Clearing an airlock in the hot system

seamus

Right, just looking for some advice on the best way to do this. I'm in a duplex where most of the taps are upstairs, including the mains feed into the kitchen. All other taps, hot and cold, come from the attic tank. The hot water comes from the immersion tank in the hot press, which is at the same level as the hot taps upstairs. I'm presuming the pressure in the hot system comes from the cold tank upstairs which feeds it.
Heating is all electric, so no rads to worry about.

I've an airlock in the hot tap in the upstairs bathroom. It's a mixer tap, and I've tried the usual backflush trick with the cold water, but that doesn't work, presumably because the pressure in the two systems is the same.

Getting a hose from the mains in the kitchen will be trickey and could lead to a big watery mess, so I'd like to avoid that

My other thought is that I could switch off the cold feed to the hot tank, open all the hot taps until the tank is drained and then switch the feed back on again. Would that work?

Buford T Justice

No. If anything it'll give rise to the possibility of more airlocks. Is the bathroom taps of the same feed from the tank, or have you easy access to the pipework going to the taps?

It could be something as simple as a pipe in the attic sloping the wrong way which is then harboring the air.

You can get hozelock tap fittings for garden hoses that will do a reasonably good job. Fit it to the taps and tie a cloth around the head of it to contain the spray. Might do the trick for you.

http://www.hozelock.com/watering/hose-fittings.html

seamus

Cheers, OK that's not the way to go so.

Not crazy on the hose solution because the pressure in the mains tap is insane (there's an external pump augmenting the public mains pressure), but if it's the most reasonable way to do it, then I guess I've no choice.

I also found a suggestion elsewhere on boards to open the airlocked tap, block up the hot water vent pipe in the attic and them force the mains into the hot system through the kitchen tap. Sounds good in theory, but could I do damage to the hot system?

Buford T Justice

seamus wrote: »

I also found a suggestion elsewhere on boards to open the airlocked tap, block up the hot water vent pipe in the attic and them force the mains into the hot system through the kitchen tap. Sounds good in theory, but could I do damage to the hot system?

Not necessarily no. Effectively you are forcing water into the system and using the airlocked tap as the osv pipe. I'd give it a try.

Be mindful though, not to forget to remove the block from the osv pipe. Mains pressure won't cause any harm to the system, but pressure from expansion of hot water will do serious damaged if the vent is left blocked. easy mistake to make.