Cold Radiators after removing them

2 Sep 2005
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United Kingdom
I took all 3 radiators off on the top floor of our house a couple of months ago to decorate, but now they are back they are not getting warm.

The boiler (Ferroli Maxima 35C) has also been moved from the Middle Floor to the Ground Floor whilst the radiators were off.

The radiators on the Ground and Middle Floor are fine and get nice and hot.

I've bled the 3 radiators until water comes out of them (and bled the other rads)

The flow and return pipes to the 3 radiators are cold.

The TRV? and LSV? valves are open (is anti-clockwise open?)

Any ideas as its now driving me nuts - is it an air lock or do they need balancing (still not getting warm after CH has been on for hours?)
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if you go to the highest radiator in the house, and open the bleed valve, does water squirt out forcefullly?

Close all the radiators in the house except the cold ones. Turn the pump up to speed 3. If one of them gets hot, turn that one off and see if the remaining ones get hot. You may have to continue bleeding if air gets pumped round.

If you turned your TRVs to "off" during the summer they may have jammed shut. Take the heads off and see if the pin moves (search "TRV" + "Pin")
Thanks for the super quick reply.

The water is coming out forcefully from the radiators (I found out the hard way when the bleed valve flew out somewhere on floor last week whilst I was bleeding it).

I didnt change the TRV's over summer, but I did double check the pin and they all spring back OK.

I'm not sure how to change the pump speed on the boiler.

Stupid question, but if I turn the TRV to "0" - is that closing the Radiator, or is it only closed when the LSV is closed as well?
circulation is stopped when either one of them is closed

It is still stopped if they are both closed.

If you have taken the TRV heads off I wonder if you might have fitted them too tightly, so they are pressing the pin down. They may be adjustable but you wil need to find the instructions. You cannot rely on the numbers meaning what they say if there is an adjustment. If you take the heads out the pin should pop up so they are constantly open.

If you find the pump I expect it will have a small plastic knob on it that turns the speed from 1,2,3.
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thanks for answering the valve question - I've always wondered about that!

I only took the TRV heads off when trying to fix the heating problem - not before - I dont think that they're too tight and the pin does pop up on all 3 radiators.

I found the Grundfos pump(s)... the boiler has one for the HW and one for the CH - it doesnt have any numbers on either pump though and seems to be turned to the max where the arrow is pointing (anticlockwise)
I thought you turned it clockwise :confused: but you will hear the pump get noiser as it goes to faster speed.

numbers may be moulded into the plastic and need a torch to see, or they may appear in a little window beside the knob.
My immediate reaction is that as the boiler was presumably moved by a competent CORGI then he should be asked to investigate the problem.

Yes, the boiler was moved by a competent CORGI installer and I've spoken to him on the phone. However he is very busy at the moment due to the time of year, and also his son has left the business so he is on his own.

He asked me to check the pins as they could be stuck on the radiators - but they are not stuck.

He said that he can come out to investigate, but it wont be until the week after next.

I just thought that if it was something obvious that I could try.

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