Automatic bleed valves for radiators

[sotal]

I've posted on here about having to change a radiator because it rusted through from the inside.

I'm trying to ensure any corrosion doesn't continue. For the whole time we've lived at this house (9 years) none of the radiators have needed bleeding except for the bathroom radiator. This was the highest radiator in the house (if that is a possible reason, it is 100mm taller than the other upstairs rads).

I have replaced the rad that rusted through and I have also replaced the bathroom radiator with an even taller towel radiator (1.5m tall).

I'm wondering if it is worth fitting an automatic bleed valve to the towel rad to automatically expel the air or if this is just masking the problem?

We had the boiler replaced 6 years ago and at the time they commented on how clean the system was and it did contain rather clean water, however now 6 years later it had quite a lot of sludge in. I have flushed some of this through and am going to put a bottle of cleaner through the system today.

 

[sotal]

I've just put the cleaner through the system,

In another thread someone suggested watching the f&e tank to ensure that it wasn't overpumping into the f&e causing aeration. I've just kept an eye on it for 20 minutes and it doesn't appear to be at all.

Could the air in the rads just be from corrosion within the system?

Will running this cleaner through for 2 weeks, then replacing with inhibitor stop this happening?

 

[stem]

I'm wondering if it is worth fitting an automatic bleed valve to the towel rad to automatically expel the air or if this is just masking the problem?

With a properly designed, installed and maintained system the radiators should only need bleeding after initial filling. If they are getting air in subsequently, there is another issue that needs resolving.

 

[sotal]

I'm wondering if it is worth fitting an automatic bleed valve to the towel rad to automatically expel the air or if this is just masking the problem?

With a properly designed, installed and maintained system the radiators should only need bleeding after initial filling. If they are getting air in subsequently, there is another issue that needs resolving.

Thanks for the reply, any clues on working through a diagnosis? To try and identify the issue?

 

[muggles]

An AAV is just making the problem, sounds like you need more corrosion inhibitor in your system

 

[Aquaheat]

@sotal Hi, We aren't great fans of these auto vents for a couple of reasons. Firstly they are just masking an issue with your system and you have no idea of how much water is being put into the system. This has the effect of reducing your inhibitor level and creating further issues. Secondly the constant introduction of fresh aerated water being put into the system will speed up the rusting and sludging problem no end!

If there is a problem this can be checked by carrying out a water test where samples are sent off and they will tell you what is going on in the system and what is causing it.

Alternatively you could drain the system and flush chemically to attempt a clean but if radiators are rusting through this could cause issues and you may need to budget for replacing some of the rads.

As mentioned if the system is constantly needing venting then there are underlying issues. It may be air or it could be hydrogen that you are venting.

Jon

 

[sotal]

Thanks for the replies.

I will avoid the automatic bleed valve then!

I drained the system fully yesterday 3 times (due to a leak!) - and I also flushed it through for a while. Today I have it full and running with a bottle of cleaner in. I'm going to leave the cleaner in for a couple of weeks then I will replace with inhibitor instead.

I guess the first thing is to see if the air continues to gather in the radiator once this is done. If it does I'll post some more questions!

 

[Aquaheat]

If you can get yourself some pH testing strips and test the water quality should be between 7 and 8 before you put in the inhibitor.

Get a cheap TDS meter from ebay. Less than a fiver and measure the Total Dissolved Solids in the water against your mains water. The reading should be within 10%

If you run the system for a bit and it still catches "air" then when bleeding it off catch the "air" and with a lit taper or some some sort of lighter see if the gas will ignite with a pop. Remember the old science experiments? If you get a pop it indicates that it is hydrogen and the "air" is being created from a corrosion process. If not it could be that you have a small weep somewhere that is drawing air into the system.

Those are a few simple and cheap tips for a bit of diagnosis. Otherwise as mentioned I'd get a sample kit and send it off.

One like this will do:

http://www.sentinelprotects.com/uk/products/domestic/central-heating-systems/sentinel-systemcheck

Jon