Going up from 8 to 10mm to radiator.

[briwire]

I am fitting a new radiator in place of an old one. All the others have 10mm feeds but for some reason this has 8mm, so I have two 8mm capped ends to connect my new radiator to.

I am struggling to get 8mm valves. B&Q are sold out and my local merchant, who is a lot cheaper has 10mm but with an adaptor to drop it to 8 (which I would prefer not to use).

I have some 10mm pipe spare and a bender etc so i would like to use 10mm. I know nothing about the principles of liquid flow so would there be any detrimental effect from using a reducer (the opposite way round) to go up from 8 to 10mm. Would it affect the heating effect at all?

 

[calorific]

No problem.

 

[leakydave]

You can enlarge 10mm pipe very slightly and solder 8mm directly inside it if you are stuck. Otherwise just use 8/10mm reducing set at the valve connection.

 

[conny]

No problem.

Surely there will be a problem with pressure? How can you adequately supply a 10mm pipe from an 8mm feed? Best way to do this would surely be to replace all the 8mm pipe with at least 10mm?

 

[calorific]

No problem.

Surely there will be a problem with pressure?

Pressure has nothing to do with the size of pipe. Flow rate is all that really matters anyway and this won't be affected.

How can you adequately supply a 10mm pipe from an 8mm feed?

In the same way that the rest of his system has been done - in particular on the return for this leg . In any case, water enters and leaves the radiators though 1/2" and when inside there are volumes involving greater surface areas.

Best way to do this would surely be to replace all the 8mm pipe with at least 10mm?

Best way would be to replace the whole system with 15mm

 

[conny]

No problem.

Surely there will be a problem with pressure?

Pressure has nothing to do with the size of pipe. Flow rate is all that really matters anyway and this won't be affected.

How can you adequately supply a 10mm pipe from an 8mm feed?

In the same way that the rest of his system has been done - in particular on the return for this leg . In any case, water enters and leaves the radiators though 1/2" and when inside there are volumes involving greater surface areas.

Best way to do this would surely be to replace all the 8mm pipe with at least 10mm?

Best way would be to replace the whole system with 15mm

Sorry Cal but I beg to differ on there not being a difference in pressure /flow rate. If you are pumping something through an 8mm bore at x pressure that pressure will drop when you have the same flow rate through a 10mm bore. You will still be pumping y litres of liquid per minute but the pressure through the larger bore will drop.

 

[Dan Robinson]

Are you on drugs?

 

[calorific]

Conny, flow rate is all that matters. You want heated water to flow through the system and occasionally into a big wide metal thing for is to pass some of this heat into a room before it moves on (a bit cooler) to the next radiator etc or back to the boiler to be re-energised with heat. Flow provides this, not pressure.

How long the water needs to stay in any radiator is determined by a combination of balancing, TRV's and the ambient temperature of the rooms. TBH you'll find that sometimes the lockshields/TRVs will have been closed down to a gap of smaller cross-sectional area than an 8mm pipe, with the outlet side of it being the 1/2" radiator tail leading into a larger cavern within the radiator itself.

 

[sooey]

Think of a sealed system with various pipe sizes pressurised to one bar, if you neglect the effect of gravity the pressure will be one bar throughout the system. The direction the water flows in won't affect that.

 

[conny]

Ok gentlemen, I will bow down to your knowledge, its good to be able to learn something each day. Thank you for the explanations.

And to Dan, I have never taken drugs in my life apart from those prescribed by a GP and smoking cigarettes. Totally un-called for comment because I didn't understand the principles of pressure/flow rate.

 

[Dan Robinson]

Don't argue something you know you don't understand then

As a figure of speech I don't know what's uncalled for?

Now jog on and buy yourself a Trelor book, there's a good fellow

 

[CBF]

Good job Dan is in a good mood

I'm guessing the "fellow" is actually a lady looking at her name

 

[Dan Robinson]

Aye, consider fellow to be androgynous- I am all for equality.


Good job I didn't say to "go and grow a pair" instead


Skins have to be thick in the construction industry. I don't see why DIY'ers should not have to play by the same rules when they are doing our jobs instead of us

 

[conny]

Aye, consider fellow to be androgynous- I am all for equality.


Good job I didn't say to "go and grow a pair" instead


Skins have to be thick in the construction industry. I don't see why DIY'ers should not have to play by the same rules when they are doing our jobs instead of us

My, my! Aren't we the big man?
From working in the engineering industry most of my life I have a skin like a rhino, and I usually find those that give stick on the likes of these places, as opposed to constructive criticism or help by explanation, are weak in real life. It takes a bigger man(?) than you to even come near to hurting my feelings.
Keep up the name calling if it boosts your ego.

Once again Thanks to Cal and Sooey for their help.

 

[Dan Robinson]

oh dear.... another one with engineering pedigree.


Trust me, I'm big enough