No hot water on what I believe to be a gravity system

[kyle]

Hi all, as you can tell im new to this, bear with me,,,

Ok, I have no hot water.
The radiators are piping hot.
I have a room stat but no cylinder stat.
The boiler is a back boiler with 28 mm pipework going to cylinder.
I can see the pump, it works and I believe this is for the radiators.
I cant see any type of valve but there is a section that is boarded off leading from boiler in front room up wall under floor behind more boxed off section to cylinder.
When I ask for hot water I get nothing.
When I ask for hot water both pipes to/from the cylinder remain cold but the 28mm near the boiler are hot and other slightly less hot. Pipes to the pump is red hot.

What do you think, like i said im new, thx to anyone that can help...

 

[ferret]

do you have rads upstairs? , you defo have a gravity hot water system with pumped heating , and it sounds like the header tank is empty or cold feed blocked ,

 

[sdsparks]

Maybe the diverter valve is broke, is there a mid position valve that is stuck?

 

[kyle]

Thx for advice, I cant remember if there were rads upstairs, it isnt my boiler.
I too was thinking ball valve stuck, block in cold feed,possibly the gate valve stuck etc but it seems open, i was gonna loosen flow pipe into cylinder to see whats there,air or water.....
Thx, keep info coming in, very usefull.....

I cant see any valves at all anywhere, unless theyr hidden?, i dont think so though

 

[kyle]

What do you lot think of the threads that advise removing the phial for a short time to boil away the air lock?, sounds very risky to me,,,,,

 

[johnmcginty]

I'll put 10p on a broken 2 port valve

 

[kyle]

I dont see any valve anywhere , would it have a valve if it was gravity dhw, no cylinder stat.

 

[ferret]

No kyle it wouldn,t !! don,t know why people keep suggesting valves as you have stated that there is none.

 

[johnmcginty]

Ahh can you remove the cover at all so you know exactly the layout ?

 

[kyle]

I think it would be a last resort to remove the panelling, wanted to see what peeps thought before I went into the demolition business,lol.
I have had a few people tell me to remove phial, observe boiler, get friend in attic, boil air lock away??,sounds dicy
I have had friend tell me to cut open pipework on cold feed to remove air lock??
Also read here it might be cold feed blockage.....
Which one, hehe

 

[johnmcginty]

So you think there is air in the coil?

 

[boilerman]

Lots of the old type back boiler installations had gravity hot water and suffered from the header tank running dry or a blocked cold feed pipe.The central heating would still work if that was the case

 

[johnmcginty]

There maybe a manual air vent near the cyl boxed in. Or cold feed blocked. I did it on an old elson tank and just cracked the nut a little on the primary flow which did the trick.

 

[kyle]

Cool thx for feedback, will start with checking tanks, then cracking nut , hopefully this will sort problem, cheers,,,I will update post tomorrow.