New stat, banging & bubbling?

[markdon]

Making more banging noises again.

Is there a way of delaying the pump shutting off a few seconds after the boiler stops?

I cant understand how the old 1970's stat allowed this, but the new digi one does not?

Thanks.

 

[JohnD]

If it is a room stat that you mean, it has no effect on causing or preventing the bubbling. The cause is something different.

It might be for example that the pump is worn out, or that sediment was disturbed and washed into the boiler. A back-boiler is usually old, open-vented and full of dirt and sludge, so cleaning and descaling it are good first steps and will often help.

Have you gone into the loft and checked that the Feed & Expansion Tank is (1) full (2) not muddy (3) not getting pumping-over from the Vent pipe which is curved over the top of it?

I am not familiar with the TSSM cleaner you mention.

Sentinel products are good, and X100 is a well-known inhibitor.

If there is black sludge is the system, you could add a litre of X400 to the circulating water. If the water turns black within a day you will know it is working because it has loosened the black sludge. In that case you leave it in for 4 weeks then drain and rinse. You will need new X100 on the final fill and can add X200 if you think it might have limescale (do not drain these two out). These chemicals cost about £15 a litre each.

X400 is a very mild cleaner, there are more powerful ones that work faster. Some of these are acidic and aggressive.

Or if you have confidence in your heating engineer, ask him to diagnose the problem.

I am a householder not a pro.

 

[markdon]

Thanks for the reply, yes its a honeywell dt90e non programmable room stat, i've fitted the honeywell st9400c which is set to miniprogrammer mode.

From what was talked about earlier, i thought if there was a way of delaying the pump shut off for a few seconds, the residual heat would still be pumped into the system, rather than it sitting in the boiler & bubbling away.

I've been up in the loft, the tank seems to be filling ok, the water seems to be clear, slight colour on the bottom of the tank. While i was up there there was no water coming out of the Vent pipe, though it did seem damp, as if something had come out recently.

When the engineer was here he stripped the fire down & pulled everything apart, cleaned it with wire brush & put it back together. This was done when the system had been drained but before the sludge treatment had been used, should this have been done after?

When i've been checking the rads for air the water out of all the rads has been clear, one rad put a bit of black water out for a while, but that one is clear now.

Any suggestions? Wife is getting worried about the noise incase it "blows up" i dont think its that bad personally.

Thanks.

 

[JohnD]

tie a bit of cloth round the vent pipe, so that it will get wet in the event of pumping over and you will see it if you check in a couple of days.

If your opinion is that there is no great amount of black sludge in the system, go straight to the X200 (try a Homebase if there is one near you as it may be reduced) as the noise may be from limescale in the heat exchanger.

No need to drain out the X100 first, or to drain out the X200 after it has done its job. However you do need to drain a bucket of water out of the drain cock, after tying up the float in the F&E, before stirring in the X200, so that when you untie the float, the chemical will be drawn down into the system.

 

[markdon]

I have to go away to leeds today, but when i get back on friday i will do all of this & report back. What will be the problem if the vent pipe is flowing water into the tank?

Thanks again for all your help!

 

[JohnD]

Pumping over is usually caused by an obstruction in the pipework (sometimes by poor design and build), usually sludge or scale. However as it is like a fountain, it aerates the water, and the dissolved air speeds up rust and corrosion inside the system, very soon, rads get holes in them. Also of course the corrosion deposits increase blockages.

 

[D_Hailsham]

Hi all, we have an older back boiler in our house

Make and model no please?

I doubt if your boiler has pump overrun.

 

[markdon]

Off the top of my head its a baxi barricuda, but i cant remember the rest, will get the wife to dig out the paperwork and will report back.

So it may not be since ive changed the stat, more likely to be the cleaning of the system thats caused it? Can't win! Leave it, it'll break, clean it, it'll break!

 

[markdon]

Hi all, just got back from working away.

Went into the loft, took out the water, further i went down the browner it got. Lots of residue in the bottom so i removed the lot & cleaned it out.

Drained some water out of one of tge rads with the ballcock jammed. Added the x200 and stirred as i filled the tank back up.

I dont know how long it might take to start working but its the same as it was at the minute.

Also 95% sure the vent pipe has been flowing water back into the tank.

Anything else i should do or just wait for the x200 to activate?

Thanks for all the help.

Mark.

 

[JohnD]

tie a bit of cloth round the vent pipe, so that it will get wet in the event of pumping over and you will see it if you check in a couple of days.

Did you do that?

 

[markdon]

Hi, sorry its been a while, yes i did that & it was wet.

Another part of the puzzle, we have had the dining room plastered & they removed the rad so they could do the full wall. On removing it & tipping it up outside to drain it, there was a thick black sludge that came out of it, which means, i'm guessing, the last drain & flush, cleaner, flush, inhibitor & scale remover have done naff all??

The bubbling seems to be happening alot now & there seems to be a slight drone from the boiler at the same time now.

Is this going to be expensive to fix.......

 

[JohnD]

can you afford an extra hundred pounds or so for a Maglaclean or Spirovent? The Magnaclean is particularly good for capturing black sludge particles that have been loosened by a cleaner such as X400. It has the advantage that in this case you do not have to drain it out when it starts to lose its power after 4 weeks, as it is mild and non-aggressive. The Magnclean continues trapping sludge for years to come before it can settle into a new blockage. X400 loosens sludge, but you can never get it all out (though a powerflusher makes a good attempt)

Sediment also wears out the pump bearings, which might be the cause of the drone you mention (I believe your boiler does not have an electric fan)

if the rag is getting wet, you have a pumping-over problem which will make corrosion worse, and will overcome the oxygen-scavenging power of the inhibitor.

sit up there watching the F&E while someone turns the boiler on and off, with the pump set to fast, medium and then slow.

 

[markdon]

Problem with the pump, its been fitted in a way that you cant see the front of it, i will try and get some pics of what i mean, its built inbetween all the pipework in the side of the chimney breast, slightly annoying so i dont know what its set on!

Will look into magnaclean, is it an external filtration system? I would say there was about 30ml of sludge out of one rad, just worried theres the same in all the rest of them. there are 10 rads in the house, is it worth draining the system (again), and removing them one by one & pressure washing them, refitting, then adding the inhibitor etc?

Getting quite annoying now!

 

[markdon]

Just bumping this up to see if i can get any more advice, i've been working away from home for the last month or so & just home for the weekend.

I've been in the loft & there is water coming out of that vent, and when i sit next to the fire every now & then there is a hiss, like a drop of water hitting a hot surface?

I put the noise reducer in at the beginning of feb, its mid march now. When i put that in i cleaned the tank out and the week after when i checked it was still fairly clean. Now the water is horrible & orangey yellow. Will try and go get some pics.

Any additional help would be great, thanks.

 

[markdon]

best pics i could get...

What has been used...

I'm guessing another flush & another treatment of the above would not be a bad idea?

Cheers.