locating central heating pump

[Mike S]

I wonder whether anyone can help me? I have a gas central heating boiler that was installed about 4 years ago. It has recently been cutting out when it should be on (ie thermostat and time set correctly) . I have been advised by a heating engineer that it may be overheating due to having too much air in the system which could be caused by a build up sludge and scale etc.

The system is open-vented and having investigated the expansion/feeder tank in the attic I’ve discovered that there is a lot of sludge in there. The tank has also started overflowing recently through the overflow pipe. I went up to look at what was happening there on one occasion and noticed that there were big bubbles coming up through outlet pipe that feeds the system. When the system is switched off the tank level seems normal and the ball valve operates normally. What seems to be happening when the system gets switched on is that the water enters the tank from the ball valve, but it also comes up from below, raising the water level to the point where it starts overflowing. There is nothing coming out of the vent pipe to affect the water level.

Could this have anything to do with the positioning of the central heating pump? I recently discovered that the company that installed the boiler and pump has a reputation for shoddy work and have recently ceased trading. I’m beginning to worry whether or not they installed it correctly. I’ve noticed on the boiler instructions that the pump which is installed upstairs in the airing cupboard along with the hot water tank should be closer to the feed pipe from the expansion tank than to the vent pipe. However it has actually been connected directly to the vent pipe and is nowhere near the feed pipe from the expansion tank which goes directly down to the boiler without ever passing the pump. Could this have anything to do with why sludge seems to back up into expansion tank via the feed pipe? And could this have anything to do with the build up of sludge in the system, and resulting problems with air in the system and the boiler overheating?

Would be grateful for any advice. Thanks!

 

[Agile]

Without a picture or layout its difficult for me to immagine your system.

I think that you may need a competent heating engineer to advise.

You should not really use the heating until its sorted as it can very quickly degrade until all the rads are blocked. That can happen in days not weeks!

Tony

 

[Mike S]

Thanks for the quick reply!

... it can very quickly degrade until all the rads are blocked. That can happen in days not weeks!
Tony

You say it can very quickly degrade... you means since the start of the overheating and overflowing problem?

 

[Agile]

Yes!

New oxygen rusts the inside of the rads and that quickly blocks the pipes!

Tony

 

[Mike S]

Hmm... that's bad news especially since I have microbore pipes on all the radiators!

Yes, time to get a heating engineer in. Thanks for the advice.

 

[Mike S]

I've had engineer in to look at the problem now and he has quoted for reconfiguring pipes so that the feed from expansion tank does not join the return to boiler but joins just before the pump which lies on the feed side of the boiler (2 hours work apparently, which sounds OK to me).

However, he has also recommended a full powerflush, but says that there is no guarantee offered on this because the rads are connected to microbore. The whole lot + installation of Magnaclean comes to £850. That would be OK if there was some guarantee that it would work. But without that guarantee I'm wondering what to do next. The engineer (BG) himself admitted that it could possibly make the problem worse, by loosening material and sending it to a new location to create blockages in the microbore. He said the only sure way of sorting out the problem would be repipe the whole house (12 rads) with 15mm (ie get rid of all the microbore).

Does that sound reasonable? It would be nice to know the probability of the powerflush working. If it was 90% I would probably go for it, if it were 20% I wouldn't, but I guess nobody can tell me that. Up until now all radiators except one (which needs frequent bleeding) have been working fine.. heating up as they should. There have been no indications that the microbore might be causing problems. Would be grateful for any advice on this matter.

Cheers,

Mike

 

[namsag]

Twin entry microbore rad valves not meant to be powerflushed as it won`t get all of shi#e out off the rads and yes it could loosen up debri and move into manifolds best idea to repipe completely and as open vent etc need altering if boiler is suitable why not make system presurised instead at same time as repipe .

 

[Softus]

Mike, you've had some very good advice there from the BG engineer. I suggest you get hold of his contact details so that when he leaves BG you can keep him as your heating engineer!

 

[Mike S]

Yes, the engineer seemed to very competent and was honest and upfront about the situation. I'm still in dilemma about what is the greater risk.... the risk that £850 of remedial work will have no effect or make matters worse... or the risk that the many thousands of pounds (I'm guessing at this stage) that it would cost to repipe the whole house and associated upheaval will be completely unneccessary.

 

[nickso]

i would do the immediate work and hope the magnaclean picks up the majority of the debris that gets loosened.

are you a gambling man mike?

 

[Mike S]

Thanks Nickso,

i would do the immediate work and hope the magnaclean picks up the majority of the debris that gets loosened.

are you a gambling man mike?

no I'm not a gambling man, and I'm not a risk assessor either... but I guess if I was, I would need to know the price of the two options (relatively straightforward) and the probability that the first would fail (less obvious) and then I'd have some sort of answer...

as it is, I'll probably do what you suggest unless I get more information to suggest otherwise....

Thanks!

Mike

 

[JohnD]

changing the F&E pipe layout will stop it getting worse

A magnaclean will trap the loose sediment that's floating round or gets dislodged

The powerflush is an expensive job.

If you have the first two things done, and add some chemical cleaner like X400, it will (even without powerflushing) loosen sediment so that it can be washed round in suspension (as "black water") and trapped by the Magnaclean. I wouldn't expect it to dislodge hard lumps that would cause blockages, but I am not a plumber.

That still leaves you the (expensive) options in reserve if necessary.
Sentinel now say that X400 can be left in the system indefinitely, and your Magnaclean will also carry on trapping any circulating sediment indefinitely. You will need inhibitor as well.

You can easily add the chemicals and empty out the Magnaclean yourself.

in this pic, the black coating is sediment that has been pulled out of the water by the Magnaclean
http://i113.photobucket.com/albums/n228/JohnD_UK/POL_0166.jpg
and this one shows the (white) magnaclean sleeve after I have scraped the sediment off it.
http://i113.photobucket.com/albums/n228/JohnD_UK/POL_0167.jpg

p.s. you can bale out the sludge from the F&E into a bucket which will prevent it getting down into the radiators or boiler.

 

[Mike S]

Thanks for that advice.

Sentinel now say that X400 can be left in the system indefinitely...

Interesting what you say about the X400. I actually bought some of that, but then realised it would be difficult to get out of the system again.... all my downstairs rads are twin-valve systems fed from upstairs and without any draincocks, making it impossible (I believe) to drain the system completely without removing the rads. What you are saying is that I don't need to remove the X400?

Mike

 

[JohnD]

that's what sentinel say
http://www.sentinel-solutions.net/en/heating/X400

but everbody needs drain valves!

you can get these for a few pounds each depending what you have at each end of your rads

edited: as you say you have the twin-entry microbore you would need something else... I bet someone will be along in a minute who knows what to use

However with the Magnaclean you don't have to keep emptying and flushing the water out with the suspended sediment, because the sediment in the water gets trapped and taken out of circulation.

 

[Softus]

that's what sentinel say
http://www.sentinel-solutions.net/en/heating/X400[/QUOTE]
John, where on that site does Sentinel say that you don't have to remove the X400?