Air lock on a main pressure hot water Clyender

[StudentPlumber]

Please help!!
I am so confused I went to a golf club today as they had no hot water (literally no water from hot taps) the combination valve is ok and the tundish is dry there is water in the cylinder as you can let it out from the PRV and here it refill. The hot outlet is very hot. I cracked a nut down the line to see if water came out but pipe was cold and no water! I then herd a lot of air movement and am then we had hot water!!
Any ideas on how a sealed mains hot water can have airlocks??

 

[Caduceus]

Not to be offensive, StudentPlumber, but just a year ago you didn't know what a service line was. You should really be working with a journeyman in the field not by yourself. Not having an experienced mentor to teach you these things could be very dangerous for you and your customer. Is there a journeyman plumber available to you for a proper apprenticeship?

 

[StudentPlumber]

Offence not taken as I am a STUDENT working as an apprentice with a very good company with great mentors. As I have already completed level 1,2 and 3 at college and now starting my NVQ2 I felt silly asking possibly a simple question, that's the reason i come to this site in order to get people's views and answers.
Thanks
Callum

 

[Matt30]

The only stupid question is the one you didn't ask. As journymen it's not just our job to handle the big jobs, it's also to teach and mentor apprentices. I would be somewhat offended if someone working with me opted to ask questions on the internet rather than ask me directly.

 

[frodo]

need more information.

is the system your talking about feed from a city water supply?
what is the psi?
is the system on a upper floor? or street level?
is there a pump involved ? psi of discharge ?

ck psi at prv with gauge, not with site

 

[Mr_David]

Even this old guy can learn something new.
What is a TUNDISH? The WEB is so cool. Knowledge at your finger tips.

http://inspectapedia.com/plumbing/Tundish.php

Question?? Does the hot system have a recirculating system?

Recirculating pumps are not true pumps. They do not pump water, they move the water by cupping it. The pumps can become air locked and fail to move the water through the system. I have seen a lot of systems that have to be manually bled of air every time it gets shut down.

 

[Caduceus]

The only stupid question is the one you didn't ask. As journymen it's not just our job to handle the big jobs, it's also to teach and mentor apprentices. I would be somewhat offended if someone working with me opted to ask questions on the internet rather than ask me directly.

That was my point. I always encourage questions as I had plenty to ask as I was an apprentice, but with being at the job itself you should have a journeyman with you and instruct/explain as you work. Your question gives the impression that you were alone with nobody to help you understand the situation and explain the reason for the outcome. I find that it would be unfair to the apprentice to leave him to self educate on the job. By asking your question I assumed that you had no guidance on the job.

 

[Caduceus]

The apprentice that I worked with today had no questions during our installation. I feel he learned nothing. How would I know differently?

 

[phishfood]

I like an apprentice to ask questions.

But as an apprentice, I often learned by watching. So just because they have their butt in gear and their mouth in idle, doesn't mean they aren't learning.

 

[frodo]

apprentice should be asking questions.

had he preform this task before?

 

[StudentPlumber]

Yes from mains coming in at just under 4 bar and at street level (well about 2/3 steps high) there is not pump just normal mains pressured hot water I do think there was auto air bleeds randomly located
Thanks for all your help

 

[StudentPlumber]

I do ask my mentor questions all the time I just had not seen a fault like this before. I did ask all my colleague and they where puzzled

 

[frodo]

Yes from mains coming in at just under 4 bar and at street level (well about 2/3 steps high) there is not pump just normal mains pressured hot water I do think there was auto air bleeds randomly located
Thanks for all your help

where you from, ? i dont know the meaning to the word bar

was the city workers performing maintaince on the water main?

possible they had introduced air in the line while working?

 

[phishfood]

SCUBA diving taught me all kinds of things. One those things is that a "bar" is a measurement of pressure equal to atmospheric pressure at sea level. IIRC, it translates to roughly 14.7 PSI.

 

[frodo]

SCUBA diving taught me all kinds of things. One those things is that a "bar" is a measurement of pressure equal to atmospheric pressure at sea level. IIRC, it translates to roughly 14.7 PSI.

I knew that!!! just did not know I know,