space-i am just trying to learn about boilers as i am interested. sorry if my question made no sense or stupid.
Boilers - the workings?
- Thread starter liverpoolboy
- Start date
space-i am just trying to learn about boilers as i am interested. sorry if my question made no sense or stupid.
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a few posts hadn't appeared.
in my mind conventional means c/f.
baxi amongst others make/made c/f boilers with spark ignition with fsd of various descriptions.
in my mind conventional means c/f.
baxi amongst others make/made c/f boilers with spark ignition with fsd of various descriptions.
Liverpool boy
evidence that a flame is present is fundamental to safety as the main danger of methane (the combustble component in natural gas) is it's explosiveness. This is why gasfitters are always happy to run a gas pipe externally. In open air you will never manage to make a bomb out of methane. in a confined space without ventilation (caverty wall house cupboard underfloor) boomb! is very easy to achieve.
So boilers have to continually check for presense of a flame.
Broadly speaking this is flame supervision. in the olden days and in somecases such as oxypilots today the heat from the flame was the indicator that gaswasbeing burned. Whether it heated two different metals thus bending them to maintain gas or heated a liquid wich turned into a gas and massively expanded to operate a valve or whether an electronic current was produced by two dissimilar metals being heater in proximity.
Today presence of flame can be sensed by passing a dc current through flame. If the flame is not present no current flows. Originally when the people with large foreheads thought this one up they passed ac through the flame. However the dodgy person who must always be predicted in the interests of safety could simply bridge the sense electrode to earth and defeat the safety device. unbelievably yes people to defeat safety devices. It is amaising what lack on heat and hot water does to people. i still can't fathom out what is so important about it. Such people must have had no hardships in life whatsoever. but anyway i digress.
So what the eggheads thought up was using the flame as a rectifier. The cowboy can't justcl;ipleed any more as it won't rectify. He would need tohave enough intelligence to buy a diode. If he were that bright he wouldn't be dodgily providing people heat and hot water at risk of blowing a terrace sky high.
evidence that a flame is present is fundamental to safety as the main danger of methane (the combustble component in natural gas) is it's explosiveness. This is why gasfitters are always happy to run a gas pipe externally. In open air you will never manage to make a bomb out of methane. in a confined space without ventilation (caverty wall house cupboard underfloor) boomb! is very easy to achieve.
So boilers have to continually check for presense of a flame.
Broadly speaking this is flame supervision. in the olden days and in somecases such as oxypilots today the heat from the flame was the indicator that gaswasbeing burned. Whether it heated two different metals thus bending them to maintain gas or heated a liquid wich turned into a gas and massively expanded to operate a valve or whether an electronic current was produced by two dissimilar metals being heater in proximity.
Today presence of flame can be sensed by passing a dc current through flame. If the flame is not present no current flows. Originally when the people with large foreheads thought this one up they passed ac through the flame. However the dodgy person who must always be predicted in the interests of safety could simply bridge the sense electrode to earth and defeat the safety device. unbelievably yes people to defeat safety devices. It is amaising what lack on heat and hot water does to people. i still can't fathom out what is so important about it. Such people must have had no hardships in life whatsoever. but anyway i digress.
So what the eggheads thought up was using the flame as a rectifier. The cowboy can't justcl;ipleed any more as it won't rectify. He would need tohave enough intelligence to buy a diode. If he were that bright he wouldn't be dodgily providing people heat and hot water at risk of blowing a terrace sky high.
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thanks for helping Paul.
Really appreciate it.
I was reading a central heating fault finding & repair book, and the only section i wasn't understanding too well was the boiler section (for obv reasons)!
What I was trying to work out is the starting sequence for a gas boiler.
Another book I was reading by Treloar, called Plumbing! was suggesting that each boiler had 2 solenoids (a main one and one for the pilot), and they were part of the multifunctional gas valve.
I suppose different boilers (condensing / modern types) have different starting technquies now to the older back/conventional boilers!
Really appreciate it.
I was reading a central heating fault finding & repair book, and the only section i wasn't understanding too well was the boiler section (for obv reasons)!
What I was trying to work out is the starting sequence for a gas boiler.
Another book I was reading by Treloar, called Plumbing! was suggesting that each boiler had 2 solenoids (a main one and one for the pilot), and they were part of the multifunctional gas valve.
I suppose different boilers (condensing / modern types) have different starting technquies now to the older back/conventional boilers!
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