Dry taps

[ds0rco]

I drained my hot water tank yesterday to install a new three-way valve. Did the job and then refilled the tank. Opened the hot taps and got no water out.
I drained the tank again and refilled it with all the taps open - still no water.
I turned on the cold water fully on the kitchen mixer tap hoping venturi effect would drag the hot water through. The hot water ran after the cold was turned off but only for about 20 seconds then dry again.
What am I doing wrong? All suggestions gratefully received.

Ta,
Russ.

 

[MANDATE]

Did you hold valve in mid positon while re filling (lever on side of valve).

 

[ds0rco]

No I had it in the hot water position, would that make a difference?

 

[MANDATE]

Sorry I think I may have misread your post.
I understand the valve should be mid way when refilling after fitting a new valve, but this is not related to your problem.
The three way valve supplies water for CH and/or the heating coil in your indirect hot water cylinder.
The water from your hot taps is from a seperate source with seperate tank and is not related to the valve.
So do I take it that you emptied the small tank that feeds the boiler/heating circuit and also the larger tank that feeds the hot water cylinder.

 

[ds0rco]

I'm probably not explaining myself properly
I drained the central heating system via a drain cock above the boiler and I drained the hot water sytem by running the hot taps in the bathroom and kitchen until dry.

Cheers.

 

[slippyr4]

You've probably got an air lock. You can clear this by forcing mains cold back up the hot tap. Search for air lock on these forums, there are loads of threads.

 

[ds0rco]

Smashing, thanks for your help Mandate and slippy.

Russ.

 

[MANDATE]

I think with taps open air could easily escape with the pressure available.
I would think the blockage is more likely to be sludge from the water tank when the tank was drained. The suggestion by Slippy should clear it, but it will force the sludge back into the tank. As an alternative you can try drain wire or curtain wire down the feed pipe from the tank.
Also make sure any valve between tank and cylinder is fully open.

 

[Softus]

I think with taps open air could easily escape with the pressure available.

I think you're wrong there MANDATE. I see air locks all the time after refilling the I cold storage cistern.

I would think the blockage is more likely to be sludge from the water tank when the tank was drained. The suggestion by Slippy should clear it, but it will force the sludge back into the tank.

What is this sludge of which you write? It's not something I've ever seen.

As an alternative you can try drain wire or curtain wire down the feed pipe from the tank.

Please don't try this at home anyone.

Also make sure any valve between tank and cylinder is fully open.

Good advice, this bit.

 

[PEDANTICVINDICTIVEMAN]

Lost me with this one, you drained the domestic hot water cylinder to change the mid position valve !, why, they aint related !!!!!!!!

 

[Softus]

Don't steam in too hard there PVM - I was giving him some leeway. After all, we don't all mean the same thing when we say "three way valve" - could be a TMV, for example

Either way, for whatever reason it was drained, it got drained. Following that, air locks shouldn't be a surprise

 

[PEDANTICVINDICTIVEMAN]

Whats a TMV ??????

 

[Softus]

Like what one of these here are, so it is.

 

[PEDANTICVINDICTIVEMAN]

Oh right, got it, let the boggers burn, shouldn't keep living so long, draining NHS services as well as the hot tank, never enough left for me to have a bath.

 

[Softus]

You should be on the stage PVM