How do I increase my gas supply volume to a large capacity supply?

Userlevel 2

I am looking to increase my gas flow volume at a residential property.  We are just about to add a new extension and its looks as though I will need to increase the KW of our boiler to 60kw.  I also have a 16kw gas fire and hob.


Is it a case of changing the meter or does the pipe need to be changed to the road?  From what I can gather most standard gas meter can provide around 6 cubic metres and a larger boiler needing this alone without any of the other appliances.  Any advice or help appreciated. 

18 replies

Userlevel 7
Badge +4

Hi there @bonjourpaul and welcome to the OVO Forum! :)

We can definitely try to answer this one for you, but I could do with having a few snaps of your gas meter. This helps us to work out which one you’ve got and we can then (usually) grab the datasheet for that model. Transparent usually takes Wednesday’s off, so I can’t ask for his thoughts today, but he’ll probably see this thread when he next checks in.

If you could upload a few photos of your gas meter in your next reply, that would be great.


Userlevel 2


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Userlevel 2

Thx Blastoise much appreciated. Looking for options - photos should be above any other info please let me know. 

Userlevel 7

Great question this one, @bonjourpaul - and one that’s not been covered in depth here before.


It sounds like you’ve already done some research as you’re nearly spot on in terms of the capacity of a standard gas supply. The standard gas meters (also known as G4/U6 meters) have a maximum output of 64.6 kWh, in order to confirm that your current supply will need an upgrade you’ll need a gas safe engineer to calculate your ‘Service Pipe Energy  Value’ (SPEV) in kWh which covers the total amount of gas used by all appliances (or planned appliances) in your home. If the standard gas meter isn’t going to be able to supply enough to fire up all the planned appliances, you’ll need to upgrade to a G10/U16 gas meter. These ones have a maximum capacity of 172.3 kWh.


How does a U16 upgrade work?

It’s a bit of a long process as we’re not the only party that need to be involved. To summarise, the process for upgrading to U16 is:

  • We send the SPEV information (the max load capacity required by your home) to your gas transporter, via a GT1 form
  • The transporter perform a service upgrade to incoming pipework if necessary
  • You may need to have a new meter box (kiosk) fitted (the U16 meters are larger than standard meters and might not fit in your current meter box)
  • National Grid Metering replace the meter for free for a U16 meter (there might be a site-survey cost to pay - see more here)
  • You’ll need to organise a gas-safe engineer to connect up the pipework afterwards


Hope this helps outline the steps which need to be taken. Have you already had the ‘SPEV’ confirmed? 

Userlevel 7
Badge +4

No worries, these are absolutely perfect. :)

I can definitely confirm that your gas meter is a SMETS1 Secure Liberty EG4v 10, so your electricity meter right now is almost certainly a SMETS1 Secure Liberty 100 (or another one in the Secure Liberty 1xx family).

I’ve never seen anyone ask this question before myself, but luckily I did manage to find an existing question that’s somewhat related.

It’s quite likely that a Meter Exchange (MEX) will be needed to upgrade your gas supply. I can’t seem to find any calculators that can help do the number crunching, but I wouldn’t be surprised if you’d need to get an upgrade or two on the supply. There may be a charge for this service. I’ve grabbed the jobs list for you so you can get an idea.

In theory, I think the MEX from U6 to U16 job sounds like the closest match, but I might not be on the right one. What I can say is that if I am on the right track, the MEX itself might be free but you’ll probably need a Site Survey. Worst case scenario is that you could end up paying for a few jobs that would need doing. I’m afraid I can’t identify exactly what they are and I wouldn’t be able to give you a proper quote as I don’t have the authority to do that as a forum volunteer. But I can try to give you a rough guess.

Assuming that the MEX turns out to be chargeable and a paid Technical Site Survey is also needed, you could be looking at £106 for the MEX itself and £106 for the Technical Site Survey - assuming that the Site Surveys for Gas cost the same as the Site Surveys for Electricity. You might potentially be able to get away with only paying for one of the two, but I don’t know for sure.

It is also possible that your Electricity Meter might need to be replaced as well, especially if the new Gas Meter would be SMETS2 since you can’t mix S1 and S2 kit - it won’t work!

If you’re happy to go ahead with this, I’d definitely suggest giving the Support Team a call and discuss it with them. If you let the team know about this thread and tell them that Blastoise186 has already given you some advice on the OVO Forum, that will speed things up a little. My name is a bit of a secret password, in a way. :stuck_out_tongue:

And then it turns out Jess beat me to it! XD

Userlevel 2

Thx all.  That larger meter would cover it and give us all the options we would need. 

My next question is - how would I know if my current pipe would take this larger meter / cubic delivery ? 

Is this a simple calculation based on my pipe diameter ?

I am in a small close and at the back of the close which is private. I would really like to avoid digging up all the way to the road due to both due to the costs and making good afterwards. 

thx again. 

Userlevel 7

Great question - and this is something we’d have to check with your local gas transporter once you’ve had a gas safe engineer confirm your  ‘Service Pipe Energy  Value’ (SPEV). 


If you’ve already got this figure calculated it’s worth contacting the Support Team ,who’ll guide you through the next steps of the upgrade process.


Let us know how it goes and if you’ve got any more queries along the way. :relaxed:

Userlevel 7
Badge +5

For the sake of others who come across this topic at a later date, I’d like to clarify the above comments.

There are two completely separate issues being mentioned here.


a: A Medium-pressure gas main is one that operates up to 2 Bar pressure. They are normally used to interlink towns on the Local Distribution Zone - the gas equivalent of the regional Distribution Grid for electricity.

Within a town the pressure is reduced to 75mBar which serves our houses.

In some locations there is no low-pressure pipe. Connection is therefore made to a Medium-pressure pipe  using a special meter. That’s what’s described in the topic about the Medium pressure Supply.


b: The question is this topic relates to the need to obtain a larger than normal gas supply from a standard Low-Pressure pipe.

It’s that issue which @Jess_OVO answered by referring to the U16 meter.


Userlevel 2

I have spoken to a gas safe engineer regarding the ‘service pipe energy value’ he hadn’t heard of this and suggested I spoke to the transporter.  I asked if this was transco and he thought likely southern. 


His other suggestion was to just put in another standard meter near to the new appliance or for the extension.  His thoughts were that gas pressure is 75 and no one appliance is rated above 20mb so he thought that there should be capacity in my existing pipe ( obviously with the caveat that I would need to check) 

So how do I check ?

Are you able to tell me how to tell this gas engineer to do it or would the transporter know and have the diagrams of the close ( built 20 years ago) to determine the best route.  


Obviously happy to do the leg work on this but its knowing where to direct my energy..  :)

Userlevel 7
Badge +4

Wow, this is really turning out more complicated than first expected! I’d have to try and research this a bit further tonight.

But in my personal opinion, I would recommend against having another gas meter in these circumstances. As @TomThumb will no doubt agree, doing that is asking for trouble. :(

Most suppliers will choke if you have weird setups like one electric meter and two gas meters - especially if one is a Smart Gas Meter and the other is a Traditional Gas Meter. It would also increase your Standing Charges so it’s not really a recommended option in most cases.

Userlevel 7
Badge +5

This question needs to be directed firstly at your regional Gas Distribution Network operator.

They own the pipes up to and including the disconnection valve (the vertical one with the red handle in your photo above).

You can find out if you are in the region for Southern Gas Networks by using their Postcode checker. Then go to their website page for householder enquiries on altering an existing connection.


As a separate issue you will then need to check if OVO can provide you with two separate SMETS2 Smart Gas Meters.

This has been discussed extensively here on the topic I have three meters.

There are two factors to be considered

1: the software in the current Communications Hub which sits on top of your Smart Electricity Meter, can only handle data from a single linked Gas Meter.

2: OVO’s in-house Billing System may not yet cope with a single customer account that has more than one gas meter.

Userlevel 2

Ok great that’s given me something to work on - thank you. 


My preference is not for two meters but only considered this on the advice of the gas engineer.  I will make some enquiries and based on the above and update the thread hopefully with some useful conclusions. 

Userlevel 5
Badge +1

@bonjourpaul  My situation is somewhat similar to yours, but as the evaluation / consultation / installation had all been set out & implemented before I purchased this property, you have more of an influence on the outcome than I did.

In short I have 2 gas boilers & 2 gas meters,

The reason given to me, was, 

the maximum draw if both boilers fired at the same time exceed the supply rate of a single meter.


As 1 boiler has a typical use & 1 boiler has summer use only, the chance of them both firing up at the same time is very slim, but the combined draw is key.

Hopefully the forum will put my layman terms into something more technical

@Transparent )


If you total the maximum draw of the gas fire & hob,

subtract that total from the maximum gas meter supply rate,

= the maximum new boiler draw rate.

Can you spec a new boiler for your needs within the remaining total?


I know boilers are becoming more economical these days, so my situation might have a different outcome if it had to be implemented with today’s equipment & higher efficient boilers.


Edit additional info (just in case it’s relevant,) maybe for future consideration!

having had a minor gas leak outside our property, a few years ago, this was resolved by inserting a yellow polly pipe into the existing metal pipe, 

so dose a smaller diameter pipe ! equate to a slightly reduced supply rate?

on a domestic supply under normal circumstances this would not be an issue!

but if maximum supply is near it’s limit?

PS: on a side note @Blastoise186  & @Jess_OVO  my dd forecast on my traditional gas meter is behaving nicely on Orion, even tho it has had some heavy usage over the last couple of weeks, 👍

PPS, sry Jess, my bad,  the saga of my 3 meters was prior to your coming onboard, so while I’m quiet about them, it means all is well 😀


Userlevel 2

Form GT1 Submitted to Southern Gas Networks this evening.   The form is not particularly easy to find ( the ‘download a copy ‘ link on the SGN website doesn’t get you the form ) but its here -


Its a zip file and just choose the GT1 Form out of all the documents. 


In terms of our likely demand - 

40kw existing boiler

16kw - existing outdoor firepit


New extension - 

30kw boiler / or an upgraded boiler eg 60kw boiler to serve all

7.7kw gas hob 


From what I read our currently meter would not be able to meet all of the above in terms of demand.  I will update once I have heard from SGN. 



Userlevel 7

Some great advice given from personal experience, @TomThumb - glad to hear your multiple gas meter situation has settled in the past few months!



Form GT1 Submitted to Southern Gas Networks this evening.   The form is not particularly easy to find ( the ‘download a copy ‘ link on the SGN website doesn’t get you the form ) but its here -


Some great research done here as well, @bonjourpaul - it’s worth mentioning here that our Support Team are also able to process the GT1 form on your behalf. 


Either way the Support Team will be the ones to contact to arrange a U16 meter upgrade once you’ve had a response from your transporter.


Do keep us updated here though - it will be really helpful to others who also plan to make this upgrade in future. :slight_smile:


Userlevel 2

just a short update SGN have been out, looked at the meter and a vey accurate map showing where the pipe ran and more importantly split into a couple of smaller pipes to myself and neighbour.   Next the info makes it way back to the office for someone to make a calculation based on the pressure and the length of the pipe run ( and maybe some other factors that I am not aware of)   Will update once this has made its way back to me.