Air in boiler - is plumber giving me the runaround?!

[James4791]

Hi,

I would be very grateful for your thoughts on my boiler situation!

About 2 weeks ago my boiler started banging and popping on a Friday evening. I switched it off for a while, then restarted it over the weekend and still the same. I called a gas safe engineer on Monday who identified it as air in the system.

His first suggestion was to have the hot water set at the lowest setting on the boiler and on constantly for a few days - his thinking was that at a low temp it was less likely to 'bang' and would hopefully eventually push the air around the system to the tank where it would be released(?).

We did this for a week and no joy. So he returned to put a chemical into one of the radiators to feed around the system. We've had this chemical before and it's supposed to break down the sludge in the radiators/pipes (and needs to be drained once it's done its job). His thinking was that this thicker solution in the pipes would help push the air around the system if, again, we had the hot water (and now also the central heating) on constant low for several days (that was 4 days ago).

Again, nothing has happened - the boiler still bangs when it occasionally fires up and therefore, obviously, the water isn't being heated and neither are the radiators. Thankfully we have an immersion for the water in the meantime. The plumber has now said leave the chemical in until the end of the week. That would make 3 weeks since the problem started.

As I'm not sure about plumbing, his suggestions may all be logical, but to me, 3 weeks (at least) to fix air in the system seems a really long time?!

He did suggest that if the chemical didn’t work, then he’d probably need to fit a new pump. Again – that’s double dutch to me, but might be logical??

Any suggestions or thoughts would be very welcomed...

thanks

James

 

[twgas]

need more info, boiler and system type(s), did the plumber do anything to confirm his diagnosis of air

 

[JohnD]

when you bleed the radiators does air or gas come out? can the gas be ignited with a match (be careful of flames). what colour is the water that comes out? how did you choose your engineer and did he show you his gas safe card?

I gather you have a sealed system, right? there is no feed and expansion tank in the loft, but your boiler has a pressure guauge? how often does it need topping up?

look at the bottles or tubes of chemicals he used and tell us what it was

how old are the radiators?

are you in a hard water area?

 

[tonybhoy]

Sounds to me like the pump has gone or there is no or very little water in the system.

 

[expertgasman]

James, have you no hot wqter because the boiler doesn't fire, or is it simply that because it is noisy, you turn it off?

It may well be simply that the boiler is scaled, and the questions that precede this post are all very relevant.

I'm not getting a good feeling about your plumber, but it wouldn't necessarily be fair for us to criticise him - yet.

 

[James4791]

Hi,

Thanks for your replies!

Please excuse some of my answers – I will try to answer with what I know (which isn’t a great deal)…

I have an Ideal Icos HE24 – just a traditional gas heating system with a cold water tank in the loft and hot water tank in the airing cupboard and no pressure gauge that I can see. The plumber didn’t say he’d done anything to confirm his diagnosis, but went up and down to the hot water tank a few times first (??).

The water seems to be pretty clearish when bled, but no air coming out. I would say some of the radiators are 10+ years old – but not tens of years old. We do live in a hard water area. The chemical was called Sentinel X400.

Also, as an aside, we recently had a new bathroom fitted (by a different plumber, not gas safe registered, but did a good job). In doing his work, he mentioned that we had ‘no pump overrun’ and did our boiler ever bang (no idea how those two relate)? The next day it started banging! I did mention this to the gas safe plumber and he thought it probably wouldn’t be a problem having no pump overrun – he thought that the new bathroom work was probably the cause of the air in the system.

The hot water has been ‘on’ constantly for the past 2 weeks, but the boiler very very rarely fires – when it does, it bangs within 30 seconds, then stops again – so no hot water (unless we use the immersion).

I confess I haven’t seen his gas safe card, but he’s a local village guy who advertises in the village leaflet as the village’s gas safe engineer and has done for years (was corgi before).

Does that help??

Thanks again

James

 

[tonybhoy]

I would change the pump as a matter of course. Has you man checked that there's a feed an expansion tank for the heating in the loft and if there is, is there water in it?

 

[JohnD]

bleed the highest radiator in the house, and see if water squirts forcefully out of it, with no loss of pressure.

If the pump is circulating X400, then the water should have gone black.

If you are fit enough, go into the loft and look at your feed and expansion tank (about 1ft x 1ft x 2ft) and see how deep the water is, what colour, is there brown mud at the bottom, has it got a lid, when you press the ball float down does water run into the tank.

 

[Agile]

X400 takes 4-6 weeks to work!

You dont have to have pump over run on your boiler IF its piped correctly.

It sounds to me as if the pump is sluggish at starting. If it has three speeds and is on "2" as it should be, then turn it up to "3" and see what difference that makes.

Tony Glazier

 

[James4791]

Thanks Tony, Tony & John,

Here’s the update…

Re-bled two top radiators and both run clear water at a constant trickle – but nothing forceful. Just looked at the pump which is already on setting ‘3’ – not sure if the plumber had moved this up last week though?

In the loft the expansion tank was about half full and water ran into it when I pressed the ball float. It did also have horrible brown mud at the bottom and edges.

Does that lead to it being in likely need of a new pump?? If so, I suppose the plumber was right with his first diagnoses??

Thanks

James

 

[mickyg]

You say your using the immersion so presumably the heating and hot water are not working, in which case the X400 will do diddly squat with no circulation. Total waste of time. I would of expected a diagnosis after a few hours not a few weeks.

 

[James4791]

Hi Micky,

That's right - the plumber suggested we turn off all radiators except one, so we would know when the water started to circulate as that one radiator would warm up.... 5 days on and it's still flat cold and he's suggesting we leave it until the end of the week...

james

 

[JohnD]

 

[Agile]

Did the plumber spin the pump?

Can you spin it or check that its turning? ( See FAQ )

Tony

 

[James4791]

Hi Tony,

I don't think he did - I seem to remember him saying that he could hear the pump running, but that's all.

James