Which is better - intermittent heating or leaving it on for longer periods

VonLuck

I guess this is an efficiency question. I have a gas boiler and now that it's getting colder, I've been switching on the heating. What I'm wondering is, is it better to have the gas on for longer periods of time e.g. continuous for say 3 hours or else switching it on or off regularly in a 6 hour period e.g. on for 1/2 hour, off for 1/2 hour.

Both scenarios have the heating on for 3 hours, but would it cost the same and would the heat levels be noticeably different (ignoring variables like insulation levels)? Is there an efficiency from maintaining water at a certain temperature as opposed to heating water that has cooled down a bit in the half hour drop.

Just trying to figure out the most efficient way to keep my apartment warm!

Ush1

Continuous is more efficient, especially if you have a condensing boiler. Try lowering your flow temp and leave on the heating for longer periods. Should be a more comfortable heat also.

VonLuck

https://www.boards.ie/discussion/comment/119970934#Comment_119970934

Is there any way of knowing what the flow temp is, or what the optimum level would be?

Ush1

https://www.boards.ie/discussion/comment/119971072#Comment_119971072

It can be tricky depending on the modulation of your boiler. You want to avoid excessive cycling of the boiler. With flow temps, generally the lower the better so best thing is to set the flow temp down and keep going until it's either not heating the house or the boiler is cycling too much. The very cold weather we are having should reduce cycling some what anyway.

10-10-20

https://www.boards.ie/discussion/comment/119970934#Comment_119970934

This is correct if you're in the house full-time and have a need for the house to be heated over that duration, but I will add in that some people believe that it's still most efficient to leave heating on continuously while out of the house or when the occupation is low. It might seem obvious to some but not others.

Where I am I get some moderate solar gain and this negates the heating on during bright days - even today I only had it on for an hour in the AM, but on an overcast day it will be running until afternoon.

So the generic answer very much is: it depends on the circumstance.

unnamed

It also depends on the heating type. In most cases, underfloor heating with an Air to Water heat pump should be left on.

VonLuck

Thanks. How much more efficient is it running this way in reality? Like if I'm turning the heating on for 30 minutes just to get the room temp up to a bare minimum, should I just leave it on for an hour to a bit more of a comfortable temp as it's not much of an extra cost?

Am I right in comparing it to having an initial intense start up stage where more gas is consumed (similar to a car accelerating) and then it's a steady lower consumption maintaining at the higher temp (car travelling at a constant speed)?