P
Patrick Walpole
Hi.
I have a hot water high pressure problem that my heating engineer (and other engineers that he has spoken to) cannot fix. I’m hoping someone on the forum can explain what is happening and how to resolve it.
My hot water system uses an air bubble at the top of the hot water tank for expansion.
The air bubble slowly shrinks and after a few weeks it needs to be replenished when I see the pressure gauge climbing above it’s normal position.
After performing this task for years I decided put an end to the repetitive job and arranged for a heating engineer to fit an expansion vessel.
A few weeks after the vessel was fitted I noticed the pressure gauge was showing high pressure and the high pressure relief valve was releasing water outside.
The heating engineer advised that a mains supply pressure reducing valve was required and fitted one. It made no difference.
I’m back to replenishing the bubble every few weeks and the heating engineer has left me to sort out the problem myself.
I setup several test situations. The most significant result (to me) was that the pressure in the system increased if the hot water heating was turned off and the tank was allowed to cool.
Here is a recent test I made...
20/10/22.
The hot water tank expansion bubble was replenished. This now provided approximately 73L of expansion in the hot water tank plus an additional 18L from the new expansion vessel.
21/10/22.
The hot water heating was switched off. Normal hot water usage continued.
22/10/22.
Baths were taken. The water in the tank was now only very warm. The gauge read 1.8 bar.
The shower mixer tap and the mains supply were turned off. The house was vacated.
24/10/22.
I returned home 55 hours later. The gauge read 3.63 bar and the high pressure relief valve had released water outside and filled, to overflowing, the empty 1L bottle I had placed under the pipe.
Any ideas or thoughts would be much appreciated.
I have a hot water high pressure problem that my heating engineer (and other engineers that he has spoken to) cannot fix. I’m hoping someone on the forum can explain what is happening and how to resolve it.
My hot water system uses an air bubble at the top of the hot water tank for expansion.
The air bubble slowly shrinks and after a few weeks it needs to be replenished when I see the pressure gauge climbing above it’s normal position.
After performing this task for years I decided put an end to the repetitive job and arranged for a heating engineer to fit an expansion vessel.
A few weeks after the vessel was fitted I noticed the pressure gauge was showing high pressure and the high pressure relief valve was releasing water outside.
The heating engineer advised that a mains supply pressure reducing valve was required and fitted one. It made no difference.
I’m back to replenishing the bubble every few weeks and the heating engineer has left me to sort out the problem myself.
I setup several test situations. The most significant result (to me) was that the pressure in the system increased if the hot water heating was turned off and the tank was allowed to cool.
Here is a recent test I made...
20/10/22.
The hot water tank expansion bubble was replenished. This now provided approximately 73L of expansion in the hot water tank plus an additional 18L from the new expansion vessel.
21/10/22.
The hot water heating was switched off. Normal hot water usage continued.
22/10/22.
Baths were taken. The water in the tank was now only very warm. The gauge read 1.8 bar.
The shower mixer tap and the mains supply were turned off. The house was vacated.
24/10/22.
I returned home 55 hours later. The gauge read 3.63 bar and the high pressure relief valve had released water outside and filled, to overflowing, the empty 1L bottle I had placed under the pipe.
Any ideas or thoughts would be much appreciated.
