Central heating "Copper down to plastic impact" and "central heating pipes outside" query

[shd1970]

Hi all,

I'm looking for some input regarding the following that i'm thinking about :

So I had a tall 1800mm Vertirad radiator at the end of my extension, which from memory used to take a lot longer to get as hot as the rest. It always seemed a bit naff on the heat output and was ugly too so I've now removed this.

From investigating, for some reason only known to them, the builders tapped off from my existing copper system and used HEP2O so converted down to plastic for the length of my extension which is approximately 4 m and then reverted back to copper for down the wall, so there are 2 x push fits for each pipe (F & R) in the ceiling.

I’m contemplating whether to replace the plastic pipe with copper but as it’s in the ceiling, it’s not gonna be easy to do without chopping a hole or two in the ceiling which obviously I would rather avoid

I’m replacing the radiator with a Stelrad 800 x 600 K2 to match the others in the room

My reason for thinking about replacing the plastic pipe and use all copper would be that I’m assuming that copper would give me a far better heat conduction and flow rate, considering Wavin have confirmed the internal diameter for the HEP2O inserts needed for plastic is 9.7mm compared to the internal diameter for normal 15mm copper being 13.6mm so a 4mm reduction at 2 points on each pipe

First question
What’s everyone’s thoughts on how much of a reduction in flow and heat output having a 4m run of plastic and the required 2 inserts (-4mm diameter) would have on the radiator performance and I include in that, speed to warm up ?
Surely throttling the flow by 30% (9.7mm vs 13.6mm) twice on a pipe can't be good ??

This is the furthest radiator on the system and nearest to the largest patio doors/windows in our house so what I class as an important radiator

Secondly, rather than chopping holes in the ceiling, are there any regulations for having central heating copper pipes outside my extension and clipped to the wall of my extension and insulating ?

I know this wouldn’t be ideal, but I’ve seen some products called Armacell that I'm checking to see if it might be suitable, but outside would be a far easier fix and make the system completely copper, and make them more accessible should I need too

What should i do....leave as is as the benefits i'll make will be minor ?


Thanks for reading and many thanks for anyone willing to share their thoughts on the above dilemma

 

[jj4091]

What size pipes have they T-eed into and were they supplying other radiators.

 

[oldbuffer]

1. The internal area of standard 15mm copper pipe is approximately 145 sq.mm.
2. The internal area of a 0.7mm diameter insert is approximately 74 sq.mm
3. Whether or not it matters depends on your system. There are plenty of systems running on 10 mm microbore quite satisfactorily.
4. No matter how good the insulation, it won't stop any pipes (copper or plastic) freezing if exposed to low temperatures long enough.
5. I'd re-use the existing plastic as far as possible and see if it gives the results you want. If it doesn't, might be the time to rethink pipe sizes.
6. Before testing, make sure your system is properly balanced, so that each radiator is getting its fair share of the available heat.

 

[shd1970]

What size pipes have they T-eed into and were they supplying other radiators.

So the radiator I’m talking about was tapped off the pipework supplying our bedroom at the back of the house
Our bedroom and the next bedroom along (our box room and the last radiator on that side of the house) were both always really warm
The pipes were 15mm

 

[Exedon]

So the radiator I’m talking about was tapped off the pipework supplying our bedroom at the back of the house
Our bedroom and the next bedroom along (our box room and the last radiator on that side of the house) were both always really warm
The pipes were 15mm

More to do with what's the total heat load on the 15mm pipework section.
As has been pointed out many systems run happy on 10mm pipework its all down to heat load and pipework length.
8mts or so of 15mm plastic shouldn't really cause a problem.

 

[shd1970]

Thanks for the replies @jj4091 @oldbuffer @Exedon
I’ll reuse what is already there then which is the easiest although a little new copper pipework is needed at the radiator end and ill give it a try
As mentioned, having the 4m plastic run and then revert back to copper and the necessary push fit inserts reducing the flow and copper v plastic heat conduction was the basis of my query

 

[Elsa TLC]

This is what happens when builders do plumbing.

Plastic used well is not a problem. I still prefer copper.

Lots of new builds have used 10mm copper and plastic. Both will work well if installed correctly. But you can't tee off 10mm.

If most of the system is 15mm then the last radiator may struggle.

However if the radiator you took out was a directional designer radiator; then that may have been your problem.

 

[Elsa TLC]

Have you Ballanced your system at all?

 

[shd1970]

This is what happens when builders do plumbing.

Plastic used well is not a problem. I still prefer copper.

Lots of new builds have used 10mm copper and plastic. Both will work well if installed correctly. But you can't tee off 10mm.

If most of the system is 15mm then the last radiator may struggle.

However if the radiator you took out was a directional designer radiator; then that may have been your problem.

Thanks for the reply @Elsa TLC
I think the biggest problem and concern I had is that for a totally copper system, why did they decide to use 4 m plastic lengths and then revert back to copper ?
To me, it makes no sense whatsoever and considering I was paying the bill
It was around 14 years ago, so the lesson learned for me is to keep a closer eye if and when we ever have an extension built again

Just to clarify, there is no 10 mm in my system
The flow and return pipework from the boiler is 22 mm for the initial run where it gets into the actual boundary of the house
I say that because the boiler is in the garage
When the 22 mm pipe arrives in the house, it reduces down to 15 mm for all the radiators
They tapped off this 15 mm and used hep2o connectors to then run a 4m length of plastic and then used some more hep2o connectors to convert back to 15 mm copper coming down the wall to this radiator that I’m referring to
Using hep2o connectors for connecting copper to plastic and then at the other end plastic back to copper means the need for 2 of the hep2o inserts so 2 points for each F & R where the flow reduces
There is no other plastic pipe on the central heating system

 

[shd1970]

Have you Ballanced your system at all?

No, I never tried this but once I’ve replaced this radiator cleaned the system and have inhibitor in the system. I plan to balance all the radiators.
So it’s on the list to do

 

[Elsa TLC]

Ive stopped questioning why pretend Plumber's do this or do that. I see so much sh¡t plumbing.

However converting to plastic then copper again, I don't think is your problem.


Was the radiator you had that didn't work well
a designer Radiator?

 

[dal5band]

The inserts in the plastic pipe are only about a cm, presumably the rest of the plastic pipe is about the same ID as the copper so the resistance to flow is not that bad. I'd turn off the radiators in the upstream bedrooms as a start and slowly open them a little at a time until you get all three heating at the same rate.

 

[Elsa TLC]

The inserts in the plastic pipe are only about a cm, presumably the rest of the plastic pipe is about the same ID as the copper so the resistance to flow is not that bad. I'd turn off the radiators in the upstream bedrooms as a start and slowly open them a little at a time until you get all three heating at the same rate.

@shd1970
Thats Ballancing

 

[johnny2007]

The problem is not copper to plastic, many systems have that without any problem.
I think that you have 2 issues here:
1. Balancing as already mentioned and this might just solve the problem
2. All good heating engineers fit a backbone of 22mm pipe in the system from which 15mm pipe branch off to various locations and finally connect to radiators. You say that as soon as 22mm pipes enter your house, they revert to 15mm. Of course it also depends from the number of radiators and length of pipes.

 

[justigator]

The house I bought in 2019 had three vertical designer radiators which all had rubbish heat output. I replaced two with ordinary type 22 horizontal radiators from Toolstation a year or two ago and they are much improved from the heat output point of view. I have just replaced the third but won't really be able to tell how it does until we get some cold weather. A plumber/Gas Safe guy I have known for 20 years says that tall designer radiators often have poor output. I very much doubt that your piping is a problem.