Low pressure at boiler - advice from Gas Engineer please

[fizzykoi]

My aged inlaws (80+ years) recently had a regular British Gas service, Despite having the same back-boiler/fire serviced with no problems for many years, the engineer issued a "Do not use" label and threatened to cut off the gas - he eventually left it on "as a favour". He said he could only measure 14mbar gas pressure at the boiler and that it was therefore unsafe.
He suggested that they should get the supply pipe (meter - boiler) upgraded. He also said there could be leaves in the pipe!! - either my inlaws have lost it or perhaps he was actually from British Rail javascript:emoticon('')
Could a qualified gas engineer please advise:
- Have the specs changed recently or are British Gas trying to drag some more cash out of vulnerable customers?
- Is it really unsafe at 14mbar or is this just "elf'n'safety" arse covering?
- What would be the likely "dangers" of low pressure?
- Is it likely that the supply pressure was just lower than normal on the day? (v. cold - everybody else had heating on...)
I'm told the pressure test was done with boiler and fire on full-bore but my inlaws say they barely ever use the fire above the min setting.
Any informed advice gratefully received.

 

[ianmcd]

14Mbar inlet working pressure is the recommended pressure where the appliance changes from NCS (not to current standards) to AR (At Risk) the danger basically is that the manufacturer doesnt certify the appliance as burning safely at this lowered supply pressure as it would have only been certified at normal operating pressure currently 21 Mbar +/- 2 Mbar it seems odd but not totally unusual that this has not been picked up during previous service visits, a road you may want to consider is contacting BG and asking why it has never been picked up before and why it wasnt noticed during the initial inspection carried out by them, it could however just be a partial blockage in the pipework but not by leaves, most likely black dust from the old cast iron mains pipes

 

[CBF]

where do you get this croak of .... from ? anything more than 1mb working pressure difference from the meter to the appliance has always been AR it's never been NCS, wether the boiler can work at this low pressure is neither here nor there.

 

[ianmcd]

where do you get this croak of .... from ? anything more than 1mb working pressure difference from the meter to the appliance has always been AR it's never been NCS, wether the boiler can work at this low pressure is neither here nor there.

You obviously havent been keeping up to date with the regs, some manus will actually accept 16Mbar at appliance and state this in the manus instructions (Worcester and Ideal state this on some models) and just in case you arent sure MIs CAN contravene general guidance in GSIUR Im afraid your 1Mb is well out of date, OP this doesnt affect the fire and BBU that you have, when your appliance was manufactured the 1 Mb rule was and still is the correct way to go but BG will only AR if 14Mb or below

 

[landyandy]

Can we take this to the cc gents.

 

[ianmcd]

Can we take this to the cc gents.

Why ? the Op has asked a perfectly reasonable question and as far as I can tell he or she has no intention of carrying out any gas work whatsoever he or she is just asking if the BG engineer was acting correctly which in my opinion he was, whether the engineers that attended before him acted in the correct manner is questionable, yes i agree that at 14Mb he should have Ar the BBU but I for one wont jump up and down that he left it on , I have had 14Mb inlet working pressure and rated appliances and still got correct burner pressure and gas rate, if all checks pass then I wouldnt AR either

 

[fizzykoi]

Thanks for the feedback but I still don't understand if it's dangerous or will the boiler just run less efficiently?
Should my inlaws live with it as-is; get a re-test; or upgrade the supply (which has been OK for some 20ish years)?
It's worrying for them at their age but I don't want them to spend the money unless it's really necessary.
Thanks.

 

[Phill Peck]

If what he guy is saying is true then he is correct.

that would make the appliance AR (at risk) he only should turn off the appliance. Turning off at fused spur will suffice and issue paperwork. You then have the option of turning it back on.

The term "at risk" is exactly that- it is not currently dangerous but there is potential for risk/danger.

What you need is a second opinion. Find a local independent and explain the situation. Most should have the equipment to provide a printout of the operating pressure if required.
Expect to pay somewhere around £70 depending on area (some may charge less or even look for free, personally I would charge)

If there are leafs in the pipes then someone put them there

 

[ianmcd]

If what he guy is saying is true then he is correct.

that would make the appliance AR (at risk) he only should turn off the appliance. Turning off at fused spur will suffice and issue paperwork. You then have the option of turning it back on.

The term "at risk" is exactly that- it is not currently dangerous but there is potential for risk/danger.

What you need is a second opinion. Find a local independent and explain the situation. Most should have the equipment to provide a printout of the operating pressure if required.
Expect to pay somewhere around £70 depending on area (some may charge less or even look for free, personally I would charge)

If there are leafs in the pipes then someone put them there

Good and proper advice from an experienced gas engineer

 

[Agile]

OP, the pressure at the boiler means nothing if he did not measure the pressure leaving the meter which should be a nominal 21 mB.

There is a little muddled thinking going on within some of the replies that you have been receiving. But since you are not training to be an engineer its of little relevance to you.

One of the problems is that the supply at the meter can fall well below the nominal 21 mB when the demand is high when its cold and people are at home like Sundays!

I found a boiler misbehaving and discovered the distribution pipework pressure was only 15 mB and after the meter only 13.5 mB.

Be wary of anyone who suggests a unit of Mb. That would burst pipes and might be the pressure at the centre of the sun! The correct unit is mB ! You can blow about 25 mB !

Edit: just checked the pressure at centre of the sun and it measures about 100,000 MB !

Tony

 

[ianmcd]

Tony even you should know that the working pressure at the meter can be legally as low as 19mb or as high as 23mb the regulations in case you need reminding are now 21mb +/- 2mb, why you always feel the need to come out with this carp is beyond me ? the Op doesnt want to know or needs to know this he/she is just concerned about his/her parents BBU witha working pressure of 14mb

 

[Agile]

I know exactly what the pressure at the meter should be!

I also know its not measured in either "Mb" or "mb" but mB !

Tony

 

[Phill Peck]

Tony I'm sure you are correct. Just not relevant

The op wants to know if it should be used or if the BG guy is making it up

The only way to find out really is to test again, and yes anyone who knows what they are doing would test at the meter aswell

 

[landyandy]

Can we take this to the cc gents.

Can we take this to the cc gents.

 

[stardanny]

Working pressure? Isn't the first check for correct pressure is the burner pressure at the bbu? If the burner pressure is within range of manu instruction with correct gas rate and if necessary a flue analyser then it should be fine. Reg 26 (9).

Dan.