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Boiler fuel consumption

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Seems that some people are getting through heating oil rather faster than perhaps they should??

Apart from the obvious poor building insulation, pipe insulation and draughtproofing, there may be a lack of efficient control and operation of the heating system - and I realise that most people have inherited their system.

  • timers/programmers - simple to install, can provide both improved comfort and economy. Correctly set and USED of course...
  • room thermostats - correctly sited, correctly set will provide control over temperature and thus energy use
  • Thermostatic radiator valves (TRVs) - control the temperature in each room - save energy - don't fit one where the room stat is
  • balance the system - are all the radiators equally hot?
  • can the system water flow well? - if you have black sludge in the rads, don't expect an efficient system
  • regulate the boiler temperature - anything more than 60/65C is wasted - if the house won't warm at this, the rads are too small, or blocked
  • frost stat - rather than keep a system running all night, let a frost stat run the system only when needed
  • Hot water temperature - applies to Chauffe-Eau too - anything hotter than 65C is wasted energy and can scald - turn it down
  • make sure the hot water is on a programmer too....
  • does your boiler keep switching on and off? - it should do, but if it comes on for a minute or two every few minutes, the boiler power is far too high - inefficient and the burner will wear out quickly. Have the power reduced and save big money.
  • Is the boiler running efficiently? - is it clean inside? - has it been correctly set-up? does it smoke?
  • Is your mixer valve set correctly? - the vannes melangeuse is a bit of a joke, if you have one, make sure it is fully open
  • consider fitting zone valves if your system could be split

I haven't seen a single system, of any age here that I could say was an efficient and economical system. Quite how someone can have a gas boiler fitted for 4500 Euros (yikes!) where the owner had to plug it into a socket to operate it is just *./',',/ ridiculous.



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Thanks Opel for a timely post. I am no expert but have often thought about most of the points you raised. I have just inherited a rather large system and am still learning its "personality"

Do you have any idea how much heat loss can be attributed to non insulated pipes? Approximately 70% of our living space is not occupied and yet we seem to be heating these non occupied rooms indirectly with the pipes that supply the radiators and go between the levels.

On the surface the heat control mechanism seems sophisticated with measurement of the outside temp dictating the flow temp inside. I am yet however, able to work out how the system is able to recognise the insdie temp (ie I havent seen a thermostat device inside) The outside one is obvious. What should i look for for an inside thermostat?

If one were to change the valves to thermostatic, would this necessarily mean draining the whole system? Not a nice though if you want to do some changes in the middle of winter!

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 Peter. Most Electric Temperature Control Units are normally fitted with mixing valve or burner control selector complete with external and flow pipe sensor,and daily or weekly time clock with two room temp settings it allso controls the automatic op of the circulation pump.Its allso equipped ready for attachment of an optional room sensor.This permits further temp variations of + or- 5degreesC.When i calculate heat loss on bare copper pipe i allow 20% of total circuit heat output.That might seem a bit high to some heating engs who probably allow only 10% but when taken in consideration of the u values of the walls floors roof and windows and the air changes of 1.5 to 2.0 etc in designing the system and calculating the btus of the boiler its about right for myself.. Changing to thermostatic rad valves,yes you need to drain down plus redoing the inhibitor..Happy days.
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If you are in the uk  where its still the norm just about, to have open vented systems then you could half drain the system by just putting the hose pipe over the top of a door from the ground floor drain cock.or even putting a bung in the open vent and cold feed in the feed /expansion tank and causing a vacuum.If in europe or you have a fully pressurised system then same thing just put the hose over the top of the door and just drain 1st floor.I personally think its better to keep the boiler stat low as possible say 2 in the autumn months going up as winter creeps in colder.not forgetting if the hws/ballon is allso heated by the boiler 1.5 to 2 stat setting would be low enough.Heat loss in the[pipes]in a normal domestic house is 1degree or less with the pipes lagged under the screeds/voids/roof spaces etc.[You could hire an electric freezer kit and just change the valves one at a time.]Happy heating.
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Heat loss in copper pipes is about 100W/m for 22mm, 60W/m for 16mm. This is for pipe at 80C, with an ambient temperature of 20C. So for a 10m run of 22mm you are looking at up to 1kW of loss.

The higher you set the boiler stat, the worse the losses are, obviously. I suggest the boiler flow is set to around 60C. Note that when purging the system initially, it is important to run the boiler at >80C for a period to allow the aerated water to release air. 

The room stat must control both the boiler and the pump. Normally, the switched output of the stat is used to supply mains to both the pump and the boiler, or the pump is wired to the boiler and SHOULD allow the pump to continuing running whilst the boiler switches on and off according to the heat demand. The boiler MUST NOT fire with the pump off. 

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