Auto-fill valve for central heating

[jimjordan]

Hi

Can anyone suggest a check value or similar that I can put in-line with my filler loop to allow me to leave the filler loop tap open and have the valve open and begin topping up the system automatically when the system pressure drops below 1bar and shut when it reaches 1bar?

I'm in the process of investigating a hard to find leak, but it's taking time and frequently topping up the system or shutting it off when we go away for a few days is a real nuisance.

 

[gigz]

Yes, mines called wifey

If you need to top up regularly and cant see any leaks its probably under the floor/screed. Have you checked blow off pipe outside ? Does the pressure rise significantly when your heatings on ?

 

[jimjordan]

I'm pretty certain it's under the screed but leak detection cannot locate it with any of the gizmos. It holds over 3bar of gas pressure when cold. Plus the system holds pressure when I isolate the downstairs rads using a loop I had a plumber install which means only the upstairs rads are heated. This proves it off the boiler, hot water loop too. (I have a balloon on the end of the blow-off pipe that never fills with water)

Next step is to start chasing out the screed floor, under tiles, wood and carpet which will get expensive. I'm trying to put that off to allow me to deal with insurers, adjusters to minimise the costs etc, hence the need for the temporary auto-top up solution.

 

[GavThePlumber]

Putting fresh water in regularly is going to course severe corrosion within your system.

Go rent a thermal imaging camera.

 

[jimjordan]

Have tried thermal imaging, moisture detection, gas detection, none highlight the leak or even any possible locations unfortunately.

 

[gigz]

Ignore !!! Blonde moment

 

[GavThePlumber]

Sounds like cat and signal generator time then, if you are getting no damp readings and no water discharge from boiler or any valves.

Most would choose the re-pipe option though and leave existing pipes capped off..

 

[jimjordan]

Thanks, anyone got any suggestions regarding the auto top up valve?

 

[denso13]

No such thing.

 

[gigz]

Iv'e heard someone uses an adjustable pressure reducing valve set to 1 bar (could be a 1bar prv ?) to save them running back to boiler when filling. Never tried it myself but others on here might know better. (I'm not that lazy )

 

[GavThePlumber]

There is one in Screwfix for 20 quid, adjustable from 1 - 5 bar.

 

[TCCHeating]

Stick a bottle of fernox leak sealer in it.

As already said what you are suggesting (putting a pressure reducing valve in line with the filling link) is going to screw your system after a while.

 

[twgas]

If you go for the "dig up" method, start at a carpetted area. Carpets can be refitted easily, unlike wood or tiles. If you disconnect the down stair circuit You might be able to rig up an auto fill device but cutting into sections and testing is probably the best way.

 

[Onetap]

No such thing.

There is, but the Water Regulations prohibit a direct connection between the mains and a heating system, except where there is an appropriate back-flow prevention.

In this case the device required is a reduced pressure zone valve, that has to be installed and commissioned by someone with the relevant certification. They're expensive; I've seen one of these in 30 years.

Like this
http://arrowvalves.co.uk/portfolio/reduced-pressure-zone-valves-ba/

The only other auto top-up devices are an F&E cistern or a pressurization unit (break-tank and pump).

You'd do best to sort the leak out, it will destroy the boiler, radiators and block the pipes with sludge, possibly destroying replacement boilers.

Besides that, you're suggesting connecting a continuous fill device to a system that probably already has severely corroded radiators.
What could possibly go wrong?

 

[Agile]

If I had that problem then I would try pressurising with air to about 80 psi and listening for the air escaping from the leak with a stethoscope.

I would also "listen" with a supersonic sound detector as air escaping from a small orifice tends to create high frequency sounds above 15 kHz.

Tony