CH - constant or timed?

[Isambard]

I'm sure this has been asked before but searched the forum and can't find answer:

Is it more efficient to leave CH on 24/7 or time it for 2-3 sessions per day?

My intuition (and 2nd law of thermodynamics) suggests the latter but BG engineer told me that leaving it on 24/7 and just varying the 'stat is more efficient and saves fuel (v important as we're on LPG!)

If BG engineer is right, can I fit a digital 'stat in place of the mechanical, leave the CH on CONSTANT and have timed temperature variations (ie. night & day)?

We live in a converted chapel (lots of thick stone walls) that takes ages to heat up. Have a Worcester Bosch SBi24 LPG boiler (not a combi), Honeywell ST6300A programmer, Honeywell mechanical thermostat & 'stats on all but 2 rads.

Cheers!

 

[PaulAH]

You cannot escape the principle that more heat is lost from a hot body than a cold one - in other words, the hotter your house, the more heat will disappear outside.

In the end, it's down to what you perceive as comfortable. Cold walls and hot air - fan heater scenario - do not necessarily make you feel warm because the radiant heat from your body will still be sucked away.

Since you have thick walls of high thermal capacity, you may find that it feels warmer when you pump heat into the building an hour or three before you need it. Experiment and trust your judgement.

 

[Isambard]

Fair enough - I'll start some experimenting. Timed sessions first.

Still interested in a digital thermostat though - are they more accurate than the mechanical type? The ability to programme a different temperature for day and night might be useful.

 

[bripl]

yes a digital thermostat with night set back will help.

 

[oilman]

The OFF switch saves most money, the next biggest saving is to get rid of LPG and change to oil, this is BIG-BUCKS!!!!!!!!!

 

[Isambard]

Unfortunately, OFF isn't an option at our place this time of year!!

Oil could be a player although I've used it before and the savings were nearly offset by having to have the mucky boiler cleaned & serviced every 12 months (yes I know all boilers should be serviced but gas is generally more reliable, fingers crossed....).

Digital 'stat much cheaper option initially - is it usually just a straight swap?

 

[oilman]

If it's that much of a problem, you can clean out the boiler yourself.

 

[ChrisR]

For me, Programmable stats are marvellous for being comfortable without wasting heat. Honeywell CM67 with "optimum start" was king but there are new ones all the time. If your bills are high get the outside temperature module for it too, as it will pay for itself eventually.

Also there are clever timed and radio linked TRV's which you can use for less-used rooms. These are more expensive than conventional "zoning" valves but much easier/cheaper to install .
A friend took this route and saved a lot - though his starting point was a £2000 a month oil bill!

 

[PaulAH]

DIY boiler servicing? Opening a whole worm of cans there, Oilman!

Isambard, there's no contest on the digital/mechanical front if you want different heat settings at different times of day/night. Here's one

http://www.danfoss-randall.co.uk/Si...mplateID=52&intPage=995&strLang=en&intLang=2&
intLevel=2&intInternalLink=&intLevel2ID=&intLevel3ID=&intLevel4ID=&intLevel5ID=&intLevel6ID=&intLevel7ID=
&intLevel8ID=&intLevel9ID=&intLevel10ID=

It may not bring you vast savings but it would be fun to play with!

The best thing I ever did savings-wise was to put a separate zone valve upstairs with independent controls. Since all you do upstairs is go to bed and get up (nothwithstanding other activities) there's usually no need to keep a whole storey heated.

Edit: That long address screwed up the display so I've chopped it into separate lines. It will need copying and reassembling.

 

[Agile]

Another alternative is to move to Hemel Hempstead and turn your heating off completely.

Tony

PS Even with the windows closed and at about 15 miles away, it woke me up at about 0600 with a sound like 12 seconds of very high speed wind!

 

[ChrisR]

I thought my wife had farted.

 

[PaulAH]

Have her hermetically sealed.

What are you two on about anyway - Heathrow?