New build first fix help needed

[David Lowth]

Have been sadly let down by a plumber and doing the first fix for a new build. I have questions regarding the correct procedure for chasing in pipework behind what will be dot and dabbed..

Its 3 bed bungalow with 9 radiators in total.

I was planning on running lagged plastic22mm flow / returns in the roof space to and tee off 15s for each radiator. Some of which are underneath windows.

1. How deep do you usually chase when its being dot and dabbed? And do you also just take a notch out of the wall plate?

2. Would you chase one larger channel and run both pipes in the same place?
Does the plastic need to be insulated or ducted in some way so it could potentially be removed at a later date?

3. The rads will be attached to chrome.. would compression fittings with liquid ptfe be ok to use to connect the chrome to plastic? But obvioulsy this wont be able to be removed at a later date without pulling the wall apart.

4. How would you chase it in? Straight line down the wall with an elbow at rad pipe height?

Finally anything else ive overlooked / missing? How would you usually approach this job?

Thanks in advance for any help

 

[ShaunCorbs]

How you going from chrome pipe to plastic ?

 

[David Lowth]

Was thinking Brass Compression fittings with liquid ptfe.. i havent had anything leak with that stuff i think its great

Or does it have to be copper and soldered behind dot and dabbed plasterboard?

 

[Riley]

You’re going to have joints galore in the wall from what you’re saying

 

[David Lowth]

Yes at least two per rad at a minimum which is why im trying to get advice from a professional on how they install in this situation? Or if this is acceptable?

Looking at the building regs document G i havent been able to find a clear answer yet.. but it is a long document..

 

[Scott_D]

Chrime straight into the rad valves?
I would avoid compression in the wall

 

[ShaunCorbs]

Nope on compression in the wall

 

[David Lowth]

Can you use 10mm plastic pipes into a junction box directly behind the rads?

Just seen someone suggest this. Then there would be no joints in the wall?

 

[ShaunCorbs]

Manthorpe Radiator Pipe Guide & Seal | City Plumbing Supplies

 

[Riley]

Yes you can but make sure everything is sized/designed properly. Microbore can be problematic

 

[Scott_D]

If it’s dot and dab do you need to chase the wall?
Put a pattress behind rads

 

[David Lowth]

Manthorpe Radiator Pipe Guide & Seal | City Plumbing Supplies

That looks great, thanks very much. And then just go plastic all the way into the rad valves?

I wanted to conceal as much pipe work as possible and not have any plastic on show..

Yea i get what you mean on 10mm.. i would rather use 15..

Can you get these for 15mm pipe?

Sorry if i sound like a complete moron. Im not the whole time i swear. I just had to look up what a pattress was..

So if the pipes terminate in a patress behind the rads, the dot and dab board just goes to the depth of the patress?

 

[ShaunCorbs]

No they don’t do them in 15mm

 

[Rob Foster]

Maybe you can explain the contract you established with your contractor. Show us the detail then we can see what has been achieved and crucially what has not. Have you paid any lolly up front or any part payments and if so for which part of this work which has been completed and to your satisfaction etc
regards Rob Foster aka
centralheatking

 

[David Lowth]

The issues with the contractor is he was given £3500 in october by my business partner.. unfortunately without my signoff as i was out of the country.

My business partner was told by the builders he needed to get the plumber on site asap to sort the first fix stuff before the floor went down. The builder went ahead and did this himself in the end. The plumber was supposed to have the first fix in place by three weeks ago. Then he failed to answer calls / return messages since then, would eventually get a response after days of voicemails. When he was supposed to be coming.. oh he had a hospital appointment, or a problem with his phone.. etc

Basically he has very terrible communication skills and only after saying hes taking the Sod today, and at my wits end i said just give us the deposit back ive had enough, he has said to my business partner he recieved a aggressive message from me and acting all confused and innocent, saying he could do the first fix by 28th march..

Thats too long, and holding everything up.. so asked for the deposit back.. which is likely to be a whole another problem..

 

[David Lowth]

He fitted a stopcock and a end cap tje rosd side, half a days work if that but said give us the deposit minus one days work for doing those tiny Jobs.

 

[David Lowth]

Anyway back to the job..

Can i use 10mm plastic for just the rads under the windows / dot and dab and 15mm in studwork? Or do you need to use the same type of pipe everywhere?

Some of the rads are 10,000 btu's..

 

[Riley]

10000 btu = nearly 3kw
10mm will carry approx 2.5 kw

 

[David Lowth]

Ok so 15mm on those two rad that are approx 10,000 btus and 10mm elsewhere ok?

If i balance the system and throttle down the 15mm rads slightly can you see this working effectively?

 

[Riley]

It needs proper design is it all new going in?

 

[Sharp Point]

Find another plumber

 

[David Lowth]

Yes all new going in.

Or just stick to the original plan of 22s and 15s but chase the walls and do plastic to chrome compression fittings coming out to join the rads.

I dont want to see any plastic in the rooms only chrome

 

[David Lowth]

This was my original plan

 

[ShaunCorbs]

I wouldn’t pipe the whole cold system in 15mm plastic

Would say a min of 22mm plastic

TBH your looking at 2-3 days to first fix that (a decent heating engy )

 

[Riley]

But that way you are back to having fittings the wall which you don’t want

 

[ShaunCorbs]

The only way I can see it working is to put a backplate elbow in the wall and get the boarders to put it flush to the front and use a chrome male iron

Or soldered fitting

 

[David Lowth]

Ok, ill swap for 22 cold going to the two bathrooms.

Ive pretty much got the next two weeks. Just want to make sure its done correctly before starting.

If i can find some 8000s btu rads will that take 10mm pipe so i can do it all in 22 and 10?

The room requirement is 15,500 btus the only reason we picked two 10,000s was because they were a good price for what they were and matched the other rads.

Is the other alternative to do 15mm copper and solder in the walls and give up on the idea of only chrome showing

 

[David Lowth]

The only way I can see it working is to put a backplate elbow in the wall and get the boarders to put it flush to the front and use a chrome male iron

Or soldered fitting

Thats great, thanks for your advice

 

[ShaunCorbs]

What boiler ?

 

[Scott_D]

2 heating zones?

 

[David Lowth]

No boiler yet, wss going to be a Worcester or glo worm combi but changer of gas engineer now so have none at the moment.

2 heating zones? I dont understand. The larger room at the back has a vaulted ceiling but just has 2 rads in it.. sorry only one on this plan, but needs a second one added as 15,500 btu room

 

[Scott_D]

A new build should have 2 heating zones

 

[Riley]

If I were you I would seriously be looking to get another engineer in to do this properly

 

[Murdoch]

Gobsmacked ..... diy on parts that can’t easily be upgraded or replaced without major surgery on the property ......

 

[MOSSEP]

You could use 10mm copper micro bore in the wall rather than plastic, that way you can have soldered joints in the wall rather than compression / push fit.