Replacing automatic filling valve on central heating with manual

From installing 100s of Vokera's there is no filling loop with the boiler. Your system is semi sealed and a filling loop would find it hard to fill your system, they need a bit of pressure behind them (mains water) to open the built in non-return valve. You could try putting in a manual lever valve above the auto fill valve so you can isolate.

A word of caution! I have never seen auto fill valves fitted to a semi sealed system. Are you sure it is fed from the tank? What pressure is on the Gauge?

Gdavis asks:

jeez vokera must be leaving me short that filler loop with their name on it on all those boilers i installed!!! Heinbloed,where do u get this info from?

I get this information from reading the installer manual and controlling the content of the delivered box.

The part code for the
"Filling loop flexible pipe" -in case you have order it - is 10023570
For the manual "Filling cock" it is 10023568

Outkast_IRE wrote: »

I do remember the Combi boiler vokeras had a fill loop on the pipes to the boiler it was like a 3 way valve to provide mains water to either instanteous hot water/ off / heating fill .

I am 100% about these coming with the combi a few years ago , dont remember them ever coming with standard boilers

They come with the combi's al right, not with the standard boiler which is probably what the OP has.

The pressure is just under 1 bar when on, and around half that when off.

This sounds ok. The pressure can increase in closed systems when the water gets hot and can't expand freely.

The " pipe for cold water into the cylinder " - is this the pipe for fresh water to be warmed up?

Is the " red wheel " kept closed?

Is there a expansion barrel installed? Maybe as part of the boiler, a red voluminous object?

"Originally Posted by heinbloed
Is the " red wheel " kept closed?"

and the OP


"I've never touched it, should it be closed?"

No, not permanently. As long as the non-return valve is doing it's job it should be fine as it is.
But to see if the system is leaking you could close the valve temporarily and watch the pressure. As long as the pressure stays within the usual readings (0.5-1.0 bar) there is no leak in your CH system and therefore no water added via the automatic refill.Nothing to be worried about.

After this test you should open this valve again to allow for normal operation.

In this case (when there is no leak) only very small amounts of fresh water will enter the CH system via the automatic filling. For example when 'bleeding' the radiators and when replacing the water lost via diffusion.

So there seems no problem with your heating system except that you're worried about the 'open' automatic filling valve? The domestic water is warm, the rooms are warm and the tap water not discoloured or smelly?

Ask the heating engineer/plumber when doing the anual check if there is enough corrossion inhibitant in the system. The concentration could become dilluted with leaks and consequent filling.

With a closed system there should be a pressure vat/barrel somewhere. However with well designed systems, esp. the larger ones it might no be necessesary. A larger system could have enough expansion capacity build-in, esp. when the temperatures (pressure) is not widely fluctuating.

Ask the maintenance person about it, if present this barrel should be checked as well.

heinbloed wrote: »

This sounds ok. The pressure can increase in closed systems when the water gets hot and can't expand freely.

The " pipe for cold water into the cylinder " - is this the pipe for fresh water to be warmed up?

Is the " red wheel " kept closed?

Is there a expansion barrel installed? Maybe as part of the boiler, a red voluminous object?

id say the system is sealed as ALL vokera boilers are system boilers except the water heaters!aqua nova, shut of d prv and see if pressure drops from my experiance when i come across prvs on heating system i expect theres a leak some were that plumber cant find and stick 1 on and say problem fixed!

The main reason for a auto top up system is exactly that..... no need to top up the system yearly etc, the big problem with this is that it masks any leaks that may develop in the system leading to corrosion and sludge build up unknowlingly occuring, much much better IMO to shut off the top up by simply shutting the black knob on the bottom of the PRV and checking the pressure occasionally, say every few months and topping up if required. You would generally set the pressure to 1.0bar via the adjusting screw on top of the PRV and let it at this setting and just shut the black knob after each top up.

re the semi sealed system, the top up water supply is from the small tank in the attic, these were originally open vent systems with a small feed and expansion tank in the attic, the system is then converted to a "semi" sealed system by blanking off the vent and installing a non return valve in the cold (make up) feed to the boiler and the installation of a expansion vessel, a isolating valve should be (ideally) installed in the mains make up to the F&E tank ballcock and kept closed, the tank level can then be chacked periodically, as above. I have a open vented system and keep this valve shut and have never had to top up the system.

If only for interest, came across this some years ago which seemingly will shut off in the event of a large leak but of course will still mask small leakage resulting in corrosion etc.

https://flowflex.com/news/top-up-mate-launched-keep-your-customers-warm-this-winter