Hot water tank drained causing airlock

sandsni

Owain_Moneysaver wrote: »

I found out today my landlord doesn't know how to bleed a radiator. So I told him, and lent him my key to do it at his house where a rad isn't working.

Thanks Owain, you made me smile

animalhouse

We had the same problem in our house last year - we had replaced the hot water tank and the plumber who installed the tank forgot to re-open the stockcock in the attic. After a while the heating pump got an airlock, but turning the stopcock back on fixed it immediately.

sandsni

As it turns out, the hot water hadn't stopped at all, the tenants just didn't like the amount of pressure that the tap provided, so the plumber changed it and now hopefully everyone is happy. So all my worries about hot water heaters and stuff were completely unfounded !

GDB2222

Elsewhere wrote: »

That's exactly my point

IF it is emptying, there is something very wrong with the plumbing.

I know exactly how it should work, and a water tank that's heating with little or no water in it is dangerous, and should not be possible. (I used to work in nuclear reactor safety, so get a tad concerned hearing about boilers that have lost their coolant)

Unlike your nuclear reactor vessels, most hot water cylinders are vented. The unvented ones have various backup safety features.

the biggest practical danger is that hot water gets vented into the plastic cold water storage tank. if enough hot water gets vented that way, the water can get very hot, and the plastic of the tank can melt or soften. A few years ago, a couple were killed this way, when they were covered in very hot water from what ought to have been a cold water storage tank but became a very hot water storage tank.