summersday
Registered User
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How often would most people have to top up a boiler for heating water and rads?
Most pressure losses are due to under-pressurised expansion vessels.
Because when the vessel is deflated, there is nowhere for the heated water to expand to and it usually goes out through the PRV when hot. It then cools returning to a lower pressure than previous and the sequence repeats itself.Need some help with this.
Day 1, at cold pressure on gauge is 1.5 bar
Day 30 ........0.0 bar, so top up to 1.5
Day 60........etc
So how can an under-pressurised EV contribute to this sequence?
Usually no need. If you de-press the schrader valve and if water comes out, the internal diaphragm is split. It air or nothing comes out, it just requires re-pressurising with air. However, I normally replace the schrader valve whilst I'm at it, as this is usually the culprit for the loss of pressure in first instance.It sounds similar to an issue we had with our boiler. The expansion vessel had blown, and needed to be replaced.
Because when the vessel is deflated, there is nowhere for the heated water to expand to and it usually goes out through the PRV when hot. It then cools returning to a lower pressure than previous and the sequence repeats itself.
It is the most common reason for low pressure issues in heating systems.
In order to check the EV pressure, there must be no system pressure against it, so the boiler must be drained to do this.
Usually no need. If you de-press the schrader valve and if water comes out, the internal diaphragm is split. It air or nothing comes out, it just requires re-pressurising with air. However, I normally replace the schrader valve whilst I'm at it, as this is usually the culprit for the loss of pressure in first instance.
Same as a car tyre, hence the tyre guys always replace them when working on tyres.
We have an overpriced, not very good Italian brand of boiler which doesn't have readily available parts. The plumber said the EV on that could be repaired, but it would be a lot cheaper, quicker and more effective to just add a new vessel to the system
Assuming it's a gas boiler, it won't fire if low pressure but if over-pressurised, the 3 bar safety valve will open and empty water from the system. If there is any debris in the heating system, such as magnetite, the safety valve seal may not re-seat and continue to leak. It can also lead to damage to the expansion vessel.What would happen if you put it on with too much or too little pressure?
Thanks a mil this workedDrain some water from a radiator bleed screw into a pot until the pressure reaches 1.3 bar.
Don't turn on until you do this otherwise it will over-pressurise when heated.
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