Making up a manifold from seperate fittings

[nthused]

Hello All,

I'm considering replacing 4x radiators and associated 8mm microbore pipeage with 15mm to each rad from the 22mm flow/return. This is currently done through an 8mm manifold at each end (4 out and 4 back in).

Now when I put my 15mm tubes in to each rad and back I'm looking to do this by contructing a manifold using copper soldered 22 x 15 x 22mm reducing T's and joing these together in two groups of four.

I'm doing this as I have an abundance of these fittings and preformed manifolds can be expensive.

Apart from the extra effort, can anyone see any problems with this?

 

[glasgowgas]

can`t see much wrong with that,

remember to balance system on completion

 

[clf-gas]

No problem, go for it.

 

[nthused]

Thanks for the quick answers chaps,

I'll get my blow torch primed then.....

I'll be glad to see the back of the 8mm stuff - I'm sure it has it's place but I'm not a big fan.

 

[D_Hailsham]

I'll be glad to see the back of the 8mm stuff - I'm sure it has it's place but I'm not a big fan.

This is where theory and practice part company.

In theory an 8mm pipe can carry about 2kw and a 15mm about 8kw. Now most rads are under 2kw, so an 8mm pipe link from the distribution pipework is more than adequate. Unfortunately Murphy's Law comes into operation and 8mm pipes are more prone to blocking up, so everyone uses 15mm pipe. The problem then is that the flow is much too high, so the lockshield on the radiator has to be almost closed to give the right flow through the radiator.

 

[glasgowgas]

I'll be glad to see the back of the 8mm stuff - I'm sure it has it's place but I'm not a big fan.

This is where theory and practice part company.

In theory an 8mm pipe can carry about 2kw and a 15mm about 8kw. Now most rads are under 2kw, so an 8mm pipe link from the distribution pipework is more than adequate. Unfortunately Murphy's Law comes into operation and 8mm pipes are more prone to blocking up, so everyone uses 15mm pipe. The problem then is that the flow is much too high, so the lockshield on the radiator has to be almost closed to give the right flow through the radiator.

talk him into getting a Magnaclean, Legend!!

 

[nthused]

Cheers for the info.

I did have a chat over the weekend with a plumber friend of mine and he suggested the same problem. 15mm will overcome the tendancy of 8mm to get blocked but will completely unbalance the system, especially if there is still other 8mm present, which there will be.

The runs to the new rads are quite a way from the manifold and I suspect are already partially blocked. I suppose I could put isolaters in line at the manifold end to restrict the flow - I've loads of spare ones of these as well...

 

[sooey]

The runs to the new rads are quite a way from the manifold and I suspect are already partially blocked. I suppose I could put isolaters in line at the manifold end to restrict the flow - I've loads of spare ones of these as well...

That's what your lockshield valve on the end of your rad is for.

 

[nthused]

yes I'm aware of what a lockshield valve is for, thanks. I was just trying to centralise where I restrict the flow to each branch from. I suppose it is overkill though...

 

[sooey]

If you restrict the flow through a circuit it doesn't matter where in the circuit you restrict it. It's still restricted.

 

[charliechaplinspants]

If you restrict the flow through a circuit it doesn't matter where in the circuit you restrict it. It's still restricted.

Profound.

 

[nthused]

Yes, thanks for your info sooey, I'm completely aware of what you're suggesting here and I know you're trying to help, but my only reason for having the restriction at the manifold end was to centralise where I control the restriction from, not that it would be a better place to do it from in terms of the actual job its doing.

As I said, I have loads of spare isolators and I was just going to use them up for something. I'm fully aware that the radiators lockshield valve is perfectly designed for restricting flow.

I know this is a completely unecessary addition to the design but I just like the idea of restricting all the outward flows from a central point.

It's two answers to the same problem and mine might be the slightly more unconventional way of doing it.

 

[D_Hailsham]

I know this is a completely unecessary addition to the design but I just like the idea of restricting all the outward flows from a central point.

It's two answers to the same problem and mine might be the slightly more unconventional way of doing it.

It might be unconventional for domestic installations but standard practice in commercial and industrial situations. See, for example, the Tour and Andersson Balancing Manuals