Freezing 3yr old son's bedroom HELP!

[Geyser]

What pipe is it to rads? 10mm plastic by any chance.

 

[smglasgow]

radiator profile is pretty uniform with bottom 5-10 degree cooler than top, but no cold spots

 

[smglasgow]

15mm diameter pipe to radiators and yes, plastic.

 

[smglasgow]

identical to his brothers set up which operated perfectly, and is 8 ft way, hence my confusion!!!

 

[REDSAW]

not blocked then

 

[doitmyself]

#2 removed all TRVs and opened lockshields 100%, turned room thermostat to 30-degree and blasted heating for 2hours - max temp in problem rooms 50-degrees

I assume you mean the rad temp was 50C, not the room! The result does not surprise me at all as you have completely unbalanced the system, so rads nearer the pump will get more than their fair share of the heat.

#3 started balancing the system by closing down the lockshields progressively until 1st rad in the system was 25% open, leaving both problem radiators FULLY OPEN at lockshields re-ran test: max tem 55-degrees in problem rooms after 2 hours;
#4 closed down lockshields on radiators downstairs even further (apart from lounge) which has has little effect on lounge or 3yr old bedroom;

#5 Closed all radiators apart from lounge and 3yr olds room and ran heating - again despite hot inlet pipes to rads, they only heated to 55-degrees after two hours;

You need to check the two problem rad individually; i.e turn of all the other rads but the one you are checking.

Basing the results on the temperature in the middle of the rad is not accurate enough. It's the temperature differential of the radiator's flow and return pipes which is important.

Be careful using IR thermometers as they can give false readings, e.g if pointed at unpainted copper pipe they may read 50% low. Hold them as close as possible to the surface measured.

What speed setting is the pump on?

With all TRV heads removed, measure the flow/return temperature differential of all rads. If the results vary by more than one or two degrees the system is not correctly balanced.

 

[smglasgow]

hi doitmyself.

I know the limitations of an IR THERMOMETER and have also recorded inlet and outlet temps at each radiator in the system (have excel sheet with data representing hours work). I use black tape on the copper pipe to get more reliable reading. Top of rad (white surface) is reasonable indication with IR thermometer.

Re your other points,

Pump speed was originally on speed 3, have reduced it do speed 2 after father in law's visit and his insistance speed 3 was not needed!I see no change in the system temps at speed 2.

I have turned off all rads except the ones causing the issue, again a marginal temp improvement but no where near the target temp of ~65 at top of rad. For ref, the rads giving the problems are dropping 20-degrees C between inlet and outlet pipes.

Water I have drained off is so clean and rads are not cold at bottom so i dont think i have gunked up radiator. I also, in response to an earlier poster, checked the thermostat pins, problem rads have pins which stick out the same amount at the pins on TRVs on rads that work fine, and are free to move up/down, so again doubt that is the issue. The lockshields are also fully open.

tarting to think i might have a problem in the pipework between son #2's rad and the problem rad in my sons betroom (8ft away) but looking at the pipe in the attic there are no kinks in it and its a straight run.

Back to wondering if the pump has enough "oompf" to push heat to the last rads. Then again, the problem rads have inlet temps of high 60's just no flow through them.........

 

[smglasgow]

boiler pressure when hot.

Not sure if relevant, but I see a 1-bar increase in system pressure when the heating is up to speed. 1.25bar cold, rises to 2.25bar when hot.

 

[SimonG]

How far out the pins stick has nothing to do with if its working or not. Whats the temp of the pipework at the trv on the rads you have the issues?

 

[rpm]

Doitmyself, did you bother to read the complete thread before jumping in feet first? In particular post #1!