bleeding system

[sploop]

Just fitted TRV's to rads and wondering what is the correct procedure for setting up. Do I open up TRV's and balance usuing valves on other end?? Any help please. Thanks

[fred]

In article , sploop writes

Yep, that's it, if you don't balance the system the rads on the easier paths will steal all the flow until their demand temperature is satisfied. Follow the balancing procedure in the DIY faq with TRVs fully open, then set the TRVs to your desired comfort setting and all will be well.

[John Rumm]

Usually if you take the head off the TRV it leaves the valve part fully open.

[fred]

That sounds like hard work John, would there be much benefit over just setting them to max? If there's any chance of them starting to close down, the windows could be opened wide.

[Roger Mills]

It's far better to remove them, to prevent any possibility that they are starting to close the valve. It only takes a few seconds to unscrew the locking ring which holds the thermostatic head onto the valve body.

[John Rumm]

You could, but IME, taking the heads off is very quick and easy - hold the valve head steady and push down on to the base a bit, then just undo the lock ring (which should only be finger tight). It should then come off in your hand!

[fred]

In article , Roger Mills writes

I'm not convinced. The max setting on mine is a control temperature of

23-25deg or more (sorry can't find the flimsy bit of paper that came with them), so having them fitted and set to max isn't going to affect the balancing process, certainly not with the windows open at this time of year. Yes, it's relatively easy to take them off but IMO it's unnecessary work that's not going to affect the balance to a significant degree, save the effort and do the job in less time.

[sploop]

Thanks all, will follow instructions. Only one other question? Does it matter where to start? Top radiator? Or is it not important. Many thanks again fella's

[Harry Bloomfield]

sploop used his keyboard to write :

If air is just trapped in the upper part of the radiators, then it makes no difference which order you bleed them. Often air will form in one particular radiator (bathroom in our case) for some weeks after and it may need repeat bleeding.

Sometimes it is better to bleed with the system (pump) turned off, as the pumps can cause a negative pressure.

[fred]

In article , sploop writes

For bleeding, start anywhere, for balancing, start with the radiators that you think will be stealing the most flow, most likely the ones nearest the boiler and move on to the ones furthest away. Remember it's an iterative process as the changes you make as you go round will affect the balance of radiators you have just changed.

[Roger Mills]

For balancing, quickly go round all the rads with your IR thermometer, and note the flow and return temperature of each one. Then start turning the lockshields down on the rads with the smallest temperature *drop*. Remember, you're aiming to get the same drop on all of them - and you do this by restricting the flow through the rads with too low a drop.

[fred]

In article , Roger Mills writes

A good summary, I may borrow that ;-)

Although I do use the British Standard hand for the first pass.

[Roger Mills]

Thank you - feel free!

It's a good practical method which always works without needing to carry out any complex analysis of the system.