Post by bobblehat on Nov 21, 2014 7:05:44 GMT -5
I had the classic issue of the hot water starting hot and then going cold after several minutes.
This is known to be either failure of the blending valve and/or scaling up of the heat exchanger coil.
Checking the temperature at the hot inlet of the blending valve showed that the heat exchanger was okay, as the temperature stayed well above that at the valve outlet.
So, I removed the blending valve and found that it was full of loose bits of scale that had broken off in the system. It also had a good coating of scale on most of the internal parts.
I soaked it in some strong acid (Cementone Brick and Patio Cleaner) for around 10 minutes until it stopped fizzing, refitted it and it is now working fine.
Could save you £100 to £150 on a new part!
This is known to be either failure of the blending valve and/or scaling up of the heat exchanger coil.
Checking the temperature at the hot inlet of the blending valve showed that the heat exchanger was okay, as the temperature stayed well above that at the valve outlet.
So, I removed the blending valve and found that it was full of loose bits of scale that had broken off in the system. It also had a good coating of scale on most of the internal parts.
I soaked it in some strong acid (Cementone Brick and Patio Cleaner) for around 10 minutes until it stopped fizzing, refitted it and it is now working fine.
Could save you £100 to £150 on a new part!