Vanette Hob Trouble

[avonside1563]

I have just installed a Vanette 4000 Hob, bought second hand but unused, and the burners won't stay lit when it is turned down to minimum. They run for a few seconds then pop and go out, and sometimes when on full the note of the gas changes from a hiss to a roar (although not a loud roar!).

 

I wondered if this might be due to the wrong jets being fitted? It's running on standard orange calor and the pressure and flow rate are all fine.

 

Any suggestions?

[alan_fincher]

It's running on standard orange calor and the pressure and flow rate are all fine.

How are you measuring "pressure" and is that actually at a test point near or on the hob ?

 

How are you measuring "flow rate", (this sounds harder!).

 

To confirm, is this (although "second-hand") actually a brand new unit, and does it have required flame failure devices ?

 

What do you know about it, and did the seller explain why they were getting rid of it ?

 

I'm no expert, but I can't see anyone wanting to fit one of these for jets other than for LPG - it would make no sense, as if you had the choice of natural gas, I can't see you bothering with what is basically a fairly basic caravan/boat hob.

 

As far as I know it would use the same jets on butane (blue Calor cylinder) as on Propane (red calor cylinder), although the regulator pressures for each are usually different.

 

To me it sounds like you have a problem with the supply, so I think the question that how you know the pressure is OK is most pertinent. What did you measure it as ?

[larkshall]

Get the hob seriel no, and model no and phone the makers.. They should be able to tell you the factory settings. This sounds like a flow rate problem. If it is you will need a gassafe bod to set it up properly.

[Ray T]

Just a thought, when on low is the flame keeping the thermocouple hot enough?

 

These may be of help:

 

http://www.leisureshopdirect.com/Caravan/gas/Stoves_hobs_and_cookers.aspx

Edited August 2, 2011 by Ray T

[avonside1563]

Thanks, the pressure was tested two weeks ago by a gas safe inspector at a test point just beyond the hob. He's due back to check the installation so will get him to look.

 

Yes it does have FFD and the original purchasers were selling as it didn't fit in the space they had. most of the bits were still in the original sealed packaging when I got it.

[the grinch]

if it is just going out on minimum then you should be able to adjust it yourself its not rocket science. most cookers / hobs have adjuster screws to set the minimum. these are under the knob and come in 2 variations 1. in the spindle (look and you will find a hole in the end), 2. a small hole in the hob plate again under the control knobs, a fine flat screwdriver is used to adjust

light the ring you wish to adjust on about 2/3 flame adjust the screw anti clockwise a small turn at a time, then try low flame it is set correctly when it stays alight when turned to minimum. repeat for each ring.

 

some burners do roar on high flame, this is due to flame lift take the burner cap off and the flame retention ring and wash in warm soapy water to clean of any debris under the cap & in the slots of the flame ring. (do not use cleaners etc on chromed fittings as it will damage them)

 

hope this sorts the problem if not get a gas engineer to look at it for you he must have LPG Boats on his Gassafe Register card (cards are dated on the front and his competences are on the back.

 

edit to say a few have screws that are cack handed so you may have to adjust clockwise instead, you will soon work out which way increases and which way decreases the flame speed.

very unlikely that the injectors are wrong from what you have said LPG is very floppy when a NG injector is fitted on NG with LPG injectors the flame would be huge (around 9 -12" high!)

Edited August 2, 2011 by hamsterfan

[MtB]

I have just installed a Vanette 4000 Hob, bought second hand but unused, and the burners won't stay lit when it is turned down to minimum. They run for a few seconds then pop and go out, and sometimes when on full the note of the gas changes from a hiss to a roar (although not a loud roar!).

 

I wondered if this might be due to the wrong jets being fitted? It's running on standard orange calor and the pressure and flow rate are all fine.

 

Any suggestions?

 

 

I agree with everything Alan said. He has a far clearer understanding of LPG than most gas engineers I know!

 

I'd ask the same questions. You say the gas pressure is fine, but what is pressure you have? How did you measure it? And what pressure do you believe is correct?

 

The most accurate way of measuring the operating pressure on a hob is to remove one of the gas jets and insert an adaptor (made from a scrap jet with a piece of 8mm copper soldered on). Fit your manometer hose to the adaptor then turn that particular gas ring ON to measure the standing pressure. Now light the biggest gas ring to measure the operating pressure.

 

Another, less accurate way is to find a different appliance on the system which has an inlet test nipple, eg a water heater or central heating boiler and measure the standing and dynamic pressures using that.

 

Moving on to measuring the flow rate, I'm all ears as to how you did this. The only way I know of is to weight the gas bottle at the beginning and end of an extended test period. Is this what you did or are you guessing really?

 

Anyway moving on to your symptoms, the low setting blowing out is s symptom of abnormally low gas pressure so we NEED to know the result of a working pressure test. If yours is low then the prime candidate is the bottle regulator. They are cheaply made and fail commonly. Try changing it. If a new one makes no difference we need to check the installation pipework for restriction or under-sizing.

 

The hiss-to-a-roar effect you describe on full flame is often called 'blow-back', and is where the gas flame disappears inside the burner cup and burns out of view. Can be low gas pressure again but more often caused by incorrect assembly of the burner/jet assembly.

 

Going back to the flame going out on 'low' setting, it is quite likely that the flame is too low to keep the thermocouple hot so it thinks the flame has gone out and turns the gas OFF. Low gas pressure again. If the gas pressure turns out to be correct of measuring, then the low gas flame size is adjustable on most hobs, with a little grub screw revealed if you pull the control knob off.

 

Mike

 

(Edited to correct my spelling of Alan's name!)

Edited August 2, 2011 by Mike the Boilerman

[avonside1563]

The FFD is not turning the gas off as the flame pops when it goes out but the gas continues to run for a few seconds until the FFD cools and cuts it off.

 

Chappie due back in a couple of days to check it all (he's full Gas Safe for boats) so will take on board comments and pass onto to him, although he's one of the old school and been all round the block several times so rather think I might be teaching him to suck eggs!

 

Will come back if that gives no joy!

 

Thanks chaps

[alan_fincher]

Faulty regulators occur remarkably often, and is a likely cause, but they might well affect any gas appliances, depending (possibly!) on how much gas you are trying to pass through them.

 

What other ones (if any) do you have, and are they working normally ?

 

Do they still work normally if you try and light all the gas rings at the same time, or do they also then start to misbehave ?

 

What did your gas safe engineer tell you about the pressure(s) he had measured ? Just that they were "normal", or did he give values ?

 

More information might help people advise more......

 

EDITED: Because I had managed to miss some answered questions......

Edited August 2, 2011 by alan_fincher

[MtB]

The FFD is not turning the gas off as the flame pops when it goes out but the gas continues to run for a few seconds until the FFD cools and cuts it off.

 

Chappie due back in a couple of days to check it all (he's full Gas Safe for boats) so will take on board comments and pass onto to him, although he's one of the old school and been all round the block several times so rather think I might be teaching him to suck eggs!

 

Will come back if that gives no joy!

 

Thanks chaps

 

 

Not sure you need to be trying to teach him to suck eggs, rather to answer some questions thrown up by what he has told you.

 

Given that he appears to have told you the gas flow rate is 'fine', I think it would be reasonable to ask him how he knows this given the difficulty in measuring it. It 'could' be that he has not checked it at all and was shooting from the lip as they say. Or maybe you understood him wrong and he did not say he had checked the gas flow rate.

 

In addtion it is entirely reasonable to ask what the gas pressure recorded at the appliance input was. It is supposed to be 37.0mBar (+/- 3.0mBar IIRC) with the appliances running. 'Fine' doesn't really cut it!