Hi, my boilers been playing up a bit recently so I'm suddenly paying more attention to it! But realise I don't know what is normal. Should the blue flame always be on if the heating is switched to on, or will you sometimes hear the boiler 'working' while the flame is off? It's a Vokera linea 24. Thanks for your help.
Should blue flame be on the whole time heating is on?
- Thread starter Goosey75
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Your boiler will reduce power ( modulate ) to the heating.
Depending on the amount of heat needed it may sometimes turn the flame off and leave the pump running for a few minutes.
There are too many variables and particularly the heat loss of your property and how correctly the boiler has been set up ( serviced ) for me to be able to tell you anything definite based on virtually no information.
In a small flat the boiler would usually cycle on/off every few minutes once the flat had warmed up.
In a three bed semi the boiler would be likely to stay on because the power required would be within the modulation range.
The boiler minimum output is very sensitive to the gas settings and can vary quite widely and particularly because many engineers don't bother very seriously with setting the minimum rate.
A small flat might need 2-4 kW whereas a three bed semi might need 10 kW. The boiler can give 24 kW and a minimum of about 8 kW. But on many badly adjusted boilers the minimum could vary between about 5 kW and 12 kW.
Rather a technical answer but many do like to read about all the details!
Tony
Depending on the amount of heat needed it may sometimes turn the flame off and leave the pump running for a few minutes.
There are too many variables and particularly the heat loss of your property and how correctly the boiler has been set up ( serviced ) for me to be able to tell you anything definite based on virtually no information.
In a small flat the boiler would usually cycle on/off every few minutes once the flat had warmed up.
In a three bed semi the boiler would be likely to stay on because the power required would be within the modulation range.
The boiler minimum output is very sensitive to the gas settings and can vary quite widely and particularly because many engineers don't bother very seriously with setting the minimum rate.
A small flat might need 2-4 kW whereas a three bed semi might need 10 kW. The boiler can give 24 kW and a minimum of about 8 kW. But on many badly adjusted boilers the minimum could vary between about 5 kW and 12 kW.
Rather a technical answer but many do like to read about all the details!
Tony
Which boilers allow you to adjust the minimum output? Maximum - yes; but minimum???
Seriously?
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Hi, thanks Tony. That is very helpful. I realise you can't tell me if it's all behaving normally from the info I gave. I just wanted to know whether the flame is ever off while heating on and boiler sounds 'on' - and you've answered that for me. Thanks very much, Goosey
Virtually all conventional burner boilers which modulate have a maximum and a minimum setting on the gas valve.
Unfortunately I would guess that about half of all gas engineers don't know how to set the minimum.
When I go to boilers I always check the min and max and many have the min quite a way out, usually too high.
A typical minimum burner pressure is about 1.5 mbar. If that is only 1.0 mbar or is at 2.5 mbar then you can see that it will make a big difference to the minimum power output.
Tony
Corrected my earlier post with the "g" of "gas" missing! I did try to do that immediately after posting but my computers are having a bad week!
I've never seen this info in an installation manual. Could you give me an example?
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Looks like there is a confusion between minimum rate and ignition rate. 
"Many RIG's don't bother"????????
"Many RIG's don't bother"????????
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CH minimum rate for the 24 is 1.9 mb , are you suggesting you deviate from this pressure setting? , If so could you tell me input rating based on a 1mb burner pressure? , If you would like the injector sizes then give me a shout.
Minimum CH output is 9.3 kw's.
Another sweeping generalisation from the master of sweeping generalisations there... keep them coming Tony, we love it when you look down your nose at the rest of us mere mortals
I knew that a gas valve had max and min adjusters, but didn't realize that they were for adjusting the pressure.
Most manuals show them being used to adjust the CO/CO2, so I thought that they were adjusting the amount of Oxygen. Wrong
. I assume that the fan controls that?
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Re quote; I assume that the fan controls that?
Indeed, with any air/gas mixtures, air is almost always the 'lead' or 'fixed maintained' starter and the gas is fed into the stream to a determined mixture, the 'ratio'.
The same mixing procedure is used on all package-units for example.
In the premix system, where the air/gas mixture is mixed prior to being fed to the burner, the zero governor 'servo bleeds' a flow of gas into the air stream creating the pre-mixture and causes a negative pressure at the valve seat and becomes "zero" pressure at that point (the pressure fulcrum) - In domestic burner situations it will always be the air from the fan that determines the precise burn mixtures.
Any high/low or infinitely variable gas flow rate burner has to have a minimum setting so that flame monitoring can be maintained, otherwise the main burner could go so low as to extinguish.
+1 to Agile on this topic.
Indeed, with any air/gas mixtures, air is almost always the 'lead' or 'fixed maintained' starter and the gas is fed into the stream to a determined mixture, the 'ratio'.
The same mixing procedure is used on all package-units for example.
In the premix system, where the air/gas mixture is mixed prior to being fed to the burner, the zero governor 'servo bleeds' a flow of gas into the air stream creating the pre-mixture and causes a negative pressure at the valve seat and becomes "zero" pressure at that point (the pressure fulcrum) - In domestic burner situations it will always be the air from the fan that determines the precise burn mixtures.
Any high/low or infinitely variable gas flow rate burner has to have a minimum setting so that flame monitoring can be maintained, otherwise the main burner could go so low as to extinguish.
+1 to Agile on this topic.
I knew that a gas valve had max and min adjusters, but didn't realize that they were for adjusting the pressure.
Most manuals show them being used to adjust the CO/CO2, so I thought that they were adjusting the amount of Oxygen. Wrong
I was specifically talking about conventional burner boilers like the one this topic is about.
The gas valve has a min and a max setting.
Premix boilers have a different set of adjustments which can vary widely from boiler to boiler.
But they are really outside the scope of advice for DIY work although interesting.
Tony
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