Back Boiler Hot Water Problem

[Jo1980]

Recently had a new immersion and cylinder fitted as the old cylinder had split.

Since this has been done we seem to have an airlock in the hotwater pipes of the back boiler. We can feel where the pipes are scorching hot and then become cold.

If i use the immersion I can obviously get hot water, but if i turn the immersion off (which is how we usually would have it) and try and get hot water and central heating from the back boiler, we don't get any.

If the water alone is on, we get a lukewarm water. If we have the central heating on and the hot water then we get no hot water.

We have had two plumbers round and neither can find anywhere to release this airlock, which i find strange. They have both told me the same, to leave the hot water on and hopefully it will push itself out (or something along those lines!)

Does anyone have any ideas as to remedy this situation - we are seriously considering a new boiler - although don't want to do this as the second plumber said our back boiler isn't 'that' old - (an 80s one he said) and we shouldn't need to.

any help greatly appreciated as we're freezing without the heating on!!!

x

 

[DP]

The cylinder that you have fitted is not suitable for gravity circulation. System will need to be converted to pumped HW.

 

[Jo1980]

The cylinder that you have fitted is not suitable for gravity circulation. System will need to be converted to pumped HW.

Is that a likely possibility - it's an indirect cylinder?

Thanks for your post though - will get hubby to speak to the plumber and see if this is a possibility....

This is a total nightmare though - you would think the original plumber would have known this when fitting the new immersion

 

[Jo1980]

the cylinder we had fitted is an RM Indirect Copper Cylinder 900 x 450mm - if that's any help...

thanks

 

[Jo1980]

is having the system converted to pumped HW a big/expensive job? would it be better if i just got a new boiler perhaps?

 

[Hugh Jaleak]

To convert to fully pumped involves alteration of pipework, fitting of motorised valve(s), some additional electrical wiring, and fitting of a cylinder thermostat and room thermostat (if not already there).

A new boiler wont help in this instance, without seeing the pipework arrangement its difficult to tell why its not working as is. Could you post a photo of the cylinder showing the two pipes that go in on the side, from the boiler? There should be one at the bottom and the other about half way up.

Did the hot water work ok up until you stopped using it when the cylinder split?

 

[Agile]

Its almost certain the the cylinder is not suitable because the correct type is a special order and more expensive. Its not an airlock.

Its likely your plumber was too dumb to realise what was needed for gravity. Did he speak English?

In reality he should have advised that gravity hot water is slow and inefficient and need a long reheat time and the system should be upgraded to fully pumped.

The correct solution is to convert to a fully pumped system with all the proper controls. We used to charge £240 for that.

Depending on how much he charged to fit the cylinder he should be asked to make a contribution or alternatively to fit the new equipment which costs about £95 for free if he is clever enough to do that.

We would supply and fit a standard cylinder for about £460 or if to include upgrading then about £560

Tony

 

[Jo1980]

We paid £170 for the cylinder £30 for the immersion and he charged us £90 to fit. Obviously we thought that would be it - we didn't dream that when that was all done it would leave us with this problem.

The trouble we have now is that this fella is really hard to get a hold of (even though he lives at the end of my road) - very rarely returns calls or txts and it is extremely rare for him to actually turn up when he says he will.

We don't know what to do so I have got someone else coming tonight to hopefully advise on getting this sorted out.

I shall pass all your comments on to him.

Thanks so much

 

[Agile]

We paid £170 for the cylinder £30 for the immersion and he charged us £90 to fit. Obviously we thought that would be it - we didn't dream that when that was all done it would leave us with this problem.

The trouble we have now is that this fella is really hard to get a hold of (even though he lives at the end of my road) - very rarely returns calls or txts and it is extremely rare for him to actually turn up when he says he will.

Thanks so much

At that price I am not surprised that he is not very clever! Pay peanuts.....

Perhaps you bought the cylinder yourself and asked him to fit it? In that case you only have yourself to blame and he did exactly what was asked of him! Even so under a duty of care he should have advised first that it was unsuitable.

When you see that I charge £290 and he only charges £90 there is a big difference and you cannot expect to be buying a professional service at £90. On the other hand I have to act professionally and guarantee that it will work.

There is more than meets the eye in plumbing, thats why we expect to charge a reasonable price for professional work. £90 is less that a quarter of what we would charge!

Tony

 

[Jo1980]

Tony - I'm feeling a little attacked by the words you use.

Our cylinder was leaking and our dining room ceiling fell down - our plumber friend investigated and found the cylinder was cracked. HE chose the cylinder - WE merely paid for it and picked it up. Equally, we didn't know it was only going to cost us £90 - that was what he charged us come the finish.

I agree with you that if you pay peanuts... etc. however, we are first time homeowners and have only lived here 7 weeks. I have no idea how much things 'should' cost and what is a fair price and what is a cheap price when it comes to this sort of thing. Equally we were in what to us was an emergency situation and trusted the professionalism of someone we believed was just that - a professional!!!

Irrespective of how much things cost, I do expect someone to do their job - I would have happily paid far more if i knew it required it.

 

[Hugh Jaleak]

Original question answered on another post! Did you get the new cylinder from Screwfix?

http://www.screwfix.com/prods/47140...ders/RM-Indirect-Copper-Cylinder-900-x-450mm#

Spec states large heating coil so im unsure as to why this wont work....

 

[Jo1980]

Yes that is the one which has been installed.

Someone with 40 yrs plumbing experience has advised that we should have a valve fitted so that the air can be bled from the pipes. (or something along those lines)

We are going with this advice, and hopefully it shall all be remedied.

Thanks everyone for all your help in this matter, it is much appreciated.

 

[Hugh Jaleak]

I find it unusual that your system is not self venting. I will stand corrected but with a gravity HW system I would have expected a vent pipe to rise from the primary flow at the cylinder to discharge over the F and E tank? This should allow the system to purge the air when filling, and also acts as a safety relief in the event of system failure to allow excess pressure to vent to atmosphere. I assume you have a vent on the system?

 

[kevplumb]

View media item 11263 normal cyl

high recovery coil View media item 11360 vent

 

[Agile]

Of course we have not seen it but I said that it would not be an air lock because as Hugh says above the normal design would automatically allow air to rise to the vent and get out of the system.

The assumption that "large" in relation to the heating coil is I think a wrong one!

For gravity the coil needs to be 28 mm and all the normal cylinders I ever see now have a 22 mm coil.

My interpretation of "large" is that its the normal size required to meet the reheat times but is still 22 mm and it could be said to be "larger" than the previous old cylinders.

Words like "large", "small", "good", or "bad" are just comparative and not part of a scientific specification.

To sum up, if its properly configured now then no further air bleeding will be required. If not then certainly it needs a provision to get air out.

Also if its not properly configured it needs to be checked on safety grounds to ensure that there is a vent from the boiler as otherwise it could be dangerous.

Please keep us informed. Legally if the plumber specified that cylinder and installed it then he is responsible for ensuring that it works. As he charged so little I dont see that further payments to him would be wrong.

The correct solution is to convert to a fully pumped system.

Please keep us informed.

Tony