Central Heating Valves

[cyodesigns]

Hi,

Are these valves (in the center of the photos) OK to use for central heating? I have conflicting advice from the plumber who installed them, and another plumber who fixed a leak in my bathroom but saw them and said they shouldn't be used for central heating. Aparently they have a restricted flow and could potentially leak due to the heat going through them. He suggested that full bore, butterfly or gate valves should be used instead.

The pipes go up to my loft. The heater where the pipes go to hasn't been installed yet.

Thanks!

 

[cross thread]

Our company would not use them . fit full flow lever valve

 

[stem]

Apparently they have a restricted flow

You don't specify what the "heater" is but if it is a radiator, I wouldn't be worried about the restriction. Valves that are designed specifically for radiators also have a restricted flow. And in practice they are usually reduced down even further when the system is balanced.

could potentially leak due to the heat going through them.

I've seen lots of them fitted to central heating systems, and as they are of all metal construction, not sure why there would be a temperature problem. To check, I've just had a quick look online and the lowest maximum operating temperature for such valves that I saw was 90C and the highest 200C, so within the range of a domestic central heating system, and interestingly above the 85C temperature specified for some valves specifically designed to isolate central heating circulation pumps.

He suggested that full bore, butterfly or gate valves should be used instead.

On a personal note, I have had 4 gate valves in my home, all of them failed to shut off completely when I needed them, so I ended up replacing them with full bore ball valves, and on one occasion repairing the lounge ceiling below as well

So having said that, personally I would use a full flow lever valve, but whether you can insist the fitted valves are unsuitable and that the original plumber should change them at his cost I'm not so sure.

 

[cyodesigns]

Thanks. Yes the pipes are for a radiator for my loft conversion. I think if I asked the company who is doing the loft conversion for them to be changed they would ask the plumber to change them.

 

[oldbuffer]

1. That type of isolation valve is generally not rated for the continuous high temperatures encountered in central heating systems while in operation.
2. They are often installed during building works so that the original central heating system can be used while the works progress. However, unless documented as suitable for the operating temperatures, they should be removed once the works have finished.
3. They generally leak (if they are going to) many months after installation. So if your additional radiator(s) are going to be installed soon, and the valves removed, I wouldn't worry too much.
4. If they start to leak, it will be from the operating shaft (which has the screwdriver slot in its end). Such leaks are usually very minor to start with although they can get worse over time. Very unlikely to be a catastrophic leak.
5. The reason they can leak is that the ball with a hole drilled in it which acts as the valve is seated in nylon bushes. With constant high temperature, the nylon degrades.

 

[cyodesigns]

Thanks oldbuffer, would you also suggest using a 'full flow lever valve'?

 

[oldbutnotdead]

He might not but I certainly would. The full bore lever valves are not infallible (anything with moving parts will eventually fail) but they are generally better build quality, have positive stops (some of those cheapo valves do not have a stop so you can't tell if they are off or nearly off) and don't require a tool to operate (very handy in disaster situations)

 

[dilalio]

I've had enough of them leak when operated, to avoid using them on my jobs.