What are these valves on my heating system?

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Hi everyone,

There are some section of pipes on my heating system that have these valves.

My heating system is conventional boiler with small central heating tank, cold water tank and a hot water cylinder. Curiously, there is no vent that goes back to the tanks. So is this like a feed and vent system, and these pipe sections are expansion pipes? What are the valves for and do I use them?
 

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CBW

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I think the bits you’re concerned with are air vents, one is manual, the other looks like it’s automatic. The silver box underneath is a motorised valve.
 
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Thanks Chris! How do I use them? I did think they are similar to bleed valves. I just messed around with the automatic one and somehow lots of air get into the system and took me ages to bleed all the radiators. Luckily all works now.
 

CBW

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Yes, similar to radiator bleed valves, if one is automatic, it can be left open, and the other is again for expelling air from the system.
 
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So there's no vent pipe above the smaller tank (f & e) in the loft? Bit concerning...
 
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@CBW Currently both are closed. I did try to open the automatic one, heard a lot of hissing then closed it. But then my radiators went cold and I had to bleed them for ages. Should I leave the automatic valve permanently open?
 
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So there's no vent pipe above the smaller tank (f & e) in the loft? Bit concerning...

Yes, there is no vent pipe. I did a bit of research and it seems to be the "combine feed and vent" type of system. The pipes are 22mm and the boiler is MAIN boiler. Is it very concerning? What should I watch out for?
 
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Yes, there is no vent pipe. I did a bit of research and it seems to be the "combine feed and vent" type of system. The pipes are 22mm and the boiler is MAIN boiler. Is it very concerning? What should I watch out for?
I don't know. Hopefully someone who does will happen upon this thread ..
 
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Hope someone can shed me a bit more light on how to use these air vent correctly, also comment on my "combined feed and vent" system ..
 
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Combining the feed and vent is a fast fix when pumping over becomes an issue, (new boiler/pump on old system), it can also be a solution to stop the system pulling air in but it is a bodge and doesn't address the real issue. There is a school of thought though that it could cause problems with safety venting in the event there's an overheat. Always best to have them separate.

Can also make the system a real pain in the a$$ to fill and bleed.

Not saying that's why you have a combined and have seen some do it just to save on pipe costs but it's not the way it should be IMO

Air vents .... if it's the bottle type auto vent then it should be left open to 'auto vent', until it invariably leaks then close it. The manual vent should only be used if there is trapped air and the circulation is compromised, usually during filling. Any other bleeding should really only be done through the rads.
 
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Unfortunately it's been done like this before we move into the place, so we will have leave it that way until a major refurbishment. What caution I can take when fill? I'm planning to replace a few rads.

@Madrab: Regarding the vents, I did try to open the auto vent for a while last time, but ended up introducing even more air into the system. Why do you think that is?
 
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An auto air vent only works one way so it shouldn't be introducing air, if anything , when it fails it leaks water. The only thing I can think of is that as the air was released from the system then air is being drawn in but with a combined feed and vent then that shouldn't really be happening. Only other thing I can think of is it's not air but hydrogen and that's being created by corrosion. How clean is the system water?
 
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hi
I'm not saying that's why you have a combination, and I've seen some people do it merely to save money on pipe prices, but it's not how it should be done, in my opinion. villa for sale in turkey
 
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