Air Locked Water Cylinder

JOHNPT

Hello All

I recently installed a new electric shower & had to drain the cold water tank as there was no stop-cock on pipe feeding shower.
Since then the water wont heat when the gas boiler is switched on - radiators heat fine and immersion works fine to heat water.
I suspect its an airlock - any advice on how to resolve this?

Thanks

shane0007

Assuming your system is pressurised, there should be an AAV on the flow to the cylinder. Open the screw cap to this and this should vent the system. You may need to top up the pressure when done.

Billy Bunting

JOHNPT wrote: »

Hello All

I recently installed a new electric shower & had to drain the cold water tank as there was no stop-cock on pipe feeding shower.
Since then the water wont heat when the gas boiler is switched on - radiators heat fine and immersion works fine to heat water.
I suspect its an airlock - any advice on how to resolve this?

Thanks

Did you by chance turn off or alter the balancing valve on the cylinder, gate valve on return from cylinder to boiler.

sullzz

JOHNPT wrote: »

Hello All

I recently installed a new electric shower & had to drain the cold water tank as there was no stop-cock on pipe feeding shower.
Since then the water wont heat when the gas boiler is switched on - radiators heat fine and immersion works fine to heat water.
I suspect its an airlock - any advice on how to resolve this?

Thanks

I can't see how draining your cold water tank is causing an airlock to your coil unless your system is semi sealed through a supply from your cold water tank which is now airlocked , and if this is the case you have a bad leak , you'd be better off getting a plumber in to check this out , also check that if you have a f&e tank there is water in it , or if pressurised you have 1.5 bar in the system and as Shane said open the auto air vent , then also check that if fitted your zone valve for hot water is open and the balancing valve on the coil is open slightly

aujopimur

Is the hot water cyl not heating, or is the water not flowing in the hot taps?.

JOHNPT

There is water flowing and been heated in all the hot taps when the immersion is turned on. However when the gas boiler is used to heat the water it dosent heat - this only occurred since I drain the cold tank in the attic ( approx 1 month ago).
The pipe seems to be warm on the pipe to the cylinder but cold from pipe leaving the cylinder.

Not sure if its sealed system.

aujopimur

If it's an open system you'll have an expansion tank in the attic, if not there's a fill valve or filling loop, probably near the cyl. or boiler.
As Billy Bunting says, it's possible you've closed the balancing valve for the cyl..This valve is on one of the pipes feeding the coil, check for this, if you find it, open it one or two turns.

Bruthal

JOHNPT wrote: »

There is water flowing and been heated in all the hot taps when the immersion is turned on. However when the gas boiler is used to heat the water it dosent heat - this only occurred since I drain the cold tank in the attic ( approx 1 month ago).
The pipe seems to be warm on the pipe to the cylinder but cold from pipe leaving the cylinder.

Not sure if its sealed system.

Sounds like the cylinder coil balancing valve is possibly closed or almost fully closed, especially if the rads upstairs are heating as normal as well. It may have been closed during the shower install, as often wrong valves are closed during such installs,

Turn it clockwise to see if it is closed, or until it is, then open 1 and a half turns and see if that helps.

JOHNPT

Below is a picture of tank
Apparently the top pipe is hot but the bottom pipe isint - thus the tank is not heating?

Bruthal

JOHNPT wrote: »

Below is a picture of tank
Apparently the top pipe is hot but the bottom pipe isint - thus the tank is not heating?

If all rads are fine, that would usually mean the hot water feed into the heating coil is going through much too slowly, so it gives all its heat to the cylinder(which is not enough heat to give to cylinder because of the slow flow) by the time is comes out the bottom return pipe. Or the valve might be completely closed, and just conduction from nearby flow to rads is heating the coil feed as far as the cylinder.

Try opening the hand valve on the top pipe there in the pic, about a quarter of its full movement. That is usually a gate valve. But try opening it a little more than it is in the photo.

If you open it too much, the water flows through too easily, and may stop some rads from heating properly.

JOHNPT

Rads upstairs are fine and valve seems to be opened fully.
Is it possible there is an air lock in the coil and if so can you remove it?

aujopimur

You appear to have an open system, turn off all the rads, switch on the heating and see if that clears the problem.

Bruthal

JOHNPT wrote: »

Rads upstairs are fine and valve seems to be opened fully.
Is it possible there is an air lock in the coil and if so can you remove it?

If you close all rads, that will force more water from the boiler through the coil, possibly clearing the problem alright. Or it could be that the rads need some balancing. But just close them all down to see does that cause a flow through the cylinder coil.

Did you check the expansion tank in the attic if it is an open system, to see it is full of water?