Hot Water system Airlock

[LeeK]

Help

I have a problem that has just started to affect our hot water system. We have pumped CH and gravity fed HW, but just lately we have no hot water.

I have tracked it down to what appears to be an airlock, as it is hot coming out of the boiler but cold on the HW tank inlet. Somebody advised me that if I reverse flushed via the CH drain valve it would push the air out the expansion tank. This indeed does work, but only for a few days when it eventually stops again. We also seem to have a lot of air comming from the HW taps as well.

I cant find any leaks that would indicate air could enter the system, has anybody got any idears?

Many thanks

 

[oilman]

Hot water taps have no connection with the heating water, so air in taps is not relevant.

The heating water problem may be a blockage on the cold water feed. Search the forum for information on this.

 

[LeeK]

Thanks,

Would the reverse flush have shifted the blockage though? It does seem to flow in to the expansion tank OK.

 

[oilman]

Which pipe does it flow through to get into the tank?

 

[gina56]

This happened when i replaced bath taps tried connecting cold and hot with flexi pipe (old push on shower pipe) for two secs. It worked
I dont know if this the normal way to do it but being female i did it.
Gina56

 

[LeeK]

It flows into the expansion tank via a pipe at the bottom of the expansion tank. When I shut a value off fitted to this pipe, it then flow into the tank via a pipe that loops into the tank over the top.

It looks like the pipe at the bottom of the expansion tank is connected to the cold side of the HW cylinder whilst the pipe at the top is connected to the hot side of the HW cylinder.

Hope this helps

 

[oilman]

It seems the feed pipe is not blocked so thay's ok. Do you still have the problem?

 

[LeeK]

Hi Oilman

Yes I still have the problem. I have flushed it this saturday afternoon if it follows the same pattern it won't last long before we have no hot water again.

Regards

 

[Kingsway]

what heats the cylinder

 

[ChrisR]

LeeK

This is entirely pejorative, politically terrible an'all - only trying to help though honest:

It could be that there's a communication problem here because we're blokes and you aren't.
That can mean that we all think we know what you're trying to say but you're incompetent in your use of English because pipes are involved.
So we all assume that when you say you have "no hot water", what you really meant was that your hot water tap produces cold water.

Could it mean that you mean that your hot tap produces NO water - which is what you wrote?

In which case use your shower hose trick, but for a bit longer - 15 seconds maybe. Just at the moment I can't remember any reasons why air should collecting in the pipes where it didn't before.

If I'm wrong about what you meant, it probably means my feminine side is showing and I'll have to delete the posting. Or do I mean...?

 

[oilman]

It could be that there's a communication problem here because we're blokes and you aren't

Which poster do you mean?

Could it mean that you mean that your hot tap produces NO water - which is what you wrote?

Can't see this. Leek says no hot water, and lots of air coming out of hot tap.
If air is coming out of hot tap, something must be getting in, either water or a compressor is connected to the water supply.

 

[LeeK]

Well where do I start?

ChrisR wrote:

“Could it mean that you mean that your hot tap produces NO water - which is what you wrote?”

Sorry ChrisR if you thought my English was “incompetent” but just maybe you should have your eyes checked. I re-read my original posting, which stated: -

LeeK wrote:

“just lately we have no hot water.”

Either way I could not manage to get it to read “NO water”.

But just to clarify it seems an airlock gets trapped in the hot water supply to the cylinder, as the hot water supply pipe is hot coming from the boiler but cold at the cylinder. When (and only when there is no hot water) we get air coming from the hot water taps. After back flushing to clear the airlock, no air comes from the taps.

I have no idea where the air comes from but could there be a fault in the cylinder that allows air to pass from the (indirect) hot water supply into the cylinder and so out to the taps?

Regards

 

[oilman]

You have a problem which needs someone to look at it. It's not the sort of thing that will be sorted from distance-diagnosis I suspect.

 

[LeeK]

Ok, thanks any way...