Adding inhibitor to a towel rail

[dilalio]

It's got a valve with settings on (is that a TRV?)

TRV = Thermostatic Radiator Valve

Most of them do not shut off flow into the rad completely when dialled down to zero which is when you need a decorators cap or can sometimes use a 5p coin under the head trick.

 

[Harry Singh]

Yes I have those everywhere - does it just inhibit the flow into the rad or is it fancier than that - can open/close dependent on temp? I've read somewhere they might not completely close the rad off.

 

[Harry Singh]

I've read up on TRVs and think I understand them - complicated for one with small brain such as I though.

 

[dilalio]

Dependant on brand/type, they have a liquid or wax vial which expands/contracts, according to ambient temperature, this acts upon a spring-loaded pin, in the valve body, which closes/opens the flow into the rad, dependant on what manual setting has been selected on the head gauge. They have their pros and cons but are much more dynamic than the old manual valves.
Usually though, it's not ideal to have them on towel warmers... But many installs do... It all depends on the overall system installation design.

 

[Harry Singh]

I had another go at re-pressurising the EV with the system stop cock open and got it up to 0.8bar. I closed the system stop cock and took my air compressor off. I noticed that the pressure guage on the boiler (which had started a 0) was showing about 0.6bar before I added any water through the loop. Is this the way it should be?

I'm running the system and it's jumped from idling at 1bar to almost 3bar and I think the PV might pop again.

Does this suggest I'm wasting my time on this EV or is my technique at fault?

Cheers

 

[bazdaman]

Whilst pressurising the vessel, wait for system gauge to read 0bar.

 

[ianmcd]

what system stop cock ? you need to leave a drain point open not a stop cock

 

[Harry Singh]

I might be abusing the terminology:

 

[Harry Singh]

Whilst pressurising the vessel, wait for system gauge to read 0bar.

How high should I let my compressor go to get the Boiler gauge to 0bar. I was going by 0.8bar as per some instructions on here but does it need more to throw the waetr out?

 

[ianmcd]

that is indeed the drain point and it is correct that you pressurize the air side of the vessel to 0.8 Bar, how much water did you get out of the drain point when you started your compressor on the expansion vessel ?

 

[Harry Singh]

At a reasonable guess I drained 1.5/2 litres.

It was quite quick to get upto 0.8bar on the compressor.

 

[Harry Singh]

If you have a spray nozzle from a bottle of something (window cleaner etc) you can put the dip tube of this into the top of the towel warmer and use it to squirt system water out of the rail and into a container... If you use a measuring jug, you'll know when you've emptied enough to make room for the inhibitor

That was a good idea and led me to make one of these, in the picture - it saved having to open the towel warmer at the bottom. It's only a 20ml ink cartridge syringe but I've ordered a 100ml one for next time.

 

[ianmcd]

if you have an 8L expansion vessel and it was full of water then you would have to drain 8L of water and then start the pressurising part of it , its surprising how much water comes out before you start the air part

 

[Harry Singh]

If I drain 7/8 litres of fluid off why does it drain from the EV first rather than the rads upstairs?

 

[ianmcd]

because you are pressurising the expansion vessel, the upstairs rads water will be held by vacuum unless you open a bleed screw