Gas quality change?

Mlasso

Hello, 

I work in a pizza restaurant and we have gas pizza ovens. They are small, stackable ovens, so we have three of them. All three are the same make / model.

About a month ago all three of them started having ignition issues. This happened before on one of them (faulty gas valve) and I was told that this is rare thing to fail. Also, if it fails, oven cannot work at all.

However, this time, all three ovens are working and turning off randomly. If I press ignition button manually, they manage to ignite the flame again and then work for a few minutes until they lose gas. I can turn it on again manually and they again work for a few minutes.

Considering that they can all work if pushed for ignition reset, and that all three started having the same issue at the same time (and issue it self is very rare to happen at all), I was told by technicians that probably something is wrong with the gas.

I have zero knowledge in gas, so I cannot comment, but from total amateur perspective it does seem like gas is causing issues because it is like "bad batch comes" and oven shuts down, but as soon as it is restarted it works normally.

Gas is mains gas (connected to gas meter, no refillable bottles) and provider is Pozitive Energy.

We had the exact same oven setup on CNG and when CNG failed we were transferred to Pozitive Energy. This never happened on CNG.

Does anyone have any possible explanations on how can this happen and what can be done about it?

Thanks!

Robin9

Neither CNG or Positive Energy have any control over the quality of the gas to your property.

Others on this forum will be able to give you comments on variations in Calorific Value.

What maintenance do your ovens get ?

Rodders53

You need a Gas Safe man to check gas pressure and flow rates when ovens are in use (plus check ventilation in so that it's not a lack of air to burn the gas, that then goes out).

Flame failure thermocouple position, too and that controls the gas valve shut off if faulty or not properly in the flame... Manual ignite opens valve manually rather than by thermocouple action.

You do have a CO monitor/alarm I trust.

It's possibly a regulator fault from mains gas in to meter output, so reducing/limiting the gas supply?  But Gas Safe person's measurements should be able to confirm.

NB The gas in the pipework is the same gas no matter who "supplies" it (= who you pay for it).

When were the ovens last maintained (serviced)?  

[Deleted User]

Yes, consumers do get confused by the word ‘supplier’ There is a clue in the word Grid. If I take a contract out with an energy supplier to provide me with gas, it undertakes to top up the Grid by the amount of gas that I use. The Grid top up might be from a LNG tanker in Milford Haven or from pipeline from Norway. Mixing will cause some changes to the calorific value which is why billing has to take this into account.