Central heating problem

wonka

We've been having our bathroom done this last week by the local bathroom shop. Their contractors came in on the first day and drained the central heating system, due to all the plumbing jobs they had to carry out. Since they turned it back on, we had no hot water. We told them and they checked what was wrong. Apparently we need to replace an 'Automatic Air Vent', which they offered to do for £55 all in. I did a search, and these parts are only a few quid.

They've managed to fix this temporarily, the hot water's back on now, but they say it will cause problems in future if we don't sort it out.

Do you think we could get it done cheaper?

alanobrien

What type of air vent is it ?
If its like mine it can be replaced in situ, in fact a lot of them self seal on removal to allow for cleaning.
It may be that yours just needs cleaning but you will not know until you remove it and take it apart.

It appears they are implying that your hot water system is or was air locked and if so they did not correctly vent and/or re-comissioned your system.

I find it a bit fishy that the air vent failed mysteriously just when you had some work done. More likely its blocked imho.

wonka

I don't know what type it is, that's all they told me.

It may well have been air locked already. We have to keep bleeding the radiators on a regular basis - is that what's meant by air locked?

I shall ask them if it's possible that it's blocked.

alanobrien

One definition of an air lock is a "bubble or pocket of air that stops the normal flow of fluid."

This can occur if your system is not fully vented to its highest point - which is a problem i had, as my bathroom towel rail loops into the loft then down into the airing cupboard. I resolved the problem by putting an auto vent into the loft loop.

Were you constantly bleeding air from the radiators before the work took place ? If so then the system could be dragging in air somewhere.

That said, in my experience once you fill a system it can take some weeks for it to settle down as air comes out of solution as the water heats up.