Circulation problem - and my plumber is desperate!

[Agile]

As long as there is some flow then the sludge can be treated with the right chemicals and technique.

You could test the flows by removing the rad and running the water into a bucket. This may even wash some sludge out but the main purpose will be to test the flow rate.

Its possible it just needs proper balancing!

Tony

 

[paulhodson]

Do not seal system if blr doesn't have an overheat stat

update

Plumber has converted to sealed (which seemed to sort problem out so I can only imagine that it was taking in air via F&E/vent?) - and I have just found out that the boiler is not suitable for a pressurised system - no high limit stat and sectional boiler so manufacturer says cannot guarantee holding pressure.

Now in despair

 

[Agile]

That has to be classed as "At Risk" and the boiler should be turned off and not used!

The plumber should NOT have done that! It could explode!

Has he fitted a pressure relief valve? Usually has a red knob?

If so then its not correct but should be half safe but the boiler should still have an o/h stat.

If the boiler heat exchanger is not suitable for a sealed system it could start leaking at the joints which is expensive.

You should have used a competent qualified engineer! He could be reported to his professional body.

Tony

 

[paulhodson]

That has to be classed as "At Risk" and the boiler should be turned off and not used!

The plumber should NOT have done that! It could explode!

Has he fitted a pressure relief valve? Usually has a red knob?

If so then its not correct but should be half safe but the boiler should still have an o/h stat.

If the boiler heat exchanger is not suitable for a sealed system it could start leaking at the joints which is expensive.

You should have used a competent qualified engineer! He could be reported to his professional body.

Tony

Thanks Tony - he is Corgi registered and very experienced so should have been OK! He has "checked with his plumbing friends" who said they were all unaware of the problem - especially in terms of the sectionality of the boiler. He did say he could fit an additional stat but is obviously worried himself about the boiler leaking and has advised me to turn it off. Funnily enough - I already had! There is a red pressure relief valve on the compresser unit and I had been keeping an eye on the gauge.

I think he is slightly bothered that there are a number of local installations which now have the same problem!

As you can imagine despair has set in as the system now works well - but obviously the solution was not appropriate.

Next idea is to refit the F&E tank but put it in the loft - it is currently fitted in the cylinder cupboard so that the cold feed from it is only about 5 feet above the point where it meets the primary flow to the pump. The vent is plumbed in about a foot down this pipe - is it possible that this may be the reason that the vent is allowing air into the system? Ideally I would like the vent to be moved to a point nearer the boiler rather than its current position - but this would be a major job.

Failing that I am starting to wonder if a new (pressurised) boiler is the answer - but of course it would now need to be a condensing boiler and would be an expensive job. As I am in the process of selling the house and am waiting for contracts to be exchanged this is not a desirable expense - but neither is lumbering my purchaser with a non functional or worse, dangerous installation!

 

[oilman]

Agile is right IMO. The system should be changed back to vented NOW!!

Have the radiators that work, been turned off during this exercise to see if the others get hot?

If the pump is upstairs, the problem could be insufficient head for the pump.

 

[paulhodson]

Agile is right IMO. The system should be changed back to vented NOW!!

Have the radiators that work, been turned off during this exercise to see if the others get hot?

If the pump is upstairs, the problem could be insufficient head for the pump.

Before he did anything this was tried - unsuccessfully.

Of course the system worked fine for about 30 years so the pump position should be OK. In fact it was moved by British Gas from the boiler to its present postion about 20 years ago to solve a problem relating to the hot water not getting hot because a pipe was getting blocked which they blamed on the pump position.

Whatever he did in the course of draining refilling etc, once the system was back on again (before he sealed it) most rads seemed to be getting reasonably hot - the two problem ones downstairs not so much so but after it had been on for a short time the original three hot ones stayed hot and all the others went completely, utterly cold. This happened on two days leading us to imagine that the system was dragging in air and blocking up.

Once it was sealed all was almost normal although the very large radiator in the lounge (which may well be at the end of 7 metres or more of 10 mm pipe!) was slow. Turning all others off soon got it hot though and even with them on it eventually got hot enough (if slightly cooler at the bottom) As most of the others are too hot to touch, balancing was expected to make it adequate.


Now of course I am back to square one!

 

[Nige F]

You`ve got a loft to put the f+e in then who TF put it where it is in the first place .........there was a low head setup used with open vented Glo-worm boilers years ago...we used to do them .because the boss got holidays from g.worm but I`ve not been able to find the details ........seem to remember a vent @ 45 degree angle and other configurations........thought it was bloody silly@ the time and we should`ve been installing ...........pressurised systems

 

[doitall]

Well for what its worth and looking at the state of the plumbing, I refuse to belief a plumbers been anywhere it the system.

Again a personal opinion but I think we're being taken for mugs.

Nice job with the speedfit though

 

[paulhodson]

Well for what its worth and looking at the state of the plumbing, I refuse to belief a plumbers been anywhere it the system.

Again a personal opinion but I think we're being taken for mugs.

Nice job with the speedfit though

Not sure what you mean - I hope you are not suggesting I am trying to take you for mugs - I am deadly flaming serious! This is my system and I am losing hope of getting it sorted out. Why do you think you are being taken for mugs?

I don't even know what speedfit is - although I imagine it is the plastic fittings on the vent pipe?

Please believe me - this is a genuine post If you have any serious (helpful) suggestions I would be delighted to hear them

Just to complicate matters - following advice from an internet advisory service I have been looking for evidence of magnetite blockages in the pipes with a magnet. This is strongly attracted to the pipe leading from the boiler through the floor of the airing cupboard to the junction with the cold feed. Is it possible that this is a steel pipe coated in copper? The house is 31 years old but there have been a number of changes made to the pipework in this area (as you can see!) so this section could be more recent - perhaps 17 or 18 years old? At the boiler end it is certainly copper but I do not know if it changes at any point

 

[doitall]

Put it this way if your serious, I'll apologise.

If the magnet sticks then the cold feed is blocked (common) where it joins the pipes.

Your drawing forgot to show a by-pass valve on an S plan, has it got one or not.

 

[paulhodson]

Put it this way if your serious, I'll apologise.

If the magnet sticks then the cold feed is blocked (common) where it joins the pipes.

Your drawing forgot to show a by-pass valve on an S plan, has it got one or not.

Very serious - sorry not a plumber myself - can you tell Where would the bye pass valve be? (and what would it look like?)

The magnet is sticking to the pipe coming from the boiler - not the cold feed (which ain't there now he fitted the sealed system!)

Referring back to my photograph (on page 1) of my system I have a theory! If the hot feed from the boiler to the pump is partly blocked, is it possible that the pump is sucking in air from the vent pipe causing the air locks in the system? (which of course the dangerous but effective conversion to pumped prevented.)

Bear with me guys and I will get there in the end - plumber is due tomorrow - hopefully I can try out my theory on him!

 

[Agile]

As far as I could see from the early pictures the plumber had converted from a conventional F&E tank with vent to a combined feed and vent.

That always works when the problem is caused by a pumping over problem. It will also solve a blocked feed pipe.

Whenever I see someone has used plastic pushfit fittings my opinion of the plumber goes down. I agree they are adequate on an openvented system but seem lazy to me! I am a copper man!

Do I take it he has converted back to open vented now?

Tony

 

[paulhodson]

As far as I could see from the early pictures the plumber had converted from a conventional F&E tank with vent to a combined feed and vent.

That always works when the problem is caused by a pumping over problem. It will also solve a blocked feed pipe.

Whenever I see someone has used plastic pushfit fittings my opinion of the plumber goes down. I agree they are adequate on an openvented system but seem lazy to me! I am a copper man!

Do I take it he has converted back to open vented now?

Tony

Converting back today (Friday). Bearing in mind he is a busy guy who had said the job would take two hours (as he anticipated it was a balancing problem - I did warn him I didn't agree with him) and has now spent two days on it while delaying other customer's work I will forgive him the plastic fitting shortcut!

Due to the history of changes - I am not sure exactly what has happened! An earlier plumber solved a pumping over problem by removing the vent altogether - I guess that would stop it! The first thing the current plumber did was simply to add a vent to the cold feed - see

http://www.paulhodson.f2s.com/early.jpg

then in the course of the job I think decided he needed a gate valve on the feed so changed it to this

http://www.paulhodson.f2s.com/later.jpg

I don't know what exactly has been happening. Certainly adding the vent appears to have stopped the whole system dead in its tracks - I think the pump is sucking air in through the vent causing massive air locks once the heating has run for a short while as he has managed to get it going then it stops.

That does not explain why it didn't work before he added the vent - as it could not have sucked it in from a vent that was not there. I feel it may have been a sludge blockage originally which all the draining and refilling (via mains pressure I think as it would not fill properly from the cold feed) moved only to be replaced by air from the new vent!

If so hopefully the change in position of the F&E tank today may stop this.

The magnetism of the hot feed does suggest a limited supply to the pump which may be a factor in the ingess of air from the vent. I cannot see it is getting in from anywhere else as sealing the system did cure the problem albeit not in an appropriate way for the boiler we have.

Doitall felt you were being taken for mugs - if he had had as many apparent experts as I have had making changes to this system - he would feel more like a mug than he does now! Sad thing is I know they have all been sincere guys trying to help - just out of their depths.

 

[holty]

simple rule for an openvented system is vent then feed then pump, with the vent and feed 150mm apart. simple

 

[paulhodson]

simple rule for an openvented system is vent then feed then pump, with the vent and feed 150mm apart. simple

But is there a problem if combined like this? - and why is air getting in?