DIY Doctor UK DIY Forums

Can you PLEASE PLEASE help me with my problem. About two months ago the thermostat broke on my hot water cylinder. Subsequently the water heated up to in excess of 100 degrees. The water became so hot that it even heated the cold water in the cisterns in the toilet. It eventually got so hot that it melted the plastic valves on one of the inlets to the toilet. As the immersion was on at night I did not realise this was happening until the valve melted on the toilet and the water was every where.
I immediately called a plumber and he drained the hot water cylinder that morning. Since draining the system the water pressure on the hot water has dropped considerably. It has dropped from about three and half bar to one and half. The pressure on the cold has not been affected.

My plumber indicated to me that when the water was heated to a such extreme cases that any limescale in the pipes would be releasd and when the tank emptied could possibly lodge like concrete in the pipes. I subsequently washed the hot pipes out with Fernox DS-3, this has unfortunatley not done any good.
I am wondering now would some part of a valve be be stuck in the pipework or would there be possibly a small stone stuck in the pipework as it is relatively new house, if this was the case how would you remove it or clear the pipes as the majority are underground.
I have asked numerous plumbers for advice but to date nobody can help me. The builders plumber will not even return my phone calls.
Can you please help me as I am at the end of the line for advice and have accured a lot of expense seeking help from plumbers.
The system is a sealed pressurized system if this has any bearing on things.

Thanking you in advance for any advice you might be able to pass on.

have you got an unvented cylinder,direct fed from the mains

Direct fed hot water cylinders often have pressure reducing valves in the cold supply line. These should be set on installation according to the cylinder instructions. Also, the hot water outlet may contain a strainer filter that has become blocked.

According to my plumber it is an automatic air vent. The system is gavity fed to the pump and the pump circulates the hot and cold. There is no problem with the cold pressure at all. Maybe when I drained the tanksome debris or stones got stuck in the pipework, if so how would I unblock them.

[quote="marrtin"]Direct fed hot water cylinders often have pressure reducing valves in the cold supply line. These should be set on installation according to the cylinder instructions. Also, the hot water outlet may contain a strainer filter that has become blocked.[/quote]

I spoke to my plumber and he said there is no strainer on the outlet. Any ideas? I only have poor pressure on the hot the cold is perfect.
Any ideas are very welcome. Thanks.