One upstairs radiator can turn all downstairs off!

[baradam]

I have a c/h system with 4 rads and a towel rail rad upstairs and 6 rads down. All of them have rad stats.
The bathroom originally had one rad that worked on the hot water system, that I then changed and connected to a towel rail. I then 'tapped in' to the c/h pipes going to the bedrooms and installed a further rad in the bathroom.
The system works well as long as the bathroom radiator is on. If it is turned off, or down by the rad stat, then all the radiators downstairs go off!
The 'flow and retrun pipes' come down through my kitchen, but the 'return' pipe has a T in it and a second pipe goes in to it that seems to be a feed of some sort as it is very hot.
If I turn the bathroom rad off, then the 'feed' pipe downstairs goes cold, the downstairs rads stop working and that mysterious extra pipe that goes in to the return pipes gets even hotter.
All the rads and boiler are new, so, any idea of a reason, or better still, a solution...thanks

 

[stem]

Sounds to me like you have broken into one of the pipes only with your new bathroom radiator. (ie just the flow or just the return to the downstairs radiators) rather than across the flow and return.

This would mean that the water from, or to (depending on which pipe) the downstairs radiators flows through the bathroom radiator. Then when it's turned off, then the flow to the others is stopped as well.

 

[baradam]

Thanks for the advice. What you say makes sense, however, there were two pipes crossing under the bathroom floor to the bedroom radiators and I connected one to one side of the new rad and one to the other. So, if there were two different pipes, could it be possible that they were both 'feed' pipes and that the upstairs part of the system has been plumbed in differently to the downstairs?
Other problem is....now have a tiled bathroom floor, so can't get to the pipework anymore! Any way round this problem? Thanks again.

 

[Bamber gaspipe]

Thanks for the advice. What you say makes sense, however, there were two pipes crossing under the bathroom floor to the bedroom radiators and I connected one to one side of the new rad and one to the other. So, if there were two different pipes, could it be possible that they were both 'feed' pipes and that the upstairs part of the system has been plumbed in differently to the downstairs?
Other problem is....now have a tiled bathroom floor, so can't get to the pipework anymore! Any way round this problem? Thanks again.

Your main problem is you don`t know what you are doing & don`t understand your plumbing/heating system, my advice would be to get an engineer in & let him sort out your mess.

 

[baradam]

Thanks for the advice. What you say makes sense, however, there were two pipes crossing under the bathroom floor to the bedroom radiators and I connected one to one side of the new rad and one to the other. So, if there were two different pipes, could it be possible that they were both 'feed' pipes and that the upstairs part of the system has been plumbed in differently to the downstairs?
Other problem is....now have a tiled bathroom floor, so can't get to the pipework anymore! Any way round this problem? Thanks again.

Your main problem is you don`t know what you are doing & don`t understand your plumbing/heating system, my advice would be to get an engineer in & let him sort out your mess.

Thank you again. My main problem is that the plumber who fitted my new hot water tank couldn't work out what was wrong with the rads when he checked the system. Neither did the engineer who fitted my new boiler and neither did the Corgi engineer who came to commission that boiler. So, though I usually know what to do myself, on this occasion, it seems that even the 'professionals' don't have an answer (no matter what I would be prepared to pay them to solve). My system is not in a 'mess' and works perfectly well, all I would like to know is why that one rad seems to work lioke a 'shut off' for the downstairs rads. Thank you for your 'help', though unless you could recommend a good heating engineer in this part of the world, then I guess I am back to square one.