Circulation problem - and my plumber is desperate!

[paulhodson]

What you are saying is the pipe rise from the boiler, goes through the wall somewhere, then drops back down to the floor, goes under the floor then back up to the cupboard.

And the plumbers realise this or did you keep it a secret.

So in practice the boiler has no open vent, that Sir is b****y stupid, take it how you like but the boiler is dangerous and should be turned off.

Unless I am confused - yes that is how the pipes run (and certainly no secret from the plumbers!) There is a combined cold feed and vent which runs down from the F&E in the loft to meet the hot feed in the cylinder cupboard. Not sure what the problem with this is. I feel sure I have misunderstood something along the way

 

[doitall]

The vent has rise rise continuosly from the boiler, you cannot drop it back down 8 feet and expect it to work.

The thing was safer with the expansion vessel

 

[oilman]

Having an AAV just before is a good way to let the pump suck in air. If your system is 30 years old, there is a strong chance of at least one partial blockage. I haven't seen it mentioned, and may have missed it, but has this system been powerflushed?

 

[Gasguru]

So the pipework is like this



Then you need air vents as shown, otherwise the pump will never work.

And where pipework does do this the boiler should have the overheat stat as additional protection.


Set the zone valves to the manual position and if the filling loop is still connected open it up and backfill the system. Check the F&E tank overflow is connected as it will fill up. Then bale out excess water from the tank afterwards.

 

[paulhodson]

Oh hell! The return follows the route similar to this - and I just presumed the flow was doing the same - you can't see it of course. Maybe from what you say the flow simply continues at the higher level of the laundry room/garage floor into the cylinder cupboard. Might make it easier if this needs attention anyway

Sorry if I misled you - and don't take diagram too literally!

 

[Agile]

I am very disappointed that the IPHE Registered Plumber has also failed to find the fault!

Standard systems are pretty low tech but I major in fault finding on combi boilers with electronics as my speciality.

Having had several glasses of Dumisani, I am almost inclined to wonder if I could be put to the challenge. That might be risky for my reputation though!

However, I have two constraints and may fail on either one! I have no idea of where you are located and I rarely go north of a line between Goole and Liverpool ( via Leeds ).

The other is that to be commercially viable and at least cover the costs I would at least have to charge our standard diagnostic fee. To keep the expenses to a minimum I would need accommodation for self and wife ( to keep me company ).

Of course I might fail to find the cause of the problem but we only charge our diagnostic fee if we identify the fault. No-fix no-fee !

Tony

 

[ChrisR]

ALtered your pic but it won't upload..

First thing to do is fit an auto air vent near the boiler, on the flow pipe.
Make sure it has a cap which you can close, though you should be able to leave it open.
Then make sure the vent by the pump is CLOSED. This one should NOT be an auto type. No real need for a vent there as it's by the vent pipe.
Then go over all the joints in the pipes on the input side of the pump as previously described. That's the purple pipe area.

Your response to my last advice was that you would try repressurising or change the boiler - what's the point of asking for advice if you're going to ignore it?

Later - pic:

 

[paulhodson]

Your response to my last advice was that you would try repressurising or change the boiler - what's the point of asking for advice if you're going to ignore it?

In fairness - I don't think I can do everything everybody has suggested - for a start I am sure that some of the advice will conflict with other advice and in any case practicalities have to be taken into account - including the fact I am incapable/unwilling to "DIY" when it comes to CH plumbing and am trying to reduce the impact on the rest of the house

In fact I have probably paid more heed to your comments than some of the others.

I am at the moment trying to get the engineer to give more consideration to the possibilty of the problem being on the inlet side - which fits in with your comment about "Can you get to the pipes on the inlet side of the pump? If so change a few feet, and the pump valve." One thing I will at least ask him to do is to cut through the inlet pipe where it is magnetic to check for restrictions as whether found or not I think he could repair it fairly easily.

It is difficult as his gut feeling is that it is on the return rather than the inlet - mainly I think because the inlet is very hot and the return cold. My own view is that this may be insignificant if a restriction in the inlet is reducing the flow significantly as presumably wherever it being blocked, the overall flow is the same at all points in the circuit and it may be that so little is getting through at a blockage before the pump that by the time it has got to the return all the heat in the water which does pass has been dissipated.

You have suggested also why the pressurising worked - which is one of the reasons I am considering trying it again - then if all else failed I could change to a pressurised system.

All advice is welcomed, considered as best I can, and passed on where possible.

I guess my main hesitation about some suggestions is that I know it all worked well for years and that the problem should be a development in the system rather than an inherently incorrect plumbing design - even if it ain't great.

And I am sure you would all come up with a different design if starting from scratch to install it.

I have to be fairly subtle in "advising" him - can you imagine how you would feel if a customer was telling you what you should do when you had 30 years of experience - and he was a "suit"

 

[paulhodson]

Later - pic:

The vent which you say must be closed - was until yesterday when it was changed to an automatic one by the new guy!

I will ask the previous guy who is having another (possibly brief) go on Wednesday) about the one on you suggest on the flow

 

[paulhodson]

I am very disappointed that the IPHE Registered Plumber has also failed to find the fault!

Standard systems are pretty low tech but I major in fault finding on combi boilers with electronics as my speciality.

Having had several glasses of Dumisani, I am almost inclined to wonder if I could be put to the challenge. That might be risky for my reputation though!

However, I have two constraints and may fail on either one! I have no idea of where you are located and I rarely go north of a line between Goole and Liverpool ( via Leeds ).

The other is that to be commercially viable and at least cover the costs I would at least have to charge our standard diagnostic fee. To keep the expenses to a minimum I would need accommodation for self and wife ( to keep me company ).

Of course I might fail to find the cause of the problem but we only charge our diagnostic fee if we identify the fault. No-fix no-fee !

Tony

I am pretty disappointed too! May at least take up the recommendation for the S A wine - I was there earlier this year but did not come across that one

Another few days of this and I might take you up on the other idea - but sadly I live near Stockport - just south of Manchester so it is not ideal

 

[ChrisR]

I guess my main hesitation about some suggestions is that I know it all worked well for years and that the problem should be a development in the system

Leaks and resistances are "developments"
Also older boilers with scale in will separate out dissolved gasses from the water more readily, as bubbles.