Boiler question

Leif

I recently had my boiler timer replaced under warranty, and the Worcester Bosch chap gave my boiler a check. Anyway, he found that the gas inlet, which is 22mm, had been connected to an undersized gas pipe, which restricts the flow. Consequently the boiler only operates at 25 kW rather than the full 30 kW. Does this impact the heating, or just the hot water?

I was told this would be a safety hazard had there been other appliances on the gas supply (the boiler would have temporarily cut them off, extinguishing any flames). Sadly there is no possibility of connecting a full size gas pipe, as the current one is chased into the wall.

I emailed the plumbers, and surprise surprise, no response. They were yet another CheckATrade special.

Mr_Ted

More info needed?

Such as working pressures taken at boiler inlet and at meter, actual pipe size to boiler and back to meter and length?
Also what is the boiler working pressure set to?
Is meter governor also set to require pressure, and i would also suspect the meter inlet pressure if there is large deficiency in working pressures, it has been know for main services to be insufficient pressure!

The requirement is that there must not be more that 1mb working pressure drop between meter and appliance.

Seem rather a large drop in output to just be pipework problem?

Leif

According to the Worcester Bosch appliance inspection report, the pressure at the meter is 19 mb, and the pressure at the boiler is 13 mb. Apparently it is not to the current standards, but it is not a risk. The boiler is on one side of a double skin wall, and the meter on the other (outer) side. So the copper pipe is probably less than 2m long.

Mr_Ted

Leif wrote: »

According to the Worcester Bosch appliance inspection report, the pressure at the meter is 19 mb, and the pressure at the boiler is 13 mb. Apparently it is not to the current standards, but it is not a risk. The boiler is on one side of a double skin wall, and the meter on the other (outer) side. So the copper pipe is probably less than 2m long.

:eek: Thats a hell of a big drop in 2M of pipe, there may be a bigger problem than just the pipework?
Is the 13mb the working pressure after the boiler gas valve, ie boiler operating pressure at the outlet of the boiler gas valve, or is it at the inlet to the boiler gas valve, ie appliance supply working pressure?
The operating pressure is usually adjustable to the output required for the boiler, if 13mb is that?
The appliance supply working pressure is the relevant issue here in repect of the overall working pressure drop?
The meter nominal working pressure should be 20mb, but that is minimally low but would make a slight difference?
He should also have checked the appliance output via the meter by seeing the amount of gas used as well as a pressure check?

What model and size of boiler is it?
Most boiler outputs are variable between a predetermined set range of outputs by adjusting the gas pressure at the gas valve, but the maximum should be achievable and needs to be known and checked against the manufactuers instructions?

It concerns me that there is a red herring in here somewhere and that he has checked the output to the boiler and doesnt perhaps know how to adjust it to a higher value?

If it is the pipework thats a problem, from what you say, it should not be difficult to replace it run facework?

Also by Worcester Bosch chap and plumber, do you mean 2 different people, and did you check their qualifications and registrations?

Leif

Ted: I'm afraid I can only tell you what is written on the paperwork: "low working gas pressure at boiler (13 mb), 19 mb at meter". He turned the hot tap on full, to get the boiler working, then went outside to where the supply box is, stayed there a few minutes then came back in. He might have done some other stuff. Unfortunately not being a boiler engineer, I do not know what he was doing. He was from Worcester Bosch. He had to fill in a lot of paperwork via a laptop.

The 'plumber' was a local plumbing firm who installed the boiler 18 months ago, so there may have been a team, I did not see them do it. They are without doubt qualified, if only because at the time they were on CheckATrade, and they do check qualifications. (Well, okay, they could have sent the office boy round to do it, but I doubt that.)

Curiously they are no longer on CheckATrade, maybe they get more than enough work without it, they were very busy when I used them.

Mr_Ted

I would be inclined to get a 2nd opinion and have the issues I have raised checked again?

Leif

Mr_Ted wrote: »

I would be inclined to get a 2nd opinion and have the issues I have raised checked again?

Yes, I will get it serviced in August, and ask the engineer about the pressure. For what it is worth, it has a 15mm pipe connecting to the 22mm boiler inlet.

I forgot to add that it is a Worcester Bosch 30CDI combi. And the supply comes up from below ground to the meter, then to the boiler.

Mr_Ted

Leif wrote: »

Yes, I will get it serviced in August, and ask the engineer about the pressure. For what it is worth, it has a 15mm pipe connecting to the 22mm boiler inlet.

I forgot to add that it is a Worcester Bosch 30CDI combi. And the supply comes up from below ground to the meter, then to the boiler.

http://www.worcester-bosch.co.uk/installer/literature/discontinued-product-literature/discontinued-gas-boiler-literature/greenstar-30cdi-manufactured-april-2007-july-2012-literature
Page 34, inlet pressure to boiler should be 18 mb minimum and Page 51 output determined by flue gas ratio adjustment to that recommended?

southcoastrgi

Mr_Ted wrote: »

http://www.worcester-bosch.co.uk/installer/literature/discontinued-product-literature/discontinued-gas-boiler-literature/greenstar-30cdi-manufactured-april-2007-july-2012-literature
Page 34, inlet pressure to boiler should be 18 mb minimum and Page 51 output determined by flue gas ratio adjustment to that recommended?

you should be also concerned about page 10

Under no circumstances should the size of
the gas supply pipe be less than that of the
appliance inlet connection

the inlet is 22mm therefore if the supply pipe or any part of it is 15mm then they have installed it to NCS & this is illegal, as you are not allowed to install to NCS

Leif

Thanks southcoastrgi and Ted. I have emailed Worcester Bosch customer support to clarify the pipe size issue i.e. what are the consequences. The plumbers have replied, and they have offered to inspect and if necessary replace the pipe. So that is a good response. I suppose it could go straight though the wall, and then run down the wall to the meter, leaving the existing pipe in place behind the kitchen units. It would not be hard for me to patch and paint the damaged area of kitchen wall.

heating-eng

southcoastrgi wrote: »

you should be also concerned about page 10

Under no circumstances should the size of
the gas supply pipe be less than that of the
appliance inlet connection

the inlet is 22mm therefore if the supply pipe or any part of it is 15mm then they have installed it to NCS & this is illegal, as you are not allowed to install to NCS

Undersized gas is classed as AR if it affects the appliance
You need to contact gassafe and ask them to come out and check the installation.
Did the plumber register the boiler ?