National Grid

[jaydebruyne]

Went to service a boiler today.
First tests I do is tightness/letby and then working pressure at meter and inlet on gas valve.
I was getting 10mbar at the meter working pressure. They only have the boiler, no other appliances in gas.
Boiler is a Worcester Greenstar 40CDi conventional.

Called transco as could have been a dodgy regulator. Or undersized pipework but I wanted to rule out the regulator first as standing pressure was only 21mb.

They attended when I wasn't there and changed the regulator but said nothing was wrong with the old. But they tested the meter/pressure when the boiler was in 'condensing mode' - you know when you restart the CDi's and it does the minimum rate thing for about 20 mins.

So he got a normal reading, as did I on minimum rate. But as soon as it got to max rate went straight to 9.5mb at the meter.

Turns out the run needs upping from 22 to 28 - apparently a guy did a new run which is about 9 meters with let's say 8 elbows in 22 and said everything was fine. They'd also left a 4m run of pipework completely unsupported practically hanging in mid air.

Question: do national grid have to know about boilers? Surely they'd know the boiler was in min rate mode and should have waited for max rate to kick in? Or do they rest the regulator differently?

Have turned off the boiler. Owner is gutted as they've just paid £30k having the kitchen tiled in cement tiles which is over the new gas run. Oops!

 

[Chalked]

If your getting 9.5mb at the meter, not the boiler. There is a problem with the main supply.

 

[ShaunCorbs]

No as all he was doing was purging the gas through while he was there anything from the meter not there problem

That's why if they find leaks on existing Pipework gets capped and cus gets a sheet saying you need s gas engy as you have a leak

but you need a min of at least 18 at the meter

 

[jaydebruyne]

If your getting 9.5mb at the meter, not the boiler. There is a problem with the main supply.

Working pressure?

 

[jaydebruyne]

No as all he was doing was purging the gas through while he was there anything from the meter not there problem

That's why if they find leaks on existing Pipework gets capped and cus gets a sheet saying you need s gas engy as you have a leak

but you need a min of at least 18 at the meter

Ahh ok..

Question:

How is it possible to be getting 10mb at meter working pressure, 8mb at inlet on gas valve working pressure but correct heat input and gas rate readings????

 

[Chalked]

Working pressure?

Yes mate.

 

[Chalked]

Working pressure?

Yes mate.
If it's been fine until recently. It could be a faulty governor, or a problem with the main. Is there any gas work ( new main etc) being done locally?

 

[jaydebruyne]

Yes mate.
If it's been fine until recently. It could be a faulty governor, or a problem with the main. Is there any gas work ( new main etc) being done locally?

No gas work being done. And transco put a new regulator on today. Boiler hasn't been checked in 2 years so not sure.

 

[ShaunCorbs]

Ahh ok..

Question:

How is it possible to be getting 10mb at meter working pressure, 8mb at inlet on gas valve working pressure but correct heat input and gas rate readings????

I would say reg faulty as can't handle the demand but Pipework loss looks right just working pressure down

If meter working pressure below 18 grids problem

Get them out with you there

 

[jaydebruyne]

I would say reg faulty as can't handle the demand but Pipework loss looks right just working pressure down

If meter working pressure below 18 grids problem

Get them out with you there

Could undersized pipework cause a low working pressure at meter?

 

[ShaunCorbs]

Could undersized pipework cause a low working pressure at meter?

There side or blocked pipe yes but not our side

 

[jaydebruyne]

There side or blocked pipe yes but not our side

Ok. Might go back round now and call them out.

 

[ShaunCorbs]

Ok. Might go back round now and call them out.

Yep and tell them you have already called them out

Just to check them pressures were at the meter ??

Also what's standing pressure at the meter ?

 

[jaydebruyne]

Standing was 22 or 23, 10mb working pressure with boiler on max rate

 

[ShaunCorbs]

Standing was 22 or 23, 10mb working pressure with boiler on max rate

Would say reg is fecked, as it's not regulating under load

 

[jaydebruyne]

Would say reg is fecked

But they put a new one on today and I rechecked it, same thing

 

[ShaunCorbs]

But they put a new one on today and I rechecked it, same thing

Didn't check on full load

And are you sure they changed the reg ?? Also could be some dirt has gotten into there line and blocked the new reg again

It's down to them so get them to sort it best for you to be there if pos, do your max while he's there

 

[jaydebruyne]

Didn't check on full load

And are you sure they changed the reg ?? Also could be some dirt has gotten into there line and blocked the new reg again

It's down to them so get them to sort it best for you to be there if pos, do your max while he's there

On way back now

 

[jaydebruyne]

Didn't check on full load

And are you sure they changed the reg ?? Also could be some dirt has gotten into there line and blocked the new reg again

It's down to them so get them to sort it best for you to be there if pos, do your max while he's there

Def somethings wrong. 25.5mb standing
12mb working on max rate at meter

 

[wattsie1987]

Ahh ok..

Question:

How is it possible to be getting 10mb at meter working pressure, 8mb at inlet on gas valve working pressure but correct heat input and gas rate readings????

Because it forced combustion (fan driven). I wouldn't be too hasty with the loss across installation as 2mb from meter to gas valve test point is permitted (potential 1.5mb loss from appliance iso to gasvalve if I'm not mistaken). Almost certainly undersized service pipework probably been inserted with serviflex, they use 16mm most of the time and it's way too small. When you next bump into a NG engineer ask for an ecv test point. It allows you to take a working pressure before the regulator and proves beyond doubt what the issue is. Last time I spoke with the grid they said as far as they go is turning a tap on or turning on a room stat if not a combi, they dont put appliances in forced max rate. Hope this helps.

 

[ShaunCorbs]

How you getting on jay ?

 

[jaydebruyne]

Because it forced combustion (fan driven). I wouldn't be too hasty with the loss across installation as 2mb from meter to gas valve test point is permitted (potential 1.5mb loss from appliance iso to gasvalve if I'm not mistaken). Almost certainly undersized service pipework probably been inserted with serviflex, they use 16mm most of the time and it's way too small. When you next bump into a NG engineer ask for an ecv test point. It allows you to take a working pressure before the regulator and proves beyond doubt what the issue is. Last time I spoke with the grid they said as far as they go is turning a tap on or turning on a room stat if not a combi, they dont put appliances in forced max rate. Hope this helps.

He didn't have any ecv test points :/ supply pipe is inch an quarter. He tested next door and they have no issues.

He said NG will not bother with low pressure calls unless pipework to appliances are correct. So will have to do a new 28mm run and retest, if same issue they'll have to sort the issue out themselves.

I'm surprised they put a 9m 22mm run to a 40kw boiler though

 

[ShaunCorbs]

He didn't have any ecv test points :/ supply pipe is inch an quarter. He tested next door and they have no issues.

He said NG will not bother with low pressure calls unless pipework to appliances are correct. So will have to do a new 28mm run and retest, if same issue they'll have to sort the issue out themselves.

I'm surprised they put a 9m 22mm run to a 40kw boiler though

That's utter bollox telk them to sort there side out first working pressure of 10mbar and under isn't acceptable and doesn't matter what size output pipe is still be the same

 

[jaydebruyne]

How you getting on jay ?

NG said nothing they can do until the pipework to boiler is corrected. Service pipework is 1.25 inch. He put on a new meter and tested but same issue. Gotta do a 28mm run and retest. If same issue they'll then put in a low pressure callout.

Said that undersized pipework can sometimes cause a low working pressure at meter.

 

[mfgs]

That is nonsense. Tell him your side is fine and they need to sort out the supply as they aren't given you the required pressure.

 

[ShaunCorbs]

NG said nothing they can do until the pipework to boiler is corrected. Service pipework is 1.25 inch. He put on a new meter and tested but same issue. Gotta do a 28mm run and retest. If same issue they'll then put in a low pressure callout.

Said that undersized pipework can sometimes cause a low working pressure at meter.

one way to solve it wheres meter located?

 

[mfgs]

NG said nothing they can do until the pipework to boiler is corrected. Service pipework is 1.25 inch. He put on a new meter and tested but same issue. Gotta do a 28mm run and retest. If same issue they'll then put in a low pressure callout.

Said that undersized pipework can sometimes cause a low working pressure at meter.

Range rate the boiler down to 30kw and retest with him there, if pressure still low at the meter then pointless re-running the gas as the gas run you described should be ok for 30kw

 

[mfgs]

NG said nothing they can do until the pipework to boiler is corrected. Service pipework is 1.25 inch. He put on a new meter and tested but same issue. Gotta do a 28mm run and retest. If same issue they'll then put in a low pressure callout.

Said that undersized pipework can sometimes cause a low working pressure at meter.

Range rate the boiler down to 30kw and retest with him there, if pressure still low at the meter then pointless re-running the gas as the gas run you described should be ok for 30kw

 

[jaydebruyne]

one way to solve it wheres meter located?

In basement, below the boiler on ground floor

 

[ShaunCorbs]

In basement, below the boiler on ground floor

feck if it was outside / close to a door would open the bloody thing up (dont connect outpipe) if your still getting low op pressure with nothing connected for a second or two problem isnt your side

(which i dont think it is)

 

[Atouchofgas]

Cut in test point under boiler, 2 x gauges if it's 9 at test point and 10 at meter your pipes fine.
Have they done a mains upgrade and shoved plastic up the old service?
Discon flexi at ecv and let it blow maybe water in mains?

 

[jaydebruyne]

That's utter bollox telk them to sort there side out first working pressure of 10mbar and under isn't acceptable and doesn't matter what size output pipe is still be the same

So call them out again??? :/ thing is, he said NG won't put it forward as a low pressure callout if the pipework is undersized. Hate being the new boy sometimes, now I'm gonna loook like a right idiot to my customer

 

[ShaunCorbs]

Cut in test point under boiler, 2 x gauges if it's 9 at test point and 10 at meter your pipes fine.
Have they done a mains upgrade and shoved plastic up the old service?
Discon flexi at ecv and let it blow maybe water in mains?

10mbar meter
8 mbar boiler

so not a million miles out

 

[ShaunCorbs]

So call them out again??? :/ thing is, he said NG won't put it forward as a low pressure callout if the pipework is undersized. Hate being the new boy sometimes, now I'm gonna loook like a right idiot to my customer

give me tonight have a mate who works for national grid, will see what he says

 

[jaydebruyne]

give me tonight have a mate who works for national grid, will see what he says

Cheers Shaun

 

[mfgs]

You are getting a 2mb drop from meter to gas valve in the boiler? Worcester allow a drop internally so the 2mb is fine

 

[ShaunCorbs]

Cheers Shaun

think its all bull tbh

 

[ShaunCorbs]

Cheers Shaun

think its all bull tbh

 

[newcastle phill]

10mbar meter
8 mbar boiler

so not a million miles out

Sounds about right including gas valve test point press drop but even if pipework was undersized you should still get a working pressure at the meter within spec regardless Jay.
How are you measuring pressure - digital or manometer. Water guage or single sided. If single sided you have got right fluid in. I know you had an issue the other week with a vaillant.

 

[wattsie1987]

Undersized internal pipework was NCS providing safe working of all appliances can be achieved. Now is just a recommendation. And how can you test the internal pipework with an AR meter installation? Tell them you've done your calcs and the internal run is satisfactory. At the end of the day the customer is paying for a service they are not providing them with ie 6m3 at 21 +/- 2.

 

[jaydebruyne]

Sounds about right including gas valve test point press drop but even if pipework was undersized you should still get a working pressure at the meter within spec regardless Jay.
How are you measuring pressure - digital or manometer. Water guage or single sided. If single sided you have got right fluid in. I know you had an issue the other week with a vaillant.

I use a regin premiere gauge with the regin fluid. I double checked my gauge on my meter at home and it's working fine.

Thing is, at gas college, teacher said if all appliances are on and pipework is undersized the working pressure can drop below the nominal. Is this not true then?

 

[jaydebruyne]

Undersized internal pipework was NCS providing safe working of all appliances can be achieved. Now is just a recommendation. And how can you test the internal pipework with an AR meter installation? Tell them you've done your calcs and the internal run is satisfactory. At the end of the day the customer is paying for a service they are not providing them with ie 6m3 at 21 +/- 2.

Very true. Why would NG say that they won't do anything until the pipe run is upped to 28mm?

 

[wattsie1987]

I use a regin premiere gauge with the regin fluid. I double checked my gauge on my meter at home and it's working fine.

Thing is, at gas college, teacher said if all appliances are on and pipework is undersized the working pressure can drop below the nominal. Is this not true then?

Never heard that before, can't see how it would either the other way round maybe if less than 19 at meter a larger drop across installation would be negligible tho I think.

 

[newcastle phill]

There is one stupid exception. Im sure youve heard the "peak time" caveat.

Otherwise if overall demand is upto 6m3 on a typical domestic meter then it should pretty much be in the ballpark at the meter.

 

[Last Plumber]

Your problem is either a blockage in main or undersized main.
The Nat Grid would have turned that off if they had seen it so low and investigated it.
They won't go around messing with appliances to set them on full rate. If you have an issue like that, you'd be best to arrange to meet on site and you ensure that you set the appliances running on high rate.

The internal pipe work is nothing to do with it by the sounds of it.

The only way that internals could effect the service is if you're pulling too much gas through it for it's size.

 

[jaydebruyne]

Your problem is either a blockage in main or undersized main.
The Nat Grid would have turned that off if they had seen it so low and investigated it.
They won't go around messing with appliances to set them on full rate. If you have an issue like that, you'd be best to arrange to meet on site and you ensure that you set the appliances running on high rate.

The internal pipe work is nothing to do with it by the sounds of it.

The only way that internals could effect the service is if you're pulling too much gas through it for it's size.

I was there with them in the 2nd visit and ran it at max rate. So he witnessed it at 12mbar. He still said up the internal pipework before we can call it in as low pressure service side. He also stated the next door had no issues and that's as far as he investigated as he had no ecv test points. He also said the boiler could be pulling too much gas through the pipework.

Can you buy ecv test points in the web? Might just test it myself for a definitive answer

 

[wattsie1987]

Not sure try bes

 

[jaydebruyne]

There is one stupid exception. Im sure youve heard the "peak time" caveat.

Otherwise if overall demand is upto 6m3 on a typical domestic meter then it should pretty much be in the ballpark at the meter.

I have. But this was at about 11:30am and then again at 3pm and last time at about 7pm which was the only peak time test.

 

[newcastle phill]

Yeh there is no definition of a peak time - thats whats stupid about it.

 

[jaydebruyne]

Yeh there is no definition of a peak time - thats whats stupid about it.

Lol furry muff!!