plumber competence reprised

[achrn]

Recap: I'm having an extension built with new boiler and complete re-plumb. I was slightly worried about the competence of the builder-appointed plumber. I asked for advice here and subsequently became very worried. Eventually the plumber was kicked off. He is Gas Safe registered for boilers, but no evidence has been forthcoming that he has any unvented qualification. Building Control were not advised that an unqualified person was installing an unvented cylinder.

The full detail (all 20 pages of it) is in a thread at //www.diynot.com/forums/plumbing/worried-about-my-plumbers-competence.355290/


The builder has appointed a new plumber (who I am told is qualified for gas boilers and unvented cylinders, though I haven't seen first-hand evidence of that yet because I haven't been to the house yet).

I appointed a different plumber (with no links to the builder) to inspect and tell me what he thinks needs changing.

Gas Safe came out and inspected yesterday, but I haven't had a report from them yet. The builder says the inspector only looked at gas stuff (not the unvented) and was basically happy.

There is general agreement between the two plumbers about what needs changing, and the builders new plumber is taking the view that he's not going to work with the spaghetti in the cylinder cupboard - he's going to take a good proportion of it out and redo it.

However, one aspect of disagreement is that the flow and return between boiler and cylinder cupboard are currently 22mm, with a length of about 8m each way and seven 90 degree bends and elbows (each way) en route. The boiler is a WB 30 kW GREENSTAR 30 CDi CLASSIC SYSTEM' on natural gas. It is in a two-heating-zone plus hot water setup. It does not have the optional internal diverter valve.

My plumber is saying the pipework should be 28mm. The builder says his plumber says 22mm is OK. I am nervous of the fact that the builder really really doesn't want to lift the floors and take out the bits of wall that would be necessary to replace this run of pipes, not least because that's in a room that's finished (and decorated) and the making good will not be trivial or cheap. He may well be pressuring his plumber to say it's OK.

Can anyone advise their opinion of pipe sizes? The WB installation manual doesn't seem to say anything on the topic, though I note the pipes coming out of the boiler are 22mm

 

[Breesey]

May be he meant the unvented D2 should be 28mm?

 

[hazetimesfive]

22mm = 40.2 kW capacity.

I see no need for 28 really, probably if it was you would have a hell of a time balancing the rads to get 20 degree drop.

 

[achrn]

May be he meant the unvented D2 should be 28mm?

This is referring to the pipe downstream of the tundish?

There are different problems with that - both plumbers are agreed the D2 pipe (which is 22mm) doesn't meet requirements (too long, too many bends), but it only just doesn't and replacing it will be hellish (requiring taking out a built-in steel bath and lifting flooring in a restricted crawl space I have within the eaves of the roof, or taking down a couple of finished ceilings) so I believe we're accepting a sub-standard D2.

The pipe upstream of the tundish is also wrong, but that is to be replaced.

 

[bolshy]

Have you got zoned heating?
Yes you have. I'd put 28 mm in then.

 

[Breesey]

May be he meant the unvented D2 should be 28mm?

This is referring to the pipe downstream of the tundish?

There are different problems with that - both plumbers are agreed the D2 pipe (which is 22mm) doesn't meet requirements (too long, too many bends), but it only just doesn't and replacing it will be hellish (requiring taking out a built-in steel bath and lifting flooring in a restricted crawl space I have within the eaves of the roof, or taking down a couple of finished ceilings) so I believe we're accepting a sub-standard D2.

The pipe upstream of the tundish is also wrong, but that is to be replaced.

Yes, beyond the tundish.

Accepting an incorrectly installed D2 is not really an option. It doesn't comply. It is possible to use a hepvo waterless trap and polypropolene waste into the soil stack these days. Could this be an option for you?

 

[bolshy]

So we're not talking about the flow and return pipework....
As a matter of interest, where is the tundish? Not above a habitable space? I wouldn't accept undersized relief pipework either. Not your problem, it's theirs.....to put it right.

 

[Agile]

I think the OP IS talking about the heating coil connections to the cylinder being in 22 mm.

In my view thats totally adequate!

There is also a discharge pipe sizing problem as well but thats another matter and covereb by Building Regulations too!

If the D2 is incorrect the BCO does not have to accept it!

Tony

 

[achrn]

So we're not talking about the flow and return pipework....

Yes we are. The flow and return between boiler and hot water cylinder cupboard (where the zone valves and everything else is) is 22mm and one plumber is telling me that's fine, and another is telling me that it should be 28mm.

There are ALSO problems with the tundish pipework, along with other problems with various other stuff (wrong size primary expansion vessel, cylinder expansion hooked up wrong, inaccessible components, valves where there shouldn't be, components installed backwards etc.) But I believe that those problems are going to be fixed - it's the flow and return where I'm trying to understand if it's a problem that needs fixing or not.

 

[achrn]

I think the OP IS talking about the heating coil connections to the cylinder being in 22 mm.

I'm talking about the pipes carrying the hot water between the boiler and the location where there are valves which direct water to the two heating circuits and/or the hot water cylinder as appropriate. I thought these pipes are called the boiler flow and return, but if I'm using the wrong terminology, my apologies. What should those pipes be called?

 

[doitall]

The pipes from the boiler to the MV's are the primary pipes. the size depends on the heating size and the boiler output.

As an example 8-10 average rads 22mm more and you should consider 28mm.

It probably tells you in the boiler MIs..

There's lots of other things to consider so it's only a guide.

 

[bolshy]

Your terminology is correct, it was the unvented P & T relief discharge that got in the way initially.
And I say 28mm.

 

[Breesey]

Your terminology is correct, it was the unvented P & T relief discharge that got in the way initially.
And I say 28mm.

Indeed, achrn could you go down the polyprop D2 route?

 

[achrn]

As an example 8-10 average rads 22mm more and you should consider 28mm.

OK. I have 11 double radiators, three big towel rails and a kickspace heater. Two thirds of that is one zone. The cylinder has a 20.5kW coil. The boiler is 30kW nominally.

The consensus I'm getting from the responses is that this should have primary flow and return in 28mm between boiler and where my zone valves are, but 22mm is OK for the valves and rest of the pipework further from the boiler.

I agree it should be the builder's problem. However, it becomes a problem that affects me if the work isn't finished at the time I need to be out of the flat I'm renting while the house has been rebuilt.

 

[Breesey]

I agree it should be the builder's problem. However, it becomes a problem that affects me if the work isn't finished at the time I need to be out of the flat I'm renting while the house has been rebuilt.

Surely delays caused by bad/incorrect/otherwise unacceptable workmanship are the responsibility of the builder and tradesmen onsite and, therefore, any extra costs incurred by you (like additional rent) as a result should be laid at his/their door.
You want, and need, the work completed properly don't you?