Central Heating problems - still!

[SarahHaugh]

Hi

Oilman very kindly helped me a few weeks ago with some suggestions for a noisy pump that I have. But I still have a problem, it does sound like there is air in the system, but I have no idea how it is getting in. I have one rad that gets air in it. I would normally expect a rad with air in it to be cold at the top and hot at the bottom, this is not so, it is cold on the right hand side from top to bottom and hot on the left hand side from top to bottom. I have made sure that the valve is fully open to ensure that the hot water can get in and for a few days after bleeding it the rad stays hot all over, then it starts to go cold again. If I leave it unchecked for 3 - 4 weeks then I get the scenario described above. In addition the pump is still making a gushing gurgling noise when the system first comes on, it also sounds like there is a tap running in there for the 1st five minutes when it comes on! All other rads are fine and don't need bleeding, I have bleed the pump and nothing came out of there except water. Although I did do this not long after the heating went off so maybe the air didn't get chance to collect there? I have also checked the feeder tank in the attic - this is covered so there was no debris in it, although the water was a slight murky colour, the tank was full and the ballcock is not stuck. Any suggestions as to how the air is getting in, as it must be getting in some where! As I have tried most things I wondered if it was a problem with the boiler? I have a corgi plumber who fitted the boiler 2 years ago & I have tried without success to get him to come in and service it. All other people I know are plumbers and not Corgi registered, so before I go to the expense off getting in some one new who I don't know - can any one give me some suggestions?!! Please, as another night of being woken up with the gurgling and tap running noise when the heating comes on is going to drive me mad!! OK essay over now!!

 

[Botmission]

Maybe the pipes from the header tank are wrong.

There are two pipes, one small 15mm one, which is the cold feed, and a larger 22mm one which is the open vent. The pump could be drawing air in through the open vent. Basically, the cold feed, on a newer system, should be between the pump and the open vent. If not, they may have to be altered.

Or you could just turn the pump down.

 

[oilman]

It's a pity you're probably in the wrong part of the country........but that's life, we'll have to do it by the ether.

I have come across systems where the gurgling happens when the pump first starts (er, some of the systems I've altered did it, but only on hot water).

I can't remember if we discussed the point, but what speed is the pump set to?

Turning that down may still give you enough heat without the noise.

Sorry if some of this has been said before but I've a memory slightly worse than a goldfish, it might not be air in the radiators, but hydrogen from corrosion. When was corrosion inhibitor last added to your system?

 

[SarahHaugh]

Hi Thanks for your comments.

The pump speed is at 1, but it still makes a racket and the house is so much colder compared to when I had it set at 2. The pipework was last cleaned out 2 years ago and the inhibiter stuff was supposed to have been put in. I have now been recommended a plumber who hopes to come and have a look on Friday. Hopefully he will be able to fix it!

Thanks for all your help