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Can the boiler be on while 2 out of 4 radiator are dissconne

Postby Lenasofia » Thu Sep 27, 2007 5:54 pm

Hi we are fixing up the flat so two of the radiator have been lifted off I think I read somewhere in the vokera linea manual that we should not keep the boiler on if some radiators were taken off because it is used to the pressure and that certain amount of water. Is this true...? Do we need to drain the whole system from water because that it might freeze? If so any tips on how that should be done. The whole flat only have 4 radiators and only 2 has been lifted off. Is it ok to have the boiler on and not use any hot water..or is that bad too so it wont freeze! Please answer quickly ..hopefully today the 27 of Sept.. thanx L
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Postby ollie83 » Fri Sep 28, 2007 6:30 pm

THe pressure refered to in the manual is displayed in the front of the boiler on a guage. this should read 1-1.5bar. if this is the case and the heating system is full of water (bleed rads) it will be fine to run the boiler.
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Postby ollie83 » Fri Sep 28, 2007 6:37 pm

forgot to mention that you should be sure to check that the valves on the rads that have been removed are closed and are not letting by, if they are thermostatic (have larger heads with numbers on ) they should be caped as they could automaticly open in the cold. ps you should have a filling point on the system to top up the water pressure, on the boiler or local to the boiler. check the manual. if its local to the boiler it will look like a silver flex pipe between 2 valves. good luck.
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Postby rosebery » Fri Sep 28, 2007 8:41 pm


You really ought to ask Vokera for a definitive answer but as the Linea is a combi then I'm going to give you the following [b]generic[/b] information as I don't know the specifics of your system:

A combi boiler system works under pressure - typically 1 - 1.5 bar and you have a guage to tell you the system pressure and a filling loop to top it up if the pressure falls.

If the pressure falls, for whatever reason, the boiler (well the vast majority of them) have a sensor system which says " no pressure - no start" and it won't run because they don't like to run dry.

When you took the two rads out of the system you will have drained them and therefore taken a chunk of water out of the system so the pressure is/was down. Presumably you topped it up again to the required operating pressure?

The boiler is not that clever that it can count the number of rads comnected at any one time. Apart from pressure the other variable that it can measure is temperature and there is a safe temperature over which it will not operate.

Given that there is a reduced volume of water in the system now the returning water to the boiler will be hotter than normal. If it gets too hot then the tempereture sensor should kick in and the boiler shut down. You'll probably have two sensors potentially working in opposition now. If the room stat is saying "air temp not hot enough" it will be sending a "call for heat" message but if the boiler thinks the temperature in the system is too high it should ignore the call for heat and shut down.

It shouldn't really care about the volume in the system at all just the temp and the pressure.

As far as DHW is concerned the feed for that is mains cold water at mains pressure and the combi boiler just heats what you need when you want it ie when you open a hot tap. Shut off the mains at the main stop cock and the pressure falls and the boiler won't start either. I can't really see any reason why you can't have your DHW running and your CH running even on reduced number of rads but I REPEAT I don't know the details of your system so my answer is not definitive and is offered without liability of any kind.

I'm sorry I really don't understand your reference to "freezing" at all.

If you think you have seen something in the manual, as I said at the start of this post, you really need to contact either the manufacturer or your supplier / installer with your query.

Do you have the manual so that you can check exactly what it says yourself???????

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