No Hot water and steam banging in boiler on CH it runs fine.

[sirricardo]

Hi Chaps,
I have an old glowworm CH system with 2 tanks in loft and HW cylinder in airing cupboard. There is a Y diverter valve below the boiler (looks like cast iron).
We noticed steam popping and banging from the boiler early in the morning when the water is on by itself. The hot water has got colder over the last 2 days.
I checked operation of the diverter and found that if on CH or CH/HW it runs fine.
On HW only the boiler bangs and pops very loudly.
The pump appears to be running OK on max speed, I tried slowing it down but it think it was slightly worse.
The closed system filling tank in the loft is warm and has steam and bubbles coming out of it when the boiler pops and the vent is spitting water into the tank.

Have I got a blockage in the HW circuit?
Is there an easy way to confim it and are there any tricks to clearing it.

Many Thanks for your help,
Cheers,
Rich.

 

[PlumbBobBob]

hi rich i think you really need to get someone in as a matter of urgency. your system shouldn't be doing this at all. in the meantime i would turn it off for tonight and call a gs engineer in the morning.

 

[REDSAW]

its overheating, like steve says turn it of before it ruptures.

 

[sirricardo]

Thanks for the concerned replys chaps.
It is running fine on CH. I turned the HW off.
I rang a plumber who is a mate of a work collegue and he agrees it's a blockage.
He thinks it is the cylinder.
Looks like a fun job to change it - NOT.
I might disconnect it and check it before I buy a new one.
Cheers,
Rich.

 

[PlumbBobBob]

you're welcome

 

[sirricardo]

Hi Steve,
Got is sorted. It was a blocked pipe going to the HW tank.
I pushed a 1 foot drill and a long wire in it to dislodge the sludge.
I drained it through until it ran clear.
It is working very well now.
Just got to somehow replace the iron pipe in the roof that goes to the HW tank and loft tank.
Do I use a 28mm?
Cheers,
Rich.