I Balanced My System But Now Have High Pressure

[Vinylrecords]

Hi everyone this is my first post - I have no idea what I'm doing with plumbing and heating - have had some success by reading forums etc but now I'm stuck.

I live in a townhouse with 3 floors. Never had much heat in radiators on my ground or 3rd floor. So I rebalanced the system. (Put all lockshields and TRVs to zero and went round rads in order, opening the lockshields v small amounts to aim for the fabled 12 degree difference between flow and return.)




Amazingly every rad is now roasting and heats up fast however when the heating is on the pressure goes up to 3 bar and beyond so I'm worried maybe I've not opened the lockshields enough? Would this create extra pressure? Or maybe this is ok as water has to get pumped up an extra level in my home?

(I was surprised, when I got to the rads at the end of the line, I only needed to open them a 1/4 turn or so - had expected them to need to be half open or more...)




I think the only thing that affects pressure though is amount of water in the system? When boiler is off the pressure goes low (sometimes too low) and I see beads of water where the arrow points in the picture. Is that normal?

Also nothing needs bled - I've tried and water immediately comes out.

Any help much appreciated.

PS I have a Baxi Duo Tech 40 he. 22mm flow and return.

 

[ShaunCorbs]

When the heating and rads system is cold what is the pressure in ?

 

[Ric2013]

Assuming the pressure rises with the system warming up and not the pump kicking in, then the issue is that you've now got all the water warm whereas before a part of the system remained cold. Hence more expansion. Shouldn't go as high as 3 bar, could be a design issue but more likely the expansion vessel is under or overpressured. Re your picture, possibly you have a small leak but it's nothing I'd panic about. The pressure won't be a balancing issue as a heating pump won't push at 3 bar - they aren't that powerful.

I would question your approach slightly by the way, you should have the lockshields fully open at the 'end of the line' radiators. Not a problem really, just means you might be running the pump faster than you'd otherwise need to - more noise, and more electricity used. The point of balancing is to increase resistance to flow across the radiators that have less resistance than the others, not to increase resistance across all radiators.

Now I'm really going to spoil your day, however... With a modern condensing boiler such as yours, 20°C difference would be better than 12°C, but if you can't adjust the pump speed as it's probably integral to the boiler, stick with 12°C for now.