New Radiator not heating up please help?

[hoopyman]

Hi guys I’ve teed off from an existing radiator point in my extension moved the radiator about 3 foot and upgraded it to a double rather than the 600 X 1000 single that was there and added another 600 X600 in the next room about 2 foot away in my stupidity before the tees i changed the pipe size from 8mm to 10 mm to fit the valves I could find in the DIY store (yip I see my error here I think!) the radiators have no real leaks and the valves are open ( all othe rrads working fine!) but these two are not heating up! is this because I changed the pipe size from 8 to 10 mm??
I should say I’ve had the com.. boiler updated a couple of years ago and was told it would handle another few radiators no probs!

 

[Rob]

the problem with 8mm pipework is its run from manifolds so each rad has its own flow and return and nothing is teed off.
first thing id do is try and get them hot by turning all other rads off. then it might just be a case of fine balancing them

increasing from 8 to 10mm should in theory help

 

[hoopyman]

the problem with 8mm pipework is its run from manifolds so each rad has its own flow and return and nothing is teed off.
first thing id do is try and get them hot by turning all other rads off. then it might just be a case of fine balancing them

increasing from 8 to 10mm should in theory help

I've tried that as I read that here in another post?? the top of the smaller new rad is a little warm but everything else is cold!! It was me that done the tee off from the old point so I'm trying to feed two rads through the one flow and return will this not work??

 

[Rob]

unfortunatley my knowledge of microbore systems is limited.
i would have thought not TBH but im sure some one will come along soon who will have all answers! good luck

rob

 

[hoopyman]

unfortunatley my knowledge of microbore systems is limited.
i would have thought not TBH but im sure some one will come along soon who will have all answers! good luck

rob

Thanks anyway buddy my wife is doing her nut at me so hopefully someone will help me cheer rob

 

[Slugbabydotcom]

Could be an airlock or blockage possibly caused by getting too solder happy. If its the latter then you got to rip it out and start again.

Proceed as follows

Try shutting off all the other rads apart from one of the 2 that arent working.
When you get the first one going open the next and close the first off again to force the blockage through.

If that doesnt work take your 2 naughty rads off and then run some water through each of the 4 ends into a bucket before reconnecting the rads. get someone to keep the water pressure up to over 1 bar while you do this.

No water coming out of one of the ends means the pipe is blocked solid.

 

[hoopyman]

OK will try this but I didn't use solder I used olives as I'm not allowed to have a blow torch Ha! cheers I'm I missing something easy here when you buy new rads are there anything inside (other than the cap) I should remove as pipes are hot well flow one anyway??? you don't need to burst anything inside do you???

 

[Steve__M]

Is there any 8mm pipe left between the radiators and the boiler (it wasn't clear from your post whether you'd replaced all of it or just some of it).

I've had trouble balancing a system where I have a 1.8kW radiator (about the same as your 600mm X 1000mm double panel one I'd guess) on a 6 metre long 10mm pipe. My problem was no where near as bad as your problem, but an 8mm pipe is much too small for the amount of water required, and a 10mm pipe will struggle I thinkl.

 

[hoopyman]

Is there any 8mm pipe left between the radiators and the boiler (it wasn't clear from your post whether you'd replaced all of it or just some of it).

I've had trouble balancing a system where I have a 1.8kW radiator (about the same as your 600mm X 1000mm double panel one I'd guess) on a 6 metre long 10mm pipe. My problem was no where near as bad as your problem, but an 8mm pipe is much too small for the amount of water required, and a 10mm pipe will struggle I thinkl.

Hi Steve yip the whole system seems to be made up from 8mm pipe the only 10mm pipe is from where I took the tee off so about 10 meters of 10 mm everything else is 8mm do you think I need to get a smaller rad then???

 

[Steve__M]

By the sounds of it, the system ought to cope with your 600x600 (double panel?) radiator if it previously coped with a 600x1000 single panel. What happens if you turn off the bigger of the two radiators? Are you sure that it was fine with the previous radiator?

Basically, the bigger the radiator, the bigger the flow of water required to feed it. You sound like you have at least trebled the radiator power by going to two double panel instead of one single panelled radiator.

The pipes cause a resistance to the flow of water that the pump has to overcome. Unfortunately if you treble the flow of water, the resistance goes up by a factor of about 7 times, so your pump has to be able to work about 7 times harder.

Furthermore, even if the pump is sufficiently powerful, there comes a point when the speed of the water makes it noisy. The data sheet I have suggests you are slightly above the limit for an 8mm pipe.

Bear in mind I'm a physicist, not a plumber, who has learnt from problems with my own system. With my problem radiator the design had a 15mm pipe to it, but the plumbing contractors only fitted a 10mm pipe. I managed to just about solve it by really carefully balancing the system, but I also got an important 4C temperature improvement by flushing the radiator.

Best of luck

Is there any 8mm pipe left between the radiators and the boiler (it wasn't clear from your post whether you'd replaced all of it or just some of it).

I've had trouble balancing a system where I have a 1.8kW radiator (about the same as your 600mm X 1000mm double panel one I'd guess) on a 6 metre long 10mm pipe. My problem was no where near as bad as your problem, but an 8mm pipe is much too small for the amount of water required, and a 10mm pipe will struggle I thinkl.

Hi Steve yip the whole system seems to be made up from 8mm pipe the only 10mm pipe is from where I took the tee off so about 10 meters of 10 mm everything else is 8mm do you think I need to get a smaller rad then???

 

[hoopyman]

Steve your a good man thanks for your help here I'm sure the pump can take it its the pipes I'm worried about I'm going to keep working on the balancing tonight

Cheers buddy

Tony