pressure problem

[dogfather]

I keep losing my hot water and central heating due to my system losing pressure. Every time it happens I go to the radiators at the top of my house, let air out and then fill the system back up with water until the pressure is back up with 2.0. The hot water and central heating then works for a few days until the same problem occurs again.I have a pro-therm combi boiler. Do I need to drain and refil the whole system? If anyone has any ideas I would appreciate it. Cheers.

 

[Rob]

you have a leak on the heating sytem, im assuming you havent noticed any leaks so check all rad valves, tak the caps off aswell to exspose gland nut etc. if these are ok check around boiler possible the air vent inside boiler?

if neither show anything then there is a chemical leak sealer which can be put into system, may work depending on size of leak

 

[dogfather]

Thank You Rob - Much appreciated. Haven't noticed any leaks other than water draining out of the overflow pipe on occasion. Is the air vent inside the boiler easy to check? What am I looking for ?

 

[Agile]

Before you do any of that, have you watched the pressure gauge when the boiler is operated?

If it shoots up to 3 bar then the expansion vessel is damaged or needs recharging ( see FAQ ).

The boiler does not have an "overflow". It has a pressure relief vent. If the presure exceeds 3 bar then the valve opens and lets water out to protect the boiler.

Tony

 

[ChrisR]

And once the pressure relief valves have let water out they tend to keep leaking, not always noticeable.
Check pressure vessel precharge (see FAQ)
Replace prv
Add corrosion inhibitor
If pressure still drops look harder for leaks or add leak sealer.

 

[bab]

vessels gona be low on air or part full of water. only pressure ya boiler up to 1 bar then what does it go up to when heatings been on for 30 mins.

 

[dogfather]

An Engineer came out today and pre-charged the pressure vessel. Hopefully that will be the end of it and I won't need to replace the expansion vessel. He tells me that I will know over the next few days whether this will solve it for good. The PRV doesn't appear to be leaking any more but I will keep an eye on it. I am going to try to add the anti corrosion stuff myself - sounds relatively simple. Just wanted to say a massive thankyou to everyone who took the time and replied to my problem - even if I am unable to do the work myself, it gives you confidence when talking to professionals, and having a bit of knowledge means you are much less likely to get ripped off. I learnt stuff too! Cheers also to DIYnot for a great site.