Oil Central Heating

[Nick]

Hi,

Hopefully posted in the right forum.

I have a Guillot (Cythia) oil central heating system which is working OK.

I need to leave the house for a few weeks but want to leave the heating (and hot water) on, but want to turn the mains water supply to the house off.

as the boiler is a sealed system, i'm assuming that it doesn't draw to much new water and will circulate the central heating water and normal hot water continually. I have left it on for 24 hours with both the hot water and radiators at a low setting

Am I setting up problems for myself by switching the mains water off? 

[Gyn_Paul]

I'm assuming you've had the CH system up and runnning long enough to know it doesn't lose pressure? In which case there should be no problem leaving it on in your absence (apart from the oil you'll be burning, of course!) . With the mains water turned off, even with a dripping hot tap, all that will happen is the pressure will run off the hot tank. It will still be (almost) full of water.

If you DO have to top the system up then I wouldn't recommend leaving it on.

p

[Nick]

Paul,

Thank you for your reply. You are correct, my main concern was that if there was a leakage, the burner would continue to heat a diminishing amount of water , that was not being replenished from the mains supply and would eventually run dry. I'm assuming in this worst case, the burner would have some sort of cut-off that prevented it from trying to heat a limited supply of water?

[Inca]

I have left my 10 year old Optima  sealed system on low setting for the last two winters, approx early November to mid February and fortunately, have not experianced pressure/water lose.  I did confirm with the Heating engineer that this was ok and I did have the boiler serviced.  The safety cut outs for pressure lose or running out of oil is a question I need to clarify at my next service .    

Mike 

[Gyn_Paul]

[quote user="Nick"]

Paul,

Thank you for your reply. You are correct, my main concern was that if there was a leakage, the burner would continue to heat a diminishing amount of water , that was not being replenished from the mains supply and would eventually run dry. I'm assuming in this worst case, the burner would have some sort of cut-off that prevented it from trying to heat a limited supply of water?

[/quote]

Well even if - for argument's sake - the hot tank was to split and dump its entire contents you would still be left with a boiler heating water to run in a coil inside a (now) empty tank. The coil is not much different in surface area (if somewhat different in shape) to one of those chrome multi bar bathroom towel rail-type radiators; the coil water temp is regulated by the boiler controls; it wouldn't be losing much heat so would be returning to the boiler at much the same temperature as it went therefore the boiler wouldn't light up very often: not a runaway scenario at all, in fact, no big deal, really (other than the 200l of water on the floor, of course!).

My sealed gas CH system in the UK had a habit of losing pressure quite randomly once or twice a year. Never did find where the intermittent leak was - probably under the floor somewhere - and if I didn't notice the pressure dropping it would eventually get to a state where the air dissolved in the water would boil out of solution and cavitate in the pump. If we didn't notice that, the boiler's overheat sensor would trip out. Allow to cool down, refill to 1.75 bar, reset cut-out and everything would be fine again (I'd then monitor the damn thing for MONTHS and it wouldn't alter by so much as .1bar!).

I would assume an oil boiler would behave in a similar way but cannot confirm.

Perhaps OPEL FRUIT would like to chip in here ??.........

p