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Discuss Baxi Platinum 33 HE Losing Pressure Having To Top Up in the Central Heating Forum area at PlumbersForums.net

CrazyHorse

Messages
6
Hi everyone and I hope someone can help.

Five years ago I had a new central heating system installed with a Baxi Platinum 33 HE in a 10 year warranty. It is service by a Baxi Engineer every September and I never have to touch it.

Anyway, I had a new wet room installed in my small bathroom and a towel radiator was relocated to the opposite wall.

Ever since completion I lose pressure every day, no heat, no hot water and get the error code. I have to open up the valves to top up the system for a few seconds and everything works for about another 24 hours.

Two things I have noticed though. After turning on the heating the bar pressure gauge will go slightly into the red and can go as high as right to the end of the red.

Could anyone advise what this might be. I would really appreciate it. I have also made sure all radiators are bled correctly.

Thanks,

CH
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Messages
30,322
Solutions
1
What pressure are you topping it upto ?
 

steadyon

Esteemed
Messages
1,025
1. When water is heated, it expands.
2. In a system such as yours, this expansion is accommodated in an expansion vessel. This is a closed container, with a rubber diaphragm across the middle. One side has air in it, the other is open to the water in the system. As the water expands, it compresses the air.
3. Three possible reasons for the problem you have are:
3a. The expansion vessel has lots its charge of air, so the water has "taken over" the vessel, leaving little or no room for expansion. Air charge needs to be re-established.
3b. The diaphragm has ruptured, giving the same effect as 3a, but requiring replacement of the vessel.
3c. It is normal to allow 4% of the total volume of water in the system for expansion. If the number of radiators now means that 4% of the system volume is more than the capacity of the expansion vessel the vessel cannot accommodate the expanded volume. This is the least likely of the reasons.
4. If the system cannot contain the expansion, a pressure relief valve opens and dumps water to outside. When the system then cools again, the water volume dumped is lost, and the cold pressure falls, requiring a top up.
5. Constantly topping up brings more aerated water into the system, which can cause corrosion of the radiators from the inside.
6. I'd suggest getting your regular service person to check and fix your system as soon as practical.
 

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