Worcester 42CDI problem
- Thread starter meditek
- Start date
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My understanding of this is all very hazy I don't mind admitting. But am I right in thinking that all gas appliances have to be specified and built to work safely with an inlet pressure as low as 14 mb?
If that is the case, do you think that the gas suppliers are trying to move the goalposts to suggest that this is all that they need to supply.
Thanks Tony, we'll know that on Monday morning. However, if it turns out there is a difference of over 1-2 mbar it would be helpful to know the answers to my questions a) and b) because if it is considered that taking 28mm into the meter and disconnecting the 22mm from the meter would make no difference then I suspect we're down the Swannee without a paddle unless we have the meter moved with no guarantee of success!
AFAIK the Gas Appliance Directive requires boilers to operate safely down to 14mbar.
I had a long and fruitlesss chat with corgi tech the other day on the IUSP when it comes to fully premixed burners and undersized gas pipework/low meter W.P. It's so bad round here that nothing is compliant.
With the usual ambiguous answers I was left with the impression that providing the W.P at the appliance was 14 or above it's just NCS. Despite the manufacturers quoting totally unrealistic W.P (often unachievable even on a perfect supply) it was down to an individuals judgement. So knowing the boiler is type approved down to 14 and FGA checks out ok then the opinion seems to be to stuff the MI and move on.
And yes I agree the gas transporters in their quest to cut corners are now happy to supply the legal minimum pressure. It will need a major gas incident to change the regs.
Of course corgi offer no proper guidance and sit on the fence with their thumbs up their a**e. Sponsored Links
and i thought i was the only one
easier to get a straight answer out of red ken than out of that lot
Although the next edition of IUSP is underway I suspect the manufacturers and GT's will be allowed to get away with printing nonsense in their MI's and low meter W.P's and us left to make a judgement without knowing the real story from the manufacturers eg the burners melting in some Vokeras with a lean mix on u/s pipework.
Here are the requested figures which are now accurate :-
1. mains feed to gas meter 20mm!
2. SP at meter >30mm
3. SP at boiler 30mm
4. WP at meter 21
5. WP at boiler 16
6. Flow rate 4.38 = 47kw
7. Boiler spec max flow rate 4.4
8. pipe length from meter 9m + 4 bends 28mm pipe restricted at meter and boiler - no 28mm adaptor available.
I also spoke to United Utilities who deal with the defunct Transco's Northern area. He informed me that 20mm supply pipe was no longer used and I should try and persuade Powergen (Eon now) to upgrade it!
That's the story so far.
1. mains feed to gas meter 20mm!
2. SP at meter >30mm
3. SP at boiler 30mm
4. WP at meter 21
5. WP at boiler 16
6. Flow rate 4.38 = 47kw
7. Boiler spec max flow rate 4.4
8. pipe length from meter 9m + 4 bends 28mm pipe restricted at meter and boiler - no 28mm adaptor available.
I also spoke to United Utilities who deal with the defunct Transco's Northern area. He informed me that 20mm supply pipe was no longer used and I should try and persuade Powergen (Eon now) to upgrade it!
That's the story so far.
That was with everything going full blast!
However, I phoned Powergen (eon) and told them we were short on flow. An hour later a 'Transco' (not transco now but I can't remember what they call themselves) type appeared. He measured a WP of 19 (after turning up the valve to max) and announced that it should be at least 21 and that we had a supply problem. He went off to investigate improving our supply!!! Having read comments about 'transco' I was rather surprised by his concern. He also commented that the policy nowadays was to try and blame everything on the plumber but in this case considered things were so bad he would do something else.
However, I phoned Powergen (eon) and told them we were short on flow. An hour later a 'Transco' (not transco now but I can't remember what they call themselves) type appeared. He measured a WP of 19 (after turning up the valve to max) and announced that it should be at least 21 and that we had a supply problem. He went off to investigate improving our supply!!! Having read comments about 'transco' I was rather surprised by his concern. He also commented that the policy nowadays was to try and blame everything on the plumber but in this case considered things were so bad he would do something else.
19 mbar at the meter outlet is a perfectly acceptable pressure, another "Transco" numptie that doesn't have a clue.
The drop from meter to boiler however is above the allowable 1 mbar although some boiler gas isolating/gas valves will drop another mbar or 2 between their inlet and test point.
I have not read all the previous postings but if a cooker is tee'd into the feed to the boiler the cooker should be operating to get a true working pressure at the boiler.
I don't think you have grasped the way the gas pipe sizing and the pressure regulator/governor works.
The pressure outside in the road is somewhat higher than that required at the meter outlet. This district pressure is set for that particular area (using a governor similar in appearance to that on your meter but considerably larger). Depending on the distance and pipe network this pressure will vary somewhat. Those at the end of the district network will have a reduced pressure in the road.
The governor on the meter inlet now maintains pressure to the meter outlet of 21 plus/minus 2 mbar (in theory). Therefore it is acceptable to have a pressure at the meter test point of 19 - 23 mbar. Since the pressure from the road is higher, the service pipe can be (and often is) of smaller bore than the internal pipework.
The drop from meter to boiler however is above the allowable 1 mbar although some boiler gas isolating/gas valves will drop another mbar or 2 between their inlet and test point.
I have not read all the previous postings but if a cooker is tee'd into the feed to the boiler the cooker should be operating to get a true working pressure at the boiler.
I don't think you have grasped the way the gas pipe sizing and the pressure regulator/governor works.
The pressure outside in the road is somewhat higher than that required at the meter outlet. This district pressure is set for that particular area (using a governor similar in appearance to that on your meter but considerably larger). Depending on the distance and pipe network this pressure will vary somewhat. Those at the end of the district network will have a reduced pressure in the road.
The governor on the meter inlet now maintains pressure to the meter outlet of 21 plus/minus 2 mbar (in theory). Therefore it is acceptable to have a pressure at the meter test point of 19 - 23 mbar. Since the pressure from the road is higher, the service pipe can be (and often is) of smaller bore than the internal pipework.
Gasguru, the 5 mbar drop concerned us all. The 'transo' guy muttered something about the meter being inadequate and when I suggested moving it to just outside the kitchen/boiler area was a possible solution he looked a little shocked and said the piping (28mm) was more than adequate and that it was probably our small meter that was restricting the flow. He muttered further that our supply was only good for about 5cu/m an hour which seemed to contradict his earlier remarks.
Anyway, he admits there is a problem that needs to be dealt with on the supply side and I am not going to argue with that! I intimated that we were considering gas fires and cookers too. He paled and muttered further that we could be disconnected if the pressure dropped further which was not encouraging. Fortunately, he seemed to consider that they had some sort of responsibility to supply the required gas. Whether his superiors will remains to be seen!
Anyway, he admits there is a problem that needs to be dealt with on the supply side and I am not going to argue with that! I intimated that we were considering gas fires and cookers too. He paled and muttered further that we could be disconnected if the pressure dropped further which was not encouraging. Fortunately, he seemed to consider that they had some sort of responsibility to supply the required gas. Whether his superiors will remains to be seen!
He must be a newbie, the gas transporters are finding every loophole in their contract to do the minimum they can get away with.
As I said 19 mbar is the minimum presure corgi's work off and Transco/SGN/whoever often work down several mbar below that before they actually do anything.
As I said 19 mbar is the minimum presure corgi's work off and Transco/SGN/whoever often work down several mbar below that before they actually do anything.
For that size of boiler you should have at least a 28MM gas supply or even 35MM and you might need to upgrade the gas meter to a U16 which is about the size of a microwave.
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