No hot water on gravity system?

[macka09]

Hi all. Any suggestion on possible causes?
Trapped air? Gate valve stuck?

 

[Mike Jackson]

More likely to be an air lock as whoever did the work previously wouldn't have left it not running.
Blow the mains up through the hot

You're kidding right? I've had snapped gate valves left by many a previous plumber. Last one was just before Xmas. Shower pump not working properly. It was surging, I diagnosed some sort of blockage and found the gate valve on the cold feed snapped and almost shut but apparently the handyman that did some work when the problem started hadn't touched it! Must be a poltergeist then.

If it is an airlock, easiest way of clearing it is wet vac on the hot tap.

 

[Bolty123]

As previously stated it will be due to recent works. Old vent pipe could be hovering at the water level in the new tank or something daft like that.

 

[kay-jay]

You're kidding right? I've had snapped gate valves left by many a previous plumber. Last one was just before Xmas. Shower pump not working properly. It was surging, I diagnosed some sort of blockage and found the gate valve on the cold feed snapped and almost shut but apparently the handyman that did some work when the problem started hadn't touched it! Must be a poltergeist then.

If it is an airlock, easiest way of clearing it is wet vac on the hot tap.

with you all the way........until the wetvac bit! i bought one about 3 years ago cos of everyone on here telling me it would revolutionise my life. dont know why but i cant bring myself to use it, never have and quite possibly never will.

 

[rocketmanbkk]

Rubber cones that you stick up the cold feed and vent. They vacuum the system, so you can change the gate valve with the tank full.

You bung it in the vent also?
I change a gate valve once but just bunged the outlet in the cwsc. I didn't bung the vent? Was I lucky? I thought bunging the vent may cause the tank to implode? Sure I've read it on here?

 

[tamz]

You're kidding right? I've had snapped gate valves left by many a previous plumber. Last one was just before Xmas. Shower pump not working properly. It was surging, I diagnosed some sort of blockage and found the gate valve on the cold feed snapped and almost shut but apparently the handyman that did some work when the problem started hadn't touched it! Must be a poltergeist then.

Your right enough Mike. Somehow i keep thinking "tradesmen" are not as bad as they actually are :smile:

 

[kay-jay]

You bung it in the vent also?
I change a gate valve once but just bunged the outlet in the cwsc. I didn't bung the vent? Was I lucky? I thought bunging the vent may cause the tank to implode? Sure I've read it on here?

Not if your working upstream of the cylinder. But there is no need to bung vent anyway.

You only bung vent on an f and e tank cos once youve removed a rad valve or section of pipe you have two open routes back to the tank therefore it needs to be vacuumed.

 

[Mike Jackson]

with you all the way........until the wetvac bit! i bought one about 3 years ago cos of everyone on here telling me it would revolutionise my life. dont know why but i cant bring myself to use it, never have and quite possibly never will.

I've cleared loads of air locks with a wet vac. Had one last year which several other plumbers had failed on. I got called out after a fire in a top floor flat. Firemen had turned off the water to the storage cistern in the roof and it had run dry. When it was turned back on the hot water in the basement flat was only trickling. After several failed attempts at backflushing failed the other plumbers had deduced that muck had been drawn into the pipe and it would need cutting out. I checked in the roof space and the modern cistern was fitted with a bylaw kit and properly sealed so I doubted that this was the problem. Thought that the issue was more likely to be an ailrlock in the cold feed to the cylinder. back flushing from a tap will only clear an air lock between the tap and the cylinder and push water up the open vent. I got the Wickes special wet and dry out of the van and attached it to the hot bath tap. A bit of gurgling and off she went.

 

[kay-jay]

I've cleared loads of air locks with a wet vac. Had one last year which several other plumbers had failed on. I got called out after a fire in a top floor flat. Firemen had turned off the water to the storage cistern in the roof and it had run dry. When it was turned back on the hot water in the basement flat was only trickling. After several failed attempts at backflushing failed the other plumbers had deduced that muck had been drawn into the pipe and it would need cutting out. I checked in the roof space and the modern cistern was fitted with a bylaw kit and properly sealed so I doubted that this was the problem. Thought that the issue was more likely to be an ailrlock in the cold feed to the cylinder. back flushing from a tap will only clear an air lock between the tap and the cylinder and push water up the open vent. I got the Wickes special wet and dry out of the van and attached it to the hot bath tap. A bit of gurgling and off she went.

I have one for if I get such a situation. And im Sure I could find a hundred different applications for it. I just seem to have a mental block about it and just carry on doing things the way I always have.

 

[macka09]

Thanks for all the advice. I went to the ladies house today and immediately there was water from the hot tap and the cylinder was full. Although the cylinder was stone cold due the immersion not being on. So I heated the water and all was fine. The customer complained about the pressure but the tank was only 1.5 meters above the cylinder.

 

[kay-jay]

Thanks for all the advice. I went to the ladies house today and immediately there was water from the hot tap and the cylinder was full. Although the cylinder was stone cold due the immersion not being on. So I heated the water and all was fine. The customer complained about the pressure but the tank was only 1.5 meters above the cylinder.

Its the distance between the header tank water level and the draw off point thats important.