Yep remembered that one - cold feed teed into the vent at the side of the cistern....usually off a 'Aerjec'.

Nope only if they are installed incorrectly or in poor condition.

That’s the next one mate 👍🏻

Hi Derek just a quick rant, when I started out there were no national repair company’s, you fitted a system with a old style heat only boiler that just worked( still have boilers I look after 30years old!, only had to change ,could not get replacement flue) in that time your probably go through 3 combe!, do loads of call outs for national repair company and I really question are most boiler fit for purposes , even the so call top brands are not that great, nearly every call out is a combe, pressure or over complicated control, think I better retire 🤣🤣🤣, ends up most customer have a service plan they really can’t afford or never us to have, we have gone backwards

Galvanised cisterns?

What about the ‘Plant Pot’ Servowarm F&E tank😂😂👍👍👍

Lol yeah, Also 'blocked cold feed' causing same symptom with fresh engineers not having a clue why..happy days

Went to a job once where a baby had been killed by an f and e being installed wrong. The water boiled and melted the cistern and the water came through the ceiling and killed the baby and yes the boiler had an high limit stat.

You are correct but why would you 👍🏻

@@tomkatgastraining because it makes cleaning a blocked cold feed easy by providing a compression join close to the point of blockage. Because it makes locking up easy with a 22mm speedfit stop end. Generally it just makes all the work needed more simple. Most of these systems have Mark and dirt in the expansion tank this needs to be cleared before we drained down so it doesn't end to the heating system. With an isolation valve we don't need to drain the tank or move the Mac into the system. Although some of it gets stirred up and moved into the system when we refill. In the 1990s I was doing callouts for Watford Council. We had 30 mins to fix any breakdown. An isolation valve in the cold feed make this very possible. So I think many reasons to fit an isolation valve in the cold feed when the boiler has an overheat stat. However your comments about the lack of skills in our industry are exactly correct and to encourage unskilled engineers not to fit these valves in case the boiler has no overheat stat. Properties with this type of system often still have old and out of date appliances. If we say safety first then this could be seen as poor practice. We really need some tighter controls on the quality and training what engineers in our industry. The work that you do here on KZfaq is fantastic and contributes greatly towards engineers knowledge. I like to think that I contribute to this also with my own KZfaq channel but there's such a big hole the review KZfaqrs can't fill.

​@@tomkatgastraining to confirm, you can put isolations on the water tank that feeds the hot water cylinder below but not on the CH tank?

@@grimawormtongue2014 correct 👍🏻

​@@tomkatgastraining thank you for the super quick reply. I'll be working on a f and e system today. All the hot water taps have severely restricted flow due to a blockage somewhere. I'll be cleaning out the tank and maybe I will need to cut out and replace some pipework on the hot water supply from the cylinder. Any tips please about how to drain and or clean the tank and cylinder and pipework? What checks do i need to do to trace the blockage/s? And anything i need ti look out for before cleaning and cutting pipework?

still use copper and still use pipe benders. Just the systems that are changing- more efficient with skills required elsewhere. Too many Luddites in the trades......

You could fit a lock shield valve but no need for servicing 👍🏻

On the next video mate 👍🏻

@@tomkatgastraining Thanks Del👍👍

You have just proven you know absolutely nothing about heating and regulations. Think you need to read the water regs and then say I am talking nonsense. Also it’s a cistern you ignoramus not a tank.

You obviosly not HETAS registered

I think you will find he is more skilled than all of us .

You are talking absolute 'utter' ball hooks my friend. You don't place a valve on an open vented heating system cold feed. This will create a hazard- now get back to college and look at the physics of water levels and how this system works..

@@mgbroadsterJ - replace 'all of us' with 'you'