inverted circuit raditors do not get warm (execpt for one!)

[seanmcinnes]

I am getting old fast trying to solve this one - recently moved into new house, concrete floor means all ground floor rads are served from above. All radiators upstairs get nice and hot as I would expect and can control their temps using the thermostatic control valves nicely. The radiators below are fed from the pipes feeding the same area above. I have had to move 1 radiator in the kichen area which was feeding off the pipes coming down in the guest wc - fed guest wc and kitchen rad. First problem I cannot understand as I have hooked up the guest wc rad directly to those pipes now and it doesnt get warm. Second problem is that i now moved the kitchen rad to feed from the 2 bedrooms above (so was feeding 2 radiators now 3). This radiator will not get warm but those above do. As with this radiator and another in the lounge I have now enclosed the pipes into a duct so a few 90 bends have been added, but the top of the pipe doesnt even get warm which is what confuses me - hot water just seems to bypass and go into the top bedroom radiators instead. So the radiator in the lounge also doesnt get hot. There is one further radiator in the lounge which I have not touched, but has the same symptoms and another radiator in the entrance hall that does get nice and hot (the only one working downstairs).

So I have tried to check and confirm the thermostatic valves are set on the correct directions which they appear to be. I am certain it is not an airlock as I have emptied the system more than once and refilled / bled etc.

Any ideas appreciated. Thanks in advance

 

[Razor900]

Turn off all rads in the house bar one of the affected ones, run the heating with the pump on max and wait for the gurgling

 

[bengasman]

What do you mean by: "inverted radiators"?

 

[twgas]

What do you mean by: "inverted radiators"?

think he means on drops.

 

[seanmcinnes]

yes, it is basically the radiators that are on drop runs from the first floor, there are several drops as the pipes need to drop to ground floor level and then return to first floor level back to the boiler. I believe this is called an inverted loop (my mistake to say inverted radiators!).

The situation has improved somewhat - I now have only 1 that remains very cold, another that gets luke warm and the others get nice and warm. I have done the following to achieve this -

set the pump to full (it was only on 2 of 3)
removed the trouble radiators and flushed them with a hose in the garden (I was surprised how much dirt came out, and think this restricted return flow)
replaced the thermostatic valves (I noticed that when I removed the top part of the valve things started working better which suggested to me the thermostatic valves were not opening properly)

I still have 2 rads to get working but have not yet checked the thermostatic valve on one of these so will get to that today!

 

[bengasman]

If you had mentioned that you have an open vent and rads on drop downs, you would have had several people hollering: corrosion.
The whole system needs a proper clean.