22mm pipe from cold tank to CH circuit?

[jmaxwell]

I'm replacing the ¾" steel pipe that currently runs from my small cold water tank to my central heating circuit because it's blocked with sludge from top to bottom and won't let any water pass. Should I replace with 22mm copper pipe?

 

[Steelmasons]

You fail to mention size of system along with input rating of boiler/s and you expect an answer to your question????

 

[jmaxwell]

There are 11 radiators and the boiler is a Thorn M80/100C.

Edit: Boiler heat input is 36.9 kW.

Edit: The main circuit is 1¼".

 

[oldbuffer]

If it worked with 3/4" steel pipe, the internal diameter of which is (roughly) 19mm it should work with 22mm copper, the internal diameter of which is (again, roughly) 20mm.

I'd be more worried about potential corrosion, rust / sludge particles in the 1" pipe. Needs to be kept on a diet of adequate inhibitor - probably 2 litres changed every few years.

 

[jmaxwell]

I'm planning to add Sentinel X800 (cleaner) to the system when I fill it up and flush through a couple of times after a week or so. Then fill up again with X100 (inhibitor) and leave it in. I was thinking 1l but you say I might need more...?

Does this sound like a good plan?

 

[Steelmasons]

3/4 steel has a larger ID than that of 22mm copper.

 

[oldbuffer]

I'm surprised, always thought 3/4" had an internal diameter (nominal bore) of 3/4" which is about 19mm. Oh well, you live and learn.

 

[jmaxwell]

It's 21mm ID, just measured it.

 

[Razor900]

3/4 steel has a larger ID than that of 22mm copper.

But is it pipe or tube

I wonder how many on here know the difference??

 

[Aquaheat]

3/4 steel has a larger ID than that of 22mm copper.

But is it pipe or tube

I wonder how many on here know the difference??

Pipe is a nominal OD and is affected by wall thickness (schedule) and ID remains the same, tube is an exact OD and wall thickness (gauge) affects the ID.