Due to a leak in a pipe leading to a downstairs rad (lockshield side) I had to drain the CH system to repair. Stupidly, I did not swith the CH/HW Clock off but merely set it for later than usual. The clock triggered the boiler before I had finished and needless to say I had a gush of water though the pipe I was mending. I drained this while someone held towel over the pipe! I repaired the leak reconnected and then turned the system on. I Bled all rads starting downstairs. After tweeking the lockshield valves all rads are working. However, I HAVE NO HOT WATER! I do not have a combi boiler but neither do I have an expansion tank just a cold water tank in the attic and a copper cylinger on the first floor. ALL was well with the system before the leak. Can anyone help me PLEASE??
No Hot Water after bleeding CH System
- Thread starter Glyn1959
- Start date
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B
breezer
I am not a plumber or heating engineer.
The tank in your attic is the expansion tank. Have you checked to see if there is any water in it? because it is this that also supplies the water for both your radiators and your taps.
You may also have an airlock in your cylinder which you can cure by connecting a hose to the cold water tap and putting the other end on the hot water tap and turing them both on. (do this at the lowest point, presumably your kitchen)
You have to have some one watch the tank in the attic as you will be back filling the system to force out air. if you leave it on too long the attic tank will over flow.
The tank in your attic is the expansion tank. Have you checked to see if there is any water in it? because it is this that also supplies the water for both your radiators and your taps.
You may also have an airlock in your cylinder which you can cure by connecting a hose to the cold water tap and putting the other end on the hot water tap and turing them both on. (do this at the lowest point, presumably your kitchen)
You have to have some one watch the tank in the attic as you will be back filling the system to force out air. if you leave it on too long the attic tank will over flow.
Thanks for your reply. Sorry if i did not make it clear. I have water running freely from the hot taps but it is cold. I have since drained the cylinder and had water running freely out of all hot taps (but cold). I am beginning to thing there may be an air lock in the HW pipes from the boiler. The boiler fires when i put the HW on but the tank never heats!
I am worried that this could be dangerous
I am worried that this could be dangerous
B
breezer
It sound like you have an airlock in the "primary" side of your hot water system. There should be a valve of some description wher you can bleed it.
The water in your hot water cylinder is heated by your boiler, but NOT directly, there is a coil inside it and the water in this is heated by your boiler and this should have a valve to enable you to bleed it.
As I have mentioned i am not a plumber, but this may help. It may not be your type of heating system but it explains how they work, you could also try checking the sites central heating items
http://www.gasman.fsbusiness.co.uk/fully_pumped_systems.htm
The water in your hot water cylinder is heated by your boiler, but NOT directly, there is a coil inside it and the water in this is heated by your boiler and this should have a valve to enable you to bleed it.
As I have mentioned i am not a plumber, but this may help. It may not be your type of heating system but it explains how they work, you could also try checking the sites central heating items
http://www.gasman.fsbusiness.co.uk/fully_pumped_systems.htm
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Thanks for your help on this. I found a bleed valve on the boiler itself. I switched off the mains & gas to the boiler and bled it. I now have hot water and I'm back in work having only lost half a days holiday to sort it. CHEERS 
The hot water turned out to be a result of the immersion heater being on previously. I am still without hot water. A local plumber believes I have an air lock. He suggested running the boiler for just HW full blast - No luck. Secondly he suggested removing the stat from the boiler so it would "boil" - that's out of my depth but he is coming around tomorrow. My only other thought was to put a hose pipe from the nearest cold tap and push cold water through the bleed valve in the boiler so any air lock would come out of the vent pipe above the cold water tank. However I am confident in theory but not in practice so I am leaving it to the expert.
B
breezer
i have seen that done once by accident (letting the boiler boil) DON'T DO IT
The boiler would have exploded but for the fact it burst a seal, steam every where.
(all that achieves is forcing very hot water up the expansion pipe and then it has to be refilled)
But putting a hose on the vent pipe (the one that hangs over the expansion tank) and turning on the cold water tap with the heating off will shift an airlock, it will come back through the inlet of the tank
The boiler would have exploded but for the fact it burst a seal, steam every where.
(all that achieves is forcing very hot water up the expansion pipe and then it has to be refilled)
But putting a hose on the vent pipe (the one that hangs over the expansion tank) and turning on the cold water tap with the heating off will shift an airlock, it will come back through the inlet of the tank
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