How do I know what the plumbing configuration / design should look like?

[Great_scot_selfbuild]

We’re approaching the point of having the plumbing first fix done and I’m not getting the confident feeling from our plumber - they’re asking for the design of the plant room and system configuration. It seems they are skilled as the practical work when told what to do, but now I’m looking into what a design should look like.

 

I’m not expecting our principal designer to provide a design of the plumbing pipework, and although I’m looking at alternative plumbers, I now want to see some examples of what to expect as to a design / configuration of the plumbing pipework.

 

If it’s not that complicated (which I don’t believe our system is) then in order to get a neat and tidy install that we’re after, I’m wanting to work out a design even if it’s just a means of me assessing whether the plumber we contract proposes something similar or miles off.

 

Help me educate myself - TIA

[FarmerN]

Our builder brought the plumber in for fist fix without sorting where everything else was to be sited, only had to change pipe layout into plant room twice !

 So my experience would suggest you need a clear plan of what is to go is to go in plant room and where it can be sited. As with everything compromises have to be made, nothing is ever quite perfect.

So coming into our plant room in ducts through floor – Water , broadband, mains electric,  duct back to garage for EV charger and battery, drain for MVHR and spare duct to outhouse for future use. Only 7 points needing varying degrees of access!

Sited in plant room GSHP, DHW, MVHR, meter, consumer units, battery control box , two expansion vessels, one UFH manifold, etc etc.

[Spinny]

Yes I would also say be careful with plumbing design.

Our architect written SoW actually said a plumbing design should be provided by the plumber and then bought off. What actually happened is the builder brought his plumber in, and then he just started work (about 7 months late) and put in what he had chosen to do, with no prior design defined or reviewed. Definitely not a good way of doing it.

 

Examples:

Plumber chose press fit MLC pipe, but this has constrictions at every press fit join where say 16mm MLC (which is actually slightly smaller than 15mm copper ID) gets reduced down to about a 6mm bore at every connection.

Plumber chose 25mm MLC to run from mains to the cylinder, but I would have chosen a size larger to maximise flow.

Plumber told me no need to upgrade the old lead pipe. Turned out to be horseshit and I had to spend money and disruption having a new 32mm MDPE mains pipe put in later. This stuff causes huge problems and delays. IMO it is better to over specify everything than be left with months or years of problems because a plumber is trying to cut costs and moximise his profit with no care for the possible effects.

 

[Nickfromwales]

You just need a good plumber who sees things holistically.

 

My jobs are all planned in advance of the construction phase, with a line out done comprehensively; line outs are used for identifying all trades requirements, for pipe and cable pathways / service risers etc, so as to delete any downstream conflicts or ‘feck ups’. A good trade will support you here, but all too many of them expect to have this handed to them on a plate so they can just paint by numbers.  
 

Time and money goes down the tubes PDQ when your double handling or moving sideways (or backwards) plus trying to find trades whilst the plates are all spinning is time consuming and stressful, hence I always say to sort this in advance.

 

Designs are wonderful if they’re done by the person responsible for bringing them to life, otherwise they’re largely ignored, or aren’t worth the paper they’re written on. In over 30 years of doing this I’ve never produced a single design as it’s a waste of time and money.

 

I did this plant room out of my brain space, from scratch. Just sat there for 4 hours in silence planning it out, then told my electrician where his cable trays needed to be so I could plumb around them, so he could get started on 1st fix before my kit even arrived.
 

The plans I was given from the supposed M&E designer went straight into the bin, utter garbage, which happens 99% of the time in the domestic sector. Commercial designs are always spot on, but the cost for that kind of setup runs into 5 figures.

 

Architects never detail this, most don’t give a plant space bigger than a phone box, and desktop designs rarely layer the accumulative multiples of disciplines; choke points and interference are often unidentified until they’re staring you in the face and ‘the ship has sailed’.

 

Just get a good (better) plumber, someone used to working more comprehensively, and ask them to help you plan this is my 2 cents.