.

Our house also got a lot worse after Decent Homes as taking the carpets up left drafts coming under the skirting boards.

[jelv]

The point is that condensing boilers don't condense if the flow temperature is above 60 and hence are not as efficient. Yes, it may take longer to heat the house, but the total amount of gas used over the longer period will be less than if the flow temperature is set too high.