One for the Experts!

[Maxx470]

I have 12 rads.
An Oil Boiler.
All in a large bungalow which also has 2 X upstairs bedrooms and a bathroom ( derived from a loft conv )

My boiler has a dial ranging from 60 - 90.
To ( I think foolishly ) save Oil I set the boiler stat to 70 ( ish). This eventually caused the room stat which is in the hall to switch off the heating. When I say eventually I mean about 3 hours from very cold.
I then decided to up the boiler setting to 80, this caused the house to feel much warmer and more so warmer much faster.
My theory is that using a higher boiler setting will use more fuel whilst it's running but it will heat the house up much faster than at a lower setting, this equalling cheaper running costs ?. Since it takes over 3 hours for the room stat to reach the desired 22 - 24 c and then switch itself off, it's now doing it in half the time. This must be more efficient ?????.

I have just today changed 10 out of twelve rad valves to TRV's as the originals were standard valves, as because we have a coal fire in the lounge and when it's lit the room is over hot, I thought having TRV's would save wasting expensive fuel.

However as a result the whole place feels hotter.
And I feel sure it will save money. What do you think experts ?.

 

[oilman]

I think you are fooling yourself.

It will always cost more to have something hotter. Your boiler knows nothing about the outside world and just keeps itself at the temperature on its thermostat. It will turn on and off as required. If you set things to be hotter, it can still provide heat at only the same rate. To raise the temperature it just burns longer. Longer burning means more fuel (as it consumes it at a fixed rate), which means more money.

The cheapest way to run it is to turn it off, and wear more clothes.

 

[Dan Robinson]

the desired 22 - 24 c and then switch itself

There's your problem...

 

[Maxx470]

Thanks Oilman,
But while I fully understand what your saying I cant help but disagree slightly. In that if the boiler is on a lower setting then surely it will be on for Longer, to reach the desired room temp. By having it at a slightly higher setting it's achieving its room temp much quicker and then in turn switching it self off.

 

[Dan Robinson]

kW in versus kW out. The size and type of your rads will have a bearing also.

 

[oilman]

Thanks Oilman,
But while I fully understand what your saying I cant help but disagree slightly.

In which case you do not understand what I am saying.

To raise the temperature of anything above its surroundings requires power. The higher the temperature the more power. If you set the temperature of your boiler lower, it will take longer to heat the house because the boiler spends more of its time OFF. If you won't believe it, sit with your boiler and note its ON:OFF ratio. Then you might accept physics.

In that if the boiler is on a lower setting then surely it will be on for Longer, to reach the desired room temp. By having it at a slightly higher setting it's achieving its room temp much quicker and then in turn switching it self off.

It is not ON for longer. It turns itself OFF more often. That's why it has a thermostat on it.