Would Heat Exchanger clog with a boiler filter?

[dagoof]

Had a couple of new rads installed yesterday and this morning the boiler cut out after some crazy noises. Thought it would just be air in the system and duly bled it but the boiler keeps cutting out (it fires for a few seconds, pressure gauge shoots up, then it cuts off).

Plumber said he thought heat exchanger was clogged from sludge in the system (we'd had a couple of disconnected rads, manufacturer tech support suggested same) and would need replaced. However, the system has an external in-line filter on it. Is clogging still possible in this case?

TIA

 

[jackthom]

Have a listen to this youtube video from around 1 minute to 1minute 10sec.
Is that the sort of thing you are hearing?

The rapid rise in pressure makes me wonder about the boiler expansion vessel.

 

[steve32]

Yes most likely blockage, new boiler time, expansion vessel doesn't cause rapid rise in temperature

 

[gigz]

Sticking pump ? Whats the make/model/age of the boiler ?

 

[dagoof]

Yeah Jacktom, that's it - happens about 10 seconds in, starting from cold though.
I've heard less severe kettling on my last boiler but not the 'clacking' this seems to be doing.
Just tried leaving filling loop running with drain pipe open but it doesn't seem to have helped.
It's an Ariston (tank system) about 8yrs old.

So, why wouldn't the filter do it's job? Just opened filling loop again, there was a little clunk and the pressure dropped momentarily. Fired up but then made same clunking and cut off again. Then filled some more and got the same clunk even with boiler off. Does seem like a block working it's way through (though possibly air)?

 

[Nozzle]

Are the suction and discharge valves of the pump really open? And/or any inlet/outlet to a magnaclean?

I say this because the pump will merily whir away (and dead head) so it's not actually circulating water but it sounds like it might be. The boil fires, but then it just boils the water, which flashes off and causes sharp spikes in pressure as it does so - and water hammer when it subsequently collapses again. This'll trigger protection on your boiler, thus causing it to cut out.

Nozzle

 

[dagoof]

Thanks Nozzle, not sure about suction/discharge valves.

It does seem like the pump was trying to work against the blockage but the protection's cutting it off after a few seconds. Even after burner has gone out, there's a quiet hum/vibration off the pump, suggesting it's still running?
It's got a Spirotech filter (similar to Magnaclean), I tried emptying that, but no progress.

Cold night too

 

[McCombi]

Edited as misread. Didnt see you had a pressure guage so rules out my thinking

 

[McCombi]

Pump may still be siezed and not spinning even if its humming

 

[dpgas]

Auto air vent in boiler not open?

 

[dagoof]

Mornin' DP - not sure, I think the fan was coming on but not sure about vent, how is that checked? Ruled out the exchanger being blocked (had it off and it's not blocked).

 

[dagoof]

We had all panels off today (including the burner faceplate) - bleed valve on the pump was closed, opened it and managed to get the boiler firing on and off in 30 second intervals (wasn't protection cut off, was more like the thermostat thought it was getting up to temp, so was continually firing up every 30 seconds). And rads were getting hot so believe pump is working ok.
However, faceplate back on and it's back to protection cut-off

 

[Agile]

And so who did all this work?

And what does he say about it?

Tony

 

[dagoof]

Plumber, but he's still relatively new to boilers so isn't sure. He's drafting in back up Tuesday.

The fact it only happened after new rad install, there wasn't anything substantial in the filter, and the pump + fan seem to be working still points towards airlock?

 

[Nozzle]

Plumber, but he's still relatively new to boilers so isn't sure. He's drafting in back up Tuesday.

The fact it only happened after new rad install, there wasn't anything substantial in the filter, and the pump + fan seem to be working still points towards airlock?

How much of the system, if any, was isolated to perform the drain down - and more importantly, was it re-open afterwards..

Nozzle